99TransAmDude

I installed a FAST 92mm Intake and FAST 92mm throttle body last week and something about the car doesn't seem right. Idle is okay (sounds slightly different) and it cruises okay at speed but it seems very shaky when accelerating. It's a 6-speed and the stick vibrates like crazy even at 1/3 throttle.

1999 Trans Am
It's mainly stock. Upgrades are high flow air lid, Edelbrock shorty headers, GMMG catback, ported MAF, EGR and secondary AIR removed and tuned out. Car had a dyno tune 2 years ago before the FAST intake/TB install

I installed the LS6 04+ valley pan to eliminate the PCV during the install with 2 new knock sensors and wiring harness since it was hard as plastic
I also installed Holley LS valve covers and new LS3 ignition coils
All hoses looked to be in good condition on the back so I don't think they're causing a vacuum leak
It doesn't seem like the throttle blade is catching like I've read in some forums. TPS is at 0 when idling
I took some carb cleaner and sprayed it around the different seals to see if the idle would jump up (never did) so I think the Intake has a good seal and the TB has a good seal.
I have an OBD2 gauge installed and I'm getting 0 misfires
I'm also reading 0 knock retard
The car doesn't smell rich at all.

Do I possibly need to do a retune?

On the positive side it does look cool.

Any ideas are greatly appreciated

Jtm2085

iTrader: (1)

When I did mine I didn't get one of the coil packs plugged all the way on and i had similar issues

99TransAmDude

I went out there and checked them at the coil and plug. They're all clicked all the way on.

Firebirdmuscle

iTrader: (16)

it may just need the tune tweaked slightly for that new setup but I wouldn't think it would cause problem that your seeing as in shaking wise.

99TransAmDude

I tried a few more things. I unplugged the MAF. It ran the same. I also tried the AC. The vent change works fine but when the AC is on at idle, it gets very rough. RPMs jump around from 1000-700. With the AC off, the idle is pretty solid, just doesn't sound quite right.

Running out of ideas.

BandDirector Blk98ZM6

iTrader: (21)

...just checking to make sure because you didn't specifically mention it, but you did replace the valley bolts with the low profile bolts included with the FAST intake, right?

I did a FAST 92mm intake swap with a Nick Williams 92 TB and didn't have any issues. It ran fine on the tune that it had when I did the swap and I couldn't tell any difference in the way it ran after I did go and have it retuned...but the dyno showed the difference

Did you do the PCM relearn prodedure after you installed the FAST? If not, I'd start there...

gtfoxy

If you can absolutely say it started right after the intake/TB then ignore me, but I will ask if you have checked the engine & transmission mounts?

Also, during this "dyno tune" did they just tune WOT?

99TransAmDude

Yep, I did replace the valley bolts that came with the intake. No I didn't see a PCM relearn procedure in the instructions. I did do a IAC one the throttle body spoke of. Is there another one?

99TransAmDude

Yeah it started right after I swapped all the parts. I'm thinking vacuum leak but can't find one. I was also thinking maybe I got a defective ignition coil or cracked a spark plug but I would think I'd detect misfire on my OBD2 gauge.

scotty2000ss

iTrader: (2)

If it were me I would sell the FAST TB and get a Nick Williams TB. The IAC holes are way too small on the FAST TB.

99TransAmDude

I've been reading that on a lot of threads. Wish I knew that before I bought the FAST TB. I ordered up a 92mm Nick Williams TB that'll be in tomorrow. Definitely worth a try and it looks pretty awesome too. The port for the airline on the fast sticks up on an angle. The TB looks good but the rubber line sticking way up and curving down towards the valve cover looks terrible.

scotty2000ss

iTrader: (2)

Good deal. Shouldn't be too hard to sell the FAST in the classifieds here.

gtfoxy

I have a FAST TB on my car & at an idle it does have a bit of side-to-side action at idle but no odd shaking at 1/3 throttle like you are having OP. I was told it has an LS9 cam when I bought it, & depending on the specs of the cam you have it may be quite different.

99TransAmDude

I did find a potential problem when pulling the FAST TB off. I didn't realize the screws for the IAC and TPS were different length. I had the longer ones holding the IAC in and it seems like the bottomed out before the IAC was flush. I did spray starting fluid around it though and the idle never changed so it might've had a seal.

Got the Black 92mm Nick Williams in today. Fits a bit better around my braided coolant vent hose and it definitely idles better. It's rock solid with the AC on. Storming all day so can't test drive till tomorrow or Thursday.

Looks pretty cool

FYI...the MSD fuel rails are not fuel rails, they are just the covers but it covers up the stock rails and wiring pretty nicely.

99TransAmDude

Still the stock cam but that will hopefully change this coming spring when I get more money. How do you like the LS9 cam?

gtfoxy

Providing it is what is, it's not too bad. I was told it had LS2 injectors but it has 42lbers... So take it for what it's worth.

It has some lope, but not excessive. Like I said, the car has a little side-to-side boogy going on which I don't mind. Throttle response with the current tune isn't too bad. It doesn't start to really wind up till about 4,500RPM, but it's no slouch down low either. Pulls 18"HG at idle.

99TransAmDude

Something is still off even with the Nick Williams TB. It idles better but still accelerates like crap. No power and sounds strange. I'm taking it in to a performance shop that did work for me in the past since I'm out of ideas. Appointment set for tomorrow.

gtfoxy

Curious to see what the prognosis will be.

But can I ask why you went with that big TB & intake right away on a stock cammed/ heads motor? Someone correct me if I am wrong, but isn't that a bit of overkill?

99TransAmDude

I have plans for doing a Cam as well but wont have the money for a while (sort of wish I took the money and did the cam first). I was thinking the same that it was a bit overkill but I've seen a lot of articles of people who did the same switch and picked up 15hp or more on a stock motor. I got a good deal on the intake and figured it would look cool.

Talking to the shop on the phone he says it's possible the MAF is reading a much larger volume of air than what it can adjust for. I guess that makes since why it idles fine since it's just getting air through the IAC but once the throttle blade opens it goes to hell. Hopefully they can fix it with a tune. I should know today and will post the results.

scotty2000ss

iTrader: (2)

Not going from the LS1 intake.