Code 29 - Anything Limping?

[Reed]

Finally got the car feeling better. Pulled the codes, got a 29 on the memory scan - no reading from the VSS. I am pretty sure this is because I screwed up my speedo gear install and I have a new one waiting to go in. What I want to know is what problems does a non functioning VSS cause?

I am going to the track in a couple weeks and would like everything to be working properly. Would the VSS not working put anything in limp mode? Thanks!

 

[HISSIN50]

You wouldnt have idle compensation while rolling - that's the biggie that comes to mind.

Good luck.

 

[Reed]

Thanks for the reply, I'm still learning a lot about these cars. What is idle compensation and why might it be important while the car is running/rolling?

 

[HISSIN50]

Thanks for the reply, I'm still learning a lot about these cars. What is idle compensation and why might it be important while the car is running/rolling?

Let's say you're coming off the highway and are coasting in neutral at idle, down the off-ramp. You hit the brakes, use power steering to change lanes, etc. All this can add up enough to bog the engine down a little. The VSS and IAC work hand-in-hand to keep the revs up while you are in neutral (and off the gas). The VSS is what notes that the car is rolling (I call it a rolling idle). And the puter will keep the rolling idle at 1100-1500 RPM (depending upon year, mods, base idle setting, etc). It keeps the car from stalling.

If you have your idle set on the higher side, you might not notice any issue (there are stangers who dont run a VSS and set the idle to accomodate a little extra bogging/accessory load). Remember, the stock idle is ~652 RPM, and that doesnt leave much room for it to go lower.

Good luck.

 

[Reed]

HISSIN I apprecaite the responses. I guess I can be lazy on the VSS a little longer. Thank you for the replies!