SouthernRex

So my 1998 WS6 A4 with about 70,000 miles has been doing one of 3 things during idle:

*It idles normally.
*It surges up and down angrily as if I had a huge vacuum leak.
*It sputters and VIOLENTLY shutters as if I threw a wrench in the engine, and I smell a VERY strong gasoline smell (no cats), which I imagine means it is stumbling because it is running way too rich. It *almost* stalls, but hasn't yet since resetting the PCM. Also, if I give it a quick stab of the throttle (while Hulk Hoganing the pedal brake) it seems to stabilize sometimes, until a few hours later where it come back randomly.

I have slow respone code and low voltage from front O2, would that cause it? If so, my headers killed new O2s in matter of 8 months....

I bought new IAC, new TPS, sprayed the **** out of the MAF with MAF cleaner (that seemed to stop my misfiring problem while driving, but no fix for idle.)

It will do it with O2's unplugged, it will do it hot warm or cold, low fuel or full fuel. I have relearned idle and TPS, reset PCM, everything. Do I need to buy ANOTHER pair of O2s? (Imma get Vette ones if so, I wonder if my problems come from the stupid extensions.)

I have full exhaust, LTH\ORY\Borla, FAST 92mm AIM\TB, SLP Airlid. All stock internals. This problem was here before I installed the FAST, but it seems to have exaggerated it. And if I had a vacuum leak, wouldn't it sputter at every idle, not just 33.3~% of the time?

bammax

Bad O2's. The fronts control fuel mixture so you need to replace them or go sd tune. Replacing the sensors is cheaper and easier. Try to stick with gm sensors since bosch are hit or miss.

SouthernRex

Yep. New O2's and she idles and drives like a dream. Sometimes the car still won't downshift from 4th to 3rd when I stab WOT, it barely goes any faster from 30-100% throttle, but I guess that's just part of having an Automatic transmission? It's embarrassing sometimes, to be honest. But I have only noticed it happen in 60+MPH (which is still ******* annoying, because I gun it from 60 to merge on the interstate, and it's like why won't you GO??!?!?!). It's like a dice roll if it will kick down in the the powerband of 3rd from cruising in 4th. Also, sometimes, if I just hold the throttle down, like 5-10 seconds later it SUDDENLY kicks gear down and takes off. But by then I'm almost to my target speed, so I didn't need to downshift anymore. **** it's annoying. lol Maybe this is something I can have Frost adjust with shift points in a tune? I don't really know how any of this works, to be honest.

EDIT: Nevermind. I'm dumb. I added a little bit of Transmission fluid, and she kicked down on 6/6 test tries at all speeds. Easy fix. LS1-Tech is Best Tech. <3

bammax

Glad everything worked out for you. Stay on top of the maintenance and you'll have a fun car for a long time.

SouthernRex

Nope. Shifting problem is back, and worse than ever. It shifts WAY too early unless I'm literally at WOT, (I wouldn't even shift that early on a manual if I was driving my Grandma around), and it won't kick 4->3 or 3->2 intermittently. I forced it to kick down once by shifting in to 3, but I just wanted to test it and I don't want to do that anymore, because it's bad for the car right? Since I can't rev match with a clutch etc.

Ugh, this is annoying as ****. It doesn't even happen all the time, just at the most inconvenient of ******* times.

zachm89

iTrader: (14)

If you're killing your O2s that quickly, you more than likely have an exhaust leak somewhere close to them or they're placed in such a way in the exhaust that they're holding condensation when you shut the car off. Had this happen to a friend of mines truck a few years back. Exhaust leak on one bank close to the sensor and the other bank the sensor had been reclocked at some point and the sensor was at a 45* angle downward in the pipe. He was burning through sensors every few months.

bammax

These trans like to shift early if you're cruising and delay the shift if you really drop the pedal. I can get anywhere in town without ever going past 1,500 rpms and a couple of those roads are at 45 mph with lights every few blocks. In cruise mode it shifts based on speed which is an odd experience to people who are used to late shifting a manual.

