odometer going backward?!?! vss, rough idle, stalling...

[boderman88]

So my car has been good to me for the past year since I've had it and shes starting to have all these problems at once. I'm having a rough idle and when i start it up, it drops rpms real fast as if it was done warming itself up. It stalls sometimes but I haven't found a connection when it does it. It will do it on the highway going 65 or even when I'm slowing down to a stop light. Some times it will start back right up and other times it will keep stalling. I've changed the spark plugs, wires, fuel filter, cleaned the throttle body and iac. It last mad power too. I feel like a grandma on the road. Some one throw me some help with this. My second problem is my demented odometer. I'm thinking its the vehicle speed sensor (which on the 3.3 is hell to get too). It will jump the speedometer, run up the odometer and register miles which haven't been driven, and two nights ago the antichrist odometer, starting going backwards. I have never seen an odometer actually turn backwards in any vehicle ever. Also can any of these problems make the tranny slip or shift irregularly? Someone help

[Keviefriend]

So my car has been good to me for the past year since I've had it and shes starting to have all these problems at once. I'm having a rough idle and when i start it up, it drops rpms real fast as if it was done warming itself up. It stalls sometimes but I haven't found a connection when it does it. It will do it on the highway going 65 or even when I'm slowing down to a stop light. Some times it will start back right up and other times it will keep stalling. I've changed the spark plugs, wires, fuel filter, cleaned the throttle body and iac. It last mad power too. I feel like a grandma on the road. Some one throw me some help with this. My second problem is my demented odometer. I'm thinking its the vehicle speed sensor (which on the 3.3 is hell to get too). It will jump the speedometer, run up the odometer and register miles which haven't been driven, and two nights ago the antichrist odometer, starting going backwards. I have never seen an odometer actually turn backwards in any vehicle ever. Also can any of these problems make the tranny slip or shift irregularly? Someone help

I'm no expert, and I don't expect that I'll be able to help you, but I can help you tune the question for those who can help.
Which car do you have?
What year?
Miles? (approx is fine, since it's not accurate)
3 or 4 speed tranny (does it have the overdrive?)

As for what you've told us thus far, I have seen an odo go backward. It was on my mom's 88 Regal. It effected the regular and trip odos, but not the speedo. We traded it instead of fixing it, however, so I have no idea how/why it happened or what to do about it.
Even if your tranny was to blame for the power loss under load, via lost gears or linkage, it wouldn't explain the stalling, or the lack of an apparent pattern.

[boderman88]

It's a 1989 Buick Century 3.3 (Vin:N). It has 158,800 Miles on it. I believe its a th125 because on my cluster it has D,2,1. It could be a th440 but I'm not quite sure. The transmission does need its fluid flushed so that can cause the slipping and funny shifting,about would the vss have to do anything with it too? Can a transmission that is going bad make a vss go bad along with it? I'm going to check the egr valve and vacuum lines whenever it gets warmer or when I'm not at work to see if thats causing the rough idle. Does anyone know an easy way to access the vss by chance too? I was thinking to jack the front of the car up and put it on stands and take off the right tire. Thanks with any advice.

[Tuddi]

Maybe it's turning into a time-machine?

[CieraSL92]

The vss on your car should only be responsible for instrument cluster function and an input at the ECM for usage of engaging the tcc. Your transmission wouldn't be electronically controlled so irregular shifting or slipping or whatever would not be caused by something electrical unless it was failure for the torque converter to lockup and that doesn't sound like an issue. If you only have PRND21 then yes it's a threespeed. If you have (D) then D its a four.

Is there any difference between symptoms when the engine is hot or cold? If I had a scanner I'd put one on it. No SES light?

Edit: Haha kevie I liked that story. My parents old 1992 Buick Regal did that for about a week then the odometer stopped working altogether. It would start working normally once you were going 85mph+ though.

