Vacumn leak in cylinders 2 cylinders causing injectors to max out?
05-29-2008, 04:57 PM
#1
Vacumn leak in cylinders 2 cylinders causing injectors to max out? I just installed a Procharger on my LS1 and the shop is tuning it and they are telling me that I have a vacumn leak in two cylinders that is causing 2 injectors to max out. Does anyone know what would cause this?
05-29-2008, 08:21 PM
#7
****UPDATE****
I talked to the tuner again and he stated that I have 16" to 17" of vacumn and the car is running in "open loop". Now, this is causing the car to run lean at an A/F of 16.5:1
So now I know that I have a vacumn leak, but this is not a good enough reason for 2 of the 8 injectors to max out.
What is a good amount of vacumn to make the car run in "closed loop"?
I talked to the tuner again and he stated that I have 16" to 17" of vacumn and the car is running in "open loop". Now, this is causing the car to run lean at an A/F of 16.5:1
So now I know that I have a vacumn leak, but this is not a good enough reason for 2 of the 8 injectors to max out.
What is a good amount of vacumn to make the car run in "closed loop"?
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05-29-2008, 09:31 PM
#9
16 to 17" of vacuum is not causing the car to stay in open loop, something else in OL/CL tables is.
Being in OL is not a reason for car to be that lean either. The car should be tuned in OL before it is put in CL anyway.
FWIW lots of people (including myself) run open loop all the time.
Being in OL is not a reason for car to be that lean either. The car should be tuned in OL before it is put in CL anyway.
FWIW lots of people (including myself) run open loop all the time.
05-30-2008, 07:19 AM
#10
my car idles at about 13" and 10-11" in gear (auto) though i am not sure why, runs fine 
spray something over the engine pay and you will find or not find a vacuum leak.
as above a leak will leak pressure under boost, and not have anything at all really to do with the wot tune up.
spray something over the engine pay and you will find or not find a vacuum leak.
as above a leak will leak pressure under boost, and not have anything at all really to do with the wot tune up.
05-30-2008, 08:01 AM
#11
my car idles at about 13" and 10-11" in gear (auto) though i am not sure why, runs fine
spray something over the engine pay and you will find or not find a vacuum leak.
as above a leak will leak pressure under boost, and not have anything at all really to do with the wot tune up.
spray something over the engine pay and you will find or not find a vacuum leak.
as above a leak will leak pressure under boost, and not have anything at all really to do with the wot tune up.
05-30-2008, 08:04 AM
#12
I have about 10" to 11" of vacuum at idle with the car is drive. This is mainly due to the big *** cam. A couple of things do not add up:
1) How do they know 2 of the cylinders have a vacuum leak? Have they done a leak down test on all the cylinders? So a cylinder to have low vacuum, the rings will have to be shot or the cylinders no longer square.
2) If the car has a A/F ratio of 16.5:1 in open loop, air is getting into the engine somewhere after the MAF sensor. Check for leaks at the MAF housing, throttle body, and intake manifold. If you have low vacuum at idle, a leak somewhere in the above sections will cause it and not the cylinders.
3) Either one of these problems will not cause certain injectors to max out. Something else is causing that.
If a shop can not figure these things out and you are forced to ask them here, I would get the car out of there ASAP.
Keith
1) How do they know 2 of the cylinders have a vacuum leak? Have they done a leak down test on all the cylinders? So a cylinder to have low vacuum, the rings will have to be shot or the cylinders no longer square.
2) If the car has a A/F ratio of 16.5:1 in open loop, air is getting into the engine somewhere after the MAF sensor. Check for leaks at the MAF housing, throttle body, and intake manifold. If you have low vacuum at idle, a leak somewhere in the above sections will cause it and not the cylinders.
3) Either one of these problems will not cause certain injectors to max out. Something else is causing that.
If a shop can not figure these things out and you are forced to ask them here, I would get the car out of there ASAP.
Keith
05-30-2008, 08:08 AM
#13
Flossin' twin turbos
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like MM said check for leaks using brake clean, spray around the intake where it meets the heads, rear part, and by the TB. the idle will change if there's a leak present.
05-30-2008, 09:09 AM
#15
I have about 10" to 11" of vacuum at idle with the car is drive. This is mainly due to the big *** cam. A couple of things do not add up:
1) How do they know 2 of the cylinders have a vacuum leak? Have they done a leak down test on all the cylinders? So a cylinder to have low vacuum, the rings will have to be shot or the cylinders no longer square.
2) If the car has a A/F ratio of 16.5:1 in open loop, air is getting into the engine somewhere after the MAF sensor. Check for leaks at the MAF housing, throttle body, and intake manifold. If you have low vacuum at idle, a leak somewhere in the above sections will cause it and not the cylinders.
3) Either one of these problems will not cause certain injectors to max out. Something else is causing that.
If a shop can not figure these things out and you are forced to ask them here, I would get the car out of there ASAP.
Keith
1) How do they know 2 of the cylinders have a vacuum leak? Have they done a leak down test on all the cylinders? So a cylinder to have low vacuum, the rings will have to be shot or the cylinders no longer square.
2) If the car has a A/F ratio of 16.5:1 in open loop, air is getting into the engine somewhere after the MAF sensor. Check for leaks at the MAF housing, throttle body, and intake manifold. If you have low vacuum at idle, a leak somewhere in the above sections will cause it and not the cylinders.
3) Either one of these problems will not cause certain injectors to max out. Something else is causing that.
If a shop can not figure these things out and you are forced to ask them here, I would get the car out of there ASAP.
Keith
05-30-2008, 07:42 PM
#16
****LAST UPDATE****
I found the problem. The intake is leaking "only" on the right bank!
Last year I installed a LS6 intake, ground down the webbing where the LS1 coolant crossover pipes run under the intake. I never seemed to have a problem even after it was tuned for just the bolt ons. Now after the Procharger install, somehow it is leaking and I can not get it to seal, so I am gonna put on the new coolant pipes and take it to the tuner again. Hopefully I have solved the problem.
The carb cleaner didn't seem to work, but maybe it was just a bad spot for it to show.
I found the problem. The intake is leaking "only" on the right bank!
Last year I installed a LS6 intake, ground down the webbing where the LS1 coolant crossover pipes run under the intake. I never seemed to have a problem even after it was tuned for just the bolt ons. Now after the Procharger install, somehow it is leaking and I can not get it to seal, so I am gonna put on the new coolant pipes and take it to the tuner again. Hopefully I have solved the problem.
The carb cleaner didn't seem to work, but maybe it was just a bad spot for it to show.
05-30-2008, 08:00 PM
#17
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Most of the cheap carb or brake cleaner's have gone cfc free and non flamable. Check the can to see what it says. It is getting harder to find "good" brake clean.
05-30-2008, 08:23 PM
#18
I was hoping to get 7-8# with the P1SC stock balancer and 3.75" pulley on my stock LS1 w/ LTH's, but I am getting 9#!! How does that happen?
I measured the diameter of the pulleys from where it contacts the belt. Am I measuring the pulley wrong?
I measured the diameter of the pulleys from where it contacts the belt. Am I measuring the pulley wrong?