Frost

iTrader: (45)

Hey guys, I was tuni ng a friend of mine's car the other evening. It's kinda nasty, 408" iron block, 243/246 112, AFR 205s, etc. It has a built 4l60e, Vig stall rated 3200 but flashes 4300 on his setup, stock 3.23s in the 10-bolt and hard radials that protect the tranny and make it a spin machine It's a 1998. It had a tune from a previous h/c 346 and told me of the problem before tuning. Oh yeah, it WILL downshift to secon gear properly.

As I got into the file, lots of the shift/mph tables had been changed. Having done this plenty before I eyed all of the part throttle and WOT tables back out but the issue persisted. I then loaded back all of the stock tables from an OEM 1998 A4 for shift MPHs globally and it still has the issue. Here is the tune of you want to see it. Basically only things non-stock in the tranny section are tq mngmnt, shift time (250mSec to disable adaption), and lockup tables to only allow lockup in 4th gear, etc.

I'll put the file here but I think it's something physical. Any ideas?

big wally 55

Was it professionally built ,was a shift kit installed , If so which one ??

performabuilt

iTrader: (25)

I have really got to get software that will allow me to read those files. lol. Does the PCM command first have you looked at the data stream and watch the part that says current gear to see what its saying when the car should be in first ?

Frost

iTrader: (45)

Yeah I have... it accurately says what gear we are in; I can't log much else, maybe it's a 98 thing. At 15 MPH it makes a lightest throttle shift into 3rd, and at 19 MPH when floored it will not kick down, even though as it moves to a WOT downshift table for that, it should be allowed at 31 MPH or less according to it AND the part-throttle table at 100% TPS. The TPS is functioning properly as well.

No idea who built the tranny or what's in it.

Frost

iTrader: (45)

Also, a downshift can be forced by pulling back the shifter OR I can even force it through my VCM Scanner software's special control section.

performabuilt

iTrader: (25)

Well that certainly does not sound like a trans issue but a very strange tuning issue probably related to the large stall the pcm becoming confused by the hi rpm. Iwould post on th HPT tuners forum

Frost

iTrader: (45)

I already posted there. I have tuned about a 40 A4s, and about a dozen setups that are nearly identical, many with looser stalls and never seen anything like this before. It's odd that it did it before and even after replacing all of the tables with OEM values that it still does the same

performabuilt

iTrader: (25)

Well you have done tuning and I have not so your most certainly ahead of me there, I have however found alot of usefull information on that site, But of interest though the syptoms were a little different we have run into issues where the MAF sensor was causing early shifts particularly at WOT but affecting all shifts and soft shifts from low line, Might be something to look at. Generally this happens after a cam or heads intake change but Im sure there are other conditions that could cause it too. But since you can comand the downshift with the tuner and it happens I would have to say its definatley not trans related.

Frost

iTrader: (45)

All of those fail codes that relat to MAF failure and line pressure jacking on DTC have been disabled.

It's wierd, if you are in the valid range to kick back to second, it will, but if it's in second, third, or fourth gear, and the downshift SHOULD go back to first, it won't downshift at all, it'll stay in the gear that's it's currently in.

performabuilt

iTrader: (25)

very strange ,Well it was and idea . Hopefully HP tuners can help and you should post in the tuning section here also

Frost

iTrader: (45)

GOT IT.... Bill of HPT fame and glory pointed to this for a similar issue for another user and it fixed me as well...

The car in question had a LARGE cam... idled in the the 66-69kPa range at best!

Turns out the issue is a stupid stock TPS range checking table and for some reason seems to only affect 98 models.... Here's the culprit table for P0121:

Cwarta

iTrader: (12)

Bump, old thread but I'm having the exact same problem with the exact same symptoms.

But my pcm and harness are 2001

Camaro98Z/28

iTrader: (4)

Frost I shot you an email hoping you can help. The attachment you provided is long gone. My car is having the exact same problem and is a 98 as well. Please help.

mrvedit

Do you have the ability to log what gear the PCM is commanding or to check the tune? Frost was looking at the tune and confirmed that it should allow a downshift into 1st. However I tune to explicitly prevent downshifts into 1st and your car may have been tuned the same way.