Welcome to the Corvette Forums at the Corvette Action Center!

Experience with "DiabloSport Tuners"

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
My 04 Z06 was modified back in 06 with a VaraRam ram air, Melrose long-tube headers, Random Technologies cats and a Corsa cat-back. It's been running great ever since (15,000 miles currently) until I decided to clean and inspect the air filter. Opened it up and wow! There's a quarter inch piece of foam for a filter. Decided I better improve this so I called VaraRam and they sent me an upgrade kit which included a new custom pleated and oiled element, supplied by "Green," and a new cover to accommodate the thicker filter. I installed it and it fit great. Off I went to test it out and by gosh it felt even stronger. Stick with me, this may test your knowledge base.

Since I'm from Michigan and was only wintering down in Florida, I shipped it back up north for the summer. This is important as it may figure into the problem. I picked it up from the shipper and filled up the tank at the local Costco. Ten minutes latter I had a "check engine" light. So, I'll now cut to the chase. It posts two codes P0171 and P0174 both indicate a "too lean" condition for banks one and two. I had everything check out and the tech concluded that it may be oil from the new filter (not a K&N but they dispute that their elements do this) or the mass airflow sensor may be faulty, doesn't check out that way but it could need replacing. He cleaned the sensor, cleared the codes and sent me on my way. 5 miles latter it's back. So, I call VarRam and the engineer there assures me that the problem is not with oil from their filter but rather it's from the engine now getting too much air. It seems that the new pleated and oiled filter flows 20% more air and in response to this the ECM is adding as much fuel as it can and posting a lean code. By the way, it seems that even though it is saying that it's way lean, it's really "rich." Go figure. The combination of the new air flow and the cool Michigan air has sent the ECM into a faults sense of reality.

So, what to do? The VarRam engineer suggested that I simply use a piece of duct tape and tape over the top half of the filter. I did this and it did make the car seem to run better but within 25 miles, the light was back again. @!#$% Next he tells me that the real fix is to purchase a "DiabloSport" tuner. This will provide a tune sufficient to solve my problem - but wait, there's more. I call Diablo and they tell me that their tunes probably won't solve my problem due to the effects of the headers. The recommend a fellow by the name of "Lew" at diablocustomtuning.comTurns out Lew has been doing these custom tunes for some time and they really work. So, for about $500 I can solve my problem and avail my self of increased performance.

I'm about 99% convinced that The DiabloSport "InTune" device purchased from Lew, with his custom tune in it is the way to go but I want to know what you think, particularly if you have ben down this road or have experience with Diablo Tuners.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
If you're 04 had an intake kit, headers, "low-restriction" cats and an exhaust, you should have had the car custom-tuned on a chassis dyno when you did all that work.

It is not likely your codes are from the Green Filter. I've used Green Filters for nearly a decade on all my Corvettes, including my 2004 Z06 with an intake kit (though not a VaraRam). Greens are not "over-oiled" from the factory, so filter oil on the MAF is not your problem. If it was, you'd have MAF codes, not codes for lean exhaust.

I'm going to guess that your engine has been too lean since you did all those mods but it wasn't so lean as to "peg" the fuel trims and set a code. Going from the cheap-assed, foam filter to a really good filter, like the Green, allowed just enough more airflow to run the LTFTs to the end of their range...then the code sets.

Keep in mind, that if the engine is lean the eventual result is engine damage.

A mail order tune might help but, if you're going to go that route, since you're in MI, I'd suggest "PCM for Less". You ship them your ECM and they'll put a calibration in it. I've worked with them on some Camaro stuff and their cals are pretty good. Find 'em on the web at PCMforless

The best way to go, however, is a custom tune, for your specific powertrain configuration done on a chassis dyno. Lots of places around Detroit can do that.
 

Toms007

Moderator
Joined
Sep 24, 2004
Messages
6,479
Location
Southwest Kansas
Corvette
2007 Atomic Orange Coupe
I think I would do an ECS (east coast supercharging) mail order tune. $149 and they have great reviews.
 

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
You nailed it!

