chris20516

alright i have put in a ms4 cam kit from tsp in a 00 ls1. So far i am not happy i think i am fighting a tuning issue. I am running a 85 mm slp maf, lt headers,4.11,ported tb with the stock ls1 intake and 853 heads. when I start the car when the engine is cold it idols great but when the engine has heat in it at start up it wants to fall on its face and takes about 10-20 sec for it to find its idol. also today sitting in traffic i found out that the idol is wondering around at times from 600-800 rpm. my question is this a timing issue, is it getting to much fuel due to the 85 mm maf or some other reason.
thanks for all the help.

98Camarod

iTrader: (43)

You need to have this tuned and report back afterwards

chris20516

im sorry i may have not been to clear on this but the car HAS already been tuned.

98Camarod

iTrader: (43)

I'd take it back to them and have them fix what you are describing. Having it tuned is not cheap.

Tzion_ben_Arthur

iTrader: (19)

He is right, take it back. I have an MS4 and we spent a while tunning it in the idle map. Mine idles at 985 nicley and serches a bit when coming to hard stop or stab and brake.

Grim

98blueSScamaro

iTrader: (14)

I am with them And also what was your AFR with the slp maf cuz i just got mine tuned and my maf was junk the afr had a bad wave to it so i am going with a Zo6 maf

chris20516

i dont know my afr cuz when he printed off the dyno sheet he never included it. Yah when i start it cold it goes right to 1025 wich is what the idle is set but when the engine has heat in it the engine takes a while for it to come up and puffs out black smoke like crazy and smells rich as hell. i was able to see how much timing i am pulling and its 27* at idle and at about 4k its 40 and then wot its back to 27*. Can someone please explain this too me why this is all over the place
thanks for all the help

bww3588

iTrader: (49)

dont mean to ***** here, but is the SLP 85 MM MAF necessary with the MS4 and heads? im looking at going with the FAST 90/90 and was wondering if the stock 75MM MAF would hold me back. if not, to the OP, maby switching back to the stock MAF will help you.

8tsixt

iTrader: (7)

I have a similar issue but with a ms3. I'll keep an eye on this one.

BigBirdTA

You need to get it re-tuned. It's not getting enough air at idle (black smoke = rich), which is very likely the reason why it doesn't hold idle well once warm (closed loop). Once you get the fueling corrected, then your tuner will need to adjust RAF, timing in the low RPM areas of the HO/LO tables and Idle Overspeed and Underspeed spark correction tables to get the idle to catch itself properly when it comes down the RPMs.

All the above is with the assumption that you have O2, ECT, IAT sensors and IAC in working condition and no vacuum leaks.

gametech

iTrader: (1)

This sounds like a classic "chasing your tail" tuning issue in closed loop. For some reason 1 cylinder misfires, pumping unburned 02 into the exhaust. The sensors show lean, causing the computer to dump in more fuel. The rich condition causes more misfires, more lean readings, more fuel, etc. The worse the problem gets the more the computer makes it worse trying to correct it, until trims max out or the engine dies. If this is the case, it will be very apparent on a scan.