About to throw this TB/plenum setup in the trash

[96Mystic1189]

Well guys I just installed an C&L plenum and 75mm Accufab throttle body on Saturday and you already know what I am going to say. Talk about insane idle hang and crazy revving. So, before I make the same basic thread let me start with the basics.

So the car either does one of 2 things every time you come to a stop or shift it. Whatever RPM you are at when you push the clutch in, is the RPM the car will stay at until you are at a complete stop. For example if I am in second gear and rev it out to 3000rpm to shift, if I push the clutch in and just sit there without shifting, it will just sit at 3000rpm or even flare up a few hundred rpm until the car comes to a stop for at least 5 seconds.. If it does decide to come down because I decelerate is really low, it will just sit at a minimum of 1500rpm until you come to a stop.

The tps sensor is set at 0.99v with the throttle shut.

I do not believe there is a vacuum leak because I sprayed all over it with throttle cleaner with no change and the fact that it comes back down to 750rpm when sitting at a light for a few seconds. Where to next? All my sensors and IAC were fine before this. Is it my SCT tune? Its just things like this that make you want to get rid of the car.

BTW this is my 97 GT 2v. Thanks for any advice you can give.

 

[the5.ohh]

Just a dopey question. What's the reason for a 75mm on an NPI 2V. Not at all trying to be a douche, just curious. I think you'd need to update your tune honestly if everything else checks out fine. Just a thought, maybe unhooking the battery and reconnecting it might help since that resets the computer.

 

[07GtS197]

Its a really common problem with our 2v's. I have it with my c&l plenum and 75mm tb as well. Have you tried pulling the neg battery terminal for 30 mins and resetting idle? Another thing you can do is buy an iac resistor plate but mine hasnt done much so far. Does the accufab tb have an adjustment screw on it?

 

[white95]

Just a dopey question. What's the reason for a 75mm on an NPI 2V. Not at all trying to be a douche, just curious. I think you'd need to update your tune honestly if everything else checks out fine. Just a thought, maybe unhooking the battery and reconnecting it might help since that resets the computer.

To be fair, I tossed a JLT CAI, Accufab plenum/75MM TB combo on mine when it was NPI still and it made a decent difference. Pulled harder than before past 4k rpms and the throttle response was much better off idle. After I installed the PI heads/cams it pulls harder than my ported head/E303/Explorer intake 306 ever did, and my 98 has 2.73s!!!

 

[white95]

That aside, your issue likely lies with the IAC valve [idle air control valve]

http://www.sn95forums.com/showthread.php?31988-How-to-make-your-own-IAC-restrictor-plate

This will fix your issue and is very cheap to do!!

 

[Tally_4.6]

To be fair, I tossed a JLT CAI, Accufab plenum/75MM TB combo on mine when it was NPI still and it made a decent difference. Pulled harder than before past 4k rpms and the throttle response was much better off idle. After I installed the PI heads/cams it pulls harder than my ported head/E303/Explorer intake 306 ever did, and my 98 has 2.73s!!!

Mine does too, AF plenum/bbk 75mm. Why on earth does it still have the 273s? I couldn't believe how slow my car was with those.

 

[g36 monkey]

It never hurts to do a good vacuum smoke test. The IAC restrictor is really more of a bandaid.

 

[white95]

Mine does too, AF plenum/bbk 75mm. Why on earth does it still have the 273s? I couldn't believe how slow my car was with those.

I drive about 100 miles a day and they're nice in stop and go traffic. Honestly, I may swap the 8.8 with 3.73's from the '95 GT into the '98 GT and then build this 8.8 up with better axles and a Torsen for the '95.

 

[g36 monkey]

3.73 would be better for stop/go than the 2.73. The 2.73 is your highway gas sipper, instead of chugger like say 4.10s lol

 

[white95]

I'm averaging 22 mpg driving the **** out of the car

 

[96Mystic1189]

Ok guys so I readjusted the set screw by turning it in using a 0.10 feeler gauge and then turning in one full turn and locking it. I did it with the battery undone and then set the tps to 0.98v when i plugged it back in. It is so much better so far. Hopefully it stays running well.

Does anyone else's exhaust kind of pop or stutter at idle every so often? Kind of sounds like a misfire but different. I have just never paid attention outside of the car until today.

I have a jlt cai, 75mm tb, and plenum because I have pi heads and and intake for the car. I am going to be camming the car as well. I am getting all my supporting mods done. It does all still make a difference on a npi especially on the top end like stated above.

 

[Frank.JD.Perez]

Seriously...273s was like no gas now I have to get gas twice to three times as much as before

 

[96Mystic1189]

I get almost 22mpg with my 3.27s but really want 4.10s. The fastest i go to work is 70mph

 

[Frank.JD.Perez]

I would gladly trade you hahahah, 410s on a daily was a horrible mistake for me

 

[Thomas_W]

I wish i got 22mpg. My 3v swap gets like 13-14mpg. Then again, the shitty tune i got for it doesnt help with a 10:1 AF ratio above 3500rpm.

 

[96Mystic1189]

I would gladly trade you hahahah, 410s on a daily was a horrible mistake for me

So fun though right? What don't you like besides the gas milage? How many rpms at 70mph do you know by chance?

 

[Frank.JD.Perez]

2500 in 5th. its fun no doubt about it i just need more gear. more gear and some better gas mileage for the moment are my only issues with 410s. no joke 65mph vs 70mph is about 150rpm difference. 80mph is about 3k. ive gone over 100mph (maybe 110?) and it was under 4500rpm

 

[Nighttrain]

It never hurts to do a good vacuum smoke test. The IAC restrictor is really more of a bandaid.

What is the right fix? If you dont fool the sensor, can you set it differently with a computer?

 

[ttocs]

only fix I found on similar problems was replacing the throttle body/plenum. I don't hear much good about C&L

 

[98snakehorse]

I know there are tons of threads on the best aftermarket plenum to buy for our cars and I thought C&L was up there but I could be wrong. I had one on my 00gt and it performed well. FWIW I have a trickflow 75mm plenum and $45 ebay 75mm throttle that work great! Does it have huge performance gains?.... couldnt tell from the seat of my pants but it looks really nice