If you're 04 had an intake kit, headers, "low-restriction" cats and an exhaust, you should have had the car custom-tuned on a chassis dyno when you did all that work.

It is not likely your codes are from the Green Filter. I've used Green Filters for nearly a decade on all my Corvettes, including my 2004 Z06 with an intake kit (though not a VaraRam). Greens are not "over-oiled" from the factory, so filter oil on the MAF is not your problem. If it was, you'd have MAF codes, not codes for lean exhaust.

I'm going to guess that your engine has been too lean since you did all those mods but it wasn't so lean as to "peg" the fuel trims and set a code. Going from the cheap-assed, foam filter to a really good filter, like the Green, allowed just enough more airflow to run the LTFTs to the end of their range...then the code sets.

Keep in mind, that if the engine is lean the eventual result is engine damage.

A mail order tune might help but, if you're going to go that route, since you're in MI, I'd suggest "PCM for Less". You ship them your ECM and they'll put a calibration in it. I've worked with them on some Camaro stuff and their cals are pretty good. Find 'em on the web at PCMforless

The best way to go, however, is a custom tune, for your specific powertrain configuration done on a chassis dyno. Lots of places around Detroit can do that.

Thanks Hib: I think you have nailed it. The mods. were put on by the original owner and I have lost contact with him and don't know if he ever had it tuned. The engineer from VaraRam, "Patrick" said essentially the same thing that you did. He said that even though the computer says it's too lean, it's really way to rich, as evidenced in the slight black coating on the exhaust and a reduction in mileage. What's the difference between using someone like "PCM for Less" and a custom tuner where they have me run a "data log" and tune from the results. BTW, I would rather take it to a dyno equipped shop and let them do it but I'm way up here in Traverse City, MI and it's a four and a half hour drive down to the Detroit area. Grand Rapids would be better but don't know of anyone there either.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
Thanks Hib: I think you have nailed it. The mods. were put on by the original owner and I have lost contact with him and don't know if he ever had it tuned. The engineer from VaraRam, "Patrick" said essentially the same thing that you did. He said that even though the computer says it's too lean, it's really way to rich, as evidenced in the slight black coating on the exhaust and a reduction in mileage.

I never said that, in spite of the codes, the engine is rich. I would never make that observation without having some O2S data taken at WOT to support that idea. Also, that you decreased intake restriction, ie: the engine is not getting more airflow, would tend not to support the idea that the engine is running rich.

What's the difference between using someone like "PCM for Less" and a custom tuner where they have me run a "data log" and tune from the results.

It's a question of how close you want the tune and if you want the car also tuned for driveability. At WOT, a tune from somebody like "PCM for Less" will get you 90-95% of your mod'ed engine's performance at WOT. A custom tune will get you even closer. You have to weight the price difference vs. the extra performance increase.

BTW, I would rather take it to a dyno equipped shop and let them do it but I'm way up here in Traverse City, MI and it's a four and a half hour drive down to the Detroit area. Grand Rapids would be better but don't know of anyone there either.

Sorry I don't have any suggestion for Traverse City/Grand Rapids.
 

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
I never said that, in spite of the codes, the engine is rich. I would never make that observation without having some O2S data taken at WOT to support that idea. Also, that you decreased intake restriction, ie: the engine is not getting more airflow, would tend not to support the idea that the engine is running rich.



It's a question of how close you want the tune and if you want the car also tuned for driveability. At WOT, a tune from somebody like "PCM for Less" will get you 90-95% of your mod'ed engine's performance at WOT. A custom tune will get you even closer. You have to weight the price difference vs. the extra performance increase.


Sorry I don't have any suggestion for Traverse City/Grand Rapids.

Hib;

Patrick from VaraRam seemed to indicate that because of the added airflow, the computer sees this as a "lean" condition and throws more fuel at it when it really doesn't need it. So you end up with "lean codes" and a "rich" mixture - go figure!

I can live with 90-95% no problem. You'll have to excuse my ignorance here but how would "PCM for Less" be able to do a better job at recalibrating my ECM than using the "Diablewtune" solution with data-logs from my actual driving experience? Is price the difference here or is there actually some added value? Also, how vulnerable are the PCM's to electrostatic charge, etc. once out of the vehicle? Where is it located on my car?

