Diagnosing and fixing my ls1
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Diagnosing and fixing my ls1 OK so hopefully this thread will be about fixing some issues my ls1 is having.
Short story:
I got the car with 125k miles on the clock, engine ran but car is a DOG. Very slow.
Did tune up, cleaned MAF, TB, IAC, fuel filter plugs wires air filter, better but no vast improvement.
Changed the oil twice now, at 130k miles. Oil pressure after 2k miles fell to 35 at idle, after fresh oil change would hover around 50.
When cold engine has piston slap and lots of valve noise, most notable on cold morning, hard to catch since it's not that ocld right now but I made this video which, if you have your volume up or know what to look for, you can hear it very plainly.
http://www.youtube.com/watch?v=YN98awbhxwM
Tried listening to it, sounds like it's coming from driver side, so I dove in.
Now I'm no expert, but everything looks fine to me. Rockers have almost no movement (they do have some.. should they?) when I lift on them. No broken springs no missing pushrods, nothing obvious. The problem goes away when the engine warms up. These rockers look to have bearings, could this be the problem?
Also during this I uh..
I thought it was a hose.. I pulled too hard and broke that tube.. anyone got a part number?
Looks like a pita to replace but whatever.. stuff happens right?
So here we are.. what's my next step yall?
Short story:
I got the car with 125k miles on the clock, engine ran but car is a DOG. Very slow.
Did tune up, cleaned MAF, TB, IAC, fuel filter plugs wires air filter, better but no vast improvement.
Changed the oil twice now, at 130k miles. Oil pressure after 2k miles fell to 35 at idle, after fresh oil change would hover around 50.
When cold engine has piston slap and lots of valve noise, most notable on cold morning, hard to catch since it's not that ocld right now but I made this video which, if you have your volume up or know what to look for, you can hear it very plainly.
http://www.youtube.com/watch?v=YN98awbhxwM
Tried listening to it, sounds like it's coming from driver side, so I dove in.
Now I'm no expert, but everything looks fine to me. Rockers have almost no movement (they do have some.. should they?) when I lift on them. No broken springs no missing pushrods, nothing obvious. The problem goes away when the engine warms up. These rockers look to have bearings, could this be the problem?
Also during this I uh..
I thought it was a hose.. I pulled too hard and broke that tube.. anyone got a part number?
Looks like a pita to replace but whatever.. stuff happens right?So here we are.. what's my next step yall?
It could be alot of things. Best thing would be to run a diagnostic scan at a reputable shop. It'll save you money in the long run. Double check easy stuff like plug wire connections. If I had to guess, I'd look at the O2 sensors. Maybe tap the catalytic converters and listen for a rattling sound (Broken cat guts can clog a cat causing sluggish performance). It could be anything... good diagnostic check will be helpful.
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car has 2 new cats 4 new o2 sensors, the noise is coming from the engine/valves I'm certain of this. I suspect a bad bearing (bearings..) in one/some of the rockers, I'm just not sure how to check them.
My father suggested to test the gap between the rocker and the springs. I assume this would help find a cam problem? a collapsed lifter? Frankly both of those seem unlikely.
I may do a compression check on the driver side since it's easy to get to, just to get a picture of how things look.
My father suggested to test the gap between the rocker and the springs. I assume this would help find a cam problem? a collapsed lifter? Frankly both of those seem unlikely.
I may do a compression check on the driver side since it's easy to get to, just to get a picture of how things look.
Compression and leak down tests are always a good idea. Collapsed lifter is certainly possible on a higher mileage motor. Is any of the valvetrain aftermarket or ever replaced previously do you know? What type/weight oil are you using?
The first problem is that that car was NOT taken care of very well. With 125K on the clock, if the previous owner changed the oil like he should have, the bottom of the valve covers and the valvetrain should def NOT be that dark and stained. That could be a symptom of never changing the oil. I wouldn't be surprised if you did have some blow by as well because of how dark that valvetrain is. Something made it filthy because thats not normal.
Also I'm assuming there is no check engine light on?
I would be very inclined to think that your decrease in performance is actually coming from the valvetrain noise. My brother had a rod bearing go and his car still had full power while making a horendous noise from the bottom end. LS1's generally have a semi-noisy valvetrain and are notorious for piston slap while cold. I would check to see if the fuel injectors are clogged after looking at that dirty valvetrain since I would assume the car was not loved very much during some of it's life. Also check the injector pigtails...make sure no wires are loose or coming out. Freind of mine dynoed 296 rwhp with a bad injector pigtail on a full bolt on LS1. Fixed it and dynoed 347 rwhp. Check those things and let us know.
