MayDay!! - Hard Accel Killed Idle

[Ωhm]

Good to see INJ PW ≈5.4ms at idle with warm engine. Idle RPM’s still seems to be hunting (up/down) for smooth idle of ≈750RPM’s. Few things to think about:
-slow to respond IAC. REM can show you what it wants the ECU to do, but is IAC moving quickly enough?
-slow to respond O2S. LEAN/RICH should switch just short of the speed of light.
-leaky/faulty injector(s). When ST drops to 90, ECU will take fuel away. ECU thinks RICH.
-try a known good ECU, if possible. I know haha.

 

Looks like you can leave EGR connected unless you can say, yes EGR is the problem.

[AnotherOldJeepGuy]

1 hour ago, Ωhm said:

Looks like you can leave EGR connected unless you can say, yes EGR is the problem

No idea where I can get a test known good ECU.

 

If I leave EGR connected I have to deal with stalling at 3%-5% or at least trying to, did you mean to say leave EGR disconnected?  No stalling with EGR disconnected.

[Ωhm]

EGR should have nothing to do with engine idle. I wonder if given time and EGR connected, could ECU learn its way out of this problem. You've done a lot.

[Ωhm]

10 hours ago, AnotherOldJeepGuy said:

At 3%-5% Throttle and with RPMs dropped due to EGR activation:

 

Keep in mind when EGR solenoid is ON no vacuum is allowed to flow and the EGR valve is OFF.

[AnotherOldJeepGuy]

11 hours ago, Ωhm said:

EGR should have nothing to do with engine idle. I wonder if given time and EGR connected, could ECU learn its way out of this problem. You've done a lot.

OK I'll try leaving the EGR valve hose connected for a bit and cross my fingers an ECU education is what is needed at this point.  Just for clarity, the problem is at 3%-5% throttle, no problem at idle (0% Throttle).

 

11 hours ago, Ωhm said:

Keep in mind when EGR solenoid is ON no vacuum is allowed to flow and the EGR valve is OFF.

In my words, EGR "activated" means the EGR valve shaft/rod is no longer at rest and has moved outward from the engine.  I do have terminology issues sometimes with my limited STMD 

[AnotherOldJeepGuy]

Just in case, I looked out there for availability of a new EGR valve.  Didn't find it at Auto Zone, O'Reilly, Napa, Rock Auto, Summit, Advance or EBay.  (Although everyone seems to have the gasket).

[Eagle_SX4]

I don't fully understand the EGR system. But it might be good to know at what instances the solenoid is providing vacuum to the EGR valve to open it. Do you have a vacuum gauge that you can hook up to EGR solenoid? 

[AnotherOldJeepGuy]

1 hour ago, Eagle_SX4 said:

I don't fully understand the EGR system. But it might be good to know at what instances the solenoid is providing vacuum to the EGR valve to open it. Do you have a vacuum gauge that you can hook up to EGR solenoid? 

So I don't have that, but I have essentially replaced that in this instance with a flashlight and vision by watching the EGR ROD, and seeing that there is a 1:1 correlation between the 3%-5%throttle stutter and the moment the rod moves.

[AnotherOldJeepGuy]

Took a 13 mile run around the area, no highway driving so lots of start stop.  I guess it was a K-12 education.  Kindergarten through Grade School was pretty rough.  Couple stalls, a few more coaxing to not stall, questionable acceleration.  Junior High was also troublesome but maybe a bit better, transitional years I suppose.  But by the time I progressed through High School things did seem to be improving, and by graduation I was able to come to a stop and start up again without it wanting to stall.  So fingers crossed.  I'm gonna head out for a higher education run in a bit and see how that goes, perhaps I might even get on the local highway if we make it to Grad School.