3 Speeding Tickets in 1 Hour? Yes

[AustinGJordan]

What I deem as "important" information, I put in red.

Background Information about my car:
-1997 Ford Mustang Convertible
-6 Cyl
-Automatic
-3.8L
-"Normal" Tires. Got them balanced/replaced 4 months prior to this incident.

Story:
Yesterday (or today), I decided to go on a brief "road-trip" with my girlfriend. It was going to be 3-4 hours there, and 3-4 hours back. The total time would then be 6-8 hours of driving in this Mustang.

We left at 3:00am; and so there was hardly any other cars (specifically, police) on the way down to my destination. After arriving and spending an hour sight-seeing and relaxing, we left around 8 or 9am to drive back.

I don't normally speed, but I wanted to show my girlfriend what the governor on my Mustang felt like (odd, yes). From past experience, my speedometer has NEVER been able to reach 100+ mph. Whenever the speedometer reached 100mph, the governor kicked in and stopped my acceleration. I know this to be accurate as I tested it several times before this moment with my girlfriend.

Being unlucky, a cop was there to greet me on the highway exactly when I was trying to show my girlfriend the governor. However, my governor didn't kick in (so I know I didn't reach 100mph according to my speedometer, FOR SURE), and my speedometer read around 95-97 mph when I glanced at it.

The cop did end up catching my speed, and told me he clocked me at 111mph (he showed me the radar gun). I told him that's not possible and that my car has a governor set at 100mph. I couldn't really argue with his radar gun, however, and I thought it was odd since my car has NEVER gone higher than 100... as it can't.

Around thirty minutes later I'm on a 70mph speed limit highway. I look at my speedometer, I'm going 76-78 MPH. I see a cop ahead, and slow down just in case even though I know I am fine as I wasn't speeding (I'm really not a huge speeder). He ends up pulling me over.

He (the cop) tells me that he clocked me at 86mph. I knew for a FACT that I was not going that fast, as I had my auto-cruise set on 76-78. I even looked at the speedometer as the cop signaled his lights and it read 76-78, before I braked.

I told the cop that my speedometer MUST be off. He then told me that if I took it to a shop and they saw that the speedometer was off; then the court would excuse that ticket.

The third ticket I received was basically the same scenario, and also happening within the same hour (I was fed up with cops at this point).

After that, I had my girlfriend take out her GPS and tell me what speed it said I was going. When I was going 65 MPH, according to my Speedometer, her GPS said I was going 75-78MPH. The higher my speedometer went, the higher the error was. I KNOW something is wrong with it.

Question:
Basically, I took my Mustang to the Ford Dealership, and they told me they checked with their computers/equipment and could find nothing wrong with my speedometer. What should I do at this point? I KNOW there is something with it, no doubt in my mind. Is there something I should tell them to check specifically? Who should I take it to? I live in Overland Park, Kansas. I did get the tickets in Missouri though.

Any information would be greatly appreciated. I really hope to resolve this, even if for future tickets as well.

 

[N8Dogg98]

Is it possible your car has a different set of rear end gears in it? It's not likely someone would install a taller gear ratio, but you never know. How about the transmission, has it ever been replaced or rebuilt? Its also possible that the transmission has a different vehicle speed sensor (VSS) than your car needs to run accurately. For example, if your car has a VSS speed sensor designed for 3.27 gears and you actually have 2.73 gears in the rear diff that would cause the speedo to run slow.

Side note... you say you never speed yet go on to say you were doing 76-78 in a 70 MPH zone in the same paragraph like it's alright to exceed the speed limit by 6-8 mph. I'm actually suprised you don't have more tickets if you constantly drive 6-8 mph over the speed limit.

Unless they verify it by strapping it to a dyno or something, I don't think Ford is really diagnosing this correctly.

 

[AustinGJordan]

Is it possible your car has a different set of rear end gears in it? It's not likely someone would install a taller gear ratio, but you never know. How about the transmission, has it ever been replaced or rebuilt? Its also possible that the transmission has a different vehicle speed sensor (VSS) than your car needs to run accurately. For example, if your car has a VSS speed sensor designed for 3.27 gears and you actually have 2.73 gears in the rear diff that would cause the speedo to run slow.

Side note... you say you never speed yet go on to say you were doing 76-78 in a 70 MPH zone in the same paragraph like it's alright to exceed the speed limit by 6-8 mph. I'm actually suprised you don't have more tickets if you constantly drive 6-8 mph over the speed limit.

Unless they verify it by strapping it to a dyno or something, I don't think Ford is really diagnosing this correctly.

I suppose it is possible it has a different set of rear end gears. I believe the owner did some work on the Mustang himself, as when I bought it I found the thermostat to be upside-down. So anything is possible if he could do that.

I don't believe the transmission has been replaced or rebuilt.

So are you mostly thinking the VSS no longer matches the gears? Would this show up in the dealership's "computer" test?

And in the area I live, it is very common to see people go 5 mph over the speed limit. On the highway, you'll see a majority of cars go 10 over as well. So by staying 8 over, especially on a 70mph highway, I would be passed by several cars still. I suppose it varies where one lives. But little did I know that staying 8 over ended up being 16+ over because of my speedometer =-/.

Should I tell the dealership to check the rear end gears and see if the VSS matches that type of gear? What would you suggest I do in order to get a mechanic to notice the problem?

 

[N8Dogg98]

I suppose it is possible it has a different set of rear end gears. I believe the owner did some work on the Mustang himself, as when I bought it I found the thermostat to be upside-down. So anything is possible if he could do that.

