idle issue...halp

[turbowop]

Over the last two months I've done an absolute sh*t-ton of maintenance on 503:

New snow tires
All new brakes...rotors, pads, and two new rear calipers
One new OE e-brake cable
Three new OE u-joints
Fixed ECU coolant temp sensor wiring that was boogered up and giving readings of the coolant minus about 20 degrees, hence the ECU never thinking the motor was fully warmed and effing with my fuel mileage. Also replaced the coolant sensor with a new OE unit
Blocked off the FIAV
New OE cam seals
New OE timing belt
New NGK BPR6es plugs
New OE valve cover gasket
...and a fresh oil change to boot

The car was running awesome, except for when at full throttle. I've been running a 2gMaf/550cc injector combo for awhile now using just an AFC to tune with. It gets the job done when cruising around but sucks for when stomping the throttle at full bore. Too rich, too much timing, fuel cut, yada yada. I've made several 3hr trips and a few trips to the local mountain since the snow has started falling as well. Zero issues. Starts fine in below freezing weather even with the FIAV blocked off too. Without me having to give it any gas as well. I assume the ISC picks up a bit where the FIAV left off. No boost leaks and the car ran amazing for a couple weeks until I swapped in this ECU/chip combo:

A local buddy of mine bought a GVR4 roller from a guy in Idaho that can burn Eprom chips. I don't know him so my buddy works as the middle man to get me a chip. So for a cheap $10 he burned me a chip that compensates for my Maf and injector combo, gets rid of fuel cut, has octane reset, and phantom knock code. I had to install the chip into 1051's ECU since I haven't had the ECU in 503 socketed yet. I figure this is fine since 1051 is sitting in the garage for winter now anyway. The chip works awesome, really awesome. The car pulls hard and cruises around great, however...

The damn car wants to stall when coming to a stop now, and sometimes when starting the car if it's already warm. It also seems to idle a bit rougher. This has me wondering if it's the ECU, or the Eprom chip. 1051 has had idle issues, but I've always attributed that to the ultra light twin disk setup it has. 1051 seems fine otherwise though. And it's hard to tell if the idle is super smooth when the car has poly motor mounts, 272's, a Maftpro speed density setup, and that damn clutch setup as well, yanno? The 1051 ECU had the caps changed by Keydiver a decade ago, when he did the socketing. The board still looks pretty good to me. I guess I can just have Terry socket the 503 ECU and swap it when I get it to see if that's the issue, but I figured I'd ask you guys yer opinions.

What do you guys think? Can an Eprom chip cause such an issue only at idle, yet work fine otherwise? Or, can the ECU have similar symptoms? /ubbthreads/images/graemlins/dunno.gif

 

[turbowop]

Soooo...

I borrowed a buddy's ECU and threw it in the car with my new chip. Car idles and drives fine. Put mine back in, car will barely run without me feathering the throttle, but seems to cruise and go wide open throttle just fine. The good ECU out of 503 is on its way to Terry for a socket job. I guess I'll be sending him the ECU out of 1051 to replace one or more ISC drivers as well. And all this time I thought 1051 would sometimes die at stopsigns and lights because of the light twin-disk clutch assembly. Fawk.

I swear, these cars have made me a 4G63 idle control expert over the last 14 years. /ubbthreads/images/graemlins/crazy.gif

 

[Barnes]

Man, that's weird. I'm curious what is wrong with it.

 

[turbowop]

It had leaky caps waaaay back in the day, but I sent Jeff O. the ECU back in like '01 to replace them, clean the board and install a socket. Maybe some of the acid crept up under some ISC traces, or one just went bad? I dunno.

 

[WaRrIoRs16]

I hate ISC drivers. Both my cars had the cap leak on the trace and blew the drivers. I replaced them on 796 and it worked out fine, but I must not have done a good job on 628 because the ISC does not have control over the idle.

 

[turbowop]

This is beginning to frustrate the everliving sh*t out of me. /ubbthreads/images/graemlins/banghead.gif

So it turns out that swapping the ECU's and getting different results was just intermittent. Also, I sent Terry the ECU I thought had issues and he said everything checked out fine so all my ECU's are in great shape.

