Hard Start got me and my mechanic puzzled
#31
What bothered me most was that it was running fine, then it started only once in a while, then at every startup. It's gonna be fun at -30 this winter.
I also noticed that if I lift off the throttle all at once it will die because revs drop too low.
Codes have been checked and rechecked. No codes or pending codes. All wiring is accounted for. Voltage output was tested while running, we backprobed the connectors. No fuel leak, fuel pressure was tested again, 38-39 PSI at startup. I also replaced a couple vacum hoses.
I also noticed that if I lift off the throttle all at once it will die because revs drop too low.
Codes have been checked and rechecked. No codes or pending codes. All wiring is accounted for. Voltage output was tested while running, we backprobed the connectors. No fuel leak, fuel pressure was tested again, 38-39 PSI at startup. I also replaced a couple vacum hoses.
#32
Exactly the same thing happened to mine. I attributed it to still having the original IACV now with 160k on it. It and it's ports are so clean you can eat off them. When I took the Base Idle screw out completely it's port and needle tip had allot of carbon so I cleaned them and two ports in the plenum. In my case I think a new IACV is in the future plus having the base idle and ECM reset.
I've been looking for a diagnostic system on the cheap that can do the resets.
I've been looking for a diagnostic system on the cheap that can do the resets.
#33
#34
I had some trouble on my last drive. After a while the truck started to hesitate as soon as I gave it throttle, but was idling fine, per the previously made adjustment.
It started slowly then became really worse, I wasn't able to go past 20 kph. When in park I wasn't able to rev it. Even if I gave it throttle slowly it woudn't go higher than 2500 rpm. No CEL, didn't have acces to a code reader to get the live data feed.
My first guess was lack of fuel/fuel pump going out, but it was backfiring when given too much throttle. Shutting it down then restarting it (starts fine) clears the issue for an undetermined period of time. It must be a faulty sensor somewhere, my toughts are on the vss, but I can't verify it as long as I don't use a code reader.
It started slowly then became really worse, I wasn't able to go past 20 kph. When in park I wasn't able to rev it. Even if I gave it throttle slowly it woudn't go higher than 2500 rpm. No CEL, didn't have acces to a code reader to get the live data feed.
My first guess was lack of fuel/fuel pump going out, but it was backfiring when given too much throttle. Shutting it down then restarting it (starts fine) clears the issue for an undetermined period of time. It must be a faulty sensor somewhere, my toughts are on the vss, but I can't verify it as long as I don't use a code reader.
#36
#38
Here is some more ideas from the web on forcing the ECU to recognize the IACV:
Fully open is 0 steps, fully closed is 180 steps. IIRC base idle is 88 steps. A scanner is not needed. In most cases the ECU will adapt very quickly. If it doesn't it's a simple matter of teaching it by the following procedure.
Key on, plug in IAC
Key off unplug IAC
key on, plug in IAC
Start engine and run at 2000rpm for 30 seconds.
You have to wait until you hear the relay drop out between steps since the IAC position with the ignition off is fully closed (180 steps).
Fully open is 0 steps, fully closed is 180 steps. IIRC base idle is 88 steps. A scanner is not needed. In most cases the ECU will adapt very quickly. If it doesn't it's a simple matter of teaching it by the following procedure.
Key on, plug in IAC
Key off unplug IAC
key on, plug in IAC
Start engine and run at 2000rpm for 30 seconds.
You have to wait until you hear the relay drop out between steps since the IAC position with the ignition off is fully closed (180 steps).
#39
#40
My other option besides the VSS and the ECU is the alarm spider.
Savannah, I tried that procedure several times without any success.
ArmyRover, when I shut it off, it cleared the issue. This makes me think it should be an electronics issue rather than mechanical.