Ignition Module question

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Dec 12, 2010 | 11:41 AM

BURNSTOUGHFORD

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From: Iowa

Ignition Module question

I have been trying to figure out my truck since i bought it. It has a miss at idle sometimes and it has a light switch effect through the rpm range. It will stumble while accelerating at part throttle and all the sudden just like a switch was hit, take off like a bat outta hell.

I cant remember which is which for closed/open loop. But if its missing and cutting out, and hessitating, if i mash it to the floor the truck picks up and runs awsome. I beleive that is closed loop.

So in open loop it runs like crap most of the time, and runs good in closed loop.

I was told that there is an ignition module on the side of the distributer that can cause this. Is this true?

Truck is a

94 F150 Reg cab. 5.8l/E40D EEC 4 system

here is a link to a thread i have started awhile back about the codes and symptoms. The only code i get now is 172.

https://www.ford-trucks.com/forums/9...ome-codes.html

So is there an ignition module?

Dec 12, 2010 | 12:27 PM

rla2005

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From: Kentucky

When you mash the throttle the system goes into open loop mode. In open loop the PCM is not using the O2 signal to sense if the mixture is lean/rich. The PCM is using a pre-programmed look-up table for the air/fuel mixture.

DTC code 172 can be caused by a vacuum leak, an exhaust leak or the O2 sensor is contaminated or worn out. They do have a finite life.

To answer your question, yes there is an ignition module in the ignition circuit. But IMHO you need to resolve the DTC 172 issue before swapping in a new ignition module.

Dec 12, 2010 | 12:49 PM

88n94

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From: South Dakota

Quote:

Originally Posted by BURNSTOUGHFORD

I was told that there is an ignition module on the side of the distributer that can cause this. Is this true?

Truck is a

94 F150 Reg cab. 5.8l/E40D EEC 4 system

So is there an ignition module?

You have an ignition module, but it is located on the drivers side fenderwell. Up to about 1991, it was located on the side of the distributor.

Dec 12, 2010 | 01:09 PM

BURNSTOUGHFORD

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well i pretty sure theres no vacuum leaks as i have found a few and havent been able to detect any more. I havet replaced an O2 yet. I was told that they dont wear out on my other thread.

Dec 12, 2010 | 01:21 PM

rla2005

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From: Kentucky

Quote:

Originally Posted by BURNSTOUGHFORD

well i pretty sure theres no vacuum leaks as i have found a few and havent been able to detect any more. I havet replaced an O2 yet. I was told that they dont wear out on my other thread.

Yes they do wear out. Either because of age or some other issue that can contaminate or otherwise damage it. Reference this from Ford Fuel Injection » Oxygen Sensor (HEGO)

Dec 12, 2010 | 01:25 PM

BURNSTOUGHFORD

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I understand that they do go bad, im not getting a code for mine. It was thought on the other thread that they are reading correctly that the engine is lean. But i could swap one. Im up for anything, i just dont want to spend 1k to fix the damn thing.

Thanks

Dec 13, 2010 | 10:27 AM

BURNSTOUGHFORD

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From: Iowa

What components does the engine look at when it goes into open loop? At least i can be sure that they are okay.

The truck only gets about 8-9mpg. Its a Reg cab short bed 5.8/e40d with 33 tires. And the speedo is dead on for mph.