Cold Weather Boosting

Alpine TSi · 10-02-2004

I was having some minor issues with my car yesterday that I am hoping are just weather related.

I couldn't slam the throttle down for an entire gear like I can in normal 70+ weather, what would happen is at about 5K rpm in 3rd I would be at about 18psi and then the car would just start missing really bad and then I would shift into fourth and it wouldn't go anywhere(at full throttle) for about 5 seconds, then it would go. I was doing fine with about 11.2-11.9 AFR's and no boost creep, so I wasn't running lean. However for giggles I decided to hit the peak/hold function on my AFC2 and the incoming MAF frequency was at 5200hz(straight value with nothing taken out by the GM MAF) at 5100rpm where I shifted out of third. Now I rarely see about 3200hz even at 25psi at the track so I am assuming that this was because the outside temp was about 35 degrees and the air was already so dense. Is this thinking correct or am entirely wrong? If I am right why would I miss so badly? Today with slightly cooler than normal temps I was fine all the way through third and fourth.

I probably should just turn the boost down at this time of year, but I really want to have as much fun with my car as I can, if it costs me my motor, so be it.

Thanks in advance.

Enes · 10-02-2004

dayam, i had same issue... wth same here, my missing went away when i set my boost to 23 and my 750 injectors to -1 max -3 on my fuel setings and this was even with 110 octane..

werd up on power, and i'm seing 44# air too

-E

npaulseth · 10-02-2004

My idle is about 300 rpms higher with the colder weather.

JustROLLIN · 10-04-2004

Quote:

Originally posted by npaulseth@Oct 2 2004, 08:43 PM
My idle is about 300 rpms higher with the colder weather.

That is completely normal until the car reaches its operating temp.

I also see a few issues with the cold weather. Due to my car running incredibly rich, I get some very poor fuel vaporization and will get a very nice back-fire up around 5k when I am WOT until I get her nice and warmed up.

A//// Guy · 10-04-2004

Mine idles 300-400 higher when its its winter vs summer. Even when its warm... but most of that is caused by the maft without the screen so metering is different.

JustROLLIN · 10-04-2004

Yeah, I am guessing that would be a maft issue as well. The car should idle at ~750rpm when it is at operating temp regardless of the ambient temp.

1slowdsm · 10-05-2004

750 is the normal idle range, huh? Mines idles at around 900 -1100. Should I go and adjust my idle? In the summer time, when I turn the A/C on my car's idle drops to a point where its about to die and it stays there for a few mins and then dies. Anyone know why thats happening?

carltalon · 10-05-2004

sounds like eveyone with problems is running maf-t . could it have something to do with the intake air temp being set at a constant 80 deg.

Alpine TSi · 10-06-2004

Now I am no electronics genius(Eric feel free to pipe in here), but wouldn't we be able to intercept the wire that sends temp from the MAF-T to the ECU and put something in, such as a potentiometer, and just give it a basic adjustment that would in hopes lower(I don't think we could raise it) the temp that the ECU sees? Wow big sentence... And if it were adjustable we could just crank it up and down based on what we think it is outside, definately not precise but in mind it would be better than it saying it was 80 instead of 15.

Anyone try this or know if it can be done with any combination of parts? Would it have any merit?

npaulseth · 10-06-2004

Quote:

Originally posted by JustROLLIN+Oct 4 2004, 09:29 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (JustROLLIN @ Oct 4 2004, 09:29 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-npaulseth@Oct 2 2004, 08:43 PM
My idle is about 300 rpms higher with the colder weather.

That is completely normal until the car reaches its operating temp.

I also see a few issues with the cold weather. Due to my car running incredibly rich, I get some very poor fuel vaporization and will get a very nice back-fire up around 5k when I am WOT until I get her nice and warmed up. [/b][/quote]
No. I mean it is 300 rpms higher after it warms up.

LightningGSX · 10-06-2004

That makes sense, the ECU uses IAT signal for calculations other than airflow.Since IAT sensors are cheap, maybe one of you guys should try to add one to the MAFT setup.

Alpine TSi · 10-06-2004

Would it be better to put the sensor before the turbo, or in my case with MAF in the UICP? How would this be done? I am very interested.

carltalon · 10-06-2004

Quote:

Originally posted by Alpine TSi@Oct 6 2004, 09:32 AM
Would it be better to put the sensor before the turbo, or in my case with MAF in the UICP? How would this be done? I am very interested.

I'm interested too. Im starting to get sick of maft's bull shit.

A//// Guy · 10-06-2004

Whats so bad about changing your idle 2 times a year?

slowbubblecar · 10-06-2004

I am not so sure about the misfiring but the cold air can really good on the car. Last year, we were able to run 20psi pump on the big 16g tuned perfectly. I would say the cold air is generally a big advantage.

LightningGSX · 10-06-2004

You can try the widely available GM IAT,GM P#25036751 and mating connector is GM P#12102620 or Napa P# ECHTSC300.If you look around you can find these for like $10-$15 with the connector.Not a perfect match though, it will read about 5-8 deg F hotter than actual, but that shoudn't make much difference.This should go before the turbo.