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Weird pulsation under light throttle, lower rpms


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Hey guys, lately I've been noticing a weird pulsation under light throttle and usually below 3000 rpm. It's difficult to describe and I have yet to see a thread describing my symptoms.

 

Basically, when I'm driving at say 2k and hit the throttle 25% I notice a pulsing feeling in the gas pedal. I know it's not the best description but I'm clueless as to what it is and looking for some input from others who may have experienced the same. It usually occurs more in 3-5th gear, but not exclusively.

 

Any help is greatly appreciated. Thanks

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  • 2 weeks later...

bump, still feeling this. Narrowed it down a little more.

 

I am getting a vibration/pulsation feel throught the gas pedal(although probably not related to that mechanism - as i do know it is drive by wire), but it usually occcurs right around 2500 rpms in 3rd, 4th, and 5th under half-full load. Any ideas would be greatly apprecaited.

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I had this problem and I think after I did my exhaust manifold it went away. I prob had an exhaust leak not sure if that will do it. Also maybe an ic leak? +1 on the MAf sensor they sell cleaner for it at autozone.
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I would clean the MAF sensor and if the issue is still there find a Tuner that will street tune the car with you driving.

 

My 09 does a little stumbling at low rpm, I just down shift and it goes away. Last Fall I had my Tuner tune the issue out. After he tuner for stage 2 I told him and showed him the stumble, he did some magic with his lap top and the issue went away.

 

I think your feeling the stumble or do you only feel it under your right foot ?

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

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Are you running stock or AM intercooler? Sounds like you have a leak somewhere in your intake tract that's bleeding air. If you have replaced your IC, I'd check the TB hose connections and failing that check all of your vacuum lines as well.
- Pro amore Dei et patriam et populum -
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Thanks everyone for the input, when i get home i will check all of the lines. I do have an aftermarket IC, and have had problems before with the TB hose clamps letting loose but that felt different, although i will defintely ensure it is on there snug.

 

MaxCapacity - i dont believe its only under the right foot, although, when accelerating, i feel it there since my foot is on the gas pedal.

 

i will inspect everything as soon as i get a chance, but would you guys recommend me giving the MAF sensor a good cleaning? or wait until i check for any possible leaks and then do the MAF if the prob. persists?

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I asked about the AM TMIC because my Perrin TM rubbed both on the clutch cylinder reservoir cover and on the slave cylinder banjo bolt. Once I fixed that issue (washered the TM 'up' a bit from the RH mount) the vibration I was feeling in the gas peddle went away. This may be different perhaps than the pulsing that you described, but shared as a possible 'fix'.
- Pro amore Dei et patriam et populum -
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CRC MAF cleaner is the best. Be very careful and read up on MAF sensors.

 

MAF sensors get dirty and they are the prime sensor for mixture. On an 05, is is very possible the MAF sensor wire is dirty.

"Belief does not make truth. Evidence makes truth. And belief does not make evidence."
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great, thanks robinlsb, i will consider all of your options and hopefully provide a solution for anyone else who is experiencing this. If there are any other things any member feels i should look at, please advise. Your help is much appreciated.
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I thought that this stumbling issue was something that all EJ25x engines had a problem with? I am in the middle of tuning this out myself after reading this thread:

 

http://www.romraider.com/forum/viewtopic.php?f=15&t=4911

 

I can let you guys know how it goes on Tuesday when I (hopefully) load the updated map with the stumbling fix.

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Mine did the same thing - was the IPR TMIC hitting clutch master (vibration in pedal).

 

The stumbling is normal on an untuned LGT, though.

 

My bone stock 05 LGT has the same stumbling. Can't wait to get that tuned out.

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Mine did the same thing - was the IPR TMIC hitting clutch master (vibration in pedal).

 

The stumbling is normal on an untuned LGT, though.

 

will check this tonight, this seems most likely the cause, as i have an IPR as well.

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