I hope one of you might be able to help me with some troubleshooting from afar this Sunday! I am worried about driving my 95 chevy TBI van home in this condition, and I'm about 100 miles from home.
The past few days the throttle has been running high on my van, I figured it was the TPS going bad again. Last night it was pretty bad, the service engine light came on and it was shifting really hard. Tunerpro showed a TPS code (I'm not sure which one), and it was running high on TPS while the vehicle was running. I mistakenly thought the TPS was high signal, which was causing a higher throttle position percentage.
I picked up a new TPS sensor and installed it this morning. With the ignition ON, and the engine not running the TPS worked perfectly.
Then I started her up, and it was high again and the service engine light came on again.It's idling around 1250 to 1500 rpm. This time two codes, TPS low and MAP low reported.
Upon troubleshooting more, I've discovered that the throttle blades are NOT returning back to zero position when the engine is running. Often, the butterflies shaft is held just a little open.
When I stab the throttle, it chokes off the engine, then recovers. If I quick jab and hold the throttle it chokes almost off, then roars to life, when I release the throttle, it doesn't go back to zero throttle.
When I manually turn the throttle shaft back to zero, it shows a proper TPS value, but the idle stays high.
I doublechecked the MAP sensor, all the connectors appear good, and vacuum lines appear connected.
I disconnected the cruise control throttle cable from the TBI to double confirm that was not the cause.
When I get the throttle shaft into the just a little open position, and shut OFF the engine, the blades turn back to closed on their own.
Any suggestions?
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Help needed, trouble away from home
Moderators: robertisaar, dex
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tony-baroni
- Posts: 10
- Joined: Tue Mar 17, 2015 4:38 pm
Update.
Trying to limp it home.
High idle, hard to stay stopped at a light.
Couldn't barely hit 50 on highway. Throttle would just barely accellerate for 4 seconds, then no throttle response for anywhere from 4 to 30 secones, then repeat. Got to auto parts store, found MAP unplugged.
New Code 45 O2 sensor rich.
Got to auto store. Replaced a vacuum line to the EGR control, which I had found had split.
Found MAP unplugged, plugged it back in. The connector may have come loose, as the snap clip is broken off, or I forgot to plug it in last time .
IAC motor position while ignition ON and engine not running is 70
@ idle @ 1900 it is 94
spark advance at 22-28 deg at high idle
Unplug MAP, idle drops to 1075.
plug map in, jumps back up to 1800
At shut off, IAC motor position at 160
Tried new MAP, same situation.
Again, not sure it's safe to drive home, but I hope with the MAP plugged in it will get up to highway speed.
Trying to limp it home.
High idle, hard to stay stopped at a light.
Couldn't barely hit 50 on highway. Throttle would just barely accellerate for 4 seconds, then no throttle response for anywhere from 4 to 30 secones, then repeat. Got to auto parts store, found MAP unplugged.
New Code 45 O2 sensor rich.
Got to auto store. Replaced a vacuum line to the EGR control, which I had found had split.
Found MAP unplugged, plugged it back in. The connector may have come loose, as the snap clip is broken off, or I forgot to plug it in last time .
IAC motor position while ignition ON and engine not running is 70
@ idle @ 1900 it is 94
spark advance at 22-28 deg at high idle
Unplug MAP, idle drops to 1075.
plug map in, jumps back up to 1800
At shut off, IAC motor position at 160
Tried new MAP, same situation.
Again, not sure it's safe to drive home, but I hope with the MAP plugged in it will get up to highway speed.
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tony-baroni
- Posts: 10
- Joined: Tue Mar 17, 2015 4:38 pm