After the explosion in my driveline last weekend, the car got fixed up and suddenly the 90mm TPIS attached to my LSx intake appears to have an attitude again.

Upon putting the clutch in the revs shoot to 2500-2600 rpms at any point, sometimes higher. However, it still idles as before and doesn't hang at stoplights like it used to. Occassionally it gets the automated cruise control back as well.

What would cause one portion of it's bad behaviour to come back but not others? It was fine for almost 2000 miles, then whoop, back to bonkerland.

On a related note, once the winter comes, should I have the PCM reprogrammed when I throw back on the LS6 or would it be alright as is. This thing is too much of a PITA for my blood.

 

My revs shoot up to between 2500-3000 RPM immediately once I fire her up after sitting for awhile. She then dips down to 300 RPM and the car sounds sick and then whamo right back up to 2500. Once warmed up the idle is just fine and she behaves as expected. Hard to figure and when this cold starting issue occurs, it varies from not too bad to screaming.

 

Dave,
The High BARO and the cold air we are having is most like the culprit.
If it was border line before and near the end of the computers ability (IAC range) to close off the TB air this will happen.

On a light note, LS2 intake and Throttlebody. You will make the same power with zero drivability issues. THe only problem is the tune for idle conrols will have to be moved back near stock.

Phil

 

I totally didn't think of the weather until I walked outside this afternoon, and I'm sure that's alot of it. I'm definitely thinking about that LS2 for the winter, and although I'd have to retune to it, it'd be more than worth it for the driveability.

p.s car feels good...for now hammered it for a bit and no shafts of any kind snapped.

 

Good to hear that you are back on the road, Dave!

 

Hahah..good, schedule is full for a bit..Earls toasted the clutch and has some other stuff he needs..

I suggest a copy of LS1 edit for youself...you can tweek and play and the price is right in the long run. I can help you thru it.

Phil

 

Do you have LS1- Edit or HP Tuners?? What is the Intake Air Temp ( IAT) at start up when the over-rev occurs???

 

I don't have any tuning equipment but rather rely on The Vette Doctors of Amityville, NY for that. The air temp in the garage at startup is approx 75 degrees. The problem with bringing it out to them to tune it is that in order to duplicate the situation, the car would have to sit overnight. Unless it can be diagnosed and corrected while warm, I'll have to wait until I leave the car there.

 

i have no idle issues what so ever,no cruise control. but sometimes at stop lights it stalls or the idle hunts

 

According to Nick Williams there should be no idling or driveability issues whatsoever. It is all a matter of tuning.

 

Easy for him to say. I'm not trying to slam anyone, but, I've nothing but horror stories about that TB.

Mark

 

really?? im happy so far with mine. i heard horror stories from the TPIS unit

 

pdd- are you saying that you don't get the "cruise effect" when you have the AC turned on with NW 90mm TB? By the way, by cruise effect, I am referring to the weird cause and effect that occurs when the AC is turned on and the idle does not want to drop when shifting gears (up or down). The idle will drop, of course, but at it's own sweet time. To me that is the MOST irritating negative of the TPIS 90mm TB.

 

If you have hptuners, look at the throttle cracker section... This adds air to the motor once the car is in motion...

 

What horror stories have you heard???

 

I agree with Bink, I'd like to hear these stories because I have nothing but good things to say about the ease of tune and quality of the Mark Williams TB....and I am not without a fair amount of knowledge and experience in tuning them.

FWIW, the TPIS is a handful but even those can be tuned to run and idle without issue.

 

I have "no" issues with Nick's TB. If your car is tuned and running well when you put Nick's TB on, it will need little or no tuning. The tuning issues seem to occur when other changes, such as a cam, are made at the same time. I believe the TPIS problems have created a bad image for 90mm TB's.
There should not be a difference in running rpm's with A/C on or off.
If the car was tuned during warm weather the fact that the tune at lower temps was not right wasn't apparent. You are not out of IAC range. Think of it as if your setting a choke on a carburator. It can't be done until it's cold out.