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06 X3 misfires

5K views 14 replies 8 participants last post by  ncord 
#1 ·
When I accellerate to merge etc.the engine sounds good till just before it shifts from 3rd to 4th gear (auto trans.).Then it seems to mis fire a bit until it shifts.I put in a bottle of seafoam,and have just replaced the plugs .Plug #2 had oil all over it ,even up the sides of it.
Cleaned up the oil & installed new plug ,but car still misfires with hard accelleration at about 4000 rpm.in 3rd gear.With reving in park or regular accell.it runs good.What could it be???
Car is an 06 3.0 with 86k.miles (car orig.from USA)
 
#2 ·
When I accellerate to merge etc.the engine sounds good till just before it shifts from 3rd to 4th gear (auto trans.).Then it seems to mis fire a bit until it shifts.I put in a bottle of seafoam,and have just replaced the plugs .Plug #2 had oil all over it ,even up the sides of it.
Cleaned up the oil & installed new plug ,but car still misfires with hard accelleration at about 4000 rpm.in 3rd gear.With reving in park or regular accell.it runs good.What could it be???
Car is an 06 3.0 with 86k.miles (car orig.from USA)
That sounds like you need to replace the valve gasket cover if your getting oil up in the plugs.

Throwing any codes? If so, list them
 
#3 ·
My '08 does something similar... It sometimes feels like it "hesitates" but only under heavy acceleration. I'm due for new plugs in roughly 25k miles, but may replace them and the ignition coils much sooner.. Someone also has suggested replacing the O2 sensors, but those are expensive and should last way past 100k miles..

My plan is to keep running Techron through the system every could thousand miles (no seafoam), then replace the plugs..then the coils.
 
#7 ·
I am going to butcher the explanation but one of the users on here recently gave a through reason why seafoam doesn't work with our engine. I will have to find the thread when I have a moment but it had something to do with our engine design is not compatible with what seafoam is designed to do. It won't harm anything but it won't help either.
 
#13 · (Edited)
Hesitation under load and no CEL, could be a sign of gas starvation. It could be just a clogged fuel filter or a fuel pump going bad. But in order to diagnose a fuel pump, you need special equipment to measure fuel pressures.
Also O2 sensors have been known to produce hesitation under acceleration when they start to fail, although not triggering a CEL.
 
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