[SCREECH]

...shes starting to have all these problems at once...rough idle...it drops rpms real fast as if it was done warming itself up...stalls sometimes...on the highway going 65 or even when I'm slowing down to a stop light. Some times it will start back right up and other times it will keep stalling...My second problem is my demented odometer...It will jump the speedometer, run up the odometer and register miles which haven't been driven...starting going backwards...It's a 1989 Buick Century 3.3 (Vin:N).
Three letters for you - E...C...M. It DEFINITELY sounds like your computer. I have an '89 Ciera with the 3300 and I just had to change my ECM. My 3300 was randomly revving WAY up at idle (like 2500+ rpms) and was running rough and stalling or not starting.

The ECM also controls your speedometer and odometer in your cluster (the VSS goes to the ECM and then the ECM feeds the instrument cluster). Here's the section of wiring diagram for a '90 Ciera 3300 ECM, the same as the '89 3300 ECM in your Century or my Ciera, which shows this - you can see the purple and yellow wires from the VSS on the tranny coming in on B9 and B10, then the brown wire on B11 going to the cluster:

http://screech.ws/miscpics/90ciera_diagrams/90ciera_vss01.jpg

You can also see http://screech.ws/miscpics/89ciera_3300ecm_wiring.jpg which is the '89 ECM diagram. I just included the pic from the '90 ECM as I had it already cropped.

So, if you can get your hands on another ECM (it's located behind the glove box, in case you're not familiar with it) you can simply pull yours down and swap the connectors over to another computer and compare how it runs. I expect that you'd be pleasantly surprised. It would be best to swap your chip from your computer to the donor computer before running it. If you need more info on how to get to your ECM or how to swap the PROM chip, just post here and we'll be happy to help you out.


I'm going to check the egr valve...to see if thats causing the rough idle.
There's no EGR on the 3300.

[boderman88]

Man.. the legend himself screech has came to help haha. I've read alot of posts you've put up. You know you stuff man. Yeah so I definitely found out that the 3.3 DOESN'T have a egr valve. funny that the haynes manual says it does. After looking for 2 hours for it I was convinced it didn't so I searched for it online and found that there isn't one. The thing that I noticed is a slight whine when push the accelerator half way. I hear my intake (K and N air intake) but I have never heard it whine like that. Could it be a vacuum leak? Also I found an orange cord hanging out of the bundle of wires in my engine bay. It was on the upper right side if you were looking at the motor from the front of the car. The rest were hooked up to the black box with the torque screws on the back of the engine bay/firewall. I'm thinking this could part of the problem. It's not havign trouble starting, but after it stalls sometimes it will start back up and die again. It usually does it in warm weather, I've noticed.I'm going to go to the junkyard soon to get a ecm. I'm guessing it doesn't matter if its a century or cierra, as long as it is a 3.3 with a 3 speed right? I also have the vss now, so I was wondering should I go ahead and change it to see if it fixes it. or will the ecm mess it up?

[boderman88]

cierasl92, I noticed that these problems will happen when the engine is running hot or cold, most of the time when it has problems its hot though. The ses light isn't on and i have scanned it tons of times without it telling me no codes. It does work though because I have taken out sensors and started it up to see if it would read anything and it has. Now that I think of it, I remember smelling something burning last night. I smelled like burning wires which freaked me out. So I pulled over and popped the hood but there was nothing. It seemed like it came from the vents though which I've been waiting for it to do it again but hasn't... strange. I'm wondering if it is the ecm. but would it burn wires out like that?

[SCREECH]

Man.. the legend himself screech has came to help haha. I've read alot of posts you've put up. You know you stuff man.
:dunno: I am but a man. If you spend enough time around these things and dive into enough "projects", you start to pick it up, and what seems like a monumental problem to one user is "just something I dealt with last week" to those that have been through it. Like I said in my earlier post, I have just recently experienced similar issues with my Ciera to tell me that it's likely your ECM. Previous experience with ECM troubles make me more confident of that diagnosis. As for the EGR, besides owning two 3300 vehicles right now, I confirmed the lack of an EGR on the 3300 earlier this month when emissions testing the '92 Cutlass Cruiser. On the other hand, thanks for the compliment! :wave:

No matter how much someone knows about something, there's always someone out there that knows more. I am still in awe about some of the things that David (Turbokinetic) posts, and FORGET about being able to tell Pat (BigNastyGS) anything about the Century GS - after acquiring half of the fleet of these cars that GM produced, I think he's got a much more well-rounded knowledge of them than anyone else this side of Mars...at least anyone that ever visits here. :lol:

I think we do quite well on this forum due to such a diversity of users and their varying skill levels.



