Engine Problem....HELP!
 

OK....today i went home for a few...and the last time i drove it the car pinged popped rattled and backfires....so i figured id change the coil wire while i had a few free mins cause i knew that was a problem. I changed it, put some new gas in it along with injector cleaner and boom the same thing happened....so i figured maybe i should get under the hood again for a better inspection. I sat there and revved it up..and listened to this thumping noise coming from the engine...i cannot explain it it almost sounds like something is loose and maybe its pinging but its a really weird noise....I really am stuck now cause this IS my set of wheels and i cannot drive the chevelle daily when it gets less than 10MPG...HELP!!!

Oh yeah the noise seems to be coming from the front of the block almost like the number 1 and 2 cylinders...
Its a 94 Z28 A4 with 60k on the clock..thanks

Cat will be gutted this weekend and New wires will go on...but i need other alternatives just incase these dont work! HELP!

If you're thinking of selling the car, let me know. I'll buy it with the knocking/pining whatever noise.

Might sound stupid, but make sure nothing is getting in the way of the pulleys and check your motor mounts too? Unless you're like 100% sure it's coming from the internal aspect of the motor.

Got any check engine lights on? Also, make sure none of your wires are touching the manifolds or anything like that. Timing could also possibly be off.


Err.. if none of that works.. drain the oil out, refill it with gear oil and slap a for sale sign on the windshield. :wink:

I have not thrown any Check engine light or anything....what are the odds that maybe my wires are just REALLY bad...this weekend i will be changing the wires, plugs, gutting the cat...so any chance this may fix it? Could this be a sign of a bad opti? Thanks

And Ian.... Ryan Kelly from HHS (my roommate) says "HI"

If it hasnt been mentioned already, check the plugs. I had a similar problem once with my 305, and the back two plugs were ruined.

HOLY CRAP! I haven't talked to him in forever! Tell him I said whats up.

Sounds like the opti-spark to me.

knock sensor or harmonic balancer even? Forgot to add those 2.

Thanks for all the ideas....as soon as i get home ill be trying all these things...I plan on gutting the cat, new 02's, new plugs, new wires, and a fresh tank of gas with some 104 addative. Lets pray....and if all else fails ill be ordering the delteq system for next weekend.

Hey slow 88 you dont happen to work over at the welding shop in fieldsboro do ya?

THanks again

Ok...did some work...and heres what happened...
Put on:
New plugs
New Wires
New 02's
did an !cat (was clogged beyone belief)

Heres what goin on:
The pinging is GONE! But...the stumble is still there. The only problem is that the stumble is only there off idle to 2,000 RPM's and then its gone! It hauls Butt after 2,000 like it has never done before. Sounds AMAZING! I still have an arc coming from the coil area (couldnt tell last night it was DARK) I am going to switch out my MSD coil to a stock one i have and see what happens...any more ideas? thanks!!!

Fuel filter?
Hope it's the coil. Check the engine grounding straps or just run your own engine ground from a valve cover bolt. See if that helps.

Fuel Filter was changed about 3 months ago....wasnt the coil I switched to a stocker and still did the ****, youre the 3rd person to tell me about a damn engine ground so im gonna try it...lol! :lol:

Check your maf sensor( could be dirty esp if you have a K&N). Also what's your coolent temp. You need at least 180F, otherwise your car stays in open loop mode

Might want to check your info.....the car will stay in open loop until the o2 sensor warms up, doesn't have anything to do with the coolant temperature.

- Justin

Last time I checked , and this comes from the service manual
"coolent tempature must attain 176F before going into closed loop mode.
The PCM ignores the O2 signal until car reached operating temp. Get yourself a scanner and you can see for yourself.

I'd bet the stumble is from a clogged EGR valve. LT1s are notorious for that, especially over 50K miles.

How do i check the EGR? Cause if its no tools needed ill go out there now and check it otherwise gotta wait till saturday