I may have found a local tuner with a dyno. Got a voicemail into him now. What specific skills should I look for in someone like this?

Jim
 

SANOLS1

Well-known member
Joined
Jul 5, 2004
Messages
129
Location
So Cal
Corvette
2004 Millenium Yellow Coupe
Sounds to me like Hib is spot on with his suggestions. If you can find a good dyno shop and someone who is skilled with the Diablo Software, they can dial you in for every range of throttle. With the mods you have I would definitely get it on a dyno. A couple of advantages to having the Diablo are:

Before a new tune is loaded, the unit will save your stock tune. This is nice to have in your back pocket if you every need a refresh or update of the ECM. (Disclaimer, this is the way I understand it) You can reload the factory tune before the refresh and then switch back to the dyno tune settings after the update. The unit will then save your new stock tune and overwrite the old one. Some dealers will load updates during other maintenance when they plug in and see an earlier revision. If they do this, it will likely wipe out your existing tune that you just paid a lot of money for, and go to the latest factory load settings.

The other thing I like about it is the ease of reading codes and resetting them versus trying to keep up with the readout on the DIC when going through the fault codes.
I think I paid about $300 for my Diablosport a few years back. Whenever I make a change I’ll go back and pay around $120 an hour for a few dyno runs and adjustments.

Good Luck!
:beer
 

db2

Well-known member
Joined
Dec 13, 2005
Messages
57
Location
Carolina
Corvette
80,85 & 02 Z.
Got the same codes on my 02Z when I added the VR Power Duct.The Halltech honeycomb MAF screen fixed my codes.

Later bought a used Preditor,installed the canned tune and got my LTFT's in the -2 to +2 range.

All is well.

\db2
carolina
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
Hib;
Patrick from VaraRam seemed to indicate that because of the added airflow, the computer sees this as a "lean" condition and throws more fuel at it when it really doesn't need it. So you end up with "lean codes" and a "rich" mixture - go figure!

IMO, What "Patrick from VaraRam" said doesn't "figure".

When the computer "sees" a lean condition, it bases that on data from the two front oxygen sensors. The only time the O2Ses will "see" a lean condition when it doesn't exist is if air is getting into the exhaust between the engine in the sensors–possible but not probable in this case because I'm assuming you don't have any exhaust leaks. So, the engine intake air flow increases, O2Ses detect lean exhaust because of that, ECM increases fuel flow (long term fuel trims go rich). If the ECM's fuel trimming function has enough range, the LTFTs will go a certain amount rich and stay there and, unless you're taking serial data, you'll never know the difference. But...if intake air flow increases a lot–to the point that the ECM cannot command enough extra fuel then OBD2 sets a code for lean exhaust, ie: the ECM is saying, "Dude, there is so much more airflow coming in, we've run out of extra fuel to give you." That you're getting them from both sides of the engine tells me the chances are good your engine is lean, ie: it's unlikely you have two identical exhaust leaks. AFR is probably lean everywhere so you want to be careful about running the motor hard. Lean at WOT is a recipe for detonation.

You can't have lean exhaust codes and a rich mixture unless the system has a problem with air getting in the exhaust between the engine and the front O2 sensors. For now, I'd ignore tailpipe or spark plug color. If you think you have an exhaust leak, I'd address that first.

I can live with 90-95% no problem. You'll have to excuse my ignorance here but how would "PCM for Less" be able to do a better job at recalibrating my ECM than using the "Diablewtune" solution with data-logs from my actual driving experience? Is price the difference here or is there actually some added value?

