Like the title says. Good, hard shifts WOT but it wants to slip at low rpms even in SD mode. I thought it was MAF problems so I ditched the MAF and it's perfect on the highway now but it has started slipping just enough to piss me off in parking lots going like 5 mph.
I know my car doesn't have electronic throttle but could the desired torque table help me out with this? I know there has to be some way to tune it out but I'm frankly at a bit of a loss.
Post your stock & latest tune, and I'll take a look at them for you. Any mods to the trans & engine?
Russ Kemp
You want to look at the input/output shaft RPM ratio
against the nominal gear ratio. That, and TCC slip RPM.
This will tell you if the trans is actually slipping or just
the converter. If shaft ratio is not rock solid then it's
a slip problem. If the ratio stays constant while you
think it's slipping then it's really not; just the converter
being sloppy.
Here's 2 scans, tune that ran them and the config to decipher them.
Originally Posted by richard head
Personally, to me it looks like all it could really be is the verter. i changed the duty cycle and it seemed to help - just not all the time. See if you see it slipping, but to me it doesn't look like it's the input vs output ratio that I'm feeling. it's a stock 2000 a4 tranny replete with the 3.23 gears. There's one part in the second log where it seemed to slip and it looks like TCC slip goes up to about 135% and the input/output shaft RPM's stay the same. Look like new verter time?
Last edited by richard head; 11-07-2008 at 10:46 AM.
Try this trans tune. Do you have the performance mode switch wired into your PCM?
Russ Kemp
Yeah, peg 71. Works like a charm
Btw, Russ, Thank You for the file! Those part throttle shift tables are much less screwy than mine were and it seems to have cut out the slippage BS too. I noticed you modified the FMC tables as well - is that to help with it on the highway? Whatever you did, it seems to be working wonderfully and I appreciate it.
Since you have the performance shift enabled, I set up your performance shift pressure table, the performance part throttle shift & TCC lock up speed tables.
Russ Kemp
Great man. Thanks!
Is it possible that this car has a mild stall? It came with 150k so it's not out of the question that a previous owner might have done something like this - could it have the impact of low RPM slippage? I've noticed in the logs that it slips a higher percentage up until around 3600 rpm - might this be an indication?
Went out tonight after I changed the O2's to simulate lean cruise for fuel economy and noticed it slipping, got the laptop and logged a few slips and a few hard launches. The launch spike turns more or less linear around 1600 rpm so I don't think it could be stalled or it would jump to like 2800 or whatever the stall was and do the linear climb from there.
That settled, the slip logs convinced me that the verter is the problem, as slip % curve will have slight bumps from around 84% where it seems to run sometimes at cruise to like 95% corresponding with increase in RPM but decrease in speed on the log. Also, input shaft/output shaft RPM logs show no change during these spikes, noted as slip in my head for when I reviewed the log.
Sound about right? Converters are expensive... but I can get one if it will fix this. It seems like this should be a relatively regular high mileage problem but I haven't found anyone who seems to know what the deal is. Tranny shops just listen to me discuss it and try to get me to buy a whole tranny - I don't know anyone I can trust on the issue. Let me know if there might be some other way to get this fixed up
Turned off simulated lean cruise mode and it went back to where it was, rarely slipping. The dealership seemed to think it was a performance issue and this is agreeable from that standpoint, could a bad o2 sensor be causing this? Without any leaks, B2 is significantly leaner all the time. If that o2 is causing it, it would make sense that giving the computer even worse readings would make the damned thing go nuts - ideas? I've got a wideband in the works anyway, sure hope that fixes it
I have a hunch that if I turn off DFCO it will help with the small amount of slipping that the car still does. I think that perhaps what's caused this is the debaffling and streamlining of my ram-air hood, which I did for performance reasons, but I think that at 70 it's forcing more air in than the PCM's calculating for and leaning out the mix. The lean cruise thing just goes to show that it IS a performance issue and not a tranny one so I have some thinking to do about how exactly to account for this. It's a load off, though, to know that the tranny's fine.
This turned out to be the fix: http://www.ls1tech.com/forums/automa...nt-lockup.html
To the best of my knowledge I do not have a stall but this fix woke it up a lot so I wouldn't exactly believe that I don't have some sort of 2800 rpm unit in there somewhere but nor will I doubt it until I see more evidence.
**edit**
yep, the converter should be locked and that is normal. my problem all along was that the converter was unlocking when it should have been remaining locked, a tuning issue.
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