Old Gas

[Bitsyncmaster]

I've been playing with my idle and find it is pretty good for about 1 or 2 minuets during cold engine but after that it gets a little ruff (not really a consistent hunt) but not as stable. I go closed loop lambda after 15 seconds after start (I have wide band) so it's not that causing the problem. I set the FV duty cycle on the warm engine (it was a little off) but that did not help. I tried another ignition ECU, that did not help. I have the recommended plugs installed from DMCH.

I'm pretty sure my gas is more than 6 months old. Am thinking that is problem. Have any of you noticed old gas gives poor idle?

[NightFlyer]

I've been playing with my idle and find it is pretty good for about 1 or 2 minuets during cold engine but after that it gets a little ruff (not really a consistent hunt) but not as stable. I go closed loop lambda after 15 seconds after start (I have wide band) so it's not that causing the problem. I set the FV duty cycle on the warm engine (it was a little off) but that did not help. I tried another ignition ECU, that did not help. I have the recommended plugs installed from DMCH.

I'm pretty sure my gas is more than 6 months old. Am thinking that is problem. Have any of you noticed old gas gives poor idle?

Happens when it gets warm, but it isn't the lambda system.

Did you check for the absence of vacuum at the WUR/CPR when it's warm - could be a failed thermal switch...

[Bitsyncmaster]

Happens when it gets warm, but it isn't the lambda system.

Did you check for the absence of vacuum at the WUR/CPR when it's warm - could be a failed thermal switch...

I will check that but I'm controlling the solenoid with my ECU. Was thinking maybe the ignition coil also but I don't have a spare one to try.

[NightFlyer]

I will check that but I'm controlling the solenoid with my ECU. Was thinking maybe the ignition coil also but I don't have a spare one to try.

WUR/CPR receives it's vacuum directly from the thermal switch. If the switch is failing to close off vacuum feed to the WUR/CPR once warm, then you'll be getting vacuum at the WUR/CPR when you otherwise shouldn't be, thus indicating a faulty thermal switch. This is a completely independent operation of the thermal switch that advances the ignition timing, which is also controlled by an intermediary solenoid and triggered by the idle micro-switch.

[Jonathan]

I'm pretty sure my gas is more than 6 months old. Am thinking that is problem. Have any of you noticed old gas gives poor idle?

Yes. And it's the easiest thing for you to test. Fill up the tank with fresh gas and go from there.

[David T]

If the idle gets better once it is warmed up then it could be the WUR aka Control Pressure Regulator.

[Rich_NYS]

I've been playing with my idle and find it is pretty good for about 1 or 2 minuets during cold engine but after that it gets a little ruff (not really a consistent hunt) but not as stable.

This sounds a lot like what my car does, but I don't think there's any old gas left in it. I haven't spent any time looking into it, but it looks like now will be a good time.

Another symptom I think is related to mine: if I listen carefully while maintaining a steady higher idle, I hear it get rough at a regular interval...almost sounds like a cylinder dropping, but nowhere near as obvious of a sound. It's kinda hard to explain, if I get a chance I'll try to get a recording and we can compare to see if we have the same issue.

[dn010]

Any smoke or fuel smell in the exhaust?

[Bitsyncmaster]

Any smoke or fuel smell in the exhaust?

No smoke or fuel smell. I thinking it's an ignition problem but will check the vacuum to the WUR and distributor tonight.

[Bitsyncmaster]

Was going to hook up a vacuum gauge on the WUR and saw the solenoid connector was pulled off.:hihi:

Put the connector back on an idle now stays at my 850 RPM (that's where I set it) from cold engine to fans on with maybe a 50 RPM "hunt". I have said before that I wanted to solder wires onto that solenoid and then a new locking 2 pin connector on the cable. I have to put that change up on my to do list.

By the way, my software change looks amazing for deceleration. It just locks right on 850 RPM when I take my foot off the accelerator. Now I need to decide if I make this new software the standard software. I'm also running at the maximum delay. I will try to road test it this weekend.

[dn010]

Glad it was a simple fix!

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[Rich_NYS]

Glad you found it Dave, maybe mine will be as easy!

I'll start a new thread with the videos of my rough idle. Please take a look and see if your symptom was similar.