AC kicks in = car dies

[boost97gst]

Is there a setting to compensate for the additional load in link? I just got my ac charged and it works fine but at a stop itll die when the compressor kicks in. Like its not bumping the rpms up appropriatley.

 

[bcjjones]

I guess you've checked your IAC?

 

[boost97gst]

Whats an IAC?? Jk, but no, i havent checked that yet. Car idles just fine without ac though. Ill have to check that.
I may have a boost leak too, mafcomp and combined ft are really wacky since the 272 cams and new turbo.

 

[luv2rallye]

Do you have the stock 4 wire connector alternator? It sends a signal to the ECU when additional loads are present (like AC clutch, etc) so the ECU can tell the IAC (Idle Air Control Motor) to speed up. If you have a 2 wire one (like a Galant one), you will be missing this function.

Also the tach signal must be present at the ECU to know the engine speed.

Also the IPS (Idle Position Switch of the Throttle Position Sensor) must be adjusted properly so the ECU knows it's in idle mode - otherwise the ECU won't try to adjust idle.

And of course the ECU must be good (eg. the IAC drivers are not blown).

 

[boost97gst]

Well, that kind of helps. Im simulating idle switch in link. Guess my problem may lie there then. Ill give it a shot tomorrow.

Fixed a vac leak on the pcv line, that helped idle but no matter what, when that ac kicks in it drags it down. I guess i can replace the IAC?? IDK

 

[boost97gst]

Im thinking its the ISC now. When i uncheck the simulate idle box, it idles pretty good but the idleswitch in the log still reads 0. It should read 1 with throttle completely closed.
I think the ecu is good since it was just sent to be socketed in january and has only seen 400 miles since then.
Im going to remove and test isc this weekend. Is the idle switch located in the ISC? or is it somewhere else? The TPS is working just fine too. reads 0-100 and base voltage is .65. When i try to do the tps adjust in link though it throws out crazy numbers and runs like shit. I have to manually enter the values now for some reason. Go figure, i upgrade the car and now this . Its always "one step forward, 100 bucks down the drain" with these damn cars.
My old 420a was the same age and had more miles and never had nearly the problems. Guess the prev owner beat the shit out of it or something.

 

[My1GLaser]

Capture ISC and see what the value is at idle. It should be roughly 32. Maybe its maxed out and pegged at 120 and when the AC kicks on it can't compensate. You change the ISC value by turning the BISS. Turning the BISS out makes the ISC value decrease. It takes a few min for it to stabilize.

 

[Lou98GSX]

you might have to bump up the idle because of your cams and when you do your going to have to readjust your tps to .63v . my idle is at 950 and when the ac kicks on the idle does drop some but doesn't stall

 

[boost97gst]

yea, my idle is at 1k due to the large cams. They have a lope to them and idling lower is really uncomfortable and annoying. My idle isc value is 85 to 95. I Will def adjust BISS to get that value down. That may be the problem. But what about idle switch? Can i still sim it?
Im having a bear of a time getting the airflow/rev and combined ft's dialed in so i might disassemble the TB and clean everything/new o rings if needed etc..
Ill set everything up perfect, let it sit, go out and itll be dumping +16% combinedft. All tests and cal's performed in operating temp. Something is amiss and its tough to track down.
Im also running 93 oct, evo8 mod 1 tables and seeing 2 degrees knock in 3rd at 15psi at around 11:1 afr. UUUUUGGHHH . One thing at a time though, right?

 

[My1GLaser]

Yeah 85-95 is way too high. Your isc open too far all the time to compensate for your idle under normal conditions.

You should also add about 200 rpm to coasting fuel adj when your idle is that high. I think its in the rpm tab. Your isc can't compensate when coming to a stop and your rpms drop too fast. A light flywheel makes it much worse!

U can post an idle log and I will check it out when I get home. V2 or v3?

 

[boost97gst]

v3, Ill post up a log from my laptop later. Thanks

 

[boost97gst]

UPDATE: BISS was the problem like i was thinking. Put a new 1g TB on with a working biss, swapped in my TPS and ISC and car idles like a dream now, even with ac on. Buuuuuut, the other day the composite material on top of the radiator neck exploded , if its not one thing its another. So im down for another 3 days. These cars, boy o boy, why do we punish ourselves? Its for the couple nice reliable days they give us and all that lovely boost when things are clickin right i guess.

 

[DSM Chase]

gotta love em

 

[boost97gst]

Forgot to mention, guess i put this in another thread: the BISS i found filled with JBweld from the PO. What a dick, right? If i could have adjusted the biss on that TB i would have got my isc say lower with a couple turns and the prob would have been fixed. Hope this helps someone else out one day. You never know what previous owners do until you get to really diggin deep on a dsm. Ah well, im happy now

 

[NHerron]

For future reference, on a 2G the only way to properly adjust the BISS is via DSMlink or take it to a dealer and they set the car in a set mode with their special (expensive!) computer equipment.

Dealer-
2G BISS Adjustment

DSMlink way- search tuners for BISS adjustment and look mainly for any info that the member "steve" provides. There are at least two good threads

 

[boost97gst]

For future reference, on a 2G the only way to properly adjust the BISS is via DSMlink or take it to a dealer and they set the car in a set mode with their special (expensive!) computer equipment.

Dealer-
2G BISS Adjustment

DSMlink way- search tuners for BISS adjustment and look mainly for any info that the member "steve" provides. There are at least two good threads

True, i did the quick n dirty method . Looks good, holds steady at 1krpms like i set in link but the lowest i could get the isc is to 50. Now i believe thats cause i set the idle to 1k instead of the stock 750. At 750 with Crower 272s you CANT idle, its terrible. I also think my old TB may have had a vac leak. Not 100% and sure as hell not going to put the old one back on but a BLT is in my near future anyway. I still havent done one after all the new upgrades. Shame on me i know