I'm almost complete with a swap from carb to a 350 TPI MAF setup. I put the key in the ignition and turn it to the on position and I have the fuel pump wired up correctly, I hear it prime for 2 seconds... I turn the engine over, cranks over fine, with the new battery anyways... I used a noid light on the injectors and it flashes while cranking, and I even get it to start for a few seconds. However, it runs horribly, it idles some but if I hit the throttle and let it go back down, the engine dies. Also, when I turn the ignition to the on position the check engine light comes on for 2 seconds, during the pump prime, and then it goes right back out again although the engine is not running or being cranked. I know this light should be on while the key is in the on position if the engine is not running. I have checked the black/white grounds at the ECM and found them to be good. Obviously the check engine light works and it does fine during a jumpered connection at the ALDL. Also, in the couple of minutes that I actually ran the car, it did throw a code 33 and 34. Obviously the ECM is at least partially working. However, I decided to go over to my local parts wholesaler... aka junk yard.. and picked up an ECM out of an 86 TPI Camaro. Brought it back and......, SAME PROBLEM... I have tried this with a stock chip and an aftermarket version and it is the same either way. Although, it is possible that both units are bad, it is even MORE possible I just screwed something up along the way. I'm hoping someone here might have encountered a similar incident in the past. Any suggestions are appreciated.

 

in my factory service manual for a 1992 TPI, codes 33 and 34 both refer to the MAP sensor. Your engine has a MAF instead, so I would suspect that the MAF is the problem.

 

Has someone done some rewiring? The SES lamp is not acting properly at all.

 

Yes Vader they have. When I said that this was a conversion, it has been one that I have learned a great deal from and one that I almost regret doing. I picked up a harness early on off of Ebay but it turned out to be for an 85 setup... I then went with a harness from a guy that had cut some of the wires.... Well, when I got it, it was hacked up pretty bad where it went in through the passenger side into the interior. Looked like someone took the plastic inside the wheel well out and then just cut the bulk of wires and then removed the harness. So when I got it, it was in two pieces. Most of the wires were easy to reconnect, which I did one by one soldering the connections as I went.... Every single one I used the schematics to locate the termination points of each wire at both ends and then used a test light to make sure that I didn't get any of the wires that were of the same or similar colors crossed. In the end, I did locate where I had two gray wires crossed (the egr gray wire and the O2 sensor ground's gray wire) I corrected this after the fact. I then went through and doulbe and triple checked every wire against the schematics again and tested all of the grounds. I'm not saying I couldn't have missed something, but I don't see how. Anyways, I have tested and retested and when I couldn't test anymore, I tested in my sleep. Every where that should be juiced has juice and everyone that shouldn't doesn't. The fuel pump primes, the car will crank on the first bump but then it immediately dies. If I keep my foot on the accelerator I can run it above about 1500 RPM's but it is amazingly rich. Also, it throws the codes I mentioned 33 & 34 in a very short amount of time after the engine cranks. I've hooked up all of the vacuum lines as of tonight and it still will not idle. Oddly enough, I was able to get the car to idle for about 10 minutes last night when it was still on ramps. During this time, I hooked up the timing light and the timing was about 8 deg. BTDC with the ESC disconntected. It sounded pretty rough but it would idle in the 600 - 800 RPM range. Oddly, when I took it off ramps it wont even begin to idle without my foot on the gas. Obviously, I'm concerned first by the fact that the check engine light doesn't stay on while the key is in the on position which makes me wonder if I don't have a crossed wire, which is possible. If so, I'm not sure which one(s) would cause this problem. Secondly, I'm concerned by the fact that the engine will not idle. Oh, I did forget to mention that if I hold the throttle open under the hood to keep it running, I can idle it back some and almost get it to where the throttle is within 1/4 " of the throttle stop screw. During this time the engine will rev up and down in surges like it is searching for an idle speed. I haven't started testing the TPS yet but will do so over the next couple of days. If this were carbed I would think it was a major vacuum leak, but that wouldn't explain why it would idle last night briefly while on ramps. I'm also going to test Fuel Pressure just to make sure but the fuel pump on there right now is an external mount T-Rex and should be supplying plenty of fuel pressure. Oh well, that's were it stands.

 

Hey still needing help here if anyone has any ideas,...

 

First I would clean the IAC & TB, then set the min. idle air. Then I would test and set the TPS, 5.4V.
If that dose not work for you.....mine did the same thing (but mine would not start after motor was hot) after alot of testing with my volt meter it ended up being the COOLANT TEMP. SENSOR & KNOCK SENSOR, I put the new sensors in, turned the key and it runs tip top.

hope this helps you.

 

I'll give the IAC cleaning a try. I've already cleaned the throttle body about as much as I can. What impact would the EGR solenoid have on the car idling when it is first started? How would the coolant temp sensor impact it? I've already got a new coolant sensor but the knock sensor is original.

 

Any idea though what would cause the Check Engine Light to not stay on with the key in the on position?

 

The only thoughts on the SES are that the ECM is locking up (not clocking) and running the engine on the backup resistor values. The 1985 TPI harness is not at all the same as '86-89. The harness with all the cut wires was not from an '85 also, was it?

 

Thanks for the reply... No, this harness is from an 87 T/A.

I noticed something tonight. I was able to get the car to run tonight some. However, it would only run if I turn the torx screw in the throttle body almost all the way out so that the screw is at it longest and it set the idle up to well over 1000+ RPMs and the exhaust smells VERY rich. I took a little carb cleaner and quickly sprayed around the runners and the idle picked up so I'm guessing I have a vacuum leak. I will look at that more on Wednesday.

Now here's the key though. As soon as the engine starts, the check engine light comes on. However, it didn't throw any codes. Weird huh??? Now, I know that the computer grounds the connection for the check engine light internally. I'm just wondering if maybe I'm getting juice when the engine runs to that circuit somehow. Perhaps the wire for the ground on it and a wire supplying positive voltage in RUN is crossed. Maybe one of my ground wires has somehow gotten connected to positive voltage in run but it would seem to me that if that were the case though, the injectors wouldn't fire at all would they? Nor would it even remotely run. Any thoughts???