Okay, I've been fighting this way too long, lol.

TPS is new and tests out fine.
Bump the key and it fires right up and sounds pretty good. However, if you so much as touch the throttle, it's dead ie shuts down.
My question is does the TPS report to ECM or PROM? I have replaced the ecm with no change.
It seems the ECM? or PROM? isn't processing the info from the TPS (or it's not getting it). I have a hard time believing that two ECMs would do the same.
Any help would be very much appreciated.

 

Did it die before you swapped out the TPS? Did you already swap an ECM? That's what it looks like you did when you said "two ECMs would do the same." What's your timing set at? Fuel pressure good? We need way more information before we can help you.

 

This started with it flooding on cold starts. Assuming I had injectors leaking and replaced the set. I had replaced the FPR back about 3 months ago. When this started, I checked the FPR and it was good. Key on engine off, fuel pressure is 42lbs.
I replaced the IAC and TPS.
I switched out the ECM (using the same prom) and it did the exact same thing.
I finally just grins replaced the distributor.
Let me clarify: This all started with a very bad cold start. Had to hold WOT to get it fire up and when it did I had to hold the RPM above about 2K. After it ran for about 90 seconds, it would settle down and run fine. While it was warm a simple bump of the key and it was running normal.
After replacing the distributor, it would fire up with a bump of the key cold, BUT any attempt to accelerate it was like I turned the key off.
I got to second guessing myself yesterday, thinking maybe a wire was pinched somewhere and I tore it down completely and checked. Nothing.
I don't have it back together today. I have another hour or hour and half to go.
Timing is 6º BTDC
.

 

Well, back together. Hit the key and it fires right up. Touch the pedal and it's dead instantly. You cannot pedal it and keep it going.

 

- your cold start injector could be leaking and dumping fuel, ie it looks like you have an 87 TPI set-up
- have you checked the ohms vs temp on the temp sender to the ECM in the front of the TPI intake... they can go bad and open circuit would lead the ECM to believe it is -40C and be adding a lot of fuel
- do you have a scanner, that would be most useful to you... ie what does the ECM say is going on?

 

Sorry, I left that out I converted it to SD and did away with the 9th injector. I also replaced the temp sensor. (below the throttle body). I don't have a scanner nor the ability to use it. Since this all started after every attempt to fix it, the last go around it set a code of 43 when I jumped the ALDL.

 

When you replaced the distributor, did you keep the same ICM or did you replace it at the same time?

Also, how old is the fuel pump? I assume you have a fuel pressure gauge. If so, what does the fuel pressure do when you try to rev the engine? Have you replaced the fuel filter recently?

 

Unplug the MAF sensor and see if the problem clears.

 

He said he switched to SD. No MAF.

 

Not having a scanner, the next best thing is a DVM and to start checking things.

Did you ever check the ohms vs temp on the old/new CTS? If the sensor checked out good against the chart, then there was no point in changing it. I would've checked the connector going to the CTS for the +5v reference and if the ground wire had good continuity to a known good ground. The CTS also shares the same ground as the MAP and could be checked against that as well.

While this doesn't have anything to do with the current issue at hand, the code 43...while it seems you've been very thorough converting the '87 MAF engine to run like a SD '90-'92. Just an FYI, '85-'89 used a 100k ohm knock sensor in conjunction with a ESC module. Converting to '90-'92 SD, you'd eliminate the ESC module and change out to a 3.9k ohm knock sensor. Having the wrong KS would trigger the code 43 which would make the engine feel sluggish as it would run with alot spark timing removed.

Have you backed probed the TPS and made sure while opening the throttle the volts increase smoothly and decrease smoothly when closing?

 

Replaced the distributor complete. Just to be sure, I took ICM to a local place that has a tester, and it was fine.
Fuel pump is about 18? months old and key on engine off it has 42lbs.
The fuel filter has been on it for several years, but I've only put 1,100 miles on since put it on.

 

When I put this all together some 20 years ago, I replaced the knock sensor with one for the 92 Camaro.
I just replaced the CTS. The old one tested the same as the new one, but I had the new one, so I put it in.
The TPS is new but just to be on the safe side I checked it and it's .54 resting and the increase/decrease is smooth.

 

Is there a way to verify the information from the TPS is getting to the ECM?

Well, went out to the garage and was going to see how it started and it wouldn't. Wonder what carb and intake would be best for this?

Found why it didn't start, the coil wire wasn't snapped down on the coil and it was jumping fire to the plenum.
Here's a video that may help?

 

Well, d*mn it. Went back out a little later thought I would start it again and it would not start.

 

when you try and crank is the tach needle moving at all? if not the ICM inside the distributor housing is likely bad (assuming you have everything connected)

 

No tach. Everything is connected right. I had the ICM tested even though it was new and it was fine.

 

When installing the IAC and TPS did you set the idle air for the IAC and voltage for the TPS?

