Rich Idle tuning

Hey All,

I took a Turbonator GLHS Stage 2 tune and made some adjustments for my ride. So far I am getting things dialed in but I am having an issue with warm idle. Let me give you some details on my setup:

1985 Omni GLH converted to GLHS T2
Ported E1 head
+20 injectors
88 Roller Cam

I have the tune scaled for 42lbs injectors, but I made some adjustments for WOT to get me in the 11.5 range (was too rich before). When I start the car cold (cold now is 75 degrees), it appears to be fine. Wideband shows AFR in an acceptable range 14.0's. Once I start driving the car, my idle AFR goes to 12.0-12.5. At cruise the AFR is perfect 14.5-14.7. If I put the car in neutral and coast, my AFR will be in the 12.0-12.5 range. If I stop at a red light, it is the same 12.0-12.5 range. What tuning parameter should I change to change this behavior?

I was able to figure this out. I had a leaky Baro solenoid.

That’s great. A nice simple fix.

I am resurrecting this thread because I thought I fixed the issue, but it seems that I still have it. To recap, here is the issue I have:

Current Setup
1985 Omni GLH converted to GLHS T2 (Running GLHS electronics)
Ported E1 head
+20 injectors
88 Roller Cam
Confirmed 52psi fuel pressure at 0psi
a555 3.50 FD

Behavior
When I start the car cold and let it warm up (3-5 min), it appears to be fine. Wideband shows AFR in an acceptable range 14.2-14.7. However, once I start driving the car, my idle AFR goes to 12.0-12.5. At cruise, the AFR is perfect 14.5-14.7. If I put the car in neutral and coast, my AFR will be in the 12.0-12.5 range. If I stop at a red light, it is the same 12.0-12.5 range. This behavior happens on a stock MP Stage 2 computer or a socketed computer using MP Tune with a Turbonator GLHS cal.


Any suggestions on what could cause this behavior? The odd thing is the issue seems to happen once the car moves. As I mentioned, if I start the car cold and don't move it, the AFR will start rich (which is expected because it is cold) and then eventually settle down in the 14s. Once I start driving it is when the behavior starts. Could this be a SDS sensor issue? Are there any tuning parameters in MPTUNE for fuel and SDS? I have an ostrich hooked up now and I can easily update the tune on the fly to try something. Appreciate the help.

Have you tried taking fuel out of the part throttle table in vacuum? Have you tuned the pumping efficiency table? The condition sounds about right when you're running the +20s with the MP GLHS cal.

I don't know that much development was ever done on the GLHS turbonator cals. I'm not sure if a table was missed for the group scaling? Perhaps someone could speak to that.

Have you thought about switching to 87 electronics? I think there is a much better base of support for those.

Quote:

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Originally Posted by cordes

Have you tried taking fuel out of the part throttle table in vacuum? Have you tuned the pumping efficiency table? The condition sounds about right when you're running the +20s with the MP GLHS cal.

I don't know that much development was ever done on the GLHS turbonator cals. I'm not sure if a table was missed for the group scaling? Perhaps someone could speak to that.

Have you thought about switching to 87 electronics? I think there is a much better base of support for those.

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I have tried the pumping efficiency table but I could never get the car to run right once I messed with it. I can try messing with the part throttle in vacuum and see how it responds, but I feel like something is feeding bad information to the computer to make it behave this way. I may convert to 87 electronics, but for now I am trying to see if I can get this to work.