IMO, there are three "levels" of aftermarket calibration:
Handheld tuners: sometimes the least expensive and certainly the easiest. They work well if the engine configuration matches the tuners' cals closely. I've used handhelds occasionally. I've used the Hypertech unit on engines with limited mods. I've use the Crane Powertuner (no longer available) on monderately modified engines when the package of mods closely matches the calibrations in the tuner.
Mailorder or "canned" tunes: This is where you remove your ECM, send it to the tuner for calibration, or you take the car to one of the tuners "dealers" and the dealer reflashes your ECM. I've found that the choices in tuning are greater when you go this route. The calibrator will have a wider variety of engine tuning choices than can be put in a handheld tuner. Mailorder tunes may be more or less expensive than a handheld tuner. Given a competent tuner, the calibration will likely be more well-suited to your selection of mods. Obviously, mailorder tunes are more complex because you either have to take out your computer or take the car to the tuner's dealer.
Custom calibration: by far the best choice. Done on a chassis dyno. The calibrator custom tunes your ECM to your specific selection of mods. This is the most complex, expensive and time consuming way to do calibration but it results in the best match of calibration and engine. I've used a several tuning services, most of them with the same chassis dyno.

Also, how vulnerable are the PCM's to electrostatic charge, etc.once out of the vehicle?
I suppose they are vulnerable but not to any extent that a consumer needs to worry about touching the computer or shipping it. Now, if you had a strong static charge in some other device and touched one of the pins on the ECM connector, you might fry the controller. But, people handle and ship ECMs all the time. Just don't zap the ECM connector with a set of jumper cables :L

Where is it located on my car?

Under the battery.

I may have found a local tuner with a dyno. Got a voicemail into him now. What specific skills should I look for in someone like this?
Oh, boy, it's hard to explain to you in an Internet post how to evaluate a tuner. I usually have to visit a tuner's facility, talk to him/her and watch them work before I decide. At this point, if I were you, I'd be more concerned with references from people who have used that tuner rather than being able to evaluate a tuner's skills, yourself.
 

catbert

Moderator
Joined
Aug 26, 2004
Messages
3,487
Location
Tobacco Road, NC
Over the years I've had mixed luck with local "tuners." There are a number of magic finger tuners out there like Jeremy Fortunato and Chuck COW (Corvettes of Westchester). These guys are savants, and I'm sure there are others, but I wouldn't bet on running across one locally, but it's possible. Both Jeremy and Chuck travel the US doing group tunes. I got one from Chuck on my 07 Z in Chandler, AZ when he came at the request of local guys. He did Vettes, GTOs Camaros, and even a Suburban. Everyone was thrilled with the results, including drivability. It might be worth youe effort to look them up.
 

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
IMO, What "Patrick from VaraRam" said doesn't "figure".

When the computer "sees" a lean condition, it bases that on data from the two front oxygen sensors. The only time the O2Ses will "see" a lean condition when it doesn't exist is if air is getting into the exhaust between the engine in the sensors–possible but not probable in this case because I'm assuming you don't have any exhaust leaks. So, the engine intake air flow increases, O2Ses detect lean exhaust because of that, ECM increases fuel flow (long term fuel trims go rich). If the ECM's fuel trimming function has enough range, the LTFTs will go a certain amount rich and stay there and, unless you're taking serial data, you'll never know the difference. But...if intake air flow increases a lot–to the point that the ECM cannot command enough extra fuel then OBD2 sets a code for lean exhaust, ie: the ECM is saying, "Dude, there is so much more airflow coming in, we've run out of extra fuel to give you." That you're getting them from both sides of the engine tells me the chances are good your engine is lean, ie: it's unlikely you have two identical exhaust leaks. AFR is probably lean everywhere so you want to be careful about running the motor hard. Lean at WOT is a recipe for detonation.

You can't have lean exhaust codes and a rich mixture unless the system has a problem with air getting in the exhaust between the engine and the front O2 sensors. For now, I'd ignore tailpipe or spark plug color. If you think you have an exhaust leak, I'd address that first.



