please help!!!

[michael ward]

your help is much appreciated !!! :bows: :confused: I went to my ford dealer today and had my 4 new 245/55/18 g-force kdws that i bought from tire rack from this site installed today my tech reprogramed new tire size but at 50mph w/tc on tc kicks in throws on tc light and shuts down engine. anybody know how to reprogram tc w/rear size on front??? or do i always have to drive w/tc off :confused:

[bugsys03]

anybody know how to reprogram tc w/rear size on front??? or do i always have to drive w/tc off :confused:

If you put the rear size on the front it wouldnt have any effect on traction control.

[michael ward]

:help:
If you put the rear size on the front it wouldnt have any effect on traction control. then how come car cant go over 50mph w/tc on?? i had no problems until today when i put rear size in all 4 corners :help: thanks

[SergntMac]

You're probably better off driving with the Traction Control off until you need it, but that's not the point. You didn't change the rear size, only the front. Let's recap what you had before the tire change?

OEM front tires are 235/50/18 and they are 27.25" tall.
OEM rear tires are 245/55/18 and they are 28.61" tall.

IMHO, you should have been okay with the rear sizes on all four corners without any program changes, and I wonder what got changed, and why? It should not have been the speedo, what was your wrench messing with?

Do you have any other mods in place that may affect this, like a rear end ratio change?

[Seneca]

i know this prolly dont have anything to do with what you guys are talking about really. but i once took my previous 03 mm in for service and they put the rear tires on the front front on the rear.. it was raining and i never noticed to look but when i got a few blocks down the road my brake light came on and O/D light came on.. and check engine too.. just thought i'de throw that out there..

[cruzer]

Sorry, you can't put rears on front on your '04 and not mess up T/C. T/C works on a pre-programed difference in rolling circumference between front and rear wheels--if you change this ratio, T/C will shut you down---I am pretty sure you cannot change the program settings--if I'm wrong, please post---this is the info I got when I had same problem on Grand Marquis with different tire on front and rear.

[Joe Walsh]

I believe that the Traction Control compares the rotation rate of the front tires to the rotation rate of the rear tires. Because there is a large difference in the OEM front vs. OEM rear tire sizes (i.e. larger rears turn less than the smaller fronts), this is what the Traction Control system considers "NORMAL". You've now made the rotation rates the same. The Traction Control system now 'sees' the rear tires turning much more than "NORMAL"...it thinks that you are spinning the rear tires and kills your engine power to correct the 'spinning' rear tires.

[michael ward]

i have no mods car is stock thank you all for your help! i'm thinking this cant be done but i'll look into it a little more ... I might have to put stock fronts back on???

[SergntMac]

i have no mods car is stock thank you all for your help! i'm thinking this cant be done but i'll look into it a little more ... I might have to put stock fronts back on???
Again, Michael, what did the installer change in your programming? Maybe he messed that up?

[rayjay]

Interesting, I am considering putting the 245/55/18's on the front and 255/55/18's on the rear. Isn't someone else here running the 235's all the way around w/out any problems? I believe Sgt Mac is on the right track. They should have left the CPU alone.

[MarauderMark]

Again, Michael, what did the installer change in your programming? Maybe he messed that up?


This sounds about right..

[michael ward]

my tech entered the rear tire size in the pcm and it calculated revs/ mile at 45 mph.. for this size 245/55/18..

[CRUZTAKER]

Sorry, you can't put rears on front on your '04 and not mess up T/C. T/C works on a pre-programed difference in rolling circumference between front and rear wheels--if you change this ratio, T/C will shut you down---I am pretty sure you cannot change the program settings--if I'm wrong, please post---this is the info I got when I had same problem on Grand Marquis with different tire on front and rear.
When we put the snows on my buddys MM with all 4 the same size, his t/c light comes on at 45 mph every time. He just turns it off.

That's all I can offer from experience, I don't have t/c, but do know of others that switch tires, say for winter applications with all for the same size, that this is typical.

I have never heard of a fix.

[MENINBLK]

your help is much appreciated !!! :bows: :confused: I went to my ford dealer today and had my 4 new 245/55/18 g-force kdws that i bought from tire rack from this site installed today my tech reprogramed new tire size but at 50mph w/tc on tc kicks in throws on tc light and shuts down engine. anybody know how to reprogram tc w/rear size on front??? or do i always have to drive w/tc off :confused:

Mike,

Take the car back and have the tech double check what he did to the PCM.
He wouldn't be making an adjustment anyway, he should have to reflash
the entire PCM with a program that supports the 4 tires being the same size.

[RF Overlord]

I don't have t/c,

Barry:

Would traction control do you any good? You should own stock in BFG...!

:P :lol:

[JohnE]

The tire size is in the PCM, but the TC computer doesn't look at the PCM value. You have to reprogram the sizes in the TC computer. Don't know if a Ford dealer has access to do this.


It is the accelleration rate of each tire that the tc computer looks at. With different diameter tires than expected, the higher the speed the greater the difference between.


I had this same exact problem on my car, only mine is expecting the same size all around. I put Michelin Pilot XGT V4 225/60VR60 on the front and Michelin Pilot Sport A/S 225/60WR60 on the rear. This was no problem and drove just fine. However one day I had the bright idea to rotate front to back. First time I was merging onto the freeway, at about 50mph the engine was shutdown hard. I had to come to a complete stop to get power back. Didn't know is was traction control at first. Come to find out the Sport A-S are 770 revs/mile and the XGT are 786 rev/mile. (Stock is 800/mile)


Tried disabling traction control in the PCM, w/o turning the in-car switch off. Well the engine doesn't get shut down, but the tc computer starts grabbing rear brakes. Since I don't use tc much anyway and having a good limited slip rear, I don't need its help. Simple modulation of the go pedal works fine for me. To top it off my tc is way more sensitive than the Marauder, hitting a slight bump accelerating on a dry road would set it off for several seconds.

I have a NC switch instead of a NO switch installed in place of the factory tc switch. And I pulled the TC light, so don't have to look at it. On a daily basis, my tc defaults to off. It's still there, with a double push of the button if I want it though.


John