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Discussion Starter · #1 ·
I made the usual throttle body upgrade for my '93 1.9 liter LX to the '97-'02 type. Since then, I've had a rough idle with the engine surging approximately 300 RPM, up and down. It will sometimes level out for a few seconds @ 750 RPM but then go back to revving up and down. After a few minutes of this, the engine will often die altogether, also often doing it at stops. I've chased all the usual possible vacuum leaks with no improvement. I've pulled my hair out to the point where there's none left. Note, it's also thrown codes of 181 and 186. Please somebody help!
 

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I dont know if it makes a difference but out of curiosity which tps did you use? The 1.9 or 2.0 one?
 

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181 Fuel system lean at part throttle Single, Right or Rear HO2S - Fuel control

186 Injector pulse width longer than expected or Mass Air Flow (MAF) lower than expected - Fuel control

Clean your MAF and see if that corrects the issue. Please use the correct cleaning fluid as using the wrong one can damage the MAF.


John
 

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Discussion Starter · #7 ·
181 Fuel system lean at part throttle Single, Right or Rear HO2S - Fuel control

186 Injector pulse width longer than expected or Mass Air Flow (MAF) lower than expected - Fuel control

Clean your MAF and see if that corrects the issue. Please use the correct cleaning fluid as using the wrong one can damage the MAF.


John
Cleaned it properly, no improvement.
 

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Discussion Starter · #8 ·
I tell you what, guys, this is driving me nuts. A little background: I've been am ASE Master Tech since 1980. I've been a shop foreman in Ford and Lincoln stores. I've got a set of the Ford CD shop manuals used by the dealerships encompassing 1992 to roughly 2000. I've followed the pinpoint tests working with a Ford breakout box step by step. The reason I asked the question here was to see if anyone had had the same problem before and what their solution was. There's something here that's hiding. I've confirmed a failed PCM recently but the new one did not correct my problem.
 

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I have a 94X that will start up easily, can be driven as long as you have your foot on the gas, and runs up to 70 nicely; BUT once you let it idle, it will run poorly for a few seconds, and die. Can always be restarted immediately. A compression test showed above 150 psi for each cylinder, testing with the throtte shut. I have replaced most of the usual stuff - except not the coil pack yet. I also replaced the PCM; first with a used one from ebay, then with a 'refurb' from rockauto, with no difference. It occurred to be that I may have a bad connection in the wiring harness.
I also have another idential 94LX wagon, that runs well and gives up about 39mpg on the interstates. Too bad there is no easy way to swap the wiring harness from the PCM to the rest of the car.
 
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