So here's what I've done now:

1. Multiple boost leak tests...all is good

2. Tried three different ISC motors... same results

3. Tried three different ECU's... same results

4. Set the BISS according to the factory manual, double and triple checked it... Good to go

5. Tried swapping the old chip back in... same results

6. Logged the various sensors in the MAF... all good

7. Logged the TPS... no issues

8. Checked alternator voltage... normal both while driving and while idling (all heat shields still in place as well)

9. Checked fuel pressure regulator for leaks... looks fine

10. Took a 200 mile round trip down the freeway... fuel trims, O2 sensor, coolant temps, blah blah blah...everything is normal

None of this started until the night I swapped in the new eprom chip. So I looked over all my wiring thinking I bumped something. Everything looks good. When I installed the SAFC, I twisted all wires, soldered them nicely, and even shrink wrapped them all.

The car acts like I'm venting the goddamn BOV to atmosphere, but I'm obviously not. I also checked the recirc hose and it's fine as well. If I come home from the grocery store and realize I forgot something ten minutes later, and try to restart the car for a return trip, the car will start, sometimes stumble, sometimes die. This problem is more prevalent when the car is warm I guess. When coming to a stop after disengaging the clutch, it won't usually die, but the RPM's will drop to like 500 or lower and then catch itself...sometimes. Sometimes it stumbles worse than others. It's really intermittent. And even then, once it catches itself, it will eventually idle perfect.

This is f***ing irritating as hell. I'm no spring chicken to these piles of sh*t, but I can't figure this out. /ubbthreads/images/graemlins/frown.gif

*edit* additional data to add: I haven't run a fuel pressure solenoid in years, so I doubt that has anything to do with it. And it's also winter here, so temps have been around the freezing level throughout the daytime.

 

[desant78]

Not sure if this helps but it seems you have addressed everything that has to do with the ignition system except for the CAS and coil pack. I had real funky issues once with a jeep running kind of odd (ended up being the crank-angle-sensor), and a gvr4 that was starting intermittently, with no ryhme or reason. Ended up being the coil pack for me.

Figured I would throw out some ideas, good luck.

 

[DR1665]

Karma? /ubbthreads/images/graemlins/devil.gif

Have you been logging things when the car is actively shitting the bed? Just because everything looks nominal while you're driving around doesn't mean it looks the same when the symptoms arise. My own idle issue was TPS-related, but I never would have suspected it had I not seen TPS @100% at idle and then flipping the f*** out right before the engine died.

And since you mention it's worse when the engine is warm (which was the case with mine as well), what's the condition of the harness at the water neck there with all the sensors in it? Shot-in-the-dark, but a warm wire is more flexible, making it more subject to vibration, which could result in an intermittent signal somewhere.

Good luck.

 

[turbowop]

Karma for what? /ubbthreads/images/graemlins/rofl.gif

I don't think it's a wiring issue. Reason being, I think this doesn't happen when cold because the ECU is still in warm up mode. RPM's still want to drop down farther than they should when disengaging the clutch at stops while it's warming up, just not as bad.

I suppose I could just start swapping CAS's, TPS's, and possibly coil packs to see if anything changes.

 

[beaner]

Crankwalk? /ubbthreads/images/graemlins/devil.gif

When you boost leak test, are you capping the system off at the turbo or where the mas is? I had a torn coupler on my intake pipe and it gave me similar symptoms.

 

[turbowop]

I'm pulling the intake off and testing from the turbo inlet on. The couplers looked okay all the times I pulled it off to do the boost leak tests but I guess that's something I can give a closer look to.

 

[cheekychimp]

Mark,

I'm shooting in the dark here a bit BUT a while ago now Jeff helped me burn two chips for the 2.3 litre as controls, whilst I was trying to sort out issues running DSMLink. One thing I specifically remember him telling me about the car stalling when coming to a stop was (a) the throttle closed switch and (b) timing being possible culprits.

I'm no expert in these areas, but Steve P recently also told me that if your throttle closed switch isn't grounded and or working the ISC won't know to activate when you take your foot off the throttle coming to a stop. Timing seems less likely to be an issue in your case because you are on the stock 2.0 litre. In my case Jeff thought the less aggressive timing on the 2.3 chip might be causing the car to stumble when coming to a halt and suggested I play around and advance timing a degree or two.

Like I said, I'm no expert and I'm guessing but I looked through your post and it doesn't appear that you have checked either the throttle closed switch or the CAS/timing so I just thought I'd throw these out there.

