Engine holds on to RPMS when revved

I

ibn_inked

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Mar 22, 2010

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Atlanta, GA

Apr 16, 2010

#1

• Apr 16, 2010

• #1

So I have a 98 GT vert with an AOD trans. I did a 2001 PI motor swap this week. Problem is when I rev the motor the RPMs SLOWLY return to idle. Not a nice crisp rev and return to idle. It revs quickly enough, just takes a few seconds to slowly drop back to idle.

I think its a tuning or ECU issue since it was this way with the 98 motor and is the same with the 01 PI motor.

Any input? Thanks

Is there any visual way to inspect the difference for 98 2V and 01-04 PI 2V?

 

wmburns

SN Certified Technician

Aug 14, 2009

5,892

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Houston Texas

Apr 16, 2010

#2

• Apr 16, 2010

• #2

The slow return to idle is for smog reasons. They all do it.

If the idle hangs for excessive periods, 1st check the throttle body linkage. Ensure it moves freely. Check the throttle return spring.

Did you alter the throttle body set screw? This could be allowing too much air to enter. This will cause a high idle.

Next check for vacuum leaks.

Finally, suspect a bad TPS.

If it really bothers you, there is a IAC restrictor gasket on ebay.

 

I

ibn_inked

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Mar 22, 2010

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Apr 16, 2010

#3

• Apr 16, 2010

• #3

It idles beautifully. The other motor did too.

It just bothers the heck out of me that it returns to idle from a rev so slowly.

I mean REALLY bothers me.

My GT500 revs smooth, sounds mean as hell, then quickly returns to idle.

My 98 with 01 PI motor revs smooth, sounds good, and (like grandma's car) slowly returns to idle over a few seconds.

I really want to get rid of this.

Throttle spring looks good and TPS screw seems fine too.....It wasn't altered when PI swap was done.

Dunno.....was thinking of ways to get rid of that slow return to idle.

 

RedDaemon

10 Year Member

Mar 31, 2005

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Apr 16, 2010

#4

• Apr 16, 2010

• #4

wouldnt a spacer and UDPs solve this ? dont quote me but i think ive seen stuff on these mods regarding a quicker return to idle

 

I

ibn_inked

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Mar 22, 2010

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Apr 16, 2010

#5

• Apr 16, 2010

• #5

Yah UDPs are in the very near future and I am planning to upgrade the throttle body to 75mm version next week too.

I am hoping as the mods increase this annoyance goes away.

Just looking for a magic bullet of sorts to fix it ASAP.

Thanks

 

ChillPhatCat

20+ Year Stangneter

Apr 22, 2002

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Apr 16, 2010

#6

• Apr 16, 2010

• #6

Why does it bother you so? It's not like it hurts performance.

Edit: UDP's didn't seem to do anything for this in my case BTW.

 

RedDaemon

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Apr 16, 2010

#7

• Apr 16, 2010

• #7

ChillPhatCat said:

Why does it bother you so?

Click to expand...

this is why :

ibn_inked said:

...My GT500...

Click to expand...

hes spoiled

 

I

ibn_inked

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Mar 22, 2010

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Apr 16, 2010

#8

• Apr 16, 2010

• #8

Yah........i just want em all to be fast as hell and sound as mean as anything out there when ya rev em.

I don't see the problem with that.

You are absolutely right....it doesn't make it any slower......and it moves a lot better with the 01 PI motor than it did with the stock 98 2V. Guess I shouldn't whine.

Thanks for the input all.

 

ChillPhatCat

20+ Year Stangneter

Apr 22, 2002

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Apr 17, 2010

#9

• Apr 17, 2010

• #9

Yeah I can see that, it was something that was kind of annoying when I first got my car... I'd be like hey doesn't this sound good? Rev.... still revving, revving slower, back to idle. It doesn't give that satisfying throttle blip of muscle cars of yore.

 

I

ibn_inked

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Mar 22, 2010

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Apr 18, 2010

#10

• Apr 18, 2010

• #10

Yah that's absolutely my point PhatCAt.

I see plenty of vids on you tube of quick revs on 01-04 GTs and am hoping that with mods and a little tuning mine will open up like that.

Just not as satisfying.

 

BlackStang03

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Mar 26, 2010

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Ohio

Apr 18, 2010

#11

• Apr 18, 2010

• #11

ibn_inked said:

I see plenty of vids on you tube of quick revs on 01-04 GTs and am hoping that with mods and a little tuning mine will open up like that.

Just not as satisfying.

Click to expand...

how do they get them that way? It is annoying

 

I

ibn_inked

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Mar 22, 2010

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Apr 18, 2010

#12

• Apr 18, 2010

• #12

Im glad Im not the only one that feels that way BlackStang03.

Dunno, and that's what I am hoping to get answers for here.

I would love to have that quick throttle blip and roar.

If I figure it out with the mods/bolt ons in the near future I'll let you know, I was just hoping someone has already been down this road and knew a fix.

 

F

flatbil

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Mar 12, 2010

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pennsylvania

Apr 30, 2010

#13

• Apr 30, 2010

• #13

iac restrictor plate will solve your problems, i made my own for about 4 bucks and my rpms drop really fast after a rev or shift, my cars rpm drop was super slow till i did this mod