87 camaro iroc-z
305 tpi 5.0L


We rebuild the transmission (T5) and put it back in. Then, when we went to start the car it would turn over, fire maybe 4-8 times and would die. We've checked fuel pressure both at the "on" position and during cranking and according to the shop manual it is ok. We've done the test with a wire in the diagnostic connector and it keeps flashing 12. We then unplugged sensors to test the ECM and it still only flashed 12. So, we replaced the ECM and tried again. Nothing changed. We've checked the starter- working and properly grounded. We've also checked most of the circuits- all working properly. We checked the cold start valve- works (injector light stayed on when plugged into it during crank).
When we went to check the fuel injectors with a test light, it would not flash. This is (according to the shop manual) supposed to flash a code error, and it isn't. We also checked the circuits for the fuel injector system- they work properly and are grounded correctly. The spark plugs fire properly.
We are completely out of ideas. Any tips or advice would be really helpful. Thanks.

 

1. Fuel
2. Spark
3. Compression
4. Timing



what is your timing set at?

 

Were you using a noid light for the injectors or by hand?

Try unplugging the MAF or swapping the MAF relays as well.

Got fuel pressure? Does the pump turn on? You can test via the 'g' terminal in the aldl and 12 volts.

 

Thanks for the tips. We tried most of them already and they didn't work. We think the ECM isn't sending a signal to the fuel injectors.

Here's what we have tried already per the shop manual:

Diagnostic circuit checked: ok
Tested power to pins in ECM connector and ground to ECM connector: ok
fuel injector circuit tested: ok
injector noid light doen't light during crank
"fuel diagnosis" tests fuel pressure: ok (pressure equals 46- drops to 43)
crank fuse: ok
cold start valve: ok (lights when noid is attached)

When we unplug sensors (MAF, cold start) the ECM doesn't generate error codes (according to the service engine light flash test)- we only get code 12 over and over. We just replaced the ECM, however, and the results didn't change. We think teh problem is with the ECM generating the signal to the fuel injectors, but we don't know how to check on this (manual just says replace ECM).
For the injectors to fire, certain checks are done by the ECM:

pulse from distributor
throttle position
coolant temperature

These are the only test that we know of. If anyone knows of the other checks done by the ECM, that knowledge would be helpful too.

Thanks for the time and help with my problem!

 

We bled the clutch, changed all of the spark plugs, and found a sensor into the block (coolant) that was unplugged. After fixing those things, it still won't run. (no visible difference)

The spark plugs we took off had a small nub in the gap that wasn't like a standard flat spark plug (burns hotter?).We put standard plugs in (new- got them before we took off the old plugs).
Didn't help.

I'm running out of ideas. Thanks for the help so far though.

 

Thanks for all of the tips and support. As it turns out, when we took off the distributor cap we found the four-way connector unplugged. Sorry I didn't check for something that simple before, but I thought it wouldn't fire with any wires unplugged. Thanks again for the help though!

PS: Tranny runs sweet now!

 

Haha I know how ya feel man, I always over think things and it turns out to be something simple.