Bucking or Cutting Out or Both
Whats up everybody?
So i got my cobalt back together after a long hiatus from bent valves and etc etc. I got the head rebuilt and its practically brand new. I got it installed over the long weekend and assembled everything else until it was up and running. Now, im having the same issue as before when my valves bent. On top of having misfires (the misfires are happening at idle and when im coasting down mostly)!!!! But when i start to lean in to the pedal and give it some gas, it starts to "buck" or cut out briefly or something of the sort.. its kinda hard to explain...... basically, i can not give it full throttle or it starts actin pretty crappy. ive got brand new plugs, coils, fuel filter, last time i checked the fuel pressure was good, ive been checking for vaccuum leaks and cant find anything............ can someone shed some light please??????? |
Do you have any idea what your air to fuel ratio is while this is happening?
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Originally Posted by jdbaugh1
(Post 7650345)
Do you have any idea what your air to fuel ratio is while this is happening?
its just been crazy man, between kids, a wife and life.. what you thinkin it may be?? lean possibly??? |
Originally Posted by Cobalt_noob
(Post 7650347)
Ive got my wideband, but ive yet to hook it up.... you think that might be a go to step??
its just been crazy man, between kids, a wife and life.. what you thinkin it may be?? lean possibly??? From what I have seen with 2.2 SC builds (similar to 2.4 I'm assuming) with canned tunes is that the fueling is usually pretty far off. Enough to cause the symptoms you are experiencing. I have seen these issues corrected with a proper tune. |
Originally Posted by jdbaugh1
(Post 7650350)
Do you have the bung on your downpipe for the wideband? If so maybe you could do a sloppy temporary install to at least see what the fuel is doing.
From what I have seen with 2.2 SC builds (similar to 2.4 I'm assuming) with canned tunes is that the fueling is usually pretty far off. Enough to cause the symptoms you are experiencing. I have seen these issues corrected with a proper tune. |
I'd bet the tune needs some serious help. I wouldn't drive it till you have the wideband and hptuners
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Originally Posted by ECaulk
(Post 7650367)
I'd bet the tune needs some serious help. I wouldn't drive it till you have the wideband and hptuners
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Its dumping buckets outside so ill have to wait unfortunately
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Alright guys, so I got the wideband up and running. The misfires have been progressively getting worse. But the wideband has been jumping erratically between 14.1 and 14.9 (this is at idle) and then all of a sudden go SUPER rich and then back up to 14.1 and 14.9 jumping around. When I give it just a wee bit of gas, it goes way way lean.
But my buddy had his scanner over (not hp tuners, just some brand) and we were able to see STFT, LTFT what the O2 Sensors reading etc... Well we were able to see which cylinders were showing misfires...... Cyl.1 - 4 total misfires .... Cyl.2 - 946 misfires .... Cyl. 3 - 100 misfires ..... and Cyl. 4 - 0 misfires. WTF?! I'm thinking the worst here, but ive got to hear it from you guys... what do you think it could be. Ive checked spark, spark plugs, vacuum, etc... I'm worried its the head gasket... please help, I'm at the end with this thing, ive gone to hell and back. |
I'd pull the plugs and compare them to the plug in Cylinder 2 and see what is different. Also compression test. Do you ever get a flashing check engine light for misfires?
I think it is part your tune but that wouldn't cause a disproportionate amount of misfires in one cylinder. |
Originally Posted by jdbaugh1
(Post 7651136)
I'd pull the plugs and compare them to the plug in Cylinder 2 and see what is different. Also compression test. Do you ever get a flashing check engine light for misfires?
I think it is part your tune but that wouldn't cause a disproportionate amount of misfires in one cylinder. I have gone through 4 brand new sets of spark plugs lol. But yeah, ill take a look at Cylinder 2 specifically and compare. Im worried that its the head gasket. Its brand new, but i installed the ARP head studs and im wondering if I got all the studs bottomed out before i torqued the nuts... this car has plagued me with misfires since ive owned the s.o.b. |
Originally Posted by Cobalt_noob
(Post 7651155)
I am going to pick up a compression tester here really soon, if not this weekend then the next.
