New 98 owner question

[EHS]

Re: EHS I can get you another 20hp

EHS,

With your modifications, you must be running fuel lean. My mods. are similar to yours, but do not have any of the problems you are having, because I have fooled my PCM electronically to think I am running lean, and the PCM has compensated me with enough spark advance to make me run 10% rich which translates to the right amount of fuel with all that air coming in. The Mass Air Flow Translator, A.K.A. "horsepower in a box" is what you need...

As c4c5specialist stated, we have tested the car a number of times, both on the dyno and on the road, monitoring the A/F ratio with the Tech II, and the car is not running lean.

Also, the MAF changes made by "tricking " the PCM are temporary, and will only last until the computer relearns the tables, and compensates for the adjustment. Why? Because you are only tricking the MAF sensor, not the O2 sensors. So even if the MAF sensor is fooled, the readings downstream in the exhaust path will be off, and the PCM will start to cancel out the modifications to the trims, until the O2 readings are again within parameters.

As c4c5specialist stated, that affects drivability. The only way to get a permanent adjustment is to reprogram the PCM itself, with a Predator, LS1Edit, or a speed shop that does that work. Given that my fuel trims were spot on, I didn't think custom programming was worth it.

While each car an year is different, we gathered enough background data to determine what the issue was, and corrected it by reinstalling the MAF ends with the screen. For my driving conditions and style, that offers the best performance -- not maximum numerical horsepower, but best all around performance.

On the difference between the LS1 and LS6, when looking at the bottom of both manifolds, to me the differences are clearly visible, to the naked eye.

 

[TODD L GRIFFITH]

Mass Air Flow Translator

On the Mass Air Flow Translator, there is a base, and a WOT setting, not just a WOT setting. It is recommended that the car be dynoed a few times to get the base setting right, due to the time and mileage it takes to reset the tables. True, using an autotap is the right procedure in getting the mixture correct. The WOT setting is immediate, and can be dialed in with one visit to the dyno. The changes to the fuel tables have been permenent, not temporary, unless I remove the translator or change the settings. I don't have any drivability problems @ 2-3000 rpm either. The MAF is a sensor, an air metering device, and cannot be fooled, but the signal back to the pcm from it can be altered for pulsewidth changes to the injectors to provide more fuel through the PCM. I could have gone with larger injectors and leaned the mixture out with the translator if felt like it. As for the two intake manifolds, I stated, I could see no visible difference between the two manifolds, I put them side by side, looked inside at both, and they are too close to tell. If there is a difference in the bottom of the thing, I'm not going to remove it to find out, I'll take your word for it, although the 99 stock intake is different than the 2001 when GM put the LS6 intake on for another 5hp to 350hp on all C5s. I guess that means if you have a stock 01' 350hp LS1 adding the Z06 intake is doing nothing for you.

 

[EHS]

Re: Mass Air Flow Translator

...The changes to the fuel tables have been permenent, not temporary, unless I remove the translator or change the settings. I don't have any drivability problems @ 2-3000 rpm either...

As for the two intake manifolds, I stated, I could see no visible difference between the two manifolds, I put them side by side, looked inside at both, and they are too close to tell...

This has been debated for several years on various fora, and the concensus is that the MAF translator only affects WOT settings. It does not permanently change anything below 80% throttle, because you are not "tricking" the O2 sensors. Here are two links:

http://forums.corvetteforum.com/zerothread?id=337318&postid=3433186#3433186

http://www.vetteguru.com/mods/howto/

And here is some of what they say:

"Remember that no matter what, the O2 sensors rule in 'closed loop' mode, and will always tell the PCM to adjust to 14.7 stociometric a/f ratio. The MAFT setting during fuel enrichment (WOT) however will always be permanent since the PCM freezes any possibility of updating its fuel trims or any other values."

and

"Why even change the part throttle settings - as you say, they will be immediately ignored by the PCM as it will look to the O2 sensors at part throttle operation."

and

"To be honest, the MAFT really only permanently changes the A/F at WOT. The part throttle changes get learned out by the 02 sensors after awhile."

The last statement was made by a vendor who actually does quite a good business selling the MAF translators to folks who feel they help.

Regarding the LS1 and LS6 manifolds, here's a photo posted by Team ZR1 some time ago. The differences are clearly visible:

and ---

here are the performance differences (in flow) between the two intakes:

Note that on an LS1, with the LS6 intake manifold (in green in the chart above), the flows (CFM) are roughly equivalent at the lower ranges as ported heads and stock manifold (in orange), and show greater flow throughout the entire range than the stock LS1 manifold (in yellow). These are numbers from MTI.

Finally, regarding "drivability" issues, please understand that we are talking about refinements that 99% of people who drive and those who modify C5s will not notice.

I recently drove a friend's completely stock 2002 Z06 (with only a Blackwing added), and he had the same issue at 2,000-3,000 rpm -- to a lesser extent -- but it was there -- that I worked with c4c5specialist to eliminate on my more modified '00 C5. Now he can't help but notice it too. Perhaps it's present on most C5s, and folks don't notice, but at this point I don't have the energy to convert mine all the way back to stock to find out. I like the car and the way it performs. It's crisp.

When I have more time, I'll be happy to post the full details, dyno charts and all, on the mods. In the mean time,

hope this helps. :bang

 

[TODD L GRIFFITH]

EHS

I agree, the only thing is, overall they did indicate a permenent change in long term fuel trims, which failed to make your quote. As for the two intakes, it does appear there is a difference between the two in the injection molding process, but flow wise, there is such a small difference, you could blow through a straw and exceed both flows and static pressures added together. Were you trying to hammer something above? You don't have to do that, just turn the key, it will start.
I appreciate the time it took to put such an enducated response all together.