Titan85

iTrader: (1)

Hey guys, I recently acquired a 1992 Z28 Convertible with the 305 TPI. It ran pretty bad when I picked it up. The cat is clogged up (blows black powder out). At first it would not idle, then it would only crank but not start. It has spark.

The check engine light is on, but flickers from time to time. I got it to flash code 14 and 15 which are CTS related, then the light flickered and it went back to code 12. I know that it had not completed the flash cycle because it only flashed 15 twice.

I believe there may be an issue with the computer because anytime the key is on, the engine fans run. I also noticed that it started pulsing the AIR diverter valves at random intervals when it is key on, engine off.

My guess so far is that something went wrong with the computer that caused the vehicle to run very rich and caused the burned cat. Is there a way to test the computer?

Zig

Do you have a noid light to check your injector drive circuitry? If you have good fuel pressure, VATS is good, TPS Voltage is under 2.5 volts and you have spark, the next step is to check injector drive circuits. With all your wierd symptoms, it does sound like an ECM though.

Titan85

iTrader: (1)

Unfortunately I do not have a noid light. I have fuel pressure, but I do not know the exact PSI. I got it to flash all the codes. It showed 14, 15, 21, 22, 23, 43, 46, and 53. I get 4.43v from the TPS at WOT and 0.5v when closed.

I pulled the spark plugs and they are fuel soaked and black. I have the plugs soaking in some carb cleaner and plan to put them in, clear the computer, and see what codes reset and if the engine starts. Given that the car would not even start on starting fluid, I am betting that the plugs were to wet to fire. I do have voltage to the plugs.

Titan85

iTrader: (1)

I pulled the ECM ground wires off the engine, cleaned, and reconnected them. After cleaning the grounds, I no longer have the flickering check engine light and am able to flash the codes with no issues.

After cleaning the spark plugs (only messed around cleaning them because they have less than 100 miles on them), the engine started and ran semi okay. I turned it off and tried to restart it but it only cranks again. It set codes 15, 22, 43, and 53 again. I pulled the number one spark plug and it is fuel soaked again.

I am pretty lost at this point. Any ideas?

310cid

iTrader: (1)

What was the problem u found wrong with it my car doing same

Titan85

iTrader: (1)

It turned out to be the ECM. It was throwing a code for system over voltage. After checking alternator output and voltage to the ECM, I found normal voltage. I figured that since I proved the code wrong, it must be an ECM error. Put a new ECM in and it ran perfect.