243,720 mile misfire! Help!

[Scarano]

Re: 243,720 mile misfire! Help!

Congratulations on so many miles!

Yes, congrats! I find if you own the car since day 1 and take proper care you will usually get high mileage. My other car is a 95 Grand Am which I had since day 1 also... I have 257,500 miles on that (roughly 414,000 Km) and still going well. I think if I wanted, I could probably drive it for at least anotyher 50k or more. My engine light is also goofy, been that way for years. The only thing I have an issue with is a slight knocking sound from the engine, which has been happening for at least 3 or 4 years... I have a faint memory of a mechanic once telling me it had something to do with a "valve" issue and that it would be a costly repair. So I never bothered with it. Mind you it's no Firebird so if it were I would have probably been more inclined to do something about it.

Sorry I don't know what could be causing your misfire but hopefully it won't be anything too costly or serious.

[R1up0n1]

Re: 243,720 mile misfire! Help!

oh yah, 150-155 psi compression kinda seems low to me, but it might just be
because your engine has a decent amount of miles.
My engine (before it died on me) was showing compression of 180 psi, which still might be a little low (32k miles).

well 100 is the minimum psi....however I think 150 psi on the 3.4L is what it's supposed to have.

sorry, didnt realize it was backfiring
reasons for backfiring:
1) bad egr
2) incorrect ignition timing (wtf?)
3) vacuum leak
4) bad valve springs or stuck valves
5) intake air (vacuum) leak

Well the only thing left is timing, and bad valve springs or valves.

Is there a way to test timing?
I bought a light, but I can't see anything when I shine it on the pulley.

[R1up0n1]

Re: 243,720 mile misfire! Help!

bump! any thoughts???

[2K3800CAMARO]

Re: 243,720 mile misfire! Help!

DEFENETLY COIL PACKS , Measuring them dont mean crap.....i had a misfire on Cyl#5 and i brought my coil pack to a shop and they tested it and said it was good and wanted me to buy new injectors. Went to Advance Autoparts got me 3 new coil packs and WHAM my car was back to 100% !!!!

[R1up0n1]

Re: 243,720 mile misfire! Help!

DEFENETLY COIL PACKS , Measuring them dont mean crap.....i had a misfire on Cyl#5 and i brought my coil pack to a shop and they tested it and said it was good and wanted me to buy new injectors. Went to Advance Autoparts got me 3 new coil packs and WHAM my car was back to 100% !!!!

It's not the coil packs! Read my list....I replaced the ICM, and all 3 coil packs....still not it.

Here is a list of everything I've replaced in no particular order and it's still not running right.

1. All 3 coil packs
2. (ICM) Ignition Control Module
3. All 6 spark plugs
4. All 6 ignition wires
5. (IAC) Idle Air Control Valve
6. O2 sensors
7. (TPS) Throttle Position Sensor
8.. Fuel Filter
- Fuel pump tested fine
- All Vacuum lines tested fine
- Camshaft Position Sensor tested out fine.

Compression Test:
-Cylinder 2 = 150 PSI
-Cylinder 4 = 152 PSI
-Cylinder 6 = 150 PSI

I bypassed the EGR Valve

[CDNFB]

Re: 243,720 mile misfire! Help!

Maybe your timing chain tensioner guides are worn out and the chain has either skipped a tooth on the gearset or is really loose and the cam is hunting (due to chain loosness) 250k is a lot of milage for the timing chain system. Have you changed the chain or chain guides yet?

[slow6]

Re: 243,720 mile misfire! Help!

DEFENETLY COIL PACKS , Measuring them dont mean crap.....i had a misfire on Cyl#5 and i brought my coil pack to a shop and they tested it and said it was good and wanted me to buy new injectors. Went to Advance Autoparts got me 3 new coil packs and WHAM my car was back to 100% !!!!

coils do not cause backfires, good try though

[R1up0n1]

Re: 243,720 mile misfire! Help!

Maybe your timing chain tensioner guides are worn out and the chain has either skipped a tooth on the gearset or is really loose and the cam is hunting (due to chain loosness) 250k is a lot of milage for the timing chain system. Have you changed the chain or chain guides yet?

I have replaced the timing chain and the guide twice. It's been about 30k miles since the last one.

However The first time I changed the timing chain it was so loose I was supprised it never fell off. 20k miles later for the 2nd time I had to replace that timing chain cover gasket and that chain was loose again! I replaced it for a 2nd time. Maybe this chain is already worn out since it's been 30k miles now. Cheap @ss advance auto parts timing chain...

I do not recall the car ever running like this before with a loose timing chain, but maybe something is really loose.

[slow6]

Re: 243,720 mile misfire! Help!

what made you decide to change the chain? visual inspection? or something else?

[Tyler]

Re: 243,720 mile misfire! Help!

I got the same problem.. MAF Sensor maybe? thats my next try

[R1up0n1]

Re: 243,720 mile misfire! Help!

what made you decide to change the chain? visual inspection? or something else?

Yeah, I had the water pup go the first time, and decided to check out the timing chain while I was at it. Then the 2nd time the timing chain cover gasket blew.

I got the same problem.. MAF Sensor maybe? thats my next try

I don't think the 3.4L has a MAF. but maybe I'm wrong...

[R1up0n1]

Re: 243,720 mile misfire! Help!

FOUND THE PROBLEM!!!

I took back the 3 new coil packs and those $h!tty Xact spark plug wires to advance auto...and I put the original 3 coil packs back on. I ordered a set of AC Delco plug wires, and that fixed the whole problem! So in the future don't run any aftermarket plug wires on that car unless you have an MSD or something.

All that time and money wasted... who would think you'd by a set of bad spark plug wires!
Now I need to figure out what's wrong with the high idle...I took the air intake filter cone off today and stuck a book in front of the hose and the engine didn't bog down too much, so I'm thinking I may need to replace the air intake gasket....which means tearing off the whole top of the engine. Other than that the car is running perfect again. I'm at 243,985 miles now....I think it will make it to 250,000+ then on to 300,000+!!!!!!!!

[slow6]

Re: 243,720 mile misfire! Help!

OE bearings are rated at only 150k miles

[R1up0n1]

Re: 243,720 mile misfire! Help!

OE bearings are rated at only 150k miles

Well I'm way past that! lol...I'm at 244k miles and it's running so smooth.

[Scarano]

Re: 243,720 mile misfire! Help!

FOUND THE PROBLEM!!!

That's great to hear man. I hate these hard to diagnose problems, so after a lot of hard work (and money spent!) it's a relief to come to a solution. I wonder how many people eventually got rid of their cars thinking something was seriously wrong, only for it to be some simple but not overly obvious issue.