3vze cold idle
02-22-2013, 04:09 AM
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3vze cold idle
I have a 92 with the 3vze runs great idles about 750-800 rpm when warm but when it's cold if u don't keep ur foot on the gas for a few min it will die and only idles at about 500 rpm till it warms up
02-22-2013, 01:10 PM
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That makes me think it's not the CSI then, there's more likely an air/fuel mixture issue . I would check the Engine Coolant Temperature sensor (ECT) and your Volume Air Flow Meter (VAFM, or sometimes called your MAF) with an multimeter per the factory service manual. If it measures out of spec (both of these change based off the temperature of the air and coolant, best to do when the engine is cold), replace. Don't buy parts unless you know they are bad since a new VAFM costs $200!
When it's cold, the engine operates in a loop where it runs off preset mixtures settings. Sounds like you have a sensor or part malfunctioning causing it to run too rich or too lean. When it's warm, it then switches to the sensors and ECU to fine tune itself which then fixes your issue.
On second thought, it really sounds like your VAFM. Check it out and post results. I had a bad ECT and it was the opposite: ran poorly when warm but great when cold. I've heard of several starting issues being solved because of a bad VAFM.
When it's cold, the engine operates in a loop where it runs off preset mixtures settings. Sounds like you have a sensor or part malfunctioning causing it to run too rich or too lean. When it's warm, it then switches to the sensors and ECU to fine tune itself which then fixes your issue.
On second thought, it really sounds like your VAFM. Check it out and post results. I had a bad ECT and it was the opposite: ran poorly when warm but great when cold. I've heard of several starting issues being solved because of a bad VAFM.
Last edited by Gamefreakgc; 02-22-2013 at 01:12 PM.
02-23-2013, 06:09 AM
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Did you have the same problem before the VAF was replaced? WHY was the VAF replaced? Your current issue is unlikely to be related to the VAF; while it has a temperature sensor it senses intake air, not engine, temperature. So it shouldn't make any difference cold v. warm.
If you know the dashpot and throttle opener are not adjusted correctly, you need to start there. While they have nothing to do with warm v. cold idle, they do set the base position of the throttle plate. I could imagine you have them set so that the throttle is closed too far for cold idle, but you have compensated for that by mis-setting the ISCV for warm idle.
DO check the ignition timing. It's easy (and necessary) to do, and can clear up your symptoms.
It's unlikely to be related to the Cold Start Injector. That's for Starting, not idling; the injector usually shuts off within a second or two of when you start cranking. It your CSI was leaking the problem wouldn't go away with the engine warming up.
Once you get the throttle positioners set to spec, the most likely culprit is the Engine Coolant Temperature (ECT) system; that's what detects the change from cold to warm and signals a mixture change.
Good luck!
If you know the dashpot and throttle opener are not adjusted correctly, you need to start there. While they have nothing to do with warm v. cold idle, they do set the base position of the throttle plate. I could imagine you have them set so that the throttle is closed too far for cold idle, but you have compensated for that by mis-setting the ISCV for warm idle.
DO check the ignition timing. It's easy (and necessary) to do, and can clear up your symptoms.
It's unlikely to be related to the Cold Start Injector. That's for Starting, not idling; the injector usually shuts off within a second or two of when you start cranking. It your CSI was leaking the problem wouldn't go away with the engine warming up.
Once you get the throttle positioners set to spec, the most likely culprit is the Engine Coolant Temperature (ECT) system; that's what detects the change from cold to warm and signals a mixture change.
Good luck!
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