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Need help with 85 tpi setup with 408" small block running rough cold, fuel system qs

I

Igor

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Hi Guys,

I am working on an 85 car. I bought it with a hurt motor and and put another motor in. I used parts that came on the car (intake, exhaust, chip(azzato), etc).

Motor
[FONT=PrimaSans BT,Verdana,sans-serif].040 400 with 2 valve relief flat tops, forged, -5.4cc, molly rings
As Cast TFS 195 heads
Comp XFI 268 Hydro FLAT tappet cam with 1.6 (224/231 at .050, .520/.515 and 113 lsa)
Edelbrock base, Superram intake, 52mm tb, 24# injectors[/FONT]
1 5/8LTs with X pipe and magnaflow mufflers, 2.5" dual, no cats.

It has 1 5/8LTs on it with no cats and off road exhaust. It still has the stock 1 wire 02.

The Evap canister system has been removed from the car. The evap line leading from the engine bay to the tank has been capped. I noticed the fuel filler cap is vented. Even so, I still get a lot of pressure when I open it to fill up. I tried reliving the pressure (open the cap) before starting it cold and it had no effect on how the car runs.

I capped the PCV system to run open breathers. I have a bit of cranckase pressurization so its pulling some oil into the pcv. I did a compression test, all cylinders come up dead even and good. Ring clerances are failry loose, .025 and .028 or so.

The car runs like crap until it reaches closed loop. Then it runs all right. I have noticed lately I do loose vacum for my brakes after long idle times but I can not find a vacum leak. Before I removed the pcv system, the car did run a little better cold, but not great cold.
I have gone on a long highway trip with the car recently, rain fairly well.
Could it be my O2 sensor failing due to a long highway ride like that?
I did not think 02 surved any purpose until closed loop.

I am not sure if I should put the pcv setup back on to try it, but I doubt that's my problem. I am more worried about the evap setup and the fuel system.

The fuel pump is a new holley unit, ran about the same with the stocker.

Thanks and am looking for any suggestions. Can I get software/cable to scan this car? I am having a very hard time finding anyone locally that will touch an 85 tpi car as far as tuning is concerned.

Thanks
 

vetteoz

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The fact that the car runs alright when in closed loop means the O2 is working because that is the only time it comes into play.But O2 has to get hot enough to work before engine will go CL.
Where is the O2 sensor located?
Too far back on collector and it will cool off at idle or not heat up fast enough from cold start meaning computer will drop back / stay in open loop tune.
Heated O2 needed maybe?

Datalogging cable and logging info here
ALDL OBD1 OBD cable OBDI OBD2 engine codes
Get the USB one if your laptop has USB port , then you don't need power from cig lighter.

Free datalogging software
TunerPro RT
TunerPro and TunerPro RT - Professional Automobile Tuning Software
The $30 donation gets rid of the nag screen.
 

vetteboy86

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If you are running an open exhaust, you may need to run a heated O2 sensor. I still dont think that explains the issue you are having in open loop.
 

Hib Halverson

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First...you can get scan test software for that car. The best stuff comes from EASE Diagnostics. You also can find scan testers (ie: hardware devices) which support an 85.

You are correct about the O2S, on an 85, it serves no purpose in open loop, other than providing the O2S signal the ECM expects, but you still need it to provide that signal.

You probably need a calibration engineer to write you a program for a chip which includes work on the open loop, low load, idle and cold enrichment parts of the cal. That's not something that a lot of people change but, in your case, with the radical engine, the lack of PCV and all the other mods, you probably need a good "cal guy" and probably a chassis dynamometer.

Understandably, there's going to be few, if any, people near Calgary who have the experience and equipment to do the calibration work you need. Think about taking a trip down to someplace like Detroit where there are people who do that sort of thing.
 
I

Igor

Guest
First...you can get scan test software for that car. The best stuff comes from EASE Diagnostics. You also can find scan testers (ie: hardware devices) which support an 85.

You are correct about the O2S, on an 85, it serves no purpose in open loop, other than providing the O2S signal the ECM expects, but you still need it to provide that signal.

You probably need a calibration engineer to write you a program for a chip which includes work on the open loop, low load, idle and cold enrichment parts of the cal. That's not something that a lot of people change but, in your case, with the radical engine, the lack of PCV and all the other mods, you probably need a good "cal guy" and probably a chassis dynamometer.

