Intermittent throttle issues

[loki_]

I have an 85 318i. The IAC system has been completely removed and plugged for nearly a year. The throttle butterfly is cracked to compensate. Idle is relatively smooth +-50 rpms when warm.

A few days ago, the other day when I was leaving for work, I started my car and it idled normally. I went into gear to leave my driveway and gave it throttle and the car wouldn't rev if I went past 1/4 throttle. When I Pressed the clutch in the idle is normal.

I don't have my multimeter to do the diagnostic test from the Bentley yet, but just figured id ask r3v's wisdom while I wait. I think this is pointing towards the TPS. Since my IAC is bypassed, I don't have the surging idle that you'd see from a bad TPS. I've read a lot about e30 TPS filling with oil so I'm going to pull that when I get home tonight and take a look.

I'd appreciate any input, thanks in advance

[thebutterson]

The TPS on the M10 cars only has switches for idle and full throttle. I noticed the wiring diagram shows the closed throttle switch going to the idle control unit and DME so its possible that its stuck in the closed position and the computer isn't allowing enough fuel to the engine because it thinks its still idling. That's just a guess though, I don't know if the computer really does that.

[loki_]

I just changed out the battery this morning, unplugged the tps and let the car idle for 30 minutes. The car sat at operating temp and idled normally the entire time. I pulled out of the driveway and went WOT down the street. The car pulled well and felt normal. Leaving the neighborhood, I took two turns and it starts misfiring when I go over 1/4 throttle. Idle is still normal. I turned around and took my wife's car to work.

It appears that unplugging the tps didn't affect anything. It's weird to me that the car drives normally for the first 1/4 mile, even after idling for 30 minutes, before it starts having that issue.

[loki_]

Pulled the plugs, they still look good and the gap looks good still. Plugs, wires, cap, and rotor are all less than 6 months old. Started the car and it would still idle normally but wouldn't rev over 1/4 throttle.

While I was at work and googling every thing I could read, I came across a post from a few years ago where someone described the same issue. They indicated that they'd unplug their afm and coolant temp sensor (blue plug), try to start the car, plug those back in, then the issue would temporarily go away for a few days. I tried just that while the engine was cold. when I plugged those sensors back in and started it up, I was able to drive around normally until at operating temp, no misfire or anything out of the ordinary, then did a few WOT pulls and drove home. Everything still good.

I'm going to clean all of the electrical connectors soon. Would that indicate that either the afm or coolant temp sensor are going bad intermittently?

[loki_]

I replaced the blue plug coolant temp sensor. I've been driving for a week now and everything is back to normal.