Okay guys,talking about a '86.First had a very rough idle(cold engine),flooding,no way driveable.Changed oil because of gasoline contemination.Now after a few backfires the car won't start.The former owner said that the car flooded all of a sudden while driving.Fried the starter after numerous attempts,lots of gasoline in the oil.So we picked it up and gave it a new starter.It ran like s**t and after a few backfires he won't start at all.Checked the fuel pressure,ignition,injectors(all 16,5 Ohm)plugs,cable,rotor,distributor cap.The weirdest thing is when you try to get the codes and use the ALDL jumper the coolingfan goes of and on and the coolinfan relay clicks(at random) all the time(bad connection or ground somewhere?).The SES light stays on instead of flashing 3x 12.So we used another ECM.Now the SES flashes 3x12 but no codes...thats because of the car NOT running so no codes are stored in the ECM.So we are kind of lost here.What if the temp sensor is bad(code 15)...maybe the 2 small catbacks are bad(no exhaust flow)The yellow wire on the ECM from the coolant sensor gave 2,20 Volts on the ECM.Coolant temp says low all the time(because engine is cold ofcourse)although once it jumped from over 100*C back to low again when crancking the engine.Can a bad temp sensor cause these problems?Any help appreciated...

Greetz Erik.

 

Hey there erik...

(multiple paragraphs are allowed in same post)


.The swapped ECM with no codes tells you that the swapped one hasn't gone out of open loop to closed loop, to get measurements from the sensors.

It does tell you there's a problem with the original ECM.

Disconnect the CSI and see if you can get it idlin' without floodin'.

 

Yes,sorry for the multiple paragraphs..:o

We will disconnect the cold start sensor and give it a go.

Greetz Erik.

 

Check for fuel in fuel reg vacuum line.
Check and see if there is a ground short on injector harness. The ECM fires the injectors by applying ground, if one bank or both are getting a ground without the ECM, flood city.
Check the operation of cold start valve.
http://members.shaw.ca/corvette86/Co...rt%20Valve.pdf

 

Both the injector banks are working..used a LED in each connector and we have an intermittant flashing LED.

Greetz Erik

 

one down, two to go.

 

Okay,car is running again...
The old ECM has a "level 2 F4F5" eprom...anybody familiar with these?
So we changed the spark plugs and tested for compression.All cilinders had the same value.We changed the ECM and fired right up.All the old plugs were soaking wet with gasoline and some did NOT fire..:o .
Changed back to the old ECM(with level 2 chip)and back to poor idling and flooding.We will change the eprom also to see whether the ECM or eprom is defect.

Greetz Erik.

 

Actually quite common symptoms when an ECM goes bad, starts running "pig rich". Obviously you foulded the plugs. The other symptom was the old ECM wasn't communicating. Think you definetly found your problem...bad ECM.