Total lack of power and miss during idle
07-26-2011, 04:50 PM
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Total lack of power and miss during idle
Long time lurker,but know this engine quite well. Have replaced a couple and the last one I just did is giving me fits.
This engine I started with is a short block with 100,000km, brand new heads(took all casting flakes off), ported the heads, intake and plenum.Also have big high end custom ground cams.Throttle body,exhaust and intake are all stock.Injectors were balanced and cleaned 100,000km. I have tried playing with the air/fuel ratio in the VAFM for months.(Any Thoughts on this)
Problem is mainly total lack of power/miss during idle and throughout driving range. Absolute dog going up hill and truly a 3.slow. This engine should be way more powerful than it is.
I have had the plenum off twice to check for vacuum leaks,valve cover leaks,PCV valve connection, etc. Checked and tightened all intake bolts.Exchanged TB's,spark plugs, wires, cap and rotor, EGR. .(All these previous items were on my good running ex-engine).
PAIR valve is the last to be changed over, but all tests tell me that is in working order. How about the EGR modulator? Is there a test for that?
I have researched this and done everything possible to resolve.
Do I need to open up the intake by getting more air through the VAFM, and/or getting an overbored TB to compensate for the air the engine "wants".
I was told the cams make the engine run lean.
What does porting AND cams do combined? Extra lean?
This engine I started with is a short block with 100,000km, brand new heads(took all casting flakes off), ported the heads, intake and plenum.Also have big high end custom ground cams.Throttle body,exhaust and intake are all stock.Injectors were balanced and cleaned 100,000km. I have tried playing with the air/fuel ratio in the VAFM for months.(Any Thoughts on this)
Problem is mainly total lack of power/miss during idle and throughout driving range. Absolute dog going up hill and truly a 3.slow. This engine should be way more powerful than it is.
I have had the plenum off twice to check for vacuum leaks,valve cover leaks,PCV valve connection, etc. Checked and tightened all intake bolts.Exchanged TB's,spark plugs, wires, cap and rotor, EGR. .(All these previous items were on my good running ex-engine).
PAIR valve is the last to be changed over, but all tests tell me that is in working order. How about the EGR modulator? Is there a test for that?
I have researched this and done everything possible to resolve.
Do I need to open up the intake by getting more air through the VAFM, and/or getting an overbored TB to compensate for the air the engine "wants".
I was told the cams make the engine run lean.
What does porting AND cams do combined? Extra lean?
Last edited by WestCoastMoose; 07-26-2011 at 04:53 PM.
07-26-2011, 05:34 PM
#2
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thats not porting, all u really did was take some out to match the intakes up so u have a strait flow when together, for a real porting u remover material all the way down usually really opening up the ports. i did shave some on mine and it made a big difference. but with out doing something to the intake, exhaust, and throttle body having cams will only help a little, to get the full potential of the cams u need to see how many cfms the injectors are pushing, stock air filter? also headers will help a lot. also check what the timing is, can advancing the timing to where it runs better help? i know i cant run the stock timing and just moved it tell my motor ran and felt like it had better power with out detonation. just some things to think about....
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