Eec iv ???

[70bucks]

Bronco has been parked for a year or so. Pulled is apart painted, reworked the gauges and seats etc. Now that it is reassembled the check engine light doesn't come on when the key is turned on. It drives fine for 30 minutes or so, then misses and wont run past 2000 RPM or so. After it sits a while its fine.

Haven't pulled codes or anything yet, I figured I would deal with the light first.

Anyone got any ideas where to start?

 

[Viperwolf1]

Check engine light is simple. One pin should have 12V when EEC relay is on. Other pin gets ground in computer on pin 17. Make sure your EEC ground is good then troubleshoot the light. Once light works you can pull codes to begin troubleshooting of other issues.

 

[70bucks]

Light is functional, I jumped it with 12v. Not sure why it would not be receiving signal input from the EEC

 

[Viperwolf1]

It needs the 12V from the EEC relay and it needs a good ground at pin 17 of the computer. Computer needs a good ground to make pin 17 become a good ground.

 

[ransil]

Light is functional, I jumped it with 12v. Not sure why it would not be receiving signal input from the EEC

+12 v should always be at the light/indicator.
When the EEC finds a fault it will ground pin 17 of the eec to make the light /indicator illuminate

 

[70bucks]

All right I have 12V to the light. I grounded the other leg and the light illuminated. These two items are eliminated.

I had the computer harness apart checked 20, 40, 49 and 60. All three had good ground with less than .4 ohms.

Any ideas where I might look next?

 

[Viperwolf1]

How about continuity in the harness between the bulb and pin 17? If it's good the ECM may be bad.

 

[67EB_in_619]

dont assume its the EFI causing problems...
do you have a fuel pressure gauge? do you lose pressure when this happens? Kinda sounds like fuel tank contaminates getting sucked in.. then when sitting, it releases and floats around again.

Does the problem happen when the engine is warm only? (195*)? Let is warm up in the driveway.. does it idle like shit once its warm?

 

[ransil]

skip the light pull codes, if you cant pull codes then it related to the indicator