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Discussion Starter · #1 ·
My '96 Camaro SS has been running real rough for a couple of weeks now. When I start it up initially it's fine, but after it warms up it will idle real rough. As I'm driving it, it seems to do fine, but when I come to a stop it will begin to idle rough. After a while it will shut off (but I'm able to start it again). I recently pulled the codes and got a p0300 (random misfire), p1441(Evap), and p0162(O2 sensor). My mechanic did a compression test on it and cylinders 2 and 3 were low. He thought it might be the piston rings failing, but I'm hoping there might be another factor to this. Any ideas? Any help is appreciated. What else could cause low compression in 2 adjacent cylinders?
 

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Head gasket failure can cause low compression in 2 adjacent cylinders. To rule out rings, your mechanic should have poured a teaspoon of oil into the low cylinders and re tested. If rings are indeed causing low compression, the oil would have raised the compression # significantly.

Also know that a blown head gasket does not necessarily mean water in the oil. If the head gasket blew out between 2 cylinders with no oil hole or water jacket involvement, then low compression on 2 cylinders and poor running can be your only symptoms.
 

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Discussion Starter · #3 ·
Head gasket failure can cause low compression in 2 adjacent cylinders. To rule out rings, your mechanic should have poured a teaspoon of oil into the low cylinders and re tested. If rings are indeed causing low compression, the oil would have raised the compression # significantly.

Also know that a blown head gasket does not necessarily mean water in the oil. If the head gasket blew out between 2 cylinders with no oil hole or water jacket involvement, then low compression on 2 cylinders and poor running can be your only symptoms.
I'll mention it to him. Is there any way a faulty injector could cause similar symptoms?
 

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Ah..2 & 3 are not adjacent, P0300 is a misfire, p1441 says Evap solenoid is open when not commanded on, probably stuck/clogged solenoid or vacuum detection switch. P0162 is bank 2 sensor 3, not a valid code for a '96 f-body. Problem sounds like either an O2 (runs crappy when hot) or ignition related (misfire). The p1441 won't cause running problems. I'd reset the PCM to clear codes and then re-scan and follow the first code that comes back other than the 1441. How low is you compression on 2 & 3 , have you visually looked at the valve train(s) when running to make sure it's not top end problem. Failing rings show oil consumption, usually not rough running unless plug is fouled..
 

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Discussion Starter · #5 ·
Ah..2 & 3 are not adjacent, P0300 is a misfire, p1441 says Evap solenoid is open when not commanded on, probably stuck/clogged solenoid or vacuum detection switch. P0162 is bank 2 sensor 3, not a valid code for a '96 f-body. Problem sounds like either an O2 (runs crappy when hot) or ignition related (misfire). The p1441 won't cause running problems. I'd reset the PCM to clear codes and then re-scan and follow the first code that comes back other than the 1441. How low is you compression on 2 & 3 , have you visually looked at the valve train(s) when running to make sure it's not top end problem. Failing rings show oil consumption, usually not rough running unless plug is fouled..
I haven't had him to go as far as taking things apart to actually verify what the problem is. I assumed the low compression was associated with it running rough. I'm hoping to eliminate other possibilities before having to re-ring pistons.
 

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Discussion Starter · #6 ·
Found out what my problem was. It was a vacuum line that wasn't routed correctly. The line came from the purge solenoid from the back of the intake. Supposedly it's a vent line and shouldn't be connected to anything but it was connected to the distributor. Once that was corrected both the p0300 and p1441 codes went away. I drove it around most of the evening and I'll put some more miles on it during the day just to make sure the issue was gone. So far no problems.
 

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Discussion Starter · #7 ·
Ok guys, I'm having somewhat of a similar issue since my last post. Now my car is giving me a p0300 code consistently and an occasional p0301 or 302 code. So far I've gone through 2 sets of plugs and reman Bosch injectors. The car will backfire through the exhaust and run rough from idle to about 3000 rpms. I currently have an MSD opti and coil on it. I've taken it to 3 different mechanics. 2 of them mentioned that the MSD opti really isn't all that great. It would seem like the opti may be the issue but I was trying not to jump to that conclusion. Also the car is getting good spark and compression is fine. Any thoughts?
 

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Just a thought, since that purge line was connected to the opti (high or low side?) was it putting oil and soot from the egr into your opti? I know it blows but I would take off the opti and inspect it. Any of the little tiny 360 holes can be clogged causing the misfire.

FWIW I've been running an MSD opti for 7 years and 40,000 miles, it's one of the first ever made with the round PITA o ring instead of the square one, but I did loctite everything before I installed it.
 

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Discussion Starter · #9 ·
Nah, the opti hasn't been off to be inspected. I was hoping that we wouldn't have to go that far, but it seems like thats the next step. I also should mention that the egr stuff has since been deleted, but I was having the problem before it was deleted.
 