IAC and TPS Adjustment - ThirdGen.Org

 

it is hard to diagnose if you can't observe what is actually happening

since it won't start seeing the tach signal would help, but have you also tried checking with a noid light are the injectors now even firing?

 

Yes they both were set. Thanks for the link, it's more clear.

 

I don't have a noid light.

It's made me feel really dumb and I built this car from the ground up.

Here's basically what has happened.

Went to start it one day and it flooded and wouldn't start.
I double checked the FPR even though it was only about 90 days old. It was fine.
Assumming, I had injectors leaking and with them likely being in the engine since 1987, I felt it wasn't a bad thing even if that wasn't the problem. So, I replaced them.
When I had it back together, it wouldn't start or run unless I started at WOT and backed off to about 2,000. It would run like crap for about 90 seconds and then level out. Once it did that, I could shut if off and restart with a bump of the key. However, it had a bad hesitation.
Thinking I must have pinched a wire somewhere putting it together, I pulled the whole thing back down. Nothing?
I replaced the ICM, rotor and cap thinking it must be an ignition issue. I put it back in and it made no difference. Brother was over and he suggested the pickup in the distributor could be failing. So, I ordered a complete distributor and put it in. Fired right up but still had a hesitation. Idled fine.
Next day, it started (still bad hesitation) but idled fine. I rechecked the TPS to be sure it was still okay. I had replaced both the IAC and TPS early on it this saga, but it was still at .54 closed throttle.
Tried to start it again 3 hours later and it wouldn't start and was popping like it was out of time? WHAT??
I have a set of plug wires on their way and a new coil sitting on the bench waiting.

Oh! I also changed the ECM. But I used the prom and Moates adapter in the second ECM. No better.

I keep thinking that maybe something failed in the PROM and or adapter?

Somewhere along in this process it set a code 43 which I understand is knock sensor trouble code.

I hate just being a parts changer and I feel like that's what I have become.

 

Been following this from your other thread...since you started putting this thing together back in '03, has this driveability issue always been an issue or did it run great back in the day then the issue reared it's ugly head??? Was the cold flood starting always an issue? Just trying to get an idea if it never ran right which leads me to...

Couple of other things...are you using an aftermarket harness? i.e. Painless Wiring

1. Reason I bring that up, in the past I've read that they don't exactly make their harness to factory spec. Someone smarter than me can enlighten us, but I don't see any issues with taking every ground point and connecting to a single ground point.

2. Being you're doing a retro into an older vehicle, does the harness employ a park/neutral switch. This is important for proper IAC control but I don't see this to be a contributor for the off idle stumble.

3. Same deal with #2 but are you employing a Vehicle Speed Sensor (VSS)? I know on my C4, PO installed a T56 and never hooked up the VSS which created a engine stall during decel coming to a stop which once again has an influence on IAC control.

As it has been mentioned by others...it would be great to be able to see the scanned data but your second best tool is a DVM. You can check all the listed wires key on engine off down in post #2 last 3 diagrams. You can also do the same key on engine on once you get it started.

 

when you replaced injectors, what did you use?

many injectors, even with "nominal" same #/hr actually flow differently, have different response to battery voltage and pulse signal and require some tuning adjustments to run properly... this though wouldn't cause a bad start since you have already at least had it started

not sure when you replaced the distributor in the recent sequence, but are you sure on the timing and position... did you get all the wires back in the right spot vs being off one way or another, double check... are both connectors to the ICM connected

after checking distributor since you can't even get it started now even stumbling to turn over, i would go back to the basics first ... fuel, air, spark
- fuel pressure, is it correct and does it stay correct, keep the fuel pressure gauge hooked up and watch, get an extended one if needed so you can put it on the windshield
- are fuel injectors firing, go to parts store / summit racing and buy a noid light and unplug an injector and see if it is firing
- you may not have the correct air, but obviously you have air and can control this with your accel pedal during start up
- get yourself a cheap tach at the parts store and wire it up... if it doesn't move while cranking almost certainly your ICM is bad

also getting a scanner would eventually help as well

just throwing parts without thinking things through and verify with some amount of data is going to be frustrating

 

Well, when I first built this car I went to a salvage yard and pulled a harness from a 92 Z28 brought it home, laid it out on a 4x8 piece of plywood. I used the pin outs 'chevythunder' had out on his web page, and removed everything that wasn't tuned port injection. I sent the PROM to a friend in Utah and removed things I didn't need or want and sent it back to me. When the time came to do or die, I got in it, hit the key and boom ran like a new car.
Today I put a new coil and new plug wires on. After a couple tries and moving the distributor it started. Still only runs at idle and even then, it will run for about 30 seconds and begin to die. Touching the pedal just speeds up the dying process.
The fuel pump is external and has been on it a couple years.
Tomorrow I'm going to try to get the fuel pressure gauge on it and see the pressure drops as it dies.
I'll recheck the TPS as well.

You guys' input is greatly appreciated.

