ECMlink Resolved - So many changes at once, what brought the issues?

[rabenne]

I am simulating the front o2 from zt2 wideband. I feel like the idle surge is the first problem to deal with. I cant think of why open loop vs closed loop would affect the way the isc operates. For example at key on after battery reset, when it should extend, it shouldnt come into play? I may be missing something though, so after another boost leak test I will put it back together and see if it enters closed loop.

 

[91talonts1]

From the first log you posted (the only one I've had a chance to look at) it's trying to run in closed loop just fine. The fuel trim is adjusting as it revs up, before the ECU cuts fuel entirely.
And no after a battery reset the ISC movement test should work no matter what the ECU last saw. if the engine isn't running it wouldn't be in either loop anyway.

 

[rabenne]

From the first log you posted (the only one I've had a chance to look at) it's trying to run in closed loop just fine. The fuel trim is adjusting as it revs up, before the ECU cuts fuel entirely.
And no after a battery reset the ISC movement test should work no matter what the ECU last saw. if the engine isn't running it wouldn't be in either loop anyway.

This is what I thought. I am emailing with Dave Mertz and it looks like we are onto something. He suggested it may be operating backwards, and verified I can go ahead and put a scope on it to try to figure out what the ecu is actually commanding.

 

[91talonts1]

If anybody can help you with an ISC problem it's Dave. I don't know if you're on the link forums, but I posted a thread there just the other week about some coasting idle problems I was experiencing. Dave and Kevin Jewer helped me get it figured out right away.

 

[rabenne]

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Not sure if the battery was disconnected before this was shot, but it looks like mine, minus the cycling of the key after initial on and off. This was presented as properly operating in the description, so I have to wonder if the idlesurge wiki is just misleading? I havent found a video of a dsm isc extending at first key on at all. Maybe I am chasing my tail here?

 

[91talonts1]

Try doing what he does in the video to see if yours behaves the same. Any logs since you adjusted the TPS? I know you said you had some where the ISCpos was moving.

 

[rabenne]

I wasnt looking very closely, I think the log I saw it move in was when I turned the engine off. Im not sure. I have not ran it today. I just spend another 2 hrs searching for boost leaks. I was not able to find anything, and wanted to share my results. In the past I have always had a faster bleed down of pressure than I do on this current setup. I know that's got to be a good thing, and I must not have any severe boost leaks. But I would love for someone to confirm that the speed a which it bleeds down pressure after removing the hose is as good as it seems to me. Let me know what you guys think,

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[rabenne]

Here is a log from just now. If I switch the box for ground timing the idle quits surging... it is still high, but not surging. TPS volts is good now. ISC position not pegged at 0


Just noticed my tps adjustment is still a tiny bit off. The throttle plate is close all the way. I have the stop backed all the way out and I can physically feel that the throttle is fully closed, with no extra tension on the cable.

 

[rabenne]

Ok so I wont be able to scope the ISC until tuesday. So I threw the old TB back on. No surprise, not even a bit of idle surge. Using just the biss I can adjust the idle wherever I want it. I even had it running at 500 rpms while playing around with it.

To me this condemns the rebuilt TB. Either something is indeed wrong with the ISC operation, or the FIAV is not closing, or both.

The FIAV adjuster is stuck, and I cant verify my ecu is trying to control the ISC correctly, so I guess I am abandoning the idea of having stock idle controls for now. If the scope signals look good I might revisit the idea.

Thanks for your help guys. I guess I should have started off with swapping the TB back out, but I wanted to actually diagnose the problem instead of just swap it out. You guys got me started in the right direction

 

[rabenne]

I want to compare a log of someone's idle surge that was caused by boost leaks. I would guess that since the air is entering the engine unmetered their mafraw would be lower than what mine was reading. I have pretty much verfied that one of the two valves on the bottom of the TB was responsible for letting in all the extra air, which tells me that it was metered on its way into the system, it simply was too much getting past the plate.

any thoughts?

 

[91talonts1]

This is very possible I have had a fiav with an internal crack that leaked before. You still have it fully functioning?
Are you swapping ISCs or you have 2?
I once used an o ring on the ISC that wasn't the right one, it was much thicker than it was supposed to be. This kept the ISC from seating all the way, and it could never fully shut.

 

[rabenne]

No 2nd isc to try. Car running excellent in garage using my old tb with the bottom completely deleted.

 

[91talonts1]

Make sure the oring on the ISC is the right one. Or maybe all you need is an fiav bypass plate.

