99 VS SIII 5.0 auto cutting out of gear and not revving occasionally.

[up2nogood]

This is a weird one... Thought I'd repost from auto elec to get some more views. That and it might not be electrical at all?

Usually after giving it a bit, the engine ceases revving for a couple of seconds.
Then it will rev again, but it no longer drives the car.
Roll to a stop, put the gearbox in neutral or park and then go for a gear (R, 1, 2, 3 or D, doens't matter), and off it goes.

And it does it in the harbour tunnel, freeway on ramps, harbour bridge on ramps and all sorts of other shitty places. And there isn't always an electronic toll booth nearby, so it ain't that either. Car is dual fuel, but it's on petrol that it plays up. I only use gas when I run out of petrol cos I haven't been stuffed filling it up.......

If I had to take a guess it seems to happen mostly after I've had to give it some berries to overtake someone and then backed off to slow down. Then when I try to accelerate again, no-one's home.

What really does my head in is that it's both the engine AND the gearbox. Once the engine is back on line, there's no drive until I stop.


As for attempts to fix:
* Has had a new ignition control module installed. The thing mounted on the front of the passenger side shock tower.
* Have changed chips back. Doesn't make a difference, it plays up with the genuine Holden chip and the aftermarket one. Now on second aftermarket chip, still doing it.
* Have sealed all the leaking LPG air cleaner installation and some sensor wires rubbed thru from the dodgy LPG installers idea of a good aircleaner fit.
* Have not touched the auto. It changes gear perfectly, no delays selecting or anything else that would suggest it's got issues.

Any ideas? Failing that I'm buying a VE SSV.........

[VrWagz1]

Just of interest, if you turn the key off then on again while driving, does the car stay in gear still or does it stay dropped out. Just wondering if this is normal for the electronic auto box.
Do the reds come on when the engine dies for those few seconds. If they dont then i would say try new rotor cap and button and some new leads while your there.

[hako]

I found this on the ImpalaSS forum so credits to them. May apply to you:
3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows about it.
The full thread is informative:
FYI 4L60E common problems / failures - Impala SS Forum

[up2nogood]

Nah, none of those. No CEL or engine cut out. The engine actually keeps running but won't rev, kinda sits around 1500rpm. After a second or two it will rev but won't drive until I pull over. Have not tried turning off ign as it usually occurs during overtaking or turning. When it's going to shit me the most, I reckon.

Leads are new, as is cap. Runs fine 99% of the time.

[VrWagz1]

at a longer shot, fuel pressure might be an issue after you give it a squirt. Blocked fuel filter maybe or daggy pump(like mine wouldnt rev over 4000rpm) or dodgy fuel reg.

[Vee-ard]

Just throwing this out there and I know this sounds weird, but the part where you said the engine wont respond and only goes up to about 1500rpm, sounds exactly like what happens when the wheels spin while traction control is on.

Do you have traction control? It could be a dodgy unit.

No idea really.

[M01ST]

Dodgy computer or something maybe search for some error codes??

And did the problems both start happening together?

[tt460]

at a longer shot, fuel pressure might be an issue after you give it a squirt. Blocked fuel filter maybe or daggy pump(like mine wouldnt rev over 4000rpm) or dodgy fuel reg.

given that the car has a gas conversion its not that much of a long shot. Most people just run them on gas and dont give the car a good decent run on petrol causing issues with pumps filters regulators seals drying out etc.

Just depends on how the OP drove the car whilst it was running the gas, eg start it on petrol and switch to gas like most people do, or took it for a decent drive on petrol once a week to keep the petrol side of things in good condition.

[up2nogood]

I have a fuel card (lucky me!) and I run on 98. LPG is only for range if I can't be stuffed filling up or can't find a Shell in time.

As for fuel, it runs fine most of the time, it's totally random.

It's a drifter from waaaay back, so no TC fitted. Nor ABS. It's really just a bucket with a V8 engine in front......

It could be random crap unsettling in the fuel tank (had this on Fords b4) and blocking the fuel pump pick up momentarily, but then it wouldn't take the gearbox offline if it were just that?