 

Have you used a timing light to verify the timing? unplug the single weatherpack pin connector (the one usually above the ac box on the 3rd gen) and your timing should be set to 6 degrees advanced

try and lock down on some specifics so you know for certain fuel pressure ok, base timing ok, etc, etc... if you don't get some of these things in the for sure correct column this is going to be very frustrating chasing ghosts

 

Well, yesterday I pulled the dist cap. got it up on number one and noted the rotor position. Ran the plug wires and triple checked them. I installed a new coil as well.
Tried to start it and nothing.
Called it a night to get away from it for a while.
This morning I put fuel pressure gauge on it
Checked the TPS again (still .54).
Moved the dist a little several times and it finally fired up, but again only at idle. Ran about 10 seconds and died. So, I advanced the timing a little more and it stayed idling. FP was 42 key n and 37 running.
I have set the timing at 6º several times through this nightmare, lol.
Car has a one wire alt that requires 8 or 9 hundred RPM to start charging so every attempt to start this thing has now pulled the battery down. I put the charger on it and now I rest.
I keep thinking that somehow the ECM or PROM isn't seeing the TPS or can't interpret it. I would consider getting someone to burn a new or sort this one out.
Two different ECMs did the same thing so I don't believe it's in the ECM itself.
I don't want this car be as fast and quick as possible but built it to be a cruiser. Dependability is what I am after.
This morning:

 

with the car now able to idle, if you put it in bypass mode by opening up the appropriate connector, what does the timing light say your base timing is set at?

are you sure your balancer and point line up at zero when you physically confirm you are at the top of compression stroke on #1? (ie has your balancer spun for example and you are being fooled by what you think the timing is?)

 

Been following along with your saga and want to give my .
I think it's time to get the proper ALDL cable, a laptop and download Tuner Pro RT or a similar software. You will be able to see in real time the input from the TPS and all your sensors. You asked about correcting your chip/prom you had made and you will need to data log the information from TP RT or it will be just taking a stab in the dark. kinda like what you are having to do now. This will also help you in the future with other issues. It is a learning curve to get this going but all the info is in the DIY Prom section on this forum. I new engine tune cannot be done without a datalog. The change to your original prom you had done was probably just to get the vats out and maybe other basic stuff to make it run.

Alan asked about your injectors and I did not see where you answered on the Brand and #hr rate. I assume this is a 5.7 so you should be using 22#hr injectors preferably the Delphi direct replacements. You said it all started by a flooding start. The injectors were changed on a assumption so we could be chasing part of the original issue or if the wrong injectors were used it is a new issue created by the injector change.
"When I had it back together, it wouldn't start or run unless I started at WOT and backed off to about 2,000. It would run like crap for about 90 seconds and then level out. Once it did that, I could shut if off and restart with a bump of the key. However, it had a bad hesitation." This sounds exactly what happens after an injector change that needs to be properly tuned to your engine.

 

Base timing is at 6º BTDC.
I think the balancer is okay.
Thanks

 

The injectors came from "Southbay Injectors" and are in fact 22#. I changed them because of the flooding so it hasn't started since they were changed.
Your right about the chip/prom, he removed VATS, rev limiter and EGR.
It has run very well for all these years before it started the flooding thing.
I wish there were someone local that could scan and program, but I haven't found them.
And yes it's a 5.7.

Todays update: I double and triple checked everything I have done everything appears correct. It started (idle only) this morning and I checked the base timing and it was at 6º. With it running I was able to move the throttle from under the hood very very slowly and brought the RPM up as far as I wanted. It was smooth going slowly.

 

Okay, I assume the PROM dictates ignition timing? Is it possible for the ECM/PROM to fire way off time? From all I have been through with this I have come to the conclusion that everything is right except ignition timing from the ECM. I believe the ECM is firing when valves are open allowing compression to blow back into the intake. Otherwise, the issue would be constant. Part of the time it will start and run at idle but other times when it's cranking you hear the compression blowing back and simulates the distributor being set wrong.

 

Is there any chance of someone here burning me PROM for a 92 5.7 and keep it stock except for deleting VATS, EGR.

That's what I have had for the last 20 years or so and it served me well.

I know it's not how most here would do one but thought I would ask.

Thanks

 

look up member here on TGO,
Tuned Performance, very knowledgeable and reasonable with his cost

 

Can't thank "Tuned Performance" enough for the chip he burned for me. This thing hasn't been this good in the past at any point. All my troubles are gone, and I can rest easy again.

 

Did you get a chance to drive it ? Odd it never had a code 41 or 51 but fingers crossed it’s fixed for good.

 

what did you believe he had wrong to come full circle on this thread... bad injector data due to the swap to different injectors?

 

All I can think of is the eeprom lost data somehow. I’ve seen sst eeproms go dead after installed and about 3 uv EPROMs but flip in 20 years of tuning . I didn’t see the old eprom to look at data . Just started from scratch on a tune .

 

I just drove it around the neighborhood, but it seems good. I need to reset the idle again because I think I set it a little high. I need to take it out where I can hammer on it a little and see how it does. But I'm optimistic.