The thing that I noticed is a slight whine when push the accelerator half way. I hear my intake (K and N air intake) but I have never heard it whine like that. Could it be a vacuum leak?
I'm going to say "probably not" to the vacuum leak question - a vacuum leak is not usually significant enough to be audible. It's possible that if you were listening to the car running with your head under the hood instead of in the passenger compartment that the sound of the engine "breathing" would be more evident...I know when I have the intake tube off of my 3300 it sounds like a rabid squirrel getting sucked into a blender when I open the throttle blade up. Perfectly normal, but not the way GM designed them to be heard. It's possible you're just hearing a bit of this since there's a little less "muffling" of that noise when you're under the hood.

If you were indeed referring to you being behind the wheel when hearing the whining sound then I would almost say conclusively that it was not a vacuum leak, as I would be shocked if you could hear one from inside the passenger compartment.

For something like a "whining" sound, it is a little more difficult to pinpoint without being able to hear it in person. I recognize that it's hard to tell exactly where it's coming from, especially if you need to be driving the vehicle to reproduce the sound. It can be very frustrating, I know.


Also I found an orange cord hanging out of the bundle of wires in my engine bay. It was on the upper right side if you were looking at the motor from the front of the car. The rest were hooked up to the black box with the torque screws on the back of the engine bay/firewall. I'm thinking this could part of the problem.
By "orange cord", did you perhaps mean an orange wire with a single terminal plug on the end? If so, I've seen this connector affixed to the outside of the engine harness on several different applications. Though I believe it to be a diagnostic connection of some sort, I haven't taken the time to verify what it's exact purpose actually is. If the problem was due to a disconnected wire it is not very likely that the problem would be intermittent, almost random. It would usually either be there full time, or it wouldn't be.


I'm going to go to the junkyard soon to get a ecm. I'm guessing it doesn't matter if its a century or cierra, as long as it is a 3.3 with a 3 speed right? I also have the vss now, so I was wondering should I go ahead and change it to see if it fixes it. or will the ecm mess it up?
It won't matter what transmission the car has, as long as it's got the 3300. From what I have read I see that the 3300 used ECM number 1228706. It was apparently only used for '89-'93 3300 cars. When you get one, as I mentioned before, just swap your chip from your ECM into the donor ECM to ensure that no subtle differences will plague you when testing the other computer. Nine times out of ten the problem is with the computer itself and not the chip anyway.

I would try the ECM before the VSS. For starters, it's easier to try the ECM than the VSS, in my opinion. And secondly, it's more likely the ECM than the VSS - in my years of playing with computerized cars I've had to swap out a handful of ECMs, and not a single VSS.

[boderman88]

So, I've narrowed it down that its the ecm or the vss. I'll do the ecm first because it seems like that has a higher chance of it being the problem. My friend who works for a gm dealership test drived it and said that the tcc acts like its not functioning properly. so the if the ecm is messing up it could give the vss problems too. the vss tells you how fast your car is going and engages the tcc. It's like connecting the dots :) I have a new vss from a friend at an auto shop. So I'll need to get the ecm first, I might not even need the vss if its the ecm but I'll put it on anyways because its free and its another part that I won"t have to worry about. If the problem damaged the tcc, is a that a new transmission or can you swap it out with some work? The orange wire did have a single connector on it. From the diagram that I saw in the haynes manual and your (screech) ecm diagram, I'm pretty sure you're right on it being the serial data wire. I think it connects to the aldl connection (looking at the diagram) but I'm not sure. This problem is bugging me because its been like that since I've had the car. I've never had the car pop up the ses light unless I pulled out a sensor. If the sensor is connected and has power going to it, it ses will turn off, but could this wire tell if the sensors are working improperly? Where exactly does this mysterious orange wire go to? I popped off the black box with all the connections on the upper right hand side where I figured it should be and the wires and noticed one should be there, but it was covered in a black silicone (I think) to prevent water to get inside of it. The previous might have had problems with it and their mechanic just took it out because the codes would quit popping up. (The same mechanic that when I switched the spark plugs left 2 old ones in because they couldn't get to them). The hose where all of the wires are in has been cut and they have been taped with electrical tape. This is all in theory though... If someone knows what this orange wire is for, it could definitely be helpful.

