Quote:
Originally Posted by timqqt
Hey guys, I got a P1128/P1130 codes at idle. My car runs great. At idle, it vibrates a little bit, but not very obvious. Here is the freezing frame.
FUELSYS1 CL
FUELSYS2 CL
LOAD_PCT 3.9%
ETC 201F
SHRIFT1 4.7
LONGFT1 0.8
SHRIFT2 4.7
LONGFT2 -0.8
RPM 680
VSS(mph) 0
I had two freezing frame of P1128. They all happens at 680 RPM and 0 mph. What could be the problem? I assume it is MAF, O2 sensor or vacuum leak. But could I locate it more precisely? Thanks!
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Your issue is affecting both banks of the engine.
Not likely to be a problem with the O2 sensors on both banks at the same time.
MAF sensor? possibly but I don't see anything unusual in your freeze frame data.
So Go with the old automotive diagnostic adage of simplest things first.
Which would be a proper vacuum test. a vacuum test gauge cost about 15-20 bucks.
A proper vacuum test will tell you if you have a vacuum leak or not.
The reason your car idles a little rough then smooths out and runs fine above idle is:
As you open the throttle and give the engine more and more air the unmetered air "vacuum leak" becomes less and less a part or percentage of the total air taken in by the engine.
So lets say at idle (throttle closed) your vacuum leak is allowing 10 percent more air into the engine at idle then it needs. Your DME OR ECU doesn't see it because the leak is after the MAF sensor. But as you open the throttle to lets say half throttle now you vacuum leak is down to say 3 percent of the air that the DME or ECU doesn't see. So now the air intake is closer to correct for the engine load so it smooths out and runs better.
Hope that makes sense
as I am not very good at explaining things.
I am reasonable sure you have a vacuum leak based on the info you provided.
But I could still be wrong: hard to be certain when I don't have the car before me.