I have gone through 4 brand new sets of spark plugs lol. But yeah, ill take a look at Cylinder 2 specifically and compare. Im worried that its the head gasket. Its brand new, but i installed the ARP head studs and im wondering if I got all the studs bottomed out before i torqued the nuts... this car has plagued me with misfires since ive owned the s.o.b. |
Originally Posted by jdbaugh1
(Post 7651158)
I'm not telling you to change the spark plugs but to take them out and compare them making sure to keep track of what cylinder they came out of. Could just be a compression leak or hg problem in that one cylinder. I don't think that one cylinder is causing all your issues either though. When my engine was running I always had more misfires in a couple cylinders than the others but they were closer than what you showed.
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Originally Posted by Cobalt_noob
(Post 7651160)
I gotcha. So you think its a combination tune and possible compression leak or head gasket problem possibly??? Sorry man, noob here
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Originally Posted by jdbaugh1
(Post 7651161)
I'm a noob as well just trying to help if I can. Hard to say. All I know is that a tune won't cause 1 single cylinder to run poorly compared to the rest but it also could amplify a small variation. You need to investigate more to see what could be causing the variance in that single cylinder. You didn't answer me if you ever got a flashing CEL or actual misfire codes.
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Yeah I was wondering if the computer decided cylinder 2 misfire count was far enough out of range to warrant it's own code and not just P0300 because I don't really have a good idea of whats normal, acceptable, or when you really have a problem as far as misfire count variation.
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Hey Guys,
Been watching this thread with interest. Looking at the misfires in cylinders 2 and 3, wouldn't that be an indication of a possible head gasket leak? As a noob also, I've been researching for issues with poor engine performance as mine seems to act weird also. I think a compression test will help shed light on your issues. Best of luck. |
Originally Posted by WICobaltSS
(Post 7651168)
Hey Guys,
Been watching this thread with interest. Looking at the misfires in cylinders 2 and 3, wouldn't that be an indication of a possible head gasket leak? As a noob also, I've been researching for issues with poor engine performance as mine seems to act weird also. I think a compression test will help shed light on your issues. Best of luck. Im not exaggerating when i say i have been plagued with misfires in this car since the day i bought it :r: |
Originally Posted by jdbaugh1
(Post 7651167)
Yeah I was wondering if the computer decided cylinder 2 misfire count was far enough out of range to warrant it's own code and not just P0300 because I don't really have a good idea of whats normal, acceptable, or when you really have a problem as far as misfire count variation.
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What did the head rebuild cost you in time and money? Debating on doing this myself.
In your case, hoping it's just a matter of thread cleaning. |
Originally Posted by WICobaltSS
(Post 7651247)
What did the head rebuild cost you in time and money? Debating on doing this myself.
In your case, hoping it's just a matter of thread cleaning. |
Few questions.
Who tunes you? Who does the engine work for you? Did you try swapping coil packs to see if the misfire follows that coil pack? I just briefly skimmed the thread. Im local to you, south of Pittsburgh. Just wondering if you got your work done locally. There are a few of us locally with HPT that hook you up with a good tuner. |
Originally Posted by royce777
(Post 7651365)
Few questions.
Who tunes you? Who does the engine work for you? Did you try swapping coil packs to see if the misfire follows that coil pack? I just briefly skimmed the thread. Im local to you, south of Pittsburgh. Just wondering if you got your work done locally. There are a few of us locally with HPT that hook you up with a good tuner. As far as all the work goes, its been me and some close friends. The head work I got done in Greensburg by P and R Engine Rebuilders. The tune I got a canned one from ZZP. As jdbaugh stated, a tune is definitely in order. But there is for certain some underlying issue at hand and can't seem to find. Coil packs were brand new, however, today we were going to definitely rule it out and swap them around. I did pull the connector one by one and verified that they were giving spark, which they are. How strong of a spark is the question and also ignition timing possibly. So I'm at the crossroads with tuning. I bought the the tuning schools book on how to tune and wondering if I should purchase HPTuners and do it myself, OR take it to this place in Export PA (around the Washington area) as they are supposedly pretty good. They're called FJ Performance. So I dunno man. |
Did you ever figure out what caused you to get bent valves last time?
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Originally Posted by royce777
(Post 7651382)
Did you ever figure out what caused you to get bent valves last time?
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