Understandably, there's going to be few, if any, people near Calgary who have the experience and equipment to do the calibration work you need. Think about taking a trip down to someplace like Detroit where there are people who do that sort of thing.

Thanks for the input guys, I do have a cable i used on a 94 lt1 wich has 0bd1 connection, could try it.

I did not think the engine is that radical. It would be cheaper for me to convert to an aftermarket controller then to drive to detroit, lol. I have some experience tuning lt1 cars with tunercat, I am assuming there is not much/nothing I can do with 85 computer. Would it be beneficial for me to upgrade to something more modern and flashable? Everything works on the car now, I would like to keep it that way.

The 02 is located in the collector and the exhaust is dual 2.5" with no cats. I am going to hook up my fuel pressure gauge and see what it does driving, although at idle it seemed fine. However my AFPR could have gone out of whack. I am not sure what brand it is, but, it has no lock nut on it, just a screw. Might be accell.
 

vetteboy86

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You can buy a kit from moates.net. This will allow you to put a flash programmable chip adapted to the 85 ecm. THis will allow you to program the IC as many times as you want. You will need a chip burner as well.

I'm not sure if tuner cat offers anything live for our cars. I usually scan, then tune, than scan some more.
 
I

Igor

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Thanks guys.

I just put a fuel pressure gauge on it, started it up. Ran as usuall, a bit rough. Fuel pressure is 50lbs prime 55lbs running. Gauge oscilates slightly, from 54 to 56 or even less.

I noticed unplugging the IAC had no effect on idle/did not throw a code.

Tapping on the maf did nothing.

Unplugging the vacuum booster and inducing a fairly major vac leak, did nothing as well.
 

vetteboy86

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Fuel pressure seems a bit high. I notice you are running 24# injectors. I think they are a bit small for your application. What kind of injectors are they? You must have an AFPR. Try backing it down to around 40 or so, and see how it runs. IMHO, I think you should look into some scanning software, and a wide band 02 setup. I have an LM1 from innovate motor sports.
 
I

Igor

Guest
Fuel pressure seems a bit high. I notice you are running 24# injectors. I think they are a bit small for your application. What kind of injectors are they? You must have an AFPR. Try backing it down to around 40 or so, and see how it runs. IMHO, I think you should look into some scanning software, and a wide band 02 setup. I have an LM1 from innovate motor sports.

Yes the pressure is a bit higher now with the new pump. I have set it that way to try and fight the fact that the car is running a touch lean (can tell by plugs). The 24lb injectors came with the car (as did most parts) and I am sure are a bit small. However instead of dumping cash into parts I want to get this car running well first, and then try to tune it/get it tuned.

I am looking into a wideband, as it does have a bung welded in the exhaust for it, and so does my 95 lt1. I could use this tool. Unlike the lt1, I am at mercy of someone else to tune this 85.

I will try to play with the IAC and go from there. I can back the pressure off a bit and then set min idle/tps (have set it before)
 

vetteboy86

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I understand where you are at. Any idea what kind of injectors they are? Is it possible that the higher fuel pressure is causing less than desirable behavior from the injector? I am thinking along the lines of spray pattern, and leak down?

The wideband is such a powerful tool.

FWIW, if you purchase the ALDL connector, you can run 20 free scans with datamaster software.
 
I

Igor

Guest
I understand where you are at. Any idea what kind of injectors they are? Is it possible that the higher fuel pressure is causing less than desirable behavior from the injector? I am thinking along the lines of spray pattern, and leak down?

The wideband is such a powerful tool.

FWIW, if you purchase the ALDL connector, you can run 20 free scans with datamaster software.

vetteboy, Thanks a lot for all your help.

I claned the IAC and compressed it all the way, with the jumper in the a/b terminals it extends fine. I have no idea if it was clogged up or stuck. But its possible.
Right now the engine is warm so its hard for me to tell, but it seems to idle up when i start it, then slowly remove the idle, which it did not do the last few days. I compressed the iac and left it unplugged when it was still cool, car started good and idles at 1500rpm and stayed there. Obviously that's too high, but motor ran good. So I am thinking 2 possibilities.

a) my IAC valve was sticking
b) the iac counts in the tune are out of whack for this motor.
c) both a and b

I have a question about setting min idle if you know.
Book calls for 450rpm in drive. Thats's nice, but with a cam its difficlut. Should a cam motor be set to 450 as well, or a touch higher?