[boderman88]

So that orange wire is actually a ground for a fuel pump. Thats not whats wrong with it, but dudley martin (GM dealership) told me that it sounds like my problem is the tcc. Back to the ECM and VSS theory... He said that replacing the tcc if its messed up is going to be hard, but I might not have to do that if the ECM and VSS can fix it before it does the damage. hmmm....

[Prospeeder]

Go to the front of the trans, find the large 5 wire round plug, disconnect it, its the TCC lock up, it wont hurt a thing, and will quickly tell you if that the problem, alot of people jsut drive around with it like that, u just look 2-3 mpgs on the highways all.

[boderman88]

i was gonna do that tomorrow because after stalling 23 times just to get to my house from the beginning of my nieghborhood, I figured the hell why not. It might save me gas mileage by all the starting up I've been doing. I noticed that when it cuts out it cuts out for a second then has trouble dieing. it almost bogs out in a way and when I let off the gas it idles the same rpms (maybe raises more) and acts if I am pressing on the gas. When I went in reverse it acted as if I was flooring the gas pedal. If I didn't have my foot on my brake I would've ended up in the ditch. I am going to sell this car whenever I get the chance and buy a different a-body car. I like the ciera but the front end of the buick looks so good... Front end conversion possible??? hmm.. we should try it. I made custom clear corner lights for it anyways.

[boderman88]

I pulled the plug on the tcc and its not slipping or shifting bad anymore. The vss is still going haywire though. It popped up code 27, 28 and code 39. (27,28- quad drive, 39- TCC switch) I figured that it would pop up because of the plug being pulled so I think that its normal. Is it easy to switch out the solenoid in this?

[Prospeeder]

it did fix your stalling? Or no? Change that ECM out, dont sell the car, fix it, its much cheaper and it will make you feel good knowing you fixed it too. I can get ECus here for 30 bucks at the junkyard

[boderman88]

well I thought it stopped... It stalled today going to school. ECM is next in line. I was driving about 25 miles an hour and just cut out. It was crazy. It seems like it just wanted to quit with no reason...

[boderman88]

so I checked the resistance on the fuel injectors and one of them is reading a 9.4 (level should be around 11.8 to 12.6). That might be the problem right there. I'm going to the junkyard to find a decent set of them (so at least i know one will work)

[SCREECH]

...when I let off the gas it idles the same rpms (maybe raises more) and acts if I am pressing on the gas. When I went in reverse it acted as if I was flooring the gas pedal. If I didn't have my foot on my brake I would've ended up in the ditch...It stalled today going to school. ECM is next in line. I was driving about 25 miles an hour and just cut out...I checked the resistance on the fuel injectors and one of them is reading a 9.4 (level should be around 11.8 to 12.6). That might be the problem right there.
One fuel injector, even if bad, is not likely going to be the cause of your problem. Re-read what I've quoted above from your earlier posts. The idle increasing on it's own, so much so that it seems like you're pressing on the gas, is EXACTLY what mine was doing before I swapped my ECM. It was racing the idle up around 2500rpm or more and I would just shut it off. Mind you, I don't actually have mine on the road yet, so it wasn't much of a problem for me, but I can see how it WOULD be a problem if you were trying to drive it and it was doing that.

Ask yourself this - how is one fuel injector, even if it IS bad, going to cause your speedometer to go crazy, your idle to rev up, your TCC to go nuts, etc, etc, etc? It won't. It's all tied into your ECM. If you haven't purchased injectors yet, don't. Swap the ECM first. Seriously. It's actually faster to try another ECM than to swap injectors.

[Prospeeder]

yea and alot cheaper.... Hes right, all that stuff points RIGHT to the ECU, it controls all of those!