OK, I have an 88 Formula. A few months back I decided to refurbish the top end. I removed the upper, middle and lower plenum, fuel rail, distributor, all vacuum lines, all water lines, thermostat housing, both valve covers, coil, egr, throttle body, egr solenoid, vapor canister, battery, etc. I had all the parts refurbished (sand blasted and powder coated) and carefully put everything back together. Things that were changed: New vapor canister, new gaskets everywhere, new vacuum lines (ss ones from Rodney), bored out throttle body with matching bored out upper plenum, new dist cap, rotor, pickup, coil, dist o-ring, new battery, new cold air intake. So, everything is hooked up properly (thanks to many of you on this site who helped me with the vacuum lines). I start the car and immediately the idle is fluctuating from 1000 to 3000 rpms. Computer is sending codes 21 and 22. So, I call my friend Justin at the Fiero Store and get a new TPS. Disconnect battery, change TPS, reconnect battery and start it up. Idle is now normal (cold at about 2500 but drops to 950 when warm). However, check engine light is still on and computer is now showing a 21 and 22. Car has a serious hesitation and backfire problem upon acceleration, so I figure that I need to set the timing since I had the distributor out. I don't have a light so I take it to a mechanic who sets it at 10 degrees. Now the car is running even worse, no acceleration whatsoever. So, the mechanic advances it to where it was and tells me that there is something else wrong because setting the timing correctly makes things worse. So, since he advanced the timing, the car is running much better, no backfiring, no hesitation. Problem now is the idle is constant at 2500 and does not drop. One more interesting fact - when I get the car up to speed (40 to 60) the check engine light goes out. It only comes back on when I stop and allow the engine to idle. Once I get it up to speed again, light goes out again. Over and over and over. I know that there are members here that are extremely knowledgeable about where to look when problems occur. So, I am seeking your expert advice on what I should do next to try to fix this. I know it may be more than one thing but I have to start somewhere. I have checked all the new stainless vacuum lines and they all seem to be hooked up correctly and tight. I appreciate any help that is provided. I just love this car but hate it when it does not run right.
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07:52 PM
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System Bot
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
you should check the wiring on your tps, the connectors may be corroded. one of the crosschecks for the tps values is the map sensor reading.
when the mechanic set the timing, did he short the a/b ternmials at the aldl connector? if not, it would timer very retarded, and would explain the moving it back up. retime it properly with the a/b pins shorted, warm motor. 10 degrees avg between cyl 1 and 4.
Do you have access to an ALDL cable and software (and PC..)? I would look at the IAC count since you had the TB bored out. If the throttle plate screw has been moved, the ECM may be having fits trying to set idle. You are looking for about 30 counts at idle. Once you get that set, take a look at your BLM, see if it is close to 128. You can also see what the ECM is doing to the timing.