It is frustrating. I've got similar but not identical low speed idle issues and those two are intermittent which makes it a PITA to diagnose.

Paul.

 

[turbowop]

Thanks for the reply, Paul.

I actually did test the idle switch (closed throttle switch) and it works great. It's a newer one that I installed a few months ago. The previous one went bad and was actually causing the engine to idle at around 1100-1200rpm when fully stopped. Replacing the switch fixed that and I rechecked it when this new idle problem reared its ugly head.

I ruled out timing since I haven't messed with the CAS in over a year, but now I'm gonna steal the one off of 1051 just to see if that changes anything.

Hopefully I can get this sorted eventually. I drove the car up to the ski area on Friday and Saturday and it did great other than the random stalling/stumbling at stops when warm. Once it catches itself finally, it idles great. Super annoying issue.

 

[grocery_getter]

I bet you're bypassing air internally.

 

[turbowop]

So tonight I changed some stuff...

I traded a local buddy my RC550's/chip/cash for his RC750's/chip. I did the install tonight and while I had the fuel rail off I swapped in a spare TPS I had laying around. After talking to Andre on the phone tonight we decided this could be the culprit.

I went out on a test drive and the car still had the idle issue. Brought it home and remembered that this chip has a 900rpm idle programmed into it. So I grounded out the appropriate connectors and readjusted the BISS. Took the car back out for another drive and idle feels great. Coming to a stop I can push in the clutch and watch the idle drop to 900rpm, see it rise to about 1100rpm while coasting/braking then once at a full stop it settles right back down to 900rpm again. I drove around for about 5mins and came to a lot of stops to see if it was consistent and it seemed pretty damn good. Time will tell I guess. /ubbthreads/images/graemlins/dunno.gif

 

[turbowop]

So the car is still doing this sh*t. I think the chip with the 900rpm idle masked the problem a bit, because it was better, but not like it should be. I installed a different chip with a normal 800 idle tonight and it's stalling again like before. I also tried a different CAS, did another boost leak test and cleaned the little MAF diode with a q-tip and some MAF cleaner. Then I pulled the f***ing throttle body off, took all the electronics off of it, and cleaned the everliving sh*t out of it with throttle body cleaner. I cleaned every nook and cranny then wiped it down, blew it off with air and reassembled it and reinstalled it. Then I readjusted everything to the same specs that it was before. BISS, TPS, yadda yadda. Felt better on the initial test drive, but it still wants to die at some stops or at least stumble before it catches itself. The only thing I haven't changed is the coil pack or transistor, but these don't seem like items that would cause an issue only when the clutch is disengaged.

So to recap:

3 different ECU's tried.
3 different ISC's tried.
2 different CAS's tried.
4 different eprom chips tried.
2 different TPS's tried.
2 different sets of injectors.
6 boost leak tests.
Idle switch is working.
BISS is set correctly.
Maf is working and clean.
Throttle body is clean.
EGR valve is blocked off and block off plate is still intact.
Alternator is charging the battery at 14.4v.
FIAV is blocked off and coolant lines removed.
Base timing is set at 5 degrees.
Fuel trims are within normal range.
I even tried a different instrument cluster to see if the reed switch was causing this. FAWK!

This leaves what?

FPR?
Fuel pump?
Fuel filter?
Coil pack?
Transistor?

None of these items seem like they would cause a stumble issue only when coming to stops or during warm starts after the car has sat for 10mins or so. I would think those items would cause problems all over the place. Since the car seems to put down good power at WOT, I assumed all that was okay.

I even made a crappy video last night showing the problem. Although it doesn't stall in the video, it does stumble when coming to stops. Tonight it was stalling.

Click for Youtube video.

 

[Nate]

Put the FIAV back in and run coolant lines to it.

 

[grocery_getter]

^^^^^^^ Quoting grocery_getter:
I bet you're bypassing air internally.

 

[turbowop]

It worked fine for months with it like that. And 1051 is blocked off the same way, with no issues. I blocked it off due to having the infamous idle surge until the car was fully warmed up. I also checked my blockoff while I had the throttle body apart. It's all intact. There is no way air is bypassing through the FIAV.

You find me a 20 year old FIAV that's good, and I'll have no issue reinstalling it.

 

[desant78]

Black magic? It seems you have almost done everything associated with fuel. Good luck!