IMO, there are three "levels" of aftermarket calibration:
Handheld tuners: sometimes the least expensive and certainly the easiest. They work well if the engine configuration matches the tuners' cals closely. I've used handhelds occasionally. I've used the Hypertech unit on engines with limited mods. I've use the Crane Powertuner (no longer available) on monderately modified engines when the package of mods closely matches the calibrations in the tuner.
Mailorder or "canned" tunes: This is where you remove your ECM, send it to the tuner for calibration, or you take the car to one of the tuners "dealers" and the dealer reflashes your ECM. I've found that the choices in tuning are greater when you go this route. The calibrator will have a wider variety of engine tuning choices than can be put in a handheld tuner. Mailorder tunes may be more or less expensive than a handheld tuner. Given a competent tuner, the calibration will likely be more well-suited to your selection of mods. Obviously, mailorder tunes are more complex because you either have to take out your computer or take the car to the tuner's dealer.
Custom calibration: by far the best choice. Done on a chassis dyno. The calibrator custom tunes your ECM to your specific selection of mods. This is the most complex, expensive and time consuming way to do calibration but it results in the best match of calibration and engine. I've used a several tuning services, most of them with the same chassis dyno.

I suppose they are vulnerable but not to any extent that a consumer needs to worry about touching the computer or shipping it. Now, if you had a strong static charge in some other device and touched one of the pins on the ECM connector, you might fry the controller. But, people handle and ship ECMs all the time. Just don't zap the ECM connector with a set of jumper cables :L



Under the battery.

Oh, boy, it's hard to explain to you in an Internet post how to evaluate a tuner. I usually have to visit a tuner's facility, talk to him/her and watch them work before I decide. At this point, if I were you, I'd be more concerned with references from people who have used that tuner rather than being able to evaluate a tuner's skills, yourself.

Thanks again Hib;

I may have misunderstood Patrick but I believe he said something like, the computer sees all this air coming in and adds as much fuel as it can before it sets the codes and the check engine light. It thinks it's lean when in fact it's way rich. He asked if my mileage was off, it is, and if the tailpipes were showing increased levels of soot, they are. Having read your post, I can see why the 02 sensors would be seeing a "lean" condition only if the mixture was lean. What about some sort of failure in the mass airflow sensor? The mechanics I took it to said it checked out but could this be a possible source of the codes. They also checked for air leaks and couldn't find any. Remember, I replaced the filter in early February while I was in Florida and drove it a few hundred miles without the check engine light coming on. Once it was shipped back to MI, I re-fuled and that's when the light came on. Patrick seemed to think that it was on the verge of setting the codes in Florida and when I got to the cool MI air, it pushed it over the edge. I did notice the bucking shortly after I replaced the filter. Patrick said this was caused because of the increase in airflow. It confused the throttle motor at idle and caused it to open and close rapidly causing the bucking sensation. This ceased once it placed duct tape over the top of the filter element, smoothed right out. Airflow?

Will I have any problems with the apparent "lean" condition if they put it on the dyno for tuning? Or is this something they can correct prior to running it up?

I'm still gathering data on the two tuners I located here but want to get this fixed asap.

Thanks again for you expert counsel.

Jim
 

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
Over the years I've had mixed luck with local "tuners." There are a number of magic finger tuners out there like Jeremy Fortunato and Chuck COW (Corvettes of Westchester. These guys are savants, and I'm sure there are others, but I wouldn't bet on running across one locally, but it's possible. Both Jeremy and Chuck travel the US doing group tunes. I got one from Chuck on my 07 Z in Chandler, AZ when he came at the request of local guys. He did Vettes, GTOs Camaros, and even a Suburban. Everyone was thrilled with the results, including drivability. It might be worth youe effort to look them up.


This is good information, thanks. It's one of those things that takes some research and evaluation prior to pulling the trigger.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
Thanks again Hib;
(snip)
What about some sort of failure in the mass airflow sensor? The mechanics I took it to said it checked out but could this be a possible source of the codes.

The two codes you listed in the OP are lean exhaust codes not codes for MAF sensor faults.

Remember, I replaced the filter in early February while I was in Florida and drove it a few hundred miles without the check engine light coming on. Once it was shipped back to MI, I re-fuled and that's when the light came on. Patrick seemed to think that it was on the verge of setting the codes in Florida and when I got to the cool MI air, it pushed it over the edge. I did notice the bucking shortly after I replaced the filter. Patrick said this was caused because of the increase in airflow. It confused the throttle motor at idle and caused it to open and close rapidly causing the bucking sensation.

