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.

[AnotherOldJeepGuy]

Just finished test drive #2, about 30mi round trip.  Followed the reset procedure a couple times.  The 3%-5% throttle stumble did not happen.  No stalling when I come to a stop.  Jumped on highway the last 10 or so and ran along a 65 for a few miles, didn't push it over that, I don't normally anyway.  All went well so I am cautiously optimistic now that maybe things are back to normal, knocking consistently and strongly on wood here.  At a stop light in Drive, Brakes on with AC on the idle may be a little less that completely smooth but not much.  And at this point I may be a bit hyper-sensitive and maybe it's really no different that it was before.  New mounts are on the to do list anyway since all of mine are still original and I'm sure that will smooth things out some also  It would not be a stretch to think that the maneuver incident that started all this took a toll on the mounts also.  Anyway a final relearn seems to have been the last step maybe.  Don't know what was actually learned, but as long as what was needed to be learned was learned, I'll take it.

[Ωhm]

RENIX 4.0L has no Closed Throttle (CT) switch unlike the 2.5L which does. This CT value is learned over time (40 or more key starts). I know TPS is set to ≈17% at CT, but that’s just a starting point. I’m with you, hope this does it for you. Take it.

[AnotherOldJeepGuy]

Three more days with successful trips, so far so good.  Can't really guess well how may key starts since I put the EGR hose back in place, probably not 40 yet, but maybe half?  

 

So another question to toss in the thread while the "Test it to 40" plan is in play.  What is the second connection used for that's to the right of where the REM connects?

[llhat]

[Ωhm]

 

[AnotherOldJeepGuy]

1 hour ago, llhat said:

Yikes!  With my computer glasses on high I can just barely make out those letters!  But good enough to squelch my curiosity.  

[MagicJames]

6 hours ago, AnotherOldJeepGuy said:

Three more days with successful trips, so far so good.  Can't really guess well how may key starts since I put the EGR hose back in place, probably not 40 yet, but maybe half?  

 

So another question to toss in the thread while the "Test it to 40" plan is in play.  What is the second connection used for that's to the right of where the REM connects?

I always thought the second connector was for ABS diagnostics 

[llhat]

11 hours ago, AnotherOldJeepGuy said:

Yikes!  With my computer glasses on high I can just barely make out those letters!  But good enough to squelch my curiosity.  

i believe a jpeg,  save to computer and enlarge..  I see OHM has posted a link also  thanks.

[AnotherOldJeepGuy]

Been over a week now and with crossed fingers knocking on wood, Jeep has not stalled after the relearning exercise documented in the last couple pages here.  including no more 3%-5% throttle stutter.  ACCEL seems smooth.  Been up to 65 a couple times without anything feeling unusual.  The only thing noticeable, to me anyway, is the idle in park, with brake on after DECEL to and waiting at a red light (AC on), is just a tiny bit less smooth that if I put it in park and/or turn off AC.  But this is very minor and as i noted earlier, I may just be a little hyper-sensitive right now.  I am tempted to install a new IAC just to see what happens, but I am not sure the $30 experiment is really worth doing, so still on the fence.  What I am planning to do today is to let it warm up from a cold start for a few minutes then capture a new full set of REM readings to see if anything has noticeably changed, and to capture a baseline just in case I need it in the future, then send back my loaner REM!

 

It's worth noting that my brakes are now working normally.  I can only assume that the reason they were not working (the assist that is) was that the vacuum was just too low during the times that the RPMs were very low.  I am not crazy with that explanation, but it's all I got.

 

Also worth noting cruise didn't start working with my vacuum improvements, oh well, I wasn't really expecting that.  If I get motivated enough to tackle that I will start a new conversation, this one needs to wind down!

[AnotherOldJeepGuy]

OK a bit more confusion for the group to explain.  To set the stage, roughly a week ago (6/28), the status was there was no stalling if I disabled the EGR valve by disconnecting the control vacuum hose and capped it off.  With the hose connected I would see the EGR move at a 3%-5% throttle and the engine would either stall or come close.  The thought was an ECU learning cycle was maybe needed.  So I connected the hose back to re-enable the EGR, and coaxed the jeep through the 3%-5% zone for somewhere in the vicinity of 15 or so miles, and "magically" the issue faded and they went away and has been gone since.  Note that EGR "open" that I was observing was a EGR plunger/rod movement of around 1/4 inch which lead to the stall situation.

 

Now for the confusion, or at least the question.

 

My assumption was that the educated ECU was "doing something" to allow the engine to run correctly with the EGR opening the observed 1/4" at the 3%-5% throttle.  But perhaps the education is not that straight forward.

 

Today as mentioned earlier I decided to capture a "final" collection of REM data.  I got to the EGR Gas Recirculation reading.  I have previously captured this reading was "OFF" at idle, and "ON" with throttle (the 1/4" rod movement).  Today I saw the same thing at idle, no movement.  Then I moved the throttle 3%-5% expecting to again see the 1/4" rod movement, but now with no stall because of the ECU being educated.  But what I saw instead was no EGR movement.  So, no surprise it is not stalling, the rod movement that caused the stalling, isn't there.  But previous input here on the forum was that the EGR is expected to move on throttle.

 

So my confusion is, is the EGR operation now correct (that is, it appropriately isn't moving at 3%-5% throttle), and is what the ECU "learned" was to not move the EGR (or more correctly stated to disable the EGR movement) at this point?  OR INSTEAD, am I just lucky it isn't moving at the moment, with the concern being it will start to move again and I am back to stalling as soon as my luck changes?

 

A final piece of related data, if I crank the throttle further I can get the EGR rod to move, but instead of the 1/4" movement I used to see at 3%-5% throttle, I now see about a 1/16" movement.

 

I realize answering this question might take a lot more writing than the amount I put in here trying to clearly ask the question.  Perhaps a shorter more direct approach is to ask, how much is the EGR supposed to move and when, and is this a constant or a variable distance?

[Gojira94]

Before, I was surprised the EGR was responding in Park just off idle, but there were a lot of other factors in question that needed to be addressed first. EGR should be operating in a transient part throttle state, in gear, car moving. I think what you see now is normal EGR operation. EGR valves are very simple mechanical devices. The parts on cars with EFI, that tell them what to do and when, sometimes more complicated. 

[AnotherOldJeepGuy]

Sometimes I think it's all too complicated to me .  But since it's running pretty well I'll go with yep .

 

I've added the "final" REM data points to the earlier ones in the attached file.  As best I can tell not too much really changed, but I did notice what looks like might be notable changes in EGR, IAC, ST and LT.  But I don't really know how to judge if the final numbers really say anything is better as far as readings go, but I captured them in GREEN throughout the attached file.

REM Gauge Readouts Engine 0705.pdf