JPrevost

So I went to go help a buddy out (no money involved) with his idle problem and I came up with a conclusion.... I don't like the 165 ecm when it has MAF code.
So first off the desired idle speed was never met, it would just sit at 950rpm no matter what we set the desired idle speed tables. You might be thinking; did he set the flag that looks up IAC step counts vs CTS, nope, it was unset so it should have been using the desired idle speed (closed loop and everything). Okay, no biggy, maybe the ARAP (our base) code doesn't do so well with 383 SR AFR 219/219 auto's. So I set the flag to use the IAC step counts and finally got the idle to come down to a respectable 800. Baby steps, baby steps. At this time I tell him to put it in reverse so he does and it stalls. This is nothing new. NOTHING has gotten rid of this stalling issue and it seems to be linked to the AE from the shock of the trans or just the speed at which his trans shifts into gear. It's violent to say the least. Anyways, 2 foot it to get it to idle in gear then remove the foot and it's got no problems holding a steady non-surging idle. 22 degree's of SA was perfect in this area. Anyways, now for the real problem. All of a sudden the IAC step's start to climb and I mean CLIMB. It doesn't take long but it just starts moving up and up and up from somewhere in the 40's all the way up to the 140's . Here's the real kicker, the idle speed isn't changing. I forgot to look at the reported MAF readings but I want to say they didn't move but maybe 1gps if that. Anyways, put the car in park/neutral and those IAC steps just rev the motor up to 2000rpm but are rapidly commanded to close. The IAC quickly recovers and pulls the rpm's back down but not before the idle surge.
Anybody know what could be causing this IAC increase? Do you think his transmission has something wrong with it? The trans was rebuild with some no-name rebuilders "custom shift kit" but it's never felt right. When I say I tried everything to get it to stop from stalling when put in gear I mean I spent 2 hours making changes focasing on just the SA, then just fuel, etc. I tried removing SA from the high LV8 lower RPM, nope, nodda, no difference and I was going 10 degrees either way.
Before I forget, this MAF was descreened and I gave him a good lecture about it. I've had very limited luck with descreened MAF's, the good one's have only been manual transmissions that have a non-load idle.
Here's the next problem. BLM's are 120 at the park/neutral idle and between 8-10gps. Put it in gear and those BLM's climb up to 132 with around 13gps. Okay, no biggy, just turn down the MAF table a little bit at 9gps and raise it a little at 13.. nope, apparently that's a biggy. Resolution is just completely removed from reality and it was then sitting at a 128 non-load idle but with load it just started to climb and climb all the way up to 138. That was with 2 hex value changes in both of those cells in the MAF 1 table. Oh, and I set the BLM update to 1 instead of 2 and decreased the time to update from over 2 seconds to about 1.35 . Part throttle tuning and WOT are excellent. So good that it's hard to keep the car pointed straight but this idle is KILLING me. Is it the 165, the ARAP code, the de-screened MAF, the modified engine, or the position of the moon in the sky that's keeping this thing from idling correctly?
Before anybody asks, the p/n switch works and Mark, if you're listening, TunerPro isn't playing nice. It just completely disconnected from the 165 and I couldn't reconnect at ALL. I didn't move, nothing. No cables, it just quit. I even tried the 160baud and that didn't work so I used winaldl and it worked, go figure. Restarted computer, nothing, TunerPro just gave up talking to the 165 in mid stream. Then there's the BLM learn flag, that's not working in the ads file you're releasing, or it's just my freaky computer.

91L98Z28

A few thoughts I had when I read your post, though I have very little experience with MAF....

1) if the trans has a violent shift from park into gear, it's probably defective (in my opinion). Probably all the accumulators are blocked off, line pressure way too high, who knows what else. the TV valve could also be stuck at full line pressure. There is no sense in having violent shifts with the throttle closed. Get a good build (I've ran a pro-built with transgo stuff) and you'll be amazed.

2) if the IAC can not effectively raise the RPM in gear at all, then it sounds like the torque converter is way too tight (too low of a stall). The fact that the engine runs up to 2k after you take it out of gear tells you the IAC stuff is working. Does the ARAP code have an idle speed in gear or idle speed modifier like $8D stuff? maybe you can set it to allow for a lower rpm in gear so that the ECM won't try to raise it.

Is there any chance that the TCC / torque converter lockup is stuck on? That might explain a few things, including the stalling when you drop it in gear and the relative inability to raise the idle rpm in gear (if the clutches in the converter are dragging/trying to engauge).

I don't suppose '730 is an option.......?

JPrevost

I'm kind of at a loss here but I'm starting to feel that it's the transmissions fault. I don't normally need to spend 2 hours with the idle. The TCC could be locked all the time causing this, that's something we need to consider.

JP86SS

iTrader: (1)

One other thing is that it would seem there was an error condition between the commanded idle speed and the current idle speed. The IAC was attempting to correct for it but the rpm just did not raise and caused it to just keep going. Might want to watch the relationship when its happening.
Could the IAC pintle not be moving? Or possibly the reading of 40 is already max'd out full stroke? Maybe pull it out and watch it step up/down with external power.
I imagine you played with it and min air for quite a while.
I would think at idle you would get some surging if the TCC was locked. Unless its really slipping smoothy?
Pull that connector on the trans just to see if it is staying locked.
May not make a difference if its a shift kit install problem.
Who knows, too many things could go wrong there.

91L98Z28

The IAC is definitely moving OK because he gets an RPM surge as soon as he pops it into neutral or park. So the IAC is opening but for some reason the engine is "dragged down" and can't gain RPM.

RednGold86Z

iTrader: (1)

Maybe ask some of the tranny guys if this can happen on a rebuild/shift kit. Call up or send a message to the Pro-Built guy. He's probably seen it all. Seems like it has to be the torque converter stuck locked, but it's not supposed to be able to be locked in 1st and reverse. I'm guessing the TC itself it fubar.

dimented24x7

iTrader: (2)

JP, How loose is the TC? My thought is that there is a leak somehwere causing the TCC to slowly apply, explaining the rising IAC counts. Definatly doesnt sound like a computer problem if it suddenly revs to 2k when you take the load off it. Sounds like the IAC counts are winding up in an attempt to keep the engine going.

As far as the idle goes, that was my exact experience as well. The engine never stalled or anything like that, but it experienced the climbing BLMs and the low resolution at idle problems. The resolution is dog poo and the O2 is needed to actually get AFRs around stoich since the MAF readings are always a few percent off.

JPrevost

Is there anyway to test of the TCC is being applied by the trans without removing it? He said the stall is around 2200rpm so I doubt it's "too tight."

doc

I dont know if my problem has anything to do with your issue, but for my 395cu.in stroker, I got the IAC count down below 10 and drilled a hole in the TB plate in order to prevent stalling when I would come to a stop.

I am using the 6E mask and the ARAP bin as a starting point.