Bad Vehicle Speed Sensor symptoms?

[jcostantino]

After taking a long break from thinking about what I can do to fix my car - and having to replace my starter, front brakes and all four wheels last week I'm back again.

I still have a problem with my car around 3200-3500 RPM with or without the Superchip in.. it seems to miss right at that point and on occasion the tranny seems to buck in/out of gear when coming to a stop.

I think the VSS is bad but I'm not sure.It seems to be the logical choice since I have an ATX and I know the VSS does a lot of work.

What are the symptoms of a bad VSS? The cruise control still works so the VSS is doing something. Is there any way to test it? This has been my biggest problem for almost the past year and no ammount of throwing parts at it has fixed it.

I have a couple CE light codes to check this weekend so I'm sure I'll have more info when I do that but if anyone has any ideas before I do it, I'd like to know. This damn car is almost paid off and I'd like to think that I might keep it for a little while instead of dumping it for a new lease.

Jeff

 

[BlackOnBlackATX]

classic symptom is once the car is heated to operating tranny slips, shifts erratically, but shifts like a champ when cold. losing your cruise control is a big one but you seem to be ok there. if the only problem youre having is bucking when coming to a stop then thats not too bad. have you had your bands adjusted?

 

[jcostantino]

The transmission was rebuilt about 35k ago... It shifts like a bitch still, I swear I chirped 2nd tonight with the chip in.

My main problem is this: if I put it in 1st or 2nd (or 3rd but it's hard to keep it in the "sweet spot") and accelerate to 3200 RPM, then lightly lift my foot off of the pedal the car starts to engin brake as if I had my foot completely off the gas. Keep in mind that it would do that in 1st or 2nd normally if I backed all the way off on the gas but I only pull my foot up maybe 1/4 to 1/2" and all the way off is like 1 1/2" of pedal travel. Now, it gets weirder: If I pull my foot up further so tha the revs drop out of the 3200-3500 range the car regains power! I could draw this real quick...

The graph is sort of wrong because it seems to say the engine goes back to idle at 3200 to 3500 when in fact the graph starts around 1200ish RPM instead of idle. Basically, there is an ENORMOUS drop in RPM at that point. I haven't tried to see how far the drop will go but it's worth giving that a try. It might engine brake all the way down to idle.

<small>[ February 06, 2003, 11:56 PM: Message edited by: jcostantino ]</small>

 

[AutoSHO]

Sounds like a TPS problem to me. Check the resistance of the middle and top terminals while opening and closing the throttle. If it has any flat spots or opens, you've found your problem.

 

[DJ SHO]

Read here about what I have expereinced with a bad VSS, just in case it's not your TPS.

 

[a_longoria_2]

I had the exact same problem about a year ago. It turned out to be the throttle position sensor. It's real cheap at autozone. Hope that's your problem. It's also real easy to change.

 

[jcostantino]

I've already changed the TPS but I could put the factory one back in to verify. I do recall that the problem wasn't changed when I swapped the TPS out. The one I got was the AutoZone part for about $25 or so.. I've heard that there is more than one version though.

What is the max and min voltage with the key on and which terminals should I back probe? I'm going to try the resistance this weekend too.

Jeff