Intermitent Check Engine Light

[thewily1]

Greetings all...have a few questions about a recently purchased FSB. First, just yesterday, in the process of positioning the vehicle to check the tranny fluid, the check engine light came on for about 5-7 secs and went off, and then about 2 minutes or so later came back on for literally a sec and then disappeared. And then this morning, driving down hill on the interstate, it came on for about 4 secs and disappeared, and has not reappeared. This appears to occur intermittently, always while the vehicle is running, whether the vehicle is in gear or not. Has only happened a few times and just started occuring yesterday. Any ideas??? What brought this to my attention, initially, was the fact that the engine, in park, is showing a tendancy to surge--revs cycling from about 800 rpm to 1400 rpm. Which leads me to my second question, why the surging? A little history is in order I guess. The vehicle has always been a little hard starting, since I've had it at least. This issue turned out to be the result of several things, each compounding the degree of the problem. Thus so far have replaced the following: starter, IAC, new battery, cracked exhaust manifold. But still surges in park. Thanks in advance.

 

[Shadow_D]

Your "looping" problem is caused by the EGR Valve and solenoid. You might want to do a full tune-up on it as well (cap, rotor, plugs, wires, air filter & O2 Sensor)

After you replace all that I mentioned you need to clear the coeds from the computer by un hooking the battery for 5 minutes.

After that you should be good again, she should start easier as well.

Good luck

 

[avp12304]

I'v got EXACTLY the same 2 problems, when i start mine after the rpm's jump around till i throw it in gear, and my check engine light comes on and stays on for a few days at a time then shuts off, then comes back on again a few days/weeks later....

 

[tveronee]

Shadow D is right it sounds to me like an EGR problem too. A quick way to check it is to remove the vacuum line to the EGR diaphram while its messing up. If it quits thats your problem. I just recently got my first Bronco its an 83 with a carburated 302 but Ive been playing with the EFI 302s in Mustangs for quite some time. The components may look a little different but they opperate the same way. Good Luck man.

 

[Streetgang44]

Have you checked to see what codes you have. If your check engine light (CEL) is working....and from your post I guess it is......all you need to do is make up a one wire jumper with two male connectors on it.....connect it......count how many times the CEL flashes....VERY easy....thats KOEO (key on engine off). You can also run a KOER (key on engine running) test to check for drive-ability problems/codes.

If you need/want more detailed instructions on running a KOEO or KOER test, and how to decipher what the two and three digit codes mean, just email me, or ask here....

 

[jc]

I think the problem is your TPS throttle positon sensor.