Engine Idles Rough and CEL Comes On....

Bird of Prey 94

Registered User
I have a 94 Tbird SC and when I travel about 60-70 mph, the engine starts to idle rough and the CEL comes on. The car's speed will not go past 60 mph. I release the accelerator peddle, and a few second later CEL goes off and the engine behaves normal. The engine temp is fine, and the needle stays on the “N” of normal. Two weeks ago I changed the idle air control unit. I am not sure if it is the throttle position device, a dirty gas filter, or what. I am just not sure where to look. I need help.
 
For starters get a code reader from a local auto parts store.
I believe the 94 is OBD II
Check out the TCCOa website for the error code list.

My swag is either engine balancer, crank sensor, DIS module, cam sensor, dirty MAF sensor.
 
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idle rough at 70? Or do you mean run rough?

have you changed the fuel filter ever? It's possible you're starving for fuel. I'd check all things recommended so far.
 
It could be your DIS module or cam sensor - but downloading the code will help with diagnosing the problem. Unfortunately all SC's are the old OBD-1 computers, but you can get a fairly cheap Actron code reader from WalMart, about $35 or so. It is cheaper to use a jumper wire on the EEC port/terminal under the hood and count the CEL flashes, but I'd recommend the code reader. Download the code/s and post them here for more help
 
My 94 did that last summer. In fact it did at a few times at slower speeds in town, too. I swapped the cam sensor with my 91 and it hasn't returned.
I should also note that i got codes for a few different things. Read the instructions for the test a few times before you actually perform it. You may still get fail codes for things your ride doesn't have.
 
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