partemisio

iTrader: (1)

I'm trying to help a friend out with his 98z. Admittedly, I don't know much about transmissions. I just got his car running but the problem is it will shut off when put into drive. It will start fine in park or neutral. It will work fine in reverse also. But when you go to put it in drive, the motor shuts off. I tried going into firs as quick as I could and it still died. So it appears it will do this with any forward gear selection. I also revved it some in neutral and pulled it into drive and it still shuts off.

98 z28
4l80e swap
High stall converter
T-rex cam
317(i think) heads with some mild work done
Ls6 intake
Hptuners

forcd ind

iTrader: (7)

my first thought is somehow the converter is locking up in forward gears-try taking that feature out for now
also ck shifter adjustment-just a wild guess there
it can happen with to tight a converter, but yours is high stall
could be the trans itself, something in the rebuild if rebuilt
could also be severe lean condition, but not likely

partemisio

iTrader: (1)

Oh yeah, forgot to mention the shifter adjustment. It seems to be fine in p,r, and n. But the point half way between neutral and drive, you can get the car moving forward. I don't know how the adjustment being off could make the car die though. I would think it would make you be in the wrong gear and thats it. It also seems wierd though that the adjustment is good in p,r,n but could be off past that point. Perhaps it's not actually off and the car moving forward is just another symptom of the same problem?

I'm assuming by your response that you can turn lock up off via hptuners? Could the lock up solenoid be the problem? And if it was, would turning it off even do anything?

mrvedit

What happens in Reverse?
Does it kill the engine abruptly or slowly?
Does the car try to move at all?

If both Drive and Reverse kill the engine, then it is could be a bad converter in which the lockup clutch is jammed always on.

Even if the trans had a serious problem with locked up gears (think transbrake), the engine would not stall because the converter is a very loose coupling at low RPM.

We will try to help you more after we have more info from my Qs.

partemisio

iTrader: (1)

It will drive fine in reverse.
Engine dies immediately.
No, it just kills it right there. If it wasn't so instant then maybe you would try to move, but I can't say for sure.

mrvedit

Since it drives fine in reverse, it is not the converter.
And you say the engine dies instantly; I was wondering if a strange electrical problem was causing it to lose ignition or fuel, but then it would take a second or so to gradually spin down. I guess that is excluded now too.

I wondered if the lockup clutch is engaging the instant you put it in drive. That would instantly kill the engine, but I cannot imagine how that is possible as the hydraulics don't even feed fluid to the TCC lockup solenoid in 1st gear. So probably scratch that too.

You said "I just got his car running".
Exactly what was wrong and what did you do?
Did you remove the trans?
Was the trans working OK before?

partemisio

iTrader: (1)

He couldn't get the car to start. That ended up being in the tune for the injectors.

I have not had to touch the transmission. He did have it out a while ago though and had it rebuilt at the local chevy dealer.

The car was driving a while ago but it has sat for some time since he was low on funds. I'm trying to get him to save money to bring it to a real tuner since I only have experience with my talon which had basic tuning . capability. But I am competent enough to get it driving tune an engine wise, I've just never had to mess with auto transmissions cause I've always owned manuals.

forcd ind

iTrader: (7)

so it ran ok after it was built, then sat a little, and now it has the problem?
with the ign. off, in drive, can you push it, or does it act like in park-if it rolls, turn on the ign and try again
just trying to eliminate things, section off areas

mrvedit

I'm glad someone else (forcd_ind) is trying to help, because I am out of ideas.

partemisio

iTrader: (1)

I will try that in a day or two and let you know.

Circle-D

iTrader: (21)

And what happens if you pull it all the way into low gear?

Chris

partemisio

iTrader: (1)

Shuts off. I tried to pull it back as fast as possible and it still shut off.

Circle-D

iTrader: (21)

Never mind..... Reread the post. Sounds like you already tried that. Can you jack the rear tires up and let the tires spin and see if you can play with it any as you put it in gear?

Chris

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iTrader: (1)

Yeah I will try that in a couple days also and let you know the results.

1-87 chevy

iTrader: (15)

since you have hp tuners check your base airflow tables they might be zeroed out and would cause this .

mrvedit

Just to be clear, how fast does the engine stop? 1 second? Or super abruptly like someone jammed a wrench in the flywheel?

If 1 second, it might be a tune or fuel supply problem, or something related to the original starting problem. Or super lean condition as mentioned.
Chris' suggestion to put the wheels in the air is good as it will put minimal load on the engine as drive is engaged. Even if the engine dies, we will want to know if the wheels moved at all.

partemisio

iTrader: (1)

I'll get a video of it happening when I go to the car.

partemisio

iTrader: (1)

Well today I put it on a lift and pulled it into drive and the rear wheels turned like they should. After that, I took a short video to show what it was doing.
As you can see in the video it worked correctly now. Im thinking something(i don't know what) was locked and causing it to cut off. Taking the wheels off the ground had to take enough pressure off the drivetrain that enabled the motor to free up whatever the problem was. That brings the question though, is something messed up still in the transmission and what would it be? It still lacks a lot of power in drive compared to reverse. The question there is, is something still dragging and robbing power or is it all in the tune, because I know it is off quite a bit (at least causing it to run real rich). I guess that might have to wait till we can get somebody to tune it because I'm not comfortable enough with hptuners to tune another persons car.


Edit: here is the link since the video doesn't seem to be working.
Youtube.com/watch?v=kOgQoqBV1-8&feature=youtube_gdata_player

partemisio

iTrader: (1)

I guess the lack of responses is a clue that this is an odd problem.

mrvedit

Yes, it is a bit of an odd problem.
Since the wheels now turn, I think a tune is the next step.
You say that something seems to be dragging. In what gear?
About the only thing that could drag in 1st gear is the band; usually they wear out enough to lose 2nd gear; dragging in 1st gear would be rare.

Trying check the endplay on the servo - press down on the servo cover with a crow bar and try to estimate how much it moves. 1/16" is minimum, 1/8" is optimal and 3/16" is the max. Anything less than 1/16" would drag the band. The band is also free in Reverse, but one direction might be tightening it more than the other. This is a bit of a wild guess at this point.