My speedo is reading low (at 70 mph my speedo shows 55). If I have a new speed sensor which didn't fix the problem and exchanged clusters and that didn't fix the problem, what exactly is the problem?

 

The original gears are in the rear. The tires on the car were slightly larger than stock, but I replaced them with stock size. I'd hate to pay $135 to have this thing put on the computer and find out that it didn't need it. I'm trying to eliminate the simplest solutions first. I'm nearly out of other solutions, though.

 

If you put a scanner on it does the speed reading from the PCM match the gauge in the dash?

If the PCM is also off by the same amount it is possible your PCM is calibrated incorrectly for the rearend ratio or tire size you are running.

If the PCM and dash gauge disagree with eachother and the PCM shows the correct speed then you have a broken dash gauge.

I've got my money on a miscalibrated PCM.

 

You posted the same "problemo" a week ago, you got pretty much the same answers and you said you were going to check the PCM to see if it was tuned for the correct gears. What was the result of that check?

http://camaross.com/forums/showthread.php?t=450303

 

And then there's the post before that including the same problem....

http://camaross.com/forums/showthread.php?t=449351

A lot of people have spent a lot of time helping you with the problem, but you don't seem to have tried any of the suggestions.

 

and a possiblity, which still means it needs the PCM recalabrated, is that, sometime in the past, someone swaped in a used PCM, from a car with different gears

 

Oh, well ya know. I only have a job at which I work about 55 hours a week. I go to college, I have 2 kids that I raise alone and I have this car which I get to work on for about 2 hours a week. Sorry if I haven't had the time to go to get the computer checked and pull the transmission and change the rear gears, etc... I'm trying to get this stuff done without a lot of money to spend. I was just looking for a little help. I appreciate the answers that I have been given so far. And if you'll read, I did put a different cluster in and I still have the problem, so I was just looking for the next logical steep to take. If it irks you that much, just ignore my posts. Maybe someone else will answer my questions without feeling like it takes so much out of their day.

 

I'm simply trying to help you. When you ask a question, and people answer you - I answered you in what I felt was a helpful manner - and you just ignore them and post the same question over and over, no one will take you seriously. When that happens, you lose credibility, and get even less help.... its just human nature.

If its too much trouble for you to just follow up on what people suggest, then I'll stop bugging you by trying to help you.

But I will fulfill my responsbility as a moderator, and continue to comment on the way you are using the forums.

 

Injuneer,
I'm just having a lot of small problems with the car and I have very limited time and money to diagnose and troubleshoot. I'm only looking for the most common remedies for the problems I'm having. I have used your advice and the advice of others and have gotten some things done. I do not have a huge budget to waste on unneeded repairs. As far as the speedo goes, I bought a speed sensor and I got another cluster, but the problem persists. I'm just looking for the next logical solution to the problem. Around here, a dianostic test and reset of the PCM is about $135, if you can get anyone to do it other than the dealer. And if that's not where the problem lies, then I've thrown that money away. I'm not trying to get on anyones bad side, but I have these little things I need to take care of in the least expensive way possible, so I thought I could ask the people who seem to know the most about this particular car.

 

Still got the problem. Here's my order of fixes: replaced VSS, went with stock tire size, changed dash cluster, had PCM reset. Does anyone know what the next logical step in solving this problem would be? It's driving me nuts.

 

Buy a scantool off ebay and see what speed the PCM is reading.

 

When you say you had the PCM reset are you saying you had a stock program loaded back on it? or... did you just disconnect it from power for a few minutes and call it a day?

Have you followed my recommendation of puting a scanner on it yet? That would of been the first thing I did. You've wasted alot of time and money replacing and checking all that stuff.

I say again... get a scanner on it.
Do you own a laptop? the scanning software is free and the interface cable is $90.

 

The PCM was reset to factory specs using the VIN#. So the PCM is good. I cannot locate anyone with a datareader to do a road test. And no, I don't have a laptop. I've got one guy I can try to get and do the road test. If that doesn't tell me anything then I may have to live with it.

 

Then your rearend gears have been changed from stock. I'm guessing your car came with 3.42 gears and someone swapped in a used rear axle that had 3.23 gears in it. Is your car M6? if it is an A4 can you give us the RPO axle code from the build sticker. It is a 3 digit code GU*.

All we can do is speculate. You really need to get it scanned.

 

Problem solved. The speedo needle was binding at around 50mph. Took cluster apart. Don't know why the other dash didn't work. Put it on a Snap-on data reader and it's dead on. But.. I found out the tranny needs rebuilding, so I had a short lived moment of glory. I'll get that done shortly.