Thanks again for all your help.
 

vetteboy86

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For your setup I think it is too low. Depending on what type of pulleys you have on it might not be enough for your alternator to keep up. I dont believe my car ever idled that low. Probably around 600 to 550 when motor was stock.

Have you cleaned your TB as well? I have heard stories about crud building up around the blades of the TB that will affect idle. How well is your TPS adjusted?
 

vetteboy86

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So you disconnected the brake vacuum booster and it made no change on engine characteristics?
 
I

Igor

Guest
So you disconnected the brake vacuum booster and it made no change on engine characteristics?

At the time yes. When I pulled the IAC and forced it opened/high idle, the brake booster seemed to operate fine.

My min idle was set to 450 and tps set to .540v, this was right after i got the base timing set.

I checked the base timing again just now (after cleaning the iac valve), set min idle to around 750 and set the tps sensor to .540 at that point.

Will report how it runs in the morning. It is possible my IAC valve had issues/was sticky. I cleaned the tb well, but seemed decent. Its possible this IAC valve is original 1985
 

vetteboy86

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When I replaced my TB two years back, my IAC appeared to be original.
 
I

Igor

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When I replaced my TB two years back, my IAC appeared to be original.

Well I think I figured it out.

After doing all i said i did, took the car for a drive and it just ran bad. Went back home and started to look closer, and think i found the issue. Tapped the maf (tried this before with no change) and car idle changed. Looked closer and found two cracks in the maf housing. I am not sure if one is from me tapping or what, but I doubt it (was gentle, used 1/4" wrench). There was a depression in the casting of the maf housing, but upon very close inspection with it removed i can see light through it. Claned maf with sensor cleaner, put ductape over the holes and started it up, totally different. It now idles high and stays that way 'till warm up, then smartens up. Must be a maf related issue, nothing else made sence.

Since I set my min idle/tps with the maf broken, i will reset it tomorrow again (too late now) and see where i stand. But this must be a part of the problem, either the maf is bad, or just the cracks in the body.
 

vetteboy86

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Certainly could be a contributor? Are you running the TPI setup still?
 
I

Igor

Guest
Certainly could be a contributor? Are you running the TPI setup still?

Its an 85 computer/maf/sensors with a super ram intake, no 9th injector. I think the injectors are accel. Have fuel pressure set at 44 now.

Ya the MAF was def. making the car a nightmare at cool idle. Its now back to "normal". From now forward I need to get a tune, or an aftermarket computer, or some way to tune the 85 myself. I really wanted to keep the cost down. I got this 400 running back in march and have been working on the rest of the car. Did all bushings, got new steering parts, 4 wheel alignmenet, new shocks, etc. The car is really tight just want to make the 85 run as perfect as possible.

I just started a short block rebuild on my 95 lt1, so really want to keep things on a budget. But the more I look at things, the cheapest solution might just be an aftermaket computer.

I will look a little more into parts to be able to burn my own chip for 85. Or a later speed density computer swap.
 

vetteboy86

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I was considering a super ram for a while. Due to availability, I am leaning now towards a mini ram. If I cannot find one, I have been looking at LT1 intake conversions. My car really pukes around 4800 to 5000. Now though, I think I am maxing out the capabilities of my MAF. The sensor reads 4.5 volts starting at 4k or so, and just plateau's.

I will tell you that tuning will require alot of reading and trial and error. I have been at it off and on for 2 years.
 
I

Igor

Guest
I was considering a super ram for a while. Due to availability, I am leaning now towards a mini ram. If I cannot find one, I have been looking at LT1 intake conversions. My car really pukes around 4800 to 5000. Now though, I think I am maxing out the capabilities of my MAF. The sensor reads 4.5 volts starting at 4k or so, and just plateau's.

I will tell you that tuning will require alot of reading and trial and error. I have been at it off and on for 2 years.


A friend of mine has a miniram. This is the only option IMO, other then maybe the lt1 conversion.

I have had several lt1 cars, and can tune with tunercat quite well. I have never maxed out an lt1 maf, but then again I never had anything radical, just boltons/cam, etc.

The super ram is a total PITA and I would never get it. The car came with it, so I chose to use it. But its casting quality is nothing to write home about, and if you have to RnR it a few times (which you do in order to get at ANYTHING), you will hate it.

The 400 running on a 350 tune makes pretty good power, but its lean and lack top end breathing. All and all would prob work well with a different air intake and engine management.
 

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