arxmechanica

I have a 99 XJ 2WD 4.0 I6

Is it going to harm anything to drive for a while with the TPS unplugged? It runs smoother and am able to drive it when it is unplugged.

I have very rough idle and misfiring that sometimes goes away for a short time.

This problem started after my horn would turn off and was blaring while driving a couple of weeks ago. I removed the fuse while it was blaring but it didn't stop the horn. didn't think to pull the relay. The fuse blew once I put it back in and now I have an intermittent airbag light. The horn relay is also removed at this time.

I have new...
Plugs
Wires
Rotor
Dist cap
Oil sensor
Alternator
TPS

I am planning to replace the clock spring this weekend.

Should I also remove the fuse box an inspect for damage?

All of this happened after a heavy rain and deep puddles.

Any thoughts? Helpful experience? Thanks.

investinwaffles

With my TPS unplugged - my XJ runs like a 3 legged dog. Acceleration is spotty, down on power all the time, etc

I would be worried about the ecu leaning out the motor or something because it doesn't know where the throttle position is in relation to the MAP and o2 sensor readings

arxmechanica

When the TPS is plugged in it lurches, misfires and goes through fuel like crazy as well. When I unplug it, it runs pretty smoothly.

drewactual

w/o the TPS the pcm uses an open loop limp strategy that severely limits any abrupt alterations in right foot input- it relies on MAP/MAF (and triangulates vacuum in the manifold in addition to the pressure/flow) and your o2's, reduces spark advance, and generally behaves badly....

that is a key element.... it can still run, but trying to 'cross zero' on the lambda or advance spark to reasonable point above base for rpm? nope... it's too risky not knowing what you're trying to do... it's trying to look out for you. ain't that sweet of it? you got a sweet truck, you.

DFlintstone

I should just butt out of a 99 thread, but I can't help it. Unless bucking or backfiring messes with something, I don't see long term damage. Idk if it could go nutty rich and cause problems with clogging the cat.

I've seen posted a few times the TPS does not like getting wet.

It IS a MAP, and in "open loop" the puter will run it on defaults to get you to Napa to buy a new friggin TPS! After the MAP, the TPS might be the next most important sensor. (well OK, where are you going without the NSS, But.......

investinwaffles

Both of these are true.

The second one is exactly how I limped it off the highway and to a local Advance Auto for a new TPS
Unplugged the sensor and drove with the throttle as closed as possible basically

arxmechanica

I replaced the clock spring this weekend and the tps data went back to normal and it runs great. Tomorrow I will drive it a distance so we will see how it does.