Rb20det Low Rpm Deadspot/hesitation

[Skylsh32]

Hey there

I've got this really weird problem with my car if I keep my foot on the throttle as if I'm

trying to hold the revs at 2000rpm it will go to something like 1800rpm then drop to approxamately 900rpm and then go back up to 1800 and will repeat this until I give it more gas sometimes hesitating to increase revs. This began happeing after a front facing plenum conversion with an 80mm throttle body. Could that have changed air/fuel ratios?

Things I've done:

adjust tps

check for airleaks(none)

check ecu codes(none)

if anyone has experienced this problem any help would be appreciated.

I should also note that this does not happen when tps has been adjusted to a higher volt setting however that results in a much higher/annoying idle

[_Ryan_]

cleaned/checked afm?

[Skylsh32]

I haven't bothered with that just yet as it happened after the conversion. I will however get around to doing that. IF my dump pipe was cracked (it's stainless steel) could this cause an issue like this.

Here's something weird that happened one time I put my foot down after the drop

in rpms as mentioned above I saw my boost gauge shake rapidly between 2-5psi! This is on idle! I will double check for airleaks.

[payback21]

What have you done to replace the original plumb back system going from the original crossover pipe to turbo intake pipe? Without it being on the engine anymore this will happen. My drift car was doing the same problem until i put all the old cross over pipe and plumb back system back on. The guy before me owning the car removed it. Its all okay now.

You may need to configure a bov with a plumb back system for your new plenum.

Edited November 5, 2009 by payback21

[Skylsh32]

What have you done to replace the original plumb back system going from the original crossover pipe to turbo intake pipe? Without it being on the engine anymore this will happen. My drift car was doing the same problem until i put all the old cross over pipe and plumb back system back on. The guy before me owning the car removed it. Its all okay now.

You may need to configure a bov with a plumb back system for your new plenum.

Thats interesting i never thought this would be a problem as I've never ran a plumbed back bov even before the plenum, definitly worth a try though as im stumped on what else it could be.

[Skylsh32]

i haven't yet tried the plumb back bov suggestion but is there anything else out of the normal i should check for? can anyone share some details on why plumbing back the bov would work? it would be good to learn from it.

[White GTS-T]

How did you adjust the tps? What voltage does it reed at idle?

[Skylsh32]

How did you adjust the tps? What voltage does it reed at idle?

I turned the key on the 3rd one of the ignition barrel just before you start the engine. grounded the black tip of the voltmeter and connected the red tip with the middle(white) wire of the tps plug. Then i unscrewed the two screws of the tps and adjusted it untill the voltmeter read .45 i have been told an acceptable voltage is between .45-.55 i have not checked the tps at idle. does it make a difference? will hit back when i do get a chance to measure it.

[Skylsh32]

okay so i have measured the tps at idle and it reads the same as it does when the engine is off. could an exhaust leak be causing this issue? i think i hear a ticking sound near the stainless steel dump pipe. However I don't think this would cause an issue seeing as though this seems to be related in such a way that its showing on my vacuum gauge. im also not running an o2 sensor this was removed when the car was tuned but it was done so before the front facing plenum conversion. this only happens at approx 1500 to 2000rpm i have a feeling it is an electrical fault so the next things i will try is cleaning the afm and try to put my o2 sensor back in.

[Skylsh32]

I've cleaned the maf with no change at all. Still puzzled

[Skylsh32]

okay finally sorted it ended up being a crooked throttle body shaft and also the tps needed some washers. stupid aftermarket item!!!

[Cefi_A31]

okay finally sorted it ended up being a crooked throttle body shaft and also the tps needed some washers. stupid aftermarket item!!!

could you post some picture of it because i have similar prob to.....