RPM's acting weird at idle....?

marylandevo8 · Nov 6, 2009, 06:55 AM

Hey guys,

So I was driving my EVO to school yesterday and noticed at a red light, with the car in 1st, I was looking at my RPM's. I noticed it mainly stays around 800-1000. Sometimes it will spike to 1,300 or so but then it would come back to normal after a couple seconds.

This was not the case yesterday. While at the red light, the RPM's were jumping from 800 to 500 back to 800 then down to 250 then 500 then 800 and so on, to the point the car was about to shut off even while the clutch was pressed in because I was in 1st gear. I guess it's also important to note when the car was sitting at idle, and the RPM's were jumping from 250-500-800, I noticed the car was running lean...

My question to you guys is....Why is this happening? I have an 05' EVO III with the following mods:

Megan Racing TBE
Injen Upper/Lower IC Piping
Injen Intake
TurboSmart BOV -- (I bought the car with this already on it)

My guess it could have something to do with my BOV...Please note, the car does NOT have a tune yet....

Im sort of strapped for funds right now...I'd like to pay off my $1,300 credit card before spending $350 on a tune but after judging how my car is running....I may want to get the tune now....

Have you guys had this similar problem? Let me know what you think, regardless.

Thanks,
Randy

marylandevo8 · Nov 6, 2009, 06:56 AM

Sorry guys....please disregard EVO III....I meant EVO VIII. lol.

Fast_Freddie · Nov 6, 2009, 07:00 AM

You may wanna pop the BOV apart and clean/lubricate it... sounds like it may be sticking open...

**MR Turco** · Nov 6, 2009, 07:08 AM

i would check the BOV also. You may also want to do a boost leak test. Now that the temp is dropping it can cause boost leaks to get worse. You may also need new TB seals which i have seen cause this issue as well.

bostonhatcher · Nov 6, 2009, 08:29 AM

Does it do this in neutral or just in gear? If it's just when it's in gear your clutch might not be fully disengaged causing the motor to bog down.

Aftermarket intakes cause ****ty idle. The maf needs to be rescaled. A tune would help some but the stock maf's don't really like aftermarket intakes. This is most likely the culprit.

Could be a boost leak. Any air that gets sucked in after the maf will cause the motor to run lean.

09Ralli · Nov 7, 2009, 10:51 AM

how do u like that megan tbe? im about to buy one, is it smooth and not too loud? noticable gain?

red03evo · Nov 7, 2009, 11:01 AM

Personally when I had the turbosmart dual port, I had idle issues. Once I swapped to my 1g diverter valve, it was a lot better.

Good luck.