Also I'm assuming there is no check engine light on?
I would be very inclined to think that your decrease in performance is actually coming from the valvetrain noise. My brother had a rod bearing go and his car still had full power while making a horendous noise from the bottom end. LS1's generally have a semi-noisy valvetrain and are notorious for piston slap while cold. I would check to see if the fuel injectors are clogged after looking at that dirty valvetrain since I would assume the car was not loved very much during some of it's life. Also check the injector pigtails...make sure no wires are loose or coming out. Freind of mine dynoed 296 rwhp with a bad injector pigtail on a full bolt on LS1. Fixed it and dynoed 347 rwhp. Check those things and let us know.
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From: Longbeach, CA
The first problem is that that car was NOT taken care of very well. With 125K on the clock, if the previous owner changed the oil like he should have, the bottom of the valve covers and the valvetrain should def NOT be that dark and stained. That could be a symptom of never changing the oil. I wouldn't be surprised if you did have some blow by as well because of how dark that valvetrain is. Something made it filthy because thats not normal.
Also I'm assuming there is no check engine light on?
I would be very inclined to think that your decrease in performance is actually coming from the valvetrain noise. My brother had a rod bearing go and his car still had full power while making a horendous noise from the bottom end. LS1's generally have a semi-noisy valvetrain and are notorious for piston slap while cold. I would check to see if the fuel injectors are clogged after looking at that dirty valvetrain since I would assume the car was not loved very much during some of it's life. Also check the injector pigtails...make sure no wires are loose or coming out. Freind of mine dynoed 296 rwhp with a bad injector pigtail on a full bolt on LS1. Fixed it and dynoed 347 rwhp. Check those things and let us know.
Also I'm assuming there is no check engine light on?
I would be very inclined to think that your decrease in performance is actually coming from the valvetrain noise. My brother had a rod bearing go and his car still had full power while making a horendous noise from the bottom end. LS1's generally have a semi-noisy valvetrain and are notorious for piston slap while cold. I would check to see if the fuel injectors are clogged after looking at that dirty valvetrain since I would assume the car was not loved very much during some of it's life. Also check the injector pigtails...make sure no wires are loose or coming out. Freind of mine dynoed 296 rwhp with a bad injector pigtail on a full bolt on LS1. Fixed it and dynoed 347 rwhp. Check those things and let us know.
There are no CELs on the motor, the car will start and drive fine unless it's below 1/4 tank then it's difficult to start.
When the car is at operating temperature (225ish) any load on the engine seems to result in a skip/misfire that severely hinders acceleration. This can make simple passing maneuvers very dificult, as it can do it up to 5-6 times. It doesn't always do this, and has improved as I have done service to the car, doing it only 1-2 times every time I kick it.
The car has "that feeling" like opening the throttle more isn't making a difference. 1/2 throttle and 3/4-wot don't feel different in acceleration, the car just makes more noise, and then you have the gas smell.
I suspected a bad coil. I picked up a set of 6.0 truck coils but they don't look like they're going to clear the fuel lines on this side, so I'm still researching that.
I changed the oil after 2000 miles of driving, pressure at cold idle was down to 35 from 50, and the oil smelled, as I would call it "like a 2 stroke motor's exhaust." Sort of a carbon.. gassy smell. I believe blowby is a real possibility here. The inside of the valve cover has this same smell.
Where does the pcv tube go? From what I can tell it just goes to the passenger side.
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Verdad Gallardo A thorough computer scan will tell you if things like knock retard are causing the computer to pull timing and so on. It'll help you pinpoint the real problem. Sure beats throwing parts at it. Though judging by the top of the heads, car was poorly maintained and probably needed to have most of that stuff replaced anyway. Good luck.
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Well, one thing I've been chewing on is replacing the motor honestly. Picking up a low mileage lq4 pullout and reconditioning the top end. It's not worth a LOT of time to work on this engine unless the bottom end is healthy, which so far yall seem to think is not the case. I'm going to check on how much a compression check setup costs and do the driver side and maybe some of the passenger side if it isn't too much.
if it IS too much.. well I'll put this thing back together and just be on the lookout for a replacement.
I mean if I gotta pull the motor for a bottom end re-work, I may as well swap in something else. The cost of a used LQ4 isn't terrible, and is going to be less than a stock rebuild on this motor and have more power potential.
if it IS too much.. well I'll put this thing back together and just be on the lookout for a replacement.
