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jeep randomly started detonating

W

whitek8gixxer

NAXJA Forum User
Location
albuqueruqe
Recently my jeep started detonating. It's an audible pinging and i'm sure of what it is as if i switch to mid grade gas it stops doing it. I had a bad fuel pump and o2 sensor. I replaced both of those thinking it would fix the problem but it didn't. I have reset the computer. The only thing i can think of is carbon build up or timing. What do you guys think?
 
I think you need to pull the plugs and post pix of the electrodes up so we can read them. People forget that we did just fine diagnosing engine problems before computers.

There are four main things to check when you have any type of driveablilty problems. First read the plugs. It gives you a first hand look at what is going on in the combustion chamber. Second is a vacuum gauge. Vacuum can spot a ton of different problems. Third is a compression test, both wet and dry. Fourth is to pull plug wires one at a time and watch the change in rpm's. All should cause similar change.
 
BASICS?
 
whitek8gixxer said:
crap sorry. 97 4.0 auto 4x4 8.25 150k miles all stock. Will do above suggested when i get off work thanks for the insight guys
Click to expand...

Ok. Wasn't sure if you had a Renix with the anti-knock sensor. I could have a**umed you didn't by your "reset computer" comment but not everyone is aware that the Renix ECU doesn't store data (it does, however, store the count of repeated limited codes, adding and subtracting the from the count).

Old man has you on the right track. If you decide you want to de-carbonize the engine the Chrysler MCCC does a really good job.

Are you getting up to full operating temperature? 200-210 degrees?
 
joe_peters said:
Old man has you on the right track. If you decide you want to de-carbonize the engine the Chrysler MCCC does a really good job. Are you getting up to full operating temperature? 200-210 degrees?
Click to expand...

I agree that Chrysler has an excellent product for decarbonizing.

And if switching to mid-grade (increase in octane) eliminates the pinging, then carbon is a primary suspect.
 
Personally I like BG44K
 
old_man said:
Personally I like BG44K
Click to expand...

I LOVE BG44K for cleaning the fuel system, but for a heavily carbonized engine I like the MCCC.
 
It worked well for carbon for me but I will have to give the other stuff a try. I used my borescope to verify carbon removal with the BG44K
 
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