Misfire, low oil presure and misc
04-14-2010, 05:56 PM
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Misfire, low oil presure and misc Ok, I just bought this car with a blown headgasket and the heads torn off of it. We cleaned the block up, had the heads pressure tested, and put new headgaskets on. The car is now running, but not the best.
The oil pressure once it warms up is setting a little more than halfway between the 0 and 20 psi mark at idle (if it were really this low, wouldnt the lifters be tapping?). When its cold at idle it sets at 42ish. We used 5w30 valvoline oil.
Next problem, its misfiring pretty badly. At idle, under load at low and high rpms, especially when hitting the gas in 6th gear.
Last problem, there is a sort of whine in the back of the car. It doesn't always do it, but when you take a right turn it always does it and when you take a left turn it quits. Sort of sounds like it could be a wheel bearing to me.
The car (according to preivous owner) has a newish (about 5k miles) water pump and opti, a new clutch, bbk headers and a flowmaster cat back, 4.10 gears and a rebuilt rear end.
It is VERY possible that we hooked something up wrong when putting the motor back together since we weren't the ones that took it apart. If any of you have any suggestions as to what any of these problems might, any help would be appreciated.
The oil pressure once it warms up is setting a little more than halfway between the 0 and 20 psi mark at idle (if it were really this low, wouldnt the lifters be tapping?). When its cold at idle it sets at 42ish. We used 5w30 valvoline oil.
Next problem, its misfiring pretty badly. At idle, under load at low and high rpms, especially when hitting the gas in 6th gear.
Last problem, there is a sort of whine in the back of the car. It doesn't always do it, but when you take a right turn it always does it and when you take a left turn it quits. Sort of sounds like it could be a wheel bearing to me.
The car (according to preivous owner) has a newish (about 5k miles) water pump and opti, a new clutch, bbk headers and a flowmaster cat back, 4.10 gears and a rebuilt rear end.
It is VERY possible that we hooked something up wrong when putting the motor back together since we weren't the ones that took it apart. If any of you have any suggestions as to what any of these problems might, any help would be appreciated.
Last edited by RawrImAMonster; 04-14-2010 at 06:10 PM.
04-14-2010, 06:08 PM
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Really? I feel like the lifters would be clicking pretty badly at that point. It goes up to 40ish at 2000 rpms though, so I guess that seems fairly normal.
04-14-2010, 08:02 PM
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Ok well I guess the misfire is the main issue then. Any suggestions on what to look for on that. The sparkplugs are brand new, but not the wires. The opti and water pump (supposedly) have about 5k miles on them so hopefully its not that.
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04-17-2010, 03:54 PM
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No it didn't have one until i unplugged the maf earlier, but now it does because of that.
Edit: The misfire does seem to get a little worse once the engine has warmed up.
Edit: The misfire does seem to get a little worse once the engine has warmed up.
04-18-2010, 08:50 AM
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as for your oil pressure 10psi per 1000rpm is acceptable by gm.
as for your misfiring, maybe nothing really was changed have you ever pulled the plugs to take a look? does it miss in all gears or just the higher loaded ones?
the whine could be a poorly installed gear set, or a sign it is about to fail. have you checked the diff?
as for your misfiring, maybe nothing really was changed have you ever pulled the plugs to take a look? does it miss in all gears or just the higher loaded ones?
the whine could be a poorly installed gear set, or a sign it is about to fail. have you checked the diff?
04-18-2010, 10:40 AM
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04-18-2010, 11:19 AM
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as for your oil pressure 10psi per 1000rpm is acceptable by gm.
as for your misfiring, maybe nothing really was changed have you ever pulled the plugs to take a look? does it miss in all gears or just the higher loaded ones?
the whine could be a poorly installed gear set, or a sign it is about to fail. have you checked the diff?
as for your misfiring, maybe nothing really was changed have you ever pulled the plugs to take a look? does it miss in all gears or just the higher loaded ones?
the whine could be a poorly installed gear set, or a sign it is about to fail. have you checked the diff?
Like I said, we bought the car with the heads torn off of it and we put it back together so the spark plugs definitely are brand new.
Could a bad fuel filter or fuel pump cause a misfire like what I described?
04-18-2010, 12:25 PM
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yes fuel not reaching the injectors, or fouling could cause it, cheapest first, filter and fuel pressure... gotta narrow it down as best you can
wet opti?
bad plugs?
bad egr?
vacuum leak? (doubtful)
check compression?
wet opti?
bad plugs?
bad egr?
vacuum leak? (doubtful)
check compression?
04-19-2010, 06:06 PM
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Miss is fixed it was bad plug wires. The car runs great now.
Now onto the rear end/wheel bearing/whatever noise.
This noise is a sort of whining that changes with speed. It gets noticeably worse during right turns and then usually disappears completely during left turns. Sometimes its there when you're just cruising in a straight line and sometimes its not.
SUPPOSEDLY the last owner rebuilt the rear end and spent around 800 in parts on it. So, I'm hoping the rear end isn't bad. I'll email him and try to find out what all he replaced exactly, but does anyone have any ideas for now?
Now onto the rear end/wheel bearing/whatever noise.
This noise is a sort of whining that changes with speed. It gets noticeably worse during right turns and then usually disappears completely during left turns. Sometimes its there when you're just cruising in a straight line and sometimes its not.
SUPPOSEDLY the last owner rebuilt the rear end and spent around 800 in parts on it. So, I'm hoping the rear end isn't bad. I'll email him and try to find out what all he replaced exactly, but does anyone have any ideas for now?
04-19-2010, 06:17 PM
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The whining coming from the rear def sounds like a bad installation on the gears. if it was the wheel bearing it would make a clicking noise when you turn the car not a whine, I believe.
