hi_c is back... with problems

[hi_c]

RE: i

yeah, I'm back in jeepz land. I don't remember the last time I was here. My wife and I had a daughter last may. That's consumed much of my time. Anyway, let's get down to business:

I got motor problems. When the motor is at operating temp (~195*) and I'm at highway speeds, the spark-knock (or pinging) starts getting bad around 2500 rpms. If I don't let off the gas a little, the motor starts... decelerating with a symptom I like to call de-compression. It's like the motor is combusting the fuel/air mix below the piston, but then combusts again above it causing my motor to slow down with the gas pedal, rather than speed up. I can only do 55. While I'm not a speed demon, I would like to at least be able to go 65. I have a feeling it's due to blow-by because after a compression check, my #3 cylinder had a very low compression.

Any ideas (other than: change the oil, change the plugs)?

corey

 

[TwistedCU]

Congrats on your baby girl! We're expecting our 5th!

Again, good to have you back on Jeepz, sorry can't help ya on the motor though.

 

[Bounty__Hunter]

RE: 2.5L question

Have you checked the timing? Check for vacuum leaks that may be throwing the timing off.

 

[hi_c]

RE: TFI is it all it is cracked up to be?

No. In fact, I don't know how to check the timing. I changed the plugs yesterday and the oil. When I added new oil, I used a can of that Restore Engine Restorer. It says that you should notice improvements around 500 miles. So we'll see. The spark knock seems to have gone away (for now).

corey
ps. any advice on checking the timing on a 2.5L would be welcomed.

 

[geopig]

RE: Opinions on thread

I'm having what sounds like the exact same problem, only with my 91 YJ with FI. I was going to post earlier in the week but didn't get around to it. Mine has what I termed "lag" at around 2700 rpm although it has been an intermittent problem. I thought it could be a bad cat also, due to the fact that it was intermittent. But I"ll check the vacuum system.

 

[judge09]

If you have an Advanced Auto Parts near you they will let you Borrow a timing light for free and they will even show you how to use it. Very helpful people.

 

[Tug-n-pull]

Try a better grade of petro! tug