Rough idle, shaking when in d and taking foot off brake.

P

polskifacet

New member
Hey guys,
New issue appeared yesterday. Car has a rough idle, tac is bouncing 50-100 rpm and when I take my foot off the brake when it's in gear it pushes the car forward makes the whole car kind of bounce forward. Boost seems ok, when the rpms are higher, it doesn't happen, has full power when I floor it. What could be the issue?
 
Maybe a vacuum leak, any codes? Are you running torque?
Did you try a new/different gas station lately.



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No codes. Only thing I have noticed in torque is the trims are pulling fuel . Ltft is -9 and it has always been +9 when running well. TC is probably fine, runs very uneven in neutral or park. Also runs crappy on low rpm even at 40. I'm leaning towards a bad coil pack. I can hear the turbo is also affected because you can hear the choppiness in the turbo whine so it has to be before the turbo. No codes. Trans temps are never higher than coolant temp, usually 160-170.
 
If LTFT is showing running rich, you may have an injector problem, any smell of gas at any time?  I'd try cleaning the MAP sensors also.

Which version of the tune are you running, and how many miles on the plugs?
 
Plugs have about 15k , I just checked them and they look ok. Lms v10 and I just installed ppe catted DPS . Haven't smelled gas. Put 87 tune in and it's the same. I assume that the lms tune already accounts for DPS.
 
From what I remember, LME does assume Downpipes are installed and they turn off the rear O2's.  Can you see what the tune is specifically called?  There used to be acronyms after the version number that would tell you if the tune accounts for Tstat, or DPs, etc.
 
I only see 93 performance v10 3 bar.  So looks like downpipes are NOT accounted for (or they ran out of room in the naming convention).  Def worth a call to LME.
 
I don't think that will be the case.  Like I said, they probably just changed the naming convention.
 
I put them in a week and a half ago. Was running great until last night. I tanked up and when I started the car, it started jerking at idle when I took my foot off the brake. I wouldn't think bad gas would affect the car that quickly.
 
polskifacet said:
The only problem I can her is an exhaust leak most likely off the turbo to downpipe connection.
Click to expand...

Is it bad? I don't know if it's contributing to your problem or not but you need to get that fixed...My downpipe cracked and my stft's were all jacked up. It was annoying at the least and my car's idle was smoother after it was fixed.....An exhaust upstream of the primary 02 will cause mis fueling everywhere...WOT , idle, cruise
 
It's only bad if I take my foot off the brake because it keeps jerking forward. Otherwise the exhaust note changed, it's louder and has a distinct lug lug lug to it. It feels like the motor is running uneven. All the plugs look ok. Compression tested the front 3 cylinders and they came back 170 psi. Still no codes or pending codes. Put in 2 bottles of HEET to maybe help if there was water in the fuel. Boosting 15-16 psi, no smoke from exhaust. I'm boggled. Only weird thing I see is the dramatic change in ltft changing 15-18 points now -9.
 
Polski it sounds like your DP as mentioned earlier have a large leak by the front turbo connection,did you install new gaskets? also check for any pinched wires from the front 02 sensor's,here's a pic of mine when changed and best of luck to ya.  Z   
aDEqkBJ.jpg
 
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