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sprinkles08
sprinkles08, ASE Certified Technician
Category: Jeep
Satisfied Customers: 21572
Experience:  Chrysler/Dodge/Jeep Master Certified, ASE Master and Advanced Certified, Trans and Hybrid Specialist
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1997 Jeep Grand Cherokee: randomly..blown..ignition coil..car ran

Resolved Question:

Still having issues with my 1997 Jeep Grand Cherokee.
While driving,it will randomly choke out and stop running,have had the experience of a backfire resulting in a blown up muffler and burned out catalytic converter.
I have had a complete tune up, replaced the ignition coil, power train sensor, 2 mufflers and catalytic converters, and have had the vacuum hoses checked visually for damaged hoses and still am having the issue of the car choking out...and it seems to do this only for me. The car ran great for two days after I got it back from the mechanic...and then it started all over again.
Any other thoughts of what I should be looking for since the first go around with asking the same question again?
Thanks!
Jeffrey Surratt
Submitted: 5 years ago.
Category: Jeep
Expert:  sprinkles08 replied 5 years ago.

Hello and welcome to JustAnswer!

 

Can you explain more about where you are referring to as "powertrain sensor"?

 

 

Customer: replied 5 years ago.

I am not sure what that is, was told by the mechanic that one of the codes from the diagnostics reader stated that it was something to that effect. I had taken it to AutoZone just prior to that and the code given stated that it was the ignition coil that needed replaced, which I purchased then and there and had put on a day or so later.

Could it be something in the engine causing this or is it coming from a different source?...the fuel pump?...fuel line?....what would cause the backfiring and residual fuel smell and ultimately ( the last muffler) to plump up like a "BallPark Frank"?

As it sits right now, the catalytic converter, which has just been replaced 3 weeks ago, has a bluish black appearance to it, like it heas eithere gotten really hot or has been heated up with a torch....

Expert:  sprinkles08 replied 5 years ago.

Do you have a bill showing all the part numbers used? The part numbers of anything used should be printed on your receipt.

 

How much was the total bill?

 

 

Customer: replied 5 years ago.

Independant mechanic....rural Texas and noone here seems to use a computer for anything...LOL....but what is a TPS censor?...possibility?

There's a website called "DyingJeep.com"....what they show is a good representation of whats happening with mine...

Expert:  sprinkles08 replied 5 years ago.

No, the TPS can't cause the problem you are having.

 

About how much was your bill when you got the Jeep back last time?

 

 

Customer: replied 5 years ago.

That bill for replacing the ignotion coil, which I provided, and the other censor was close to 90.00. Like I said, small town independant operator.

Another thought....I have noticed when Im at half tank or less of fuel, it doesn't seem to be choking up.At half tank or more, it seems to do it more frequently....thoughts about the fuel pump or fuel filter? Possibilities?...my gut is telling me to try that avenue next, but anxious about the expense.

 

Expert:  sprinkles08 replied 5 years ago.

It sounds like we're still in the same place. The P0351 is almost surely still setting. P0351 sets when there is a problem in the ignition coil's control circuit. This could be a loss of ASD feed to the coil, the coil itself, an open or short in the coil driver circuit from the PCM, or the PCM itself. The coil itself wouldn't normally give an intermittent problem.

 

They're going to need to load test the ASD circuit to the coil and the coil driver wire from the PCM to the coil. They need to load test and wiggle test the harness at the same time. If the wiring checks out ok they'll need to replace the PCM. The PCM is the cause of an intermittent P0351 on these almost 100% of the time.

Customer: replied 5 years ago.

ok....so the line of thought about the fuel pump/gas theory?

 

I will take these notes to the mechanic and see what goes. any idea of what it costs to replace the PCM?...ballpark figure?

Expert:  sprinkles08 replied 5 years ago.

P0351 and your symptoms point to a loss of spark while driving. What's happening is you are losing spark but the engine is still turning and fuel is still being injected. When the coil comes back alive there is a violent exhaust backfire when the unburnt fuel in the exhaust lights off. This is what is damaging your mufflers.

 

A remanufactured PCM from your dealer will run about $715 plus about an hour labor to install and program. An aftermarket remanufactured unit will be a couple hundred dollars cheaper. You may be able to find a decent used one for $200 or less, but if you do get a used one be sure to get one with a warranty so you aren't stuck paying for a bad part.

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