injection issues
07-18-2012, 12:31 AM
#1
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injection issues So i have a 2000 chevy 5.3l, swapped into my 79 chevy 4x4.
runs about 50-60 psi depending on the vacuum of the engine.
I just recently started having a missfire, not bad enough to throw the check engine light on.
I was thinking it may be because i have a exhaust leak before the o2 sensor for some time now and it may have fouled a plug.
NOT THE CASE. i pulled both sides out and they all looked new still ( only month old AC delco's)
ONE DTC CODE I AM GETTING IS IDLE AIR CIRCUIT HIGHER THAN SET VALUE (or something along those lines)
I swapped coils with known good set.
i also just did injectors from another intake (same part number of injector)
and still no change.
tested them all with a noid light. every injector plug-in lights it up.
but are they firing on time?
could this even be a injector ground wire issue?
cam position sensor?
crank position sensor?
knock sensor? ( these are just my assumptions..)
if i can get some help with this and get my LS back on the road i would be very happy.
appreciate any help.
thanks
runs about 50-60 psi depending on the vacuum of the engine.
I just recently started having a missfire, not bad enough to throw the check engine light on.
I was thinking it may be because i have a exhaust leak before the o2 sensor for some time now and it may have fouled a plug.
NOT THE CASE. i pulled both sides out and they all looked new still ( only month old AC delco's)
ONE DTC CODE I AM GETTING IS IDLE AIR CIRCUIT HIGHER THAN SET VALUE (or something along those lines)
I swapped coils with known good set.
i also just did injectors from another intake (same part number of injector)
and still no change.
tested them all with a noid light. every injector plug-in lights it up.
but are they firing on time?
could this even be a injector ground wire issue?
cam position sensor?
crank position sensor?
knock sensor? ( these are just my assumptions..)
if i can get some help with this and get my LS back on the road i would be very happy.
appreciate any help.
thanks
07-18-2012, 08:58 AM
#3
I would check for vacuum leaks (as stated above).. also the connectors around the intake.. IAC, TPS, TPS, MAF, Make sure they are in good working order. O-rings around the Injectors/fuel rail.
I would remove and clean the MAF and Throttle Body and check the IAC for carbon build up.
Would not worry about the cam and crank sensor that DTC... What is the DTC # ?
BC
I would remove and clean the MAF and Throttle Body and check the IAC for carbon build up.
Would not worry about the cam and crank sensor that DTC... What is the DTC # ?
BC
07-18-2012, 09:28 AM
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I would check for vacuum leaks (as stated above).. also the connectors around the intake.. IAC, TPS, TPS, MAF, Make sure they are in good working order. O-rings around the Injectors/fuel rail.
I would remove and clean the MAF and Throttle Body and check the IAC for carbon build up.
Would not worry about the cam and crank sensor that DTC... What is the DTC # ?
BC
I would remove and clean the MAF and Throttle Body and check the IAC for carbon build up.
Would not worry about the cam and crank sensor that DTC... What is the DTC # ?
BC
but it was idle air circuit higher than expected i believe.
would a intake leak really be that bad? i sprayed around the intake, and the sensors days ago when this all started..and also couldnt tell a difference in idle with is missing. ill try to also get a video
i know that every injector is getting enough power to fire up the noid light
07-18-2012, 09:49 AM
#5
also.. that 50-60 PSI..?? you really should look into why you don't have a constant 58psi as required for these engines.
And what is this "Depending on then Vacuum" ?.. do you have a vacuum referenced Fuel Regulator ? If not.. it should be a constant 58psi and idle and should not be dropping too much under load.
BC
And what is this "Depending on then Vacuum" ?.. do you have a vacuum referenced Fuel Regulator ? If not.. it should be a constant 58psi and idle and should not be dropping too much under load.
BC
07-18-2012, 08:21 PM
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also.. that 50-60 PSI..?? you really should look into why you don't have a constant 58psi as required for these engines.
And what is this "Depending on then Vacuum" ?.. do you have a vacuum referenced Fuel Regulator ? If not.. it should be a constant 58psi and idle and should not be dropping too much under load.
BC
And what is this "Depending on then Vacuum" ?.. do you have a vacuum referenced Fuel Regulator ? If not.. it should be a constant 58psi and idle and should not be dropping too much under load.
BC
i noticed today cylinder 3 and 4 both had missfires, and only a few on 5. (were logged on my computer)
pulled the injector wire to see if it got worse, and i couldnt tell any difference..
07-18-2012, 08:51 PM
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Early 5.3s had a TSB for chipped valve tips (or something along those lines) causing misfires. Also something about grounding issues on the passenger side head, but I doubt you retained that grounding for your swap.
That IAC high code suggests that you may have some sort of vacuum leak, causing the IAC to operate outside the designated range to compensate.
If your scanner has the capability, try a cylinder balance test to isolate your missfire.
That IAC high code suggests that you may have some sort of vacuum leak, causing the IAC to operate outside the designated range to compensate.
If your scanner has the capability, try a cylinder balance test to isolate your missfire.
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07-23-2012, 12:59 AM
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Early 5.3s had a TSB for chipped valve tips (or something along those lines) causing misfires. Also something about grounding issues on the passenger side head, but I doubt you retained that grounding for your swap.
That IAC high code suggests that you may have some sort of vacuum leak, causing the IAC to operate outside the designated range to compensate.
If your scanner has the capability, try a cylinder balance test to isolate your missfire.
That IAC high code suggests that you may have some sort of vacuum leak, causing the IAC to operate outside the designated range to compensate.
If your scanner has the capability, try a cylinder balance test to isolate your missfire.
check volts to the coil, and volts to the injector.. both had 14.. swapped plug wires and plugs.. and no difference...
any ideas? could this be a crank or cam sensor?
07-23-2012, 09:37 AM
#9
Just because you have voltage at the coil and injector doesn't mean they are good. Both the coil and injector might be bad and/or needs replacing. Might try swapping them around if you don't have another coil or injector to replace completely.
Just another guess on what to try next. Good Luck.
BC
Just another guess on what to try next. Good Luck.
BC
07-23-2012, 07:51 PM
#10
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Just because you have voltage at the coil and injector doesn't mean they are good. Both the coil and injector might be bad and/or needs replacing. Might try swapping them around if you don't have another coil or injector to replace completely.
Just another guess on what to try next. Good Luck.
BC
Just another guess on what to try next. Good Luck.
BC
07-23-2012, 09:57 PM
#11
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I would replace the intake gaskets to rule out a vacuum leak. The pre 2004 truck intake gaskets (orange) were known to leak air. Especially if you had the intake off and reused the gaskets. The gaskets were redesigned in 04 and work much better.
07-23-2012, 10:48 PM
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i understand, but idk how a vacuum leak can make a dead miss.. pull the injector wire and it doesnt change at all, ive done gaskets