I don't believe the transmission has been replaced or rebuilt.

So are you mostly thinking the VSS no longer matches the gears? Would this show up in the dealership's "computer" test?

And in the area I live, it is very common to see people go 5 mph over the speed limit. On the highway, you'll see a majority of cars go 10 over as well. So by staying 8 over, especially on a 70mph highway, I would be passed by several cars still. I suppose it varies where one lives. But little did I know that staying 8 over ended up being 16+ over because of my speedometer =-/.

Should I tell the dealership to check the rear end gears and see if the VSS matches that type of gear? What would you suggest I do in order to get a mechanic to notice the problem?

Yes. The VSS is a small gear mounted in the transmission and it sends a signal to the speedometer. This gear looks like this:

IIRC they are different colors depending on the rear end gear ratio. Have the dealership reconsile whether or not the VSS gear matches the rear end gear.

 

[AustinGJordan]

Yes. The VSS is a small gear mounted in the transmission and it sends a signal to the speedometer. This gear looks like this:

View attachment 186435

IIRC they are different colors depending on the rear end gear ratio. Have the dealership reconsile whether or not the VSS gear matches the rear end gear.

I think I got the dumbass among the people who work at the dealership. He told me it wouldn't run if it was the wrong VSS and made some other stuff up. He isn't the mechanic, just the person that communicates with the mechanic and me. When I mentioned the VSS, he said he "could throw another one on there and see if that fixes it." I don't think he understood (I repeated it twice). So it's sort of useless to even try and get him to do something. I'll just take it to another place and have them look at it and inspect that.

Is there a place that is well known for doing stuff like that?

Thanks for all your help thus far.

 

[N8Dogg98]

ask to speak with the manager or one of the techs

 

[wmburns]

What is the top speed listed on your cluster?

Is it possible that the cluster overlay (or the cluster itself) has been swapped from a GT? The difference almost PERFECTLY matches how much the speedometer is off.

 

[N8Dogg98]

That's a good point Burns

 

[AustinGJordan]

What is the top speed listed on your cluster?

Is it possible that the cluster overlay (or the cluster itself) has been swapped from a GT? The difference almost PERFECTLY matches how much the speedometer is off.

I have this type of cluster: http://img10.imageshack.us/img10/1770/img2241gm.jpg

 

[wmburns]

Seems unlikely to be an overlay. Seemed plausible.

Since it looks like a new to you cluster, it doesn't rule out the possibility of a problem in the cluster.

On the 96+ MY cars, the cluster speed display is a signal from the PCM. What would be nice to know is what the PCM thinks the speed is.

If the cluster and PCM agree, likely the problem is in the VSS sensor or related components (or a bad PCM "tune". For example an incorrect rear gear ratio programmed into the PCM).

If the cluster and the PCM disagree, then the problem is in the cluster.

An ODB2 scanner capable of monitoring operational data would make short work of this.

 

[N8Dogg98]

Burns, I don't think the PCM stores a gear ratio in a Mustang made before 1999. It's a simple signal from the VSS to the speedometer. IIRC it was only on the 99+ cars, that you could adjust the PCM gear ratio using a hand held tuner. I cannot do this on my '98, and instead had to use a Dallas Mustang Speedcal.

 

[MustangLX-5.0]

Hello, Austin, are you still keeping tabs on this thread? May I ask what size tires you are using EXACTLY and what rims you have on there. You said NORMAL tires, but i'd like to know what the specs are.

I'm pretty sure the speedometer is getting it's voltage signal from the speed sensor directly. On the cars that get their signal from the PCM, the gauges usually do a self-test when the key is turned on, resulting in the gauges flipping all the way to max and the back to 0 position. PRE-99's did not do this. This was only on the ones that had the digital odometer which are the '99's - '04's .

It's possible you can have the same VSS, but have a different gear on the end of the sensor. The gear IS removable for different ones which people usually do when they swap out rear end gears. The computer would not know this. They just change the VSS gears to keep the speedometer accurate after a read end gear change. Also there is a chance someone change out the rear end gears and didn't change the VSS to calibrate it. The computer will not give an error for this so in other words, the techs working on your stang at the shop won't find anything wrong with it , neither will the computer (PCM).

Are you capable with tools and the like? If you think you can handle this, perhaps take a look at the VSS gear that is on the trans. Find the color that match the stock gear ratio on a websitem then make sure you have that color, if it does not match , then someone changed either the VSS gear or the rear end gears.

FYI... the governor on my 96 cuts out at 112 MPH. I KNOW this for a fact. I've done it about 10 times. . But, I was more careful. Just saying, be careful at such speeds. I did mine on a road with NO traffic at 2 am. And I made at least 2 passes back and forth before I did this. This was in an area where no houses or businesses were. It is better to be safe, than sorry. I'm surprised the first cop didn't give you a ticket for reckless driving. That's a 6 point-er

 

[Eric98Stang]

I had a whole new rear end put on my 98 i put a 98 gt end on it and the gears are different. you might want to take your car to get the gears checked and synced with your spedometer thats what i had to do bc it was telling me i was going up to about 15 miles and hr faster than what i was doing.

 

[gtthomas]

damn that sucks man, kind of dumb though to speed at all after getting pulled over for going 100. Like everyone else said, possibly steeper gears. Alot of cars don't read perfectly when you get into the higher speeds but that is just way to far off.