I mean if I gotta pull the motor for a bottom end re-work, I may as well swap in something else. The cost of a used LQ4 isn't terrible, and is going to be less than a stock rebuild on this motor and have more power potential.
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Trying to do a compression check now. Driver side only. HUGE pita.
Will post pics of the spark plugs, but 3 of them look pretty lean, the back one is oily and darker than the others..?
Will post pics of the spark plugs, but 3 of them look pretty lean, the back one is oily and darker than the others..?
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ok so after 45 minutes of screwing around I decided a compression check wasn't important enough at this time. Anyway... I did get the plugs out and had a look. Here they are:
The back one had oil around the threads that the others didn't have. this could be the one that's misfiring under load?
Something to try that will give you a really good idea and pinpoint the problem cylinder is to try pulling the electrical plugs on each individual coilpack while the engine is running. If the rpm or sound at idle changes, the cylinder is working properly, however if it has no effect on how the car runs, then you have a sure problem somewhere. I would start with the cyliner that that dark plug came off of. Also, coils generally don't work once they heat up if they are bad. You mentioned it got worse when the car got to temp. I thought you would have gotten a CEL though if a coil went, but I could be wrong.
Another thing to try, although I have a feeling it may not be the case, is to check your fuel pressure. Never know if the pump is going bad or not. Let the car run for a while and warm up, and then throw a gauge on the fuel shrader valve. Should have around 58 psi.
EDIT: You know, on second thought, those plugs look VERY lean. The ends are bright white still with not a hint of tanning. Let me know if it's just the pic that makes them look like that but if not, you have a fuel starvation issue....most likely a pump. I would NOT be going full throttle until thats fixed since thats a recipe for disaster.
Another thing to try, although I have a feeling it may not be the case, is to check your fuel pressure. Never know if the pump is going bad or not. Let the car run for a while and warm up, and then throw a gauge on the fuel shrader valve. Should have around 58 psi.
EDIT: You know, on second thought, those plugs look VERY lean. The ends are bright white still with not a hint of tanning. Let me know if it's just the pic that makes them look like that but if not, you have a fuel starvation issue....most likely a pump. I would NOT be going full throttle until thats fixed since thats a recipe for disaster.
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Funny you say that. I did notice that the tips looked very hot/ashy on the plugs... all except one, which COULD be a leaky valve steam seal I suppose to be fair.. the car may be burning some oil, though it doesn't smoke, it did lose about 1qt in 2000 miles. The rear main seal leaks however, so it's not conclusive that it BURNED it..simply that it's not there.
When you go WOT on this car, and it actually does it.. (there are times when stomping this car will light the tires and others where it bogs down, and very slowly climbs, shifting into 2nd gear at about 5-6k rpm after a looooooong acceleration) when you stop the unburnt fuel smell that catches up with you is enough to make your eyes water.
When you go WOT on this car, and it actually does it.. (there are times when stomping this car will light the tires and others where it bogs down, and very slowly climbs, shifting into 2nd gear at about 5-6k rpm after a looooooong acceleration) when you stop the unburnt fuel smell that catches up with you is enough to make your eyes water.
Those plugs still scare me a lot. Just for reference, we pulled a plug out of my brothers 98 lS1 yesterday to check them and it had the nice normal tan coloring to it. Looked nothing like yours and his engines got 130K on it as well. First and foremost, I'd get a fuel pressure gauge on that fuel rail and keep an eye on the pressure. Even though your smelling a rich fuel smell, something is up with your fuel system.
How is the car on gas....as in mpg?
Also, you could have clogged injectors but you won't know till you check out the fuel pressure and eliminate that as a possible problem.
How is the car on gas....as in mpg?
Also, you could have clogged injectors but you won't know till you check out the fuel pressure and eliminate that as a possible problem.
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Car gets 20mpg city even with me ragging on it every now and then with some attempted hard launches.
Those plugs btw, are not even 2000 miles old.They've probably been in the car 3-4 months tops.
Also, I have an autoCAL, I can data log it.. I tried earlier but didn't save them :/ I know how to do it after I re-read my instructions.
It outputs an efi file, I'm not sure how to read those?
Those plugs btw, are not even 2000 miles old.They've probably been in the car 3-4 months tops.
Also, I have an autoCAL, I can data log it.. I tried earlier but didn't save them :/ I know how to do it after I re-read my instructions.
It outputs an efi file, I'm not sure how to read those?
Last edited by DarkFox118; Aug 1, 2011 at 02:22 PM.