I'm not convinced Patrick really knows what he's talking about. The ETC actuator ("throttle motor") doesn't get "confused" such that it opens and closes independent of driver intent.

Will I have any problems with the apparent "lean" condition if they put it on the dyno for tuning? Or is this something they can correct prior to running it up?
Your going to a tuner to get that corrected. Tell the calibration guy you think it's running lean and they'll start from that assumption. Their wide-band O2 will tell you right away if the engine is lean or rich.

I've read what Patrick has told you several times and I was wondering why he keeps telling you that the engine is not lean, but rich. Since I was not a party to the conversation, it's hard for me to try and read between the lines, but let me explain another scenario which can happen. If the MAF sensor is transmitting faulty airflow data, because of a poorly-designed intake kit, incorrect MAF sensor calibration, need of a flow straightener when one is not present or other problem, this faulty data can cause the ECM to deliver incorrect fuel flow, but that incorrect fuel flow would show up in fuel trim data or, if the problem is severe, as fault codes for rich or lean exhaust.

For example: you could have a situation were intake airflow quantity or quality changed compared stock, but because the MAF is sending faulty data, the ECM goes too rich, but....if that was the case, you'd see that in the O2S voltage, in fuel trims (LTFT less than 128 because the system is attempting to subtract fuel) or a rich exhaust code setting (the fuel trim is all the way against the lean limit and the O2Ses are still signaling the exhaust is rich).

In reality, the opposite result (lean exhaust code) is happening. Now, I suppose it's possible for the sitaution to be reversed, that is....airflow quantity or quality changes compared to stock, but because the MAF is sending faulty data, the ECM goes too lean (LTFT greater than 128 because the system is trying to add fuel) or sets a lean exhaust code (the fuel trim is all the way against the rich limit and the OS2es are still signaling lean exhaust).

As you're starting to see this engine controls s&%t with modified engines ain't easy.

Good luck.
 

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
Thanks again Hib;
(snip)


The two codes you listed in the OP are lean exhaust codes not codes for MAF sensor faults.

Remember, I replaced the filter in early February while I was in Florida and drove it a few hundred miles without the check engine light coming on. Once it was shipped back to MI, I re-fuled and that's when the light came on. Patrick seemed to think that it was on the verge of setting the codes in Florida and when I got to the cool MI air, it pushed it over the edge. I did notice the bucking shortly after I replaced the filter. Patrick said this was caused because of the increase in airflow. It confused the throttle motor at idle and caused it to open and close rapidly causing the bucking sensation.

I'm not convinced Patrick really knows what he's talking about. The ETC actuator ("throttle motor") doesn't get "confused" such that it opens and closes independent of driver intent.

Your going to a tuner to get that corrected. Tell the calibration guy you think it's running lean and they'll start from that assumption. Their wide-band O2 will tell you right away if the engine is lean or rich.

I've read what Patrick has told you several times and I was wondering why he keeps telling you that the engine is not lean, but rich. Since I was not a party to the conversation, it's hard for me to try and read between the lines, but let me explain another scenario which can happen. If the MAF sensor is transmitting faulty airflow data, because of a poorly-designed intake kit, incorrect MAF sensor calibration, need of a flow straightener when one is not present or other problem, this faulty data can cause the ECM to deliver incorrect fuel flow, but that incorrect fuel flow would show up in fuel trim data or, if the problem is severe, as fault codes for rich or lean exhaust.

For example: you could have a situation were intake airflow quantity or quality changed compared stock, but because the MAF is sending faulty data, the ECM goes too rich, but....if that was the case, you'd see that in the O2S voltage, in fuel trims (LTFT less than 128 because the system is attempting to subtract fuel) or a rich exhaust code setting (the fuel trim is all the way against the lean limit and the O2Ses are still signaling the exhaust is rich).

In reality, the opposite result (lean exhaust code) is happening. Now, I suppose it's possible for the sitaution to be reversed, that is....airflow quantity or quality changes compared to stock, but because the MAF is sending faulty data, the ECM goes too lean (LTFT greater than 128 because the system is trying to add fuel) or sets a lean exhaust code (the fuel trim is all the way against the rich limit and the OS2es are still signaling lean exhaust).