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Nah, the opti hasn't been off to be inspected. I was hoping that we wouldn't have to go that far, but it seems like thats the next step. I also should mention that the egr stuff has since been deleted, but I was having the problem before it was deleted.
I know everyone hates doing it, but in reality if you've done it once, it's only takes a hour to get to the opti, if that. And I really don't think your gonna get out of this without doing it.
 

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Ok, i googled your codes and found a u-tude vid:
- saying those are misfires in cyls #1 & #2. U got bad plugs, plug wires/shorts/grounds, opti, block injectors, water in fuel.

Good luck,
cardo
 

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Not an obd2 man, so I learned something new from the video. Namely that the pcm will cut fuel to the affected cylinder after a certain number of misfires in that cylinder. So it's important to reset the pcm and retest if you think an injector is causing the misfire.
 

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Discussion Starter · #13 ·
So just to update you guys, I've recently replaced the crank sensor and spark plugs 1 and 2 (# 2 being the worst one) because they were wet from fuel. The car doesn't backfire as much now but it's still doing it. It now seems to backfire during an upshift compared to 2500 rpms and below like before. Also the car seems to stumble through the whole rpm range instead of just low rpm ranges. My mechanic seems to be at a loss and really doesn't want to keep throwing parts at it. I most certainly am tired of messing with it at this point. My mechanic suggested to take it to the dealer to see if they have a better scanner that can pinpoint the issue, but I'm doubtful that they do. I am kinda skeptical about the problem being the opti because it hasn't thrown any codes saying could be the reason. And I also wonder if the plug wires could be the issue, but my mechanic said they looked fine. The only consistent problem that he runs into is an occasional misfire from cyl 2 and the plug associated with it always seems to be wet from fuel.
 

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I had a similar problem with mine and it turned out my header bolts were REALLY loose. It apparently was so bad that it was sucking in un-metered air, throwing all kinds of stuff off. Tightened them up and problems went away.:banghead:
 

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"looked fine" is a fairly poor diagnosis for plug wires. internally, plug wires are really fragile. it doesn't take much. you can check them for resistance to see if they're really screwy, or fire up your car at night and mist some water on them to see if you get any flashes of light.

a -spark- miss isolated to a single cylinder should be VERY easy to track down on a distributor ignition system, as there are only certain things that would be isolated to that one part of the ignition system.

those things are: damaged plug wire, misrouted plug wires, damage to that point on the optispark cap, or maybe on a total stretch, the low voltage (optical) side of the opti, but i doubt that at this point, as it would be throwing a code.

this is assuming the guy working on the car is correct about there being a consistent spark miss on a particular cylinder. i hate third hand diagnosis
 

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One thing about depending on pcm throwing a code is, sometimes there can be a problem and still no code is set. Old fashioned diagnosis still rules.
 

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Discussion Starter · #17 ·
One thing about depending on pcm throwing a code is, sometimes there can be a problem and still no code is set. Old fashioned diagnosis still rules.
The only thing with that is that this particular problem has so many different causes. I've read/heard every thing from bad O2 sensors to bad ground wire to the pcm and everything else. I really need to find a way to pinpoint the issue.
 

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Discussion Starter · #18 ·
"looked fine" is a fairly poor diagnosis for plug wires. internally, plug wires are really fragile. it doesn't take much. you can check them for resistance to see if they're really screwy, or fire up your car at night and mist some water on them to see if you get any flashes of light.

a -spark- miss isolated to a single cylinder should be VERY easy to track down on a distributor ignition system, as there are only certain things that would be isolated to that one part of the ignition system.

those things are: damaged plug wire, misrouted plug wires, damage to that point on the optispark cap, or maybe on a total stretch, the low voltage (optical) side of the opti, but i doubt that at this point, as it would be throwing a code.

this is assuming the guy working on the car is correct about there being a consistent spark miss on a particular cylinder. i hate third hand diagnosis
I'll try spraying the wires with water. I've read that in the past, I don't know why I didn't remember to try that. I do agree with you that if I'm getting a specific misfire on a cylinder that it should be a little easier to track down. It just hasn't been though...
 

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I keep my opti dry and wouldn't spray with water just to test. Well u could pull one plug wire at a time to isolate problem. But it sounds more like the opti is dying to me because of those codes. How many miles on opti?

Ok let me throw this at u. Did u have the block decked when it was stroked? Were the heads shaved? If so the intake needs to me machined to match or u could have a nasty vacuum leak. Any oil leaks?

Also did u have any welding done on the car? After a lot of welding for exh work my car was a little wacky - fans coming on and off, SES coming on and off - so i got my computer tuned and now the car is running much better with the computer reflashed (and tuned).

Hope this helps,
cardo
 

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Discussion Starter · #20 ·
Update: I finally broke down and decided to have the opti replaced. Sure enough , as I started it up after swapping optisparks the car idled smooth as hell. In the end MSD opti failed and was the thorn in my side this entire time. I really tried not to jump to that conclusion but I suppose when in doubt, blame the opti, lol. I appreciate all the insight that you guys have had though. Hopefully someone can learn from my experience.
 
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