18inchboyds

is it possible to get a prom or chip burnt for an 85 trans am with a 305 and tpi , what i ask is i have a no working speedo , is their a way to make the computer think the speedo is working so it doesnt throw the engine check light . And if this is possible who on this site does this and would do this . Thanks guys .

87tpi7749

1st. Why not fix speedo?
2nd. What tranny?
3rd. VSS is important to driveability.

18inchboyds

ummm, i dont have a good answer for number one , its a 700r4 and how does it affect drivability , its an 85 so it doesnt have too many computer controls on it , only the cruise doesnt work because of the speedo . so can it be done .

junkcltr

iTrader: (1)

If you just want it changed so that the check engine light is off then just remove the bulb. If you want max. drivability/efficiency then get the speedo fixed.
It would take more time in effort modifying the computer than it would to do one of the above two things.

DENN_SHAH

iTrader: (1)

you would also need to do a trans mod so the torque converter would lockup in overdrive or you seriously risk burning the trans up

87tpi7749

You can ground the park/neutral wire that inputs to the ecm, this will make the computer think the car is in park and won't look for a VSS signal. However being TPI, the idle may dip significantly on a stop or sudden decel, may even stall, also the engine will never get into lean burn mode for fuel ecomomy, TCC will never lock up, so possible trans damage may occur, though I've never witnessed that happen. It would be easier to fix your speedo. Its nothing more than a gear drive in trans & a cable, these are usually the only parts that wear out.

18inchboyds

you serious about the trans not locking up , i thought that was all comtrolled hydraulically on the 700r4 . I know that if i slp on the brakes now i can stall the car could that be related to the speedo ? SO i guess modding the comp is out of the question , but do you think their are any serious affect to not having the speedo working .

87tpi7749

No the trans torque convertor will not lock up without VSS. Early 700's were hydraulicly locked, the later versions use a solenoid. Slamming on the brakes (quick stop) and stalling car could be a lack of VSS, the idle is linked to VSS. How much $$ will a speeding ticket cost when you aren't sure how fast you're going.

18inchboyds

150 , i allready had one last year when i was testingit out from the shop and it didnt work , then they had it fixed and then it quit working , the shop is incompatent and id never take anything back there again , i think they used the wrong gears or something and they stripped. Before ,the first time it wasnt working it would bounce like 20-30 and then to like 85 and then after a few min of drving it would work . And then it just stopped working .