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Topic: Cant Figure Out Whats Wrong With My Cougar!! (Read 1134 times) previous topic - next topic

Cant Figure Out Whats Wrong With My Cougar!!

i'm soo frustrated..
my car randomly desires to race. i could wake up in the morning, drive through town just fine, than suddenly it idles erratically and wants to go 30mph and i have to fight the breaks to come to a complete stop.. i might drive another 5 minutes or so and it goes away..   

i replaced my throttle position sensor.. didnt fix it..
not sure what to do next..

i love this car.. it only has 130xxx miles on it, body is fantastic..
its the 1985 mercury cougar 6cyl 3.8l
i believe the previous owner might of put a throttle body on it out of a 85 capri.
however this racing problem didnt happen until just reciently..
i checked the Koer codes, i am getting 42, 13, 91, and 93.

Cant Figure Out Whats Wrong With My Cougar!!

Reply #1 –
First off, with an over-reving engine, neutral is your friend. You may want to practice shifting to neutral so that it becomes second nature if it wants to run away.
Code 93 looks like it is pointing to your problem:
Throttle position sensor voltage too low with the Idle Speed Control motor fully extended.
The fact that you get the code 93 says it is failing while running the KOER test.
Try the KOEO tests to see if you get any TPS codes.
With the KOEO check the voltages at the TPS. Back probe the connector if you can, otherwise pierce the wire with a pin.
Black wire 0 volts (ground), orange wire 5 volts and green wire sensor voltage.
Check that the sensor voltage smoothly increases as you open the throttle without any dropouts.
Check all three while jiggling stuff to see if you can cause any changes.

By the way, thanks for not making us have to go through the "how do I run codes" for the 1000th time.

Cant Figure Out Whats Wrong With My Cougar!!

Reply #2 –
It sounds like after the system goes into closed loop, the computer then tries to provide it move air for some reason. If it can't get the oxygen sensor to get in range after switching to closed loop, it will drop out of closed loop and run on the data that it has stored already, either base settings or some that were previously learned. Without enough air, it can't speed up so it is obviously getting more air. Get the code 93 fixed and if that doesn't resolve anything, start looking for vacuum leaks (possibly a hose that has cracked). That's where I'd start anyway.

How does the engine run when it isn't doing this? I assume it stumbles a bit. If not, then idle air control and the TPS sensor sure seem like the problem area. As a safety measure, if the vehicle needs to be driven, I'd adjust the throttle body open a tad more and disconnect the idle air solenoid. This would prevent the computer from being able to command more air, preventing the speed surges, until the problem can be fixed. Safety matters more than all else.
1988 Thunderbird Sport

Cant Figure Out Whats Wrong With My Cougar!!

Reply #3 –
I don't know of any differance between the Capri and Cougar 3.8L CFIs.

Try taking the air cleaner off and setting your meter up to monitor the TPS sensor voltage.
Run KOER test and watch for when the ISC motor plunger extends and see what the meter reads.

The only connectors that could be intermittenty flakey are right there at the TPS and at the EEC. Nothing in between.

I had trouble with my 84 3.8 returning to slow idle, but I did not get code 93. I did get code 13.
I wound up putting an extra return spring on the throttle linkage. The pad on the linkage was not pushing hard enough on the ISC plunger to operate the Idle Tracking Switch in the ISC. But this would not explain the code 93.

Here is the adjustment proceedure for the ISC.
The throttle stop screw should be OK unless it was messed with.
 

Cant Figure Out Whats Wrong With My Cougar!!

Reply #4 –
I remember my tbird doing that I replaced the entire throttle body but had a donor car to do so