nomind

Okay, I'm at my wits end. Before I start, I don't have the ALDL cable to see what the ECM is actually doing. Here are the things I've replaced within the last 2 months:

Distributor - Timing set to 6* unplugged
TPS set to .54/.55
New plugs
IAT
CTS
MAF
Fuel injectors (same size 19# from Southbay, still have the old ones as well)
Ground on the back of the passenger side head cleaned, and bolt replaced
Vacuum lines gone through, and many of them replaced.
EGR passages were blocked. They were cleaned when fuel injectors were replaced.
I've pulled down the ECM, and verified all of the voltages as per the 870 PDF on the 165 swap upgrade page. http://www.eecis.udel.edu/~davis/z28...ody-wiring.pdf (last page)
Tested coil good.

Car will start, and instantly the idle jumps to 1500-1700. It takes about 15 seconds for it to come down to a reasonable level (~850-1000). When I drive the car, the power feels like its on/off/on/off, even with a steady pedal. The car is running rich enough to leave black spots on the driveway if I rev the motor (no cats, so I'm not killing those). If I hold a steady RPM with the pedal, the car will pop, like a mini-backfire in the exhaust combined with a miss. I am open to any suggestions, as my other car has decided to eat its clutch, and I'm effing tired of trying to fix it.


I will note that most of my issues occurred after a loose ground on the battery caused the car to go dead when I tried to start it. When I reconnected it, I got a nice spark, and the car hasn't run right since. Not showing any codes at the moment either.

87 player bird

Sounds like timing/ ignition problem, unless computer fried?

nomind

I just replaced the whole distributor. Timing didn't jump around when I set it. I haven't checked it with the distributor plugged back in. Though, dumb question, the replacement distributor used the clamp down style cap, were the original one on my car was a screw down cap. I believe I got the CC carb distributor, would that make any difference? I'm not thinking so, as there are times when the car will run just fine, though they are few and far between now. Honestly, I would be happy to find out it was the ECU, just so I could get it fixed. I'm just not sure how you determine that the ECU is bad.

vetteoz

iTrader: (13)

Did the fan run and code 12 flash 3 times up to show the ECM was in diagnostic mode when you jumpered the ALDL ?
https://www.thirdgen.org/forums/post...799-post2.html

If not possibly a problem with the ECM

nomind

Last time I pulled codes, yes it did. (Fan kicked on, and I got the code 12)

darbysan

It's possible you have a vacuum leak. That would lead to the O2 seeing a lean condition, and trying to richen the mixture up to compensate. I've had trouble in the past with the runner gaskets not sealing properly, and now use a dab of sensor-proof RTV on them when installing. Test around your runners/plenum for a Vac leak using some starter fluid. An increase in RPM's will help pinpoint a leak.

It could also be the IAC settings, but less likely. I found I had to iterate the IAC/TPS settings a couple of times to get them settled down. Changing one changes the other.

nomind

Well, I don't think its a vacuum leak. It runs the worst when its cold (open loop), once it warms up a little, it comes around to a more reasonable idle, and it doesn't want to kill you with raw fuel smell in the exhaust. I'm pretty sure that during open loop, its not using the O2 sensor. When I cleaned the ground on the back of the head, it went from so rich it wouldn't rev past 3k, to much closer to normal, so I went out today and cleaned the battery ground to engine block connection, and it was covered in oil/grease/dirt/whatever, and the bolt was not quite snug. I started the car, and after it warmed up a little, it felt like it could be driveable. I didn't have time to take it out, and we're being hit by that ice storm tomorrow, so it probably won't be until this weekend if I see if its actually working. But its almost like the CTS sensor is providing incorrect data to the car. I guess I really need to find someone with a scan tool for this thing, and have it looked at.

Oh, and as a side note, starting the car with the MAF unplugged made no real difference in how it ran, only that I got a check engine light.

nomind

Well, if I allow the car to warm up, it seems to be running fairly well now. If I try to do anything with it while its cold, it jerks and stutters. I will try to order the ALDL cable so I can actually see what is going on, but for now, it seem driveable. I'm thinking that springtime will bring ODBII time.