Passenger side trouble
06-10-2010, 04:27 PM
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Join Date: Aug 2002
Location: Hameln, Germany
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Passenger side trouble I just completed a rebuild of an LQ9 which I bought in pieces.
Installed new cam bearings, new pistons/rings, oil pump and heads and intake
off another motor (LQ4).
The reason the motor was disassembled is not totally clear to me, it
seems the cylinders 7 and 8 were overheated and had significant ring wear.
I also noticed a worn cam bearing (second last in the back).
I reused the entire valvetrain, except for the cam, which is a Comp cam 54-412-11. Also installed yellow LS6 valve springs and new valve stem seals.
Now the problem:
Engine fired up alright but ran rough from the very beginning.
Initial analysis showed that the drivers side is running fine on all cylinders,
BUT the passenger side only fires on cylinder 4.
With my EFILive I was able to switch the individual injectors off, there was no
noticable change when switching cylinders 2,6 and 8.
Today I double checked the wiring to the injectors (vehicle used to be converted to LPG) but all seems fine, clicking of injectors can be felt.
Even went as far as installing a different fuel rail with injectors - no change.
Switched the ignition coils over from the other motor as well - no change.
The new plugs are fouled black but dry on the passenger side. Spark plug does create a bluish spark.
Scanning the ECM parameters I noticed bank 2 to have a higher injection percentage and the O2 sensor always reads 0.9V.
Checked the injection by lifting the rail with injectors to verify it would spray fuel - it does.
Oil pressure is at about 40 psi with 10W40 oil right after startup.
With fuel and spark present I am a little clueless as to what else to check for.
Disconnected the right O2 sensor with no noticable change.
Only things that come to mind are:
- timing chain not aligned properly
>> should not just affect pass side, right?
- rocker arms not torqued properly (only checked 2 so far)
- valves not closing?!
- bent pushrods (checked 2, which were OK)
- not sufficient oil pressure on pass side?? even possible??
- several bad lifters (wish I had replaced them !!)
As far as codes I get a P0300 Engine misfire code. Today also got MAF flow codes, which did not go away with a different MAF.
Other useful information might be: truck is running a programmed ECM, source unknown. Looking at the changed tables I see no reason for the truck not to idle. Air filter is an AFE drop-in replacment filter.
Next I plan on running a compression check.
Does anyone have an idea as what else to check, cause I am running out of them!
Thanks,
Lennart
Installed new cam bearings, new pistons/rings, oil pump and heads and intake
off another motor (LQ4).
The reason the motor was disassembled is not totally clear to me, it
seems the cylinders 7 and 8 were overheated and had significant ring wear.
I also noticed a worn cam bearing (second last in the back).
I reused the entire valvetrain, except for the cam, which is a Comp cam 54-412-11. Also installed yellow LS6 valve springs and new valve stem seals.
Now the problem:
Engine fired up alright but ran rough from the very beginning.
Initial analysis showed that the drivers side is running fine on all cylinders,
BUT the passenger side only fires on cylinder 4.
With my EFILive I was able to switch the individual injectors off, there was no
noticable change when switching cylinders 2,6 and 8.
Today I double checked the wiring to the injectors (vehicle used to be converted to LPG) but all seems fine, clicking of injectors can be felt.
Even went as far as installing a different fuel rail with injectors - no change.
Switched the ignition coils over from the other motor as well - no change.
The new plugs are fouled black but dry on the passenger side. Spark plug does create a bluish spark.
Scanning the ECM parameters I noticed bank 2 to have a higher injection percentage and the O2 sensor always reads 0.9V.
Checked the injection by lifting the rail with injectors to verify it would spray fuel - it does.
Oil pressure is at about 40 psi with 10W40 oil right after startup.
With fuel and spark present I am a little clueless as to what else to check for.
Disconnected the right O2 sensor with no noticable change.
Only things that come to mind are:
- timing chain not aligned properly
>> should not just affect pass side, right?
- rocker arms not torqued properly (only checked 2 so far)
- valves not closing?!
- bent pushrods (checked 2, which were OK)
- not sufficient oil pressure on pass side?? even possible??
- several bad lifters (wish I had replaced them !!)
As far as codes I get a P0300 Engine misfire code. Today also got MAF flow codes, which did not go away with a different MAF.
Other useful information might be: truck is running a programmed ECM, source unknown. Looking at the changed tables I see no reason for the truck not to idle. Air filter is an AFE drop-in replacment filter.
Next I plan on running a compression check.
Does anyone have an idea as what else to check, cause I am running out of them!
Thanks,
Lennart