As you're starting to see this engine controls s&%t with modified engines ain't easy.

Good luck.


Wow! And the mechanic that checked it out couldn't find anything and wanted to blame it on oil from the new "Green" filter. I can say that the car has run perfect since I got it until I changed the filter, or something else went bad and we aren't seeing it. I will let you know how I come out. Thanks for taking the time to help me.

Jim
 

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
More on z06 tuning issues

Ok Hib, and others who responded to my "DiabloSport" post last week.

I found a fellow in Traverse City, MI. who runs an auto fabrication business specializing primarily in Acura NSX's. He recently purchased a Mustang Dyno and is in the process of building a NSX race car for a run up Pikes Peak this July. Clearly his experience lies in the area of asian imports but he is in the process of building a 1000+ HP Camaro for a customer and has tuned LS motored Pontiac GTO's recently. Most importantly, he's close by and very easy to work with. At any rate, I took my 04 Z06 in yesterday and he spent some four hours running it up on the dyno and tuning. He uses a software suite from an internet based company called "EFI Live," apparently they are headquartered in Australia. He initially concluded that it was "lean" as the OBD2 had indicated but only in the lower and mid range, apparently it wasn't lean at the high end. He said that the fuel trim was at nearly 20%. At the end of the day, it dynoed at 375 hp at the wheels. It drove great, as it seemed to with the piece of duct tape over the top half of the filter element (I removed this first) and seemed to accelerate briskly. However, after approximately 20 miles the @%$%& "check engine light" returned. He had warned me that this may occur and if it did to bring it back and he would fix it. When I spoke to him this morning he said to give him a couple of days to do some research and then bring it back.

Do you, or anyone else that is monitoring this dialog, know what specific parameters he should adjust to eliminate this recurring lean code problem? He was fair in his fee and is very willing to work with me on this. I simply want to guide him in the right direction if I can.
 

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
Hold the presses!

Ok Hib, and others who responded to my "DiabloSport" post last week.

JUST WENT OUT AND READ THE CODES - They're different codes! Maybe another problem as a result of the tuning. New codes are as follows: 1 of 2 - P0101 Vaf Ckt Range/Perf and 2 of 2 - Maf or Vaf Ckt Range/Perf.
 

catbert

Moderator
Joined
Aug 26, 2004
Messages
3,487
Location
Tobacco Road, NC
Your tuner is using software that isn't really mainstream, and he needs help interpreting the results - what could possibly go wrong? Seriously, HP tuners and a couple other packages are the only ones I've seen used on the LX series, and there is a reason for that. Sounds like it's OJT for him, but I won't say any more. I hope someone else can help you. If any group can do it, it's CAC. Good luck.
 

SANOLS1

Well-known member
Joined
Jul 5, 2004
Messages
129
Location
So Cal
Corvette
2004 Millenium Yellow Coupe
Just a thought, After doing a series of High RPM engine pulls on the dyno, perhaps you have actually fouled the MAF. Easy things first, try cleaning it with MAF cleaner and make sure your new Green Filter is not over oiled. I have yet to have this problem on my Vette but I've had it numerous times on my Silferado. A good MAF cleaning solved the problem every time. I would usually get the fault a week or so after cleaning the K&N filter and re-oiling it.
 

4 the ride

Active member
Joined
Dec 17, 2009
Messages
31
Location
Venice, Florida
Corvette
2015 Laguna Blue Z51
Your tuner is using software that isn't really mainstream, and he needs help interpreting the results - what could possibly go wrong? Seriously, HP tuners and a couple other packages are the only ones I've seen used on the LX series, and there is a reason for that. Sounds like it's OJT for him, but I won't say any more. I hope someone else can help you. If any group can do it, it's CAC. Good luck.

Yeah, I took a risk and perhaps I will pay. Hope not though as I believe he really is going to stick with it until we get it right. Stay tuned. Good information.

Thanks
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom