I am stumped! Please help



For a while now, I have been dealing with a high idle condition that will not go away. I have an 87 GT that I bought from a guys who had it sitting for a couple of years. Initially, the idle was high and hunting but I have eliminated the hunting condition. Here are the things I have done and checked to make sure all is ok.

1. Replaced Fuel sender and pump (both were not working)
2. Replaced spark plugs. Cables looked in good condition so no change there
3. Replaced the IAC with the old one since the new one did not work.
4. Replaced vacuum lines. Old ones were brittle and broken. No vacuum leaks now. checked by spraying carb cleaner.
5. Replaced fuel injectors since old ones were not good
6. Replaced EGR and tube with one from Fiero Store
7. Fuel pump holding holding correct pressure

I have tried numerous times to set the timing per the manual instructions (at least 7 times). I now have the idle from 3K rpm down to 1800 rpm. When ALDL is grounded, the timing is at 10 degrees. Once I finish setting the timing and I remove the ground, the timing goes from 10 degrees to a higher one past the 12 degrees.

At this point I need help from one of you since I cannot find the problem and I do not know what else to do. I would gratefully appreciated.


Hi Alex,
Check both the intake temp sensor and engine coolant sensor when engine is cold. Both sensors should ohm out similarly readings. You could also check temps using Aldl readings too. Thatíd be better because then you can see what the ecm sees.
https://goo.gl/images/JBjq7x ohm table.
If the readings donít match at cold, one of them has failed.
The reasoning is if the ecm thinks the motor is cold, it will keep idle commanded high and will also not allow closed loop operations (kind of like the choke is on).
The other culprits are vacuum leaks and the biggest is the egr tube. But looks like youíve addressed that already.
Hope this helps!

Awesome. Thanks. I will try it during the weekend.



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