 

[rabenne]

I really would prefer to keep fiav functionality. I live in NY and cold starts need those extra rpms or it never warms up. I have ran without one for many years but I always sit there with my foot on the throttle until its over 180 before driving anyway. I even used to run a modified carburetor choke cable rigged to pull the throttle open to get the rpms up without my foot on it. I just threaded the choke handle and twisted an adjusting nut until idle stayed at 1800-2000 rpm, then backed it off before driving.

Its a shame there isnt a "fake FIAV functionality" check box in dsmlink. If you keep the ISC, I would think the ECU could raise the idle until warmed up.

 

[91talonts1]

While there is no "fake fiav" function, there is a table in the direct access tab called FastIdleMTISCPos. I haven't played with it myself, but from my understanding of it, it lets you make adjustments to what the ECU is telling the ISC to do based on coolant temp. With a properly working ISC this would probably do what you need it to.

The ISC already helps on its own with fast idling on cold starts even without the fiav, you can see this in that table by the higher iscpos commands at colder temps. If you were having those problems with the ISC blocked off they may go away once you have it working.

It gets colder where you live but I used to have my whole bottom half blocked off and had to hold my foot on the gas till it was warm as well. With the ISC it idles above 1200 rpm until it's at least 160 or so. I'm running ethanol so I had to add some fuel to the colder temps in the coolanttempfueladj tab to prevent stalling, other than that its had no problem.

 

[rabenne]

the TB on the car now has the bottom half blocked, so I will probably turn my block off plate into an fiav bypass plate and try again at getting the ISC working.

That is awesome about the FastIdleMTISCPos! thanks for pointing that out! I will try playing with that when I get the ISC straightened out.

 

[rabenne]

This ISC has about 5-10 degrees (crude estimate) of free play when playing with it off the car. I am going to buy a new one. Who makes them? I have some part numbers for them but I want a nice quality unit.


I can get the Intermotor unit locally and I get about 50% off on it, but I have no idea if people are getting good results out of them.

The ISC may not be the problem technically, but with this worn out old style unit its only a matter of time anyway, no idea why I bought it looking back...

 

[91talonts1]

I got mine from throttlebodys.com when I had my tb rebuilt, I'm not sure what kind it is. I do know the oem one is somewhere between $3-400 and I didn't pay that much for this one. I used a BWD one from O'reilly's once and it failed in a way that took the ecu out with it after about a year, but I suppose that could happen with any of them.

Might be worth trying it out again though with the fiav blocked off. If it was leaking air that could've been the whole problem.

 

[rabenne]

Agreed. But that leaves me with the question, what is the ISC supposed to do after a reset? Snowboarder's video shows basically the same thing as mine, and another guy has a video on there of his doing what mine does after he repaired the wiring to it (not sure if he was saying that it was working properly or not, description is brief). But what I have not seen is a video of the ISC extending fully then retracting partilly at first key on after a battery reset. This is what I was expecting to see based on theinformation in the idlesurge wiki. I wonder if the idlesurge wiki has it backwards and this isc is actually doing what it is supposed to? Who feels like pulling their working ISC for a stranger? please dont! I would feel guilty if you had a leak afterwards!

 

[rabenne]

Ok well I am done trusting the wiki as gospel as so many suggest. I think they might just have the expected ISC operation described incorrectly. My ISC still does the same thing at reset, but after welding the FIAV port in the bottom housing I have a rock solid car again. I posted a log I took just a few minutes ago. I set the base idle and it looks like everything is rock solid 950rpm idle, 28-30 isc position, I got the airflow per rev to .27 (because Im a 2.3L, correct no?), and I brought the combFT into line by pulling out about 60 ms of deadtime.

Before and after logs make it hard to believe that the small fiav port was the root of the problem. My ISCpos was pegged to zero because the FIAV was apparently way out of adjustment and never closing. I tried to turn the valve in but it became plastic dust. Welding just the one port on the bottom housing restricts all air getting in through the BISS, the balance port, and the ISC. Now that Im not overrunning it's physical abilities, the ISC seems to work beautifully.

So if its working backwards at key on but running fine to control the car who cares... but I am challenging the information in the idlesurge wiki regarding what the ISC should do at key on, after a battery reset. Unless someone can produce a video of the "expected" results.

 

[livedsm4g63]

Good to hear you figured it out.

 

[rabenne]

Thanks to everyone for your help. Hopefully nobody else is silly enough to think their used TB will have a perfectly functioning, 20+ year old thermostatic valve. I looked at the direct access tables for ISC postion based on coolant temp and now I could care less FIAV functionality is gone. I can work with ISC control only. I'm waiting for my engine to cool now so I can try some adjustments out.