Fourth-Gen Man

Last week I took my WS.6 in for a tune up and to repair a vacuum leak. It's been driving fine since then so tonight I tried driving it somewhat aggressively. It ran fine up until I went full throttle in first gear and shifted at around 5k rpm into second, then I put in the clutch and hit the brakes to slow down.

The engine started to rev up and back down on its own, and every time it revved up the temperature gauge would go all the way down as if the engine was cold. When the engine would go back down where it should be the temp gauge would go back to normal. Then it would keep repeating that trend over and over until I pulled over and shut the engine off. After that it refused to start. I called a tow truck and after about ten minutes the car started and idled okay for about 2 minutes, then it repeated the same trend as before. I'm stumped on what it could be. It did give off a smell too. It kind of smelled like it was running rich or something.

Here is what was done to the car when I took it in for a tune-up:
-New spark plugs
-New ignition wires
-New fuel filter
-New power steering fluid
-New coolant
-New water pump (it apparently started leaking when it was in the shop)
-New Thermostat
-New fuel injector O-rings
-I had to get my intake manifold re-sealed as well because when I put it on I had a small vacuum leak on both sides (it was my first time ever doing something like that before, I think I didn't clean the surfaces well enough).

I would appreciate any thoughts. I'm still pretty new when it comes to diagnosing problems and doing very many things like this. Thanks guys.

farmington

iTrader: (14)

Is it showing any codes?

Fourth-Gen Man

No, no codes showing up at all. I'm thinking maybe fuel pump, but that wouldn't explain the temp. gauge going erratic.

gMAG

iTrader: (1)

Log the engine temp independently, to verify that the gauge is accurate. If so, I'd remove the sensor and test it.
It could be a coincidence that with all the work you had done, that the sensor suddenly went haywire. It is also likely that there is a problem with the sensor wiring.

Fourth-Gen Man

It all looks good and normal until it warms up. I started it up today and it started just fine. it took a normal amount of time for it to warm up as well and the gauge climbed at the steady rate it should. All until it reached the normal operating temp right in the middle of the gauge. After it warmed up it started the same thing again where the gauge would go all the way to the left to the cold position and the engine would rev up, then go down almost til it died, then it would rev up again. It progressively got worse and worse. I let it go for about 40 seconds and then it stalled. Started up again but continued the same pattern. I think I'm gonna take it back into the shop tomorrow.

S10xGN

iTrader: (11)

That bogging is a symptom of the temp sender. When it goes dead low (-40), the PCM dumps a bunch of fuel into it. Replace the sender or fix the wiring...

Fourth-Gen Man

Oh ok so I suppose the temp sender is telling the computer that the engine is dangerously cold so it's revving up to try and quickly heat the engine up?

Fourth-Gen Man

Yep, you were absolutely right


Thank you so much for chiming in and helping me out! I just thought there was a sensor in the water pump and didn't see how it would connect to the idle going erratic. If I could buy you a beer right now I would.

Thanks everybody else too for the suggestions!