Also I've found that easy cruising followed by stomping the pedal can usually cause an awkward shift that would make you feel like the trans doesn't know what it wants to do. With a th400 you get an almost immediate kick down and the "e" trans takes a second to run some formulas and calculate square roots before it does its job. I've had the kick down be so delayed that it didn't happen until after I let off the gas.

My biggest concern is that your fluid was low. I've killed 3 "e" trans from having tiny fluid leaks and not catching them in time. The first symptom on all of them was a delayed shift into reverse that got more delayed and harsh as time went on. After that I lost first. In every case I fixed the leak and the fluid level before the reverse issue became bad, but the damage was done and the trans just kept getting worse. I'd try to find why the fluid was low and fix it asap.

RPM WS6

iTrader: (3)

I agree that the TH350 & 400 have quicker shift behavior in stock form, and I also agree that (even when in good working order) there can be some awkwardness with the shifts during certain specific/rapid inputs with a 4L60E, but what the OP is experiencing with his 4L60E is not normal IMO. Mine haven't ever behaved this way, unless they were weak. A healthy stock 4L60E would be much more consistent and not have such pronounced issues as what the OP is experiencing (and a well built & tuned one will obviously be much better in all regards).

SouthernRex

I posted on the Transmission part of this forum, and they had me check the voltage. I'm at 0.3v-0.7v at closed throttle, and 3.3v max at WOT... but this is a new TPS and I relearned it...?

UPDATE: I tightened the throttle cable with that little adjuster, slightly adjusted the throttle door (so that it was tight but not resting ON the cable or door) and re-learned idle and TPS. I'm getting 100% WOT!!! I tested it "dry" and on an empty road. It seems to kick down every time now (although, driving it a few days I will know for sure.) The early shift problem is still there, but I'm wondering if that is more from being on stock tune like you guys said?

Utinator

What do you consider an early shift? What rpms does it shift at?

My 4L60e shifted around 5k rpms at WOT. With any less throttle, and it would shift much sooner.

SouthernRex

I want to say like 1400-2200. If I was driving a manual, I wouldn't shift that early if I was driving my Grandmother and desperate to save gas money. (I almost feel like that's LESS economical of a shift to be that low in the power band.) Like, I'm talking I'm in 3rd gear by like 20MPH and then my car is struggling to climb the RPMs because it is so low in 3rd or 4th.

It didn't do this before the new AIM/TB. It also doesn't do it 100% of the time. I'll see if I can get a video tomorrow.

RPM WS6

iTrader: (3)

Those TPS values are not proper at all. But I'm assuming this was before you adjusted the cable to be tight again? Idle value should not be fluctuating like that, and WOT value should be 4.3-4.4v minimum (with a max of about 4.7v). But, again, if that was before the adjustment then perhaps you have already solved this issue.

I didn't realize that this issue was the result of modifications (Intake & TB swap), based on the description I assumed it was a problem that just developed on it's own.

As for the early shift problem, it's hard to say if this is actually a "problem". It could in fact be normal for it to upshift at those low rpms if throttle input was extremely low. I think I recall from past scanner logs that I've reached OD (4th) at speeds as low as 24mph under the right conditions, but that shouldn't be happening unless you barely have your foot on the gas or have released the pedal and are coasting.

What do the TPS voltages look like now that you've tightened the cable? And have you done another TPS reset/relearn? Perhaps there are still some issues related to this which are impacting part throttle shift points.

SouthernRex

On all tests I was getting 4.7v and reading 100% throttle at WOT while the car was off, and the car STILL wouldn't downshift at 100% throttle confirmed on scanner. It's shifting a lot more frequently, like 90% of the time instead of 20% of the time, but it's still sometimes just hanging at really low RPM and high gear, even though I'm at 100% throttle (according to Torque/OBDII.) Sigh.