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Stalling when engine-braking to a stop (RESOLVED)

EfiniX

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Oct 18, 2012
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647
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portland, or
Well I thought I had this sorted out, but it's acting up again on a long road trip today....

When I'm coasting/engine-braking to a stop, as soon as I take my car out of gear, the RPM's drop very low. Sometimes it stalls. Sometimes it doesn't. Starts right back up when it dies.

New motor. New ISC. Clean and grounded throttle body. No leaks. Pretty much new and/or tested everything. I'm running DSMLink V3 and everything looks dialed in. even did the idle set procedure. ISC postion is right around -33 and when it's idling, it's solid.

One thing I have noticed is the the AvgAirVolPerRev spikes when it happens. Also, the A/F is remaining lean, only coming back up to stoic after (and if) the low idle recovers. I say remaining because as I'm engine-braking (in-gear/no throttle), the A/F goes completely lean as one would expect. It's almost like the A/F isn't catching up with the idle when I take the car out of gear.

I'm waiting for my registration to go through on the ECMTuning forums, but if anyone here has some suggestions, I'm all ears!

Thanks

engine-braking to a stop


losing my idle after pushing the clutch in

 
Last edited:

lancerglx

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Nov 7, 2012
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malta
Hi mate.. .
I got exactly the same problem....stallls when shifting into neutral when its at normal running temp.Changed the maf becayse i was getting code 25 (barometric pressure sensor)and all was fine for a month and a half.Now im back where i started..i allso changed thee TB
isc and all tps ips etc.
 

prove_it

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Check and make sure your idle switch is set-up right. In Link you can simulate it. I'd start there.
 

EfiniX

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portland, or
Yeah, I'm already stimulating idle switch operation and the tps is calibrated both for position and voltage
 

prove_it

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Are you MAF or SD? Do you have any throttle body leaks? Clutch properly adjusted>? Wierd question I know, but I had a car once that would stall when coasting to a stop like yours. Turned out the clutch was dragging enough to bog the engine and it couldn't idle.
 
Last edited:

slugsgomoo

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Oct 16, 2003
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Tacoma, WA
lightweight clutch/flywheel assembly? I know my 1g had that problem with stock idle and the fidanza for a bit. I can't remember what I had to do to alleviate it though since it was 5-6 years ago. :/
 

EfiniX

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portland, or
Quoting prove_it:
Are you MAF or SD? Do you have any throttle body leaks? Clutch properly adjusted>? Wierd question I know, but I had a car once that would stall when coasting to a stop like yours. Turned out the clutch was dragging enough to bog the engine and it couldn't idle.



MAF. No TB leaks (all sealed up by EHMotorsports when I got a new motor/head). In fact, it was doing the same damn thing with the old motor /ubbthreads/images/graemlins/smile.gif

New clutch. Doesn't feel like drag since it happens whether it's in or not (i can pump the clutch to get into neutral and then let up immediately with the same behavior). Normal flywheel.

Weird, right? /ubbthreads/images/graemlins/smile.gif
 

prove_it

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Is your MAF draw-through or blow-through? BOV recirc or vented? Have you tried adjusting the coasting fuel offset and airflow smoothing?
 

turbowop

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I had this issue with 503 and there is a long thread I started that explains all the issues and attempts to fix it. I got it somewhat better, but never totally fixed, then I sold the car. Super annoying. Just starts doing it one day out of the blue. Good luck.
 

prove_it

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Yea, suppose I should add that I think all 4G63's do it to some degree. I think the ISC drivers and ISC itself don't have the speed needed to "catch" the falling RPM's. 715 does it, but it's an ACT flywheel and SD. Never stalls but in hot weather she'll drop fairly low but recover.
 

EHmotorsports

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Beaverton
I am starting to wonder if the resistance in the harness is increasing just enough to cause this after long hot droves.
 

prove_it

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Hmm, good thinking. There are multiple wires for the ISC. On the other hand, the harness doesn't seem like it's near any major heat sources. I'd say it's not over 200 degrees while driving, but maybe that's just enough. Good theory to test anyway.

Evan, would you agree that it seems like mostly all 4g's do this to a degree?
 

strokin4dr

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I've a few cars over the years that have had the annoying idle issues.

Every car was completely remedied by:
-installing a rebuilt (new seals) throttlebody
-installing a clean/known good ISC
-blocking off the FIAV and coolant lines to it
-confirming that base ignition timing was set correctly
-properly setting the tps with dsmlink
-dialing in the MAS properly with dsmlink until airflow/fuel trims/etc were all in line.
You would be surprised how far off a 1g/2g/3g/evo mas can be even with the "correct" base settings that are on the dsmlink wiki.

My current vr4 did this when I first got it all put together and running (even with a rebuilt t/b) so I went through these steps and it never happened again. I have the idle set @ 800rpm and it stays there when idling. While cruising, when I push the clutch to prepare to stop, it falls to about 1200 rpms and slowly decreases to 800 by the time I stop.
I do have a fidenza flywheel btw and never noticed any unusual issues with it.

I was using a 2g MAS when I originally set this car up and got it working correctly. I did switched to SD a while back, not because of drivability/idle issues but because I had everything needed just sitting here. /ubbthreads/images/graemlins/grin.gif
Good luck!
-Ryan
 

EfiniX

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portland, or
Quoting EHmotorsports:
I am starting to wonder if the resistance in the harness is increasing just enough to cause this after long hot droves.



Well it is certainly more pronounced when I've been driving for a while. Just fine when for short drives.

Interesting theory...
 

turbowop

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I disagree that all do this to a degree. 503 had this problem and wasn't very modified compared to 1051. Even with a light clutch assembly and on SD, 1051 has zero issues with stalling, even with the AC running.
 

MellowVR4

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Jul 25, 2009
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Milwaukee, Wi
Is everything tight? like the hose from the valve cover to your intake? My car had this problem when the BOV wasn't recirc. Just a thought
 

prove_it

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Sioux Falls, SD
^ with that being said, check the PCV valve and hose. You could have a leak in there, or a bad valve perhaps.
 

EfiniX

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Oct 18, 2012
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portland, or
New PVC valve. tested for leaks after assembly by EHMotorsports. Persistent issue with the old motor (and it's many, many vac leaks) and the new motor (with it's no vac leaks).

BoV isn't recirculated. I even have a nice, shiny thread here about the dodge mod I just did.

This is all so strange...
 

belize1334

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Nov 18, 2003
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Location
Bozeman, MT
When coasting down but above about 10 mph the rpms should stay up at about 1200. There are three things that can prevent this. 1) Closed throttle switch. If it isn't registering then the rpms will drop down to regular idle speed. If you're simulating it then this shouldn't be an issue. 2) Air leak. Especially the brake booster, which has the potential to draw a massive leak from the IM. 3) VSS (vehicle speed sensor). This sits in the dash and sends pulses to the ECU. If it's broken or the wiring is shorted then the car acts as if it's sitting at rest so it doesn't keep the rpms up for you. Corollary symptoms - wipers won't change speed with speed-up of vehicle. Launch control will be stuck in stop mode if you have it set up that way. If ECMLink allows you to log vehicle speed I'd start there.
 
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