Unsteady idle, drops too low when coming off the gas.
Hello,
I recently bought a '98 Previa auto-box that has been LPG converted; it had a few issues, most of which I've sorted out, but one of which I can't figure at all.
When I start the car, it chugs for a second or two until I give it some gas. If I come off the gas too fast, the revs drop way low and the engine cuts out. I've tried adjusting the idle up at the cable on the throttle-body, but as soon as the engine is stopped and restarted the problem comes back. It only has this issue when running on petrol and when running cold - with the engine cold, if it switches over to LPG the same thing happens as soon as I come off the gas peddle - revs suddenly drop through the floor and it stalls. Bizarrely, once the engine is up to temperature and has switched over to LPG, it runs like a dream. It will still stall if switched back to petrol while stationary though.
I have cleaned out the PIM sensor, the filters and the vaccuum hose between it and the throttle-body (and lost the bolt that was holding it to the floor-pan in the process - it's now gaffer-taped up out of the way), but that hasn't solved it.
I re-did the ECU reset / idle-learn procedure today, and it does seem to have solved most of the problem; it still cuts out if it switches over when stationary (i.e. when I'm not on the gas), but it seems fine other than that :-)I re-did the ECU reset / idle-learn procedure today, and it does seem to have solved most of the problem; it still cuts out if it switches over when stationary (i.e. when I'm not on the gas), but it seems fine other than that :-)
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Re: Unsteady idle, drops too low when coming off the gas.
Idle on previas is set with the air bypass screw, not the cable. Holding the actual throttle open will cause all kinds of other problems.. one of which is the transmission thinks you are still on the throttle, so its still pulling. tps needs to go to 0 for it to disengage. Try releasing the throttle cable, open up the air bypass screw which is recessed 1/2 inch diameter flathead right on the side of the throttlebody. another thing to check is the a/c idle up solenoid sometimes will fail, and cause the described problem. Ithere is an idle air control valve, which carbons up and may not react to the drop in idle speed fast enough. A can of carb cleaner taken to the valve (once removed) should help out.
Re: Unsteady idle, drops too low when coming off the gas.
Could be fuel starvation when changing over from one fuel to another.end of one/start of another,especially when engine cold and running on richer mixture .answer is only change when car is at normall temp.sorry but this is in the gas convertion manual....
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If your 1997 Mitsubishi Starwagon has been converted to run on LPG (liquid petroleum gas) and is having trouble switching back to petrol, there could be a few different issues at play. Here are a few things you could try:
Check the LPG/petrol switch: Make sure that the switch is in the correct position for the fuel you want to use.
Check the fuel lines: Make sure that the fuel lines for the petrol and LPG systems are not blocked or damaged.
Check the fuel pump: The fuel pump may not be working properly, preventing the vehicle from switching to petrol.
Check the fuel tank: Make sure that the petrol tank is not empty and that there are no blockages in the fuel lines leading to the engine.
If none of these solutions resolve the issue, it may be necessary to have the vehicle diagnosed by a mechanic. They will be able to identify the cause of the problem and recommend the necessary repairs.
The power steering pump could be going bad. The noise coming from the catalytic converter could be something as simple as a mounting bracket coming loose, or worst case something busted internally.
RUN down to Advance Auto Parts and buy a can of "SeaFoam" and add to your gas tank per instructions...drive for at least 100 miles and the problem should be gone. If not, one or more of your O2 sensors are most-likely fouled (lousy fuel quality these days). Good Luck
LPG fueled vehicles are inherently "cold-natured" due to the temperature drop when the "liquid" gas under pressure reverts to gaseous state causing a frost build up around nozzles and jets. The only solutions are to start on pump gas until up to operating temperature and the switch fuels, or allow the engine to warm up to operating temperature on LP gas before driving, thus avoiding the stall point.
I re-did the ECU reset / idle-learn procedure today, and it does seem to have solved most of the problem; it still cuts out if it switches over when stationary (i.e. when I'm not on the gas), but it seems fine other than that :-)
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