infamous 5MT low idle stall - Page 8

shotgunslade · #**106** 01-24-2006, 06:38 PM

Tom:

Here it is: HLY-11-4

I'm reading all this about how the switch that is made when the clutch is depressed is supposed to tell the ECU that the phantom 4EAT is in neutral, thus preventing stall, and I'm thinking that my neutral is hard-wired, and it is still stalling.

TomsSVX · #**107** 01-24-2006, 06:41 PM

I know, thats why I feel regaurdless of your wiring, the engine will still stall

Tom

longassname · #**108** 01-24-2006, 07:19 PM

I'm going to unsubscribe from this one. Good luck guys.

TomsSVX · #**109** 01-24-2006, 07:27 PM

listen, just being practical. Read into it and over engineer a solution all you want but in the long run it comes down to air being there to burn or not. If there is no air to burn, what good is anything else?? Now rmjjenson was onto something with the A/C being on but not running the compressor. I think that the IAC opens further and the fuel is bumped to raise idle. What we need is the same amount of fuel but a little more air. The Dash pot should cure this stalling problem by allowing the idle to settle slowly and keeping enough air in the engine for it to run.

Tom

Phast SVX · #**110** 01-24-2006, 11:26 PM

I checked tonight, and have my setup wired as lan has described. I have never experienced any stalling. I have a legacy 19lb flywheel. I dont see why we wouldnt all be haviing this problem..it must be something small

phil

#**111** 01-26-2006, 04:38 PM

I've never had a stalling problem with my 5mt. But Mine always idles at around 1000-1100 rpm. Acceleration is sluggish untill it hits 2000rpm then it feels like a turbo kicking in or a shot of nitrous(but I think having no cats is the reason.) I'm also only getting about 17mpg. And my cruise control has never worked since having the manual transmission.

svxcuseme · #**112** 01-27-2006, 07:23 AM

See above ------^

svxcuseme · #**113** 01-27-2006, 07:49 AM

I have occasional stalls since the swap. But I had occasional stalls before as well. I think mine may be related to a dirty manifold, IAC, and throttle plates. I'll let you know after cleaning this weekend.

Agree with Tom about the air issue. Did'nt want to say anything because you guys have been working on the SVX's much longer then me. A simple & cheap way to let more air in is to adjust the throttle cable to open the throttle plates ever so slightly. Opps! apparently this does'nt prove so effective,

Quote:

i've even tried to adjust the idle at the engine with the throttle cable and still no avail

. I don't see why not though. I've done this with smashing success in my other scoobies.

Edit: Top Clutch switch is wired into NSS, so ECU is aware of Neutral when Clutch pressed. 2002 WRX 5mt with stock flywheel.

rmjjensen · #**114** 02-24-2006, 12:25 PM

It dawned on my a little bit ago and I'm curious:

Has anyone tried wiring the Engine Torque Control signal of the ECU to one of the clutch switches so that the ECU cuts back during shifts? I know it cuts 3 cylinders, or reduces timing, or both....BUT ...if the engine is disconnected from the drivetrain it should still be able to free-rev perfectly fine so you can shift properly at redline ...

maybe ..who knows.

So has anyone tried this? Maybe when the ECU is in its torque control mode the engine won't stall (more control)?

ideas? I might try this but I'd have to wait til next week.

mbtoloczko · #**115** 02-24-2006, 01:38 PM

Here's what I wrote on the torque control algorithm a few years ago:

-------
... Got home this evening and wired a switch between 5 V and the torque control pin. Driving down the road and toggling between open (unreferenced) and 5 V made absolutely no difference in power. Next, I put the switch between the torque control pin and ground. This is where it got interesting. As long as the throttle position was less than about 75%, there was no difference in engine performance between grounded and ungrounded torque control pin. Above about 75% throttle position, the engine would dog dramatically when the torque control pin was grounded. I think it is indeed pulling back timing. ....
-------

rmjjensen · #**116** 02-24-2006, 01:43 PM

i read that and that makes sense for engine performance. ...but what about engine management? That's what we're trying to fix.

I'm talking about maybe the ECU controls the engine differently when the torque control signal goes low (ground). Obviously it does and will harm performance IF the engine is connected through the driveline to the wheels ...won't make power. This is obvious.

But, if the engine is disconnected from the driveline (clutch is pressed) maybe the engine wouldn't bog down at high rpms, and maybe the ECU will be controlling the engine (Idle air control valve) differently ONLY if the torque control signal is grounded.

So press the clutch in, engine isn't under a heavy load, engine torque control kicks in and smooths the engine RPMS, shift into gear, let off the clutch, engine torque control back to normal.

Hey - you never know.

mbtoloczko · #**117** 02-24-2006, 01:53 PM

I don't recall the torque control having any effect on idle (less than 75% throttle), but its been a while. If you want to check, its easy enough to test.

RisingPhoenix · #**118** 03-28-2018, 11:59 PM

Quote:

Originally Posted by Earthworm

My car would never stall as long as the A/C was running.

That's funny.. that would mean it's an vacuum issue that could be resolved with an in line reducer. The best place for one would be between the air box and manifold.
Which reminds me...when I bought my 92' SVX the air box was cracked from air hose to air hose and the Pressure valve had broken nipples I 'Frankensteined' 10 years ago with shoe goo and epoxy. (Along with cracked vacuum lines)
It's high time I check them again...that Pressure Valve I know is beyond shot...

RisingPhoenix · #**119** 03-29-2018, 06:13 AM

Quote:

Originally Posted by SVXer95

I still have the 4eat, but I have a similar issue that may or may not be related. Possibly if we figure out one it will be the answer for the other.

When I put my car in park with it idling, and move the selector toward reverse without using the brake or pushing the shift button, the car goes into a high idle. After letting go, it tries to stall. I understand why it would idle high while doing that, but I don't get why it tries to stall. Sometimes it stalls (very rarely) and most of the time the rpms just dip way down without stalling.

Perhaps the two are related and it is not a MT thing. Possibly a computer related issue like you thought.

Agree. The computer is telling the engine to run rich (excessive air) or run less (restricted air) or retard the air, thus, I think a reducer at the Air box might solve this.
Has anyone tried installing a resistor/transistor to any of the transmission wires?
A resistor just may be enough to give that proper 'balance' the computer needs between engine control and transmission. JMT

SoCoNoHa · #**120** 04-11-2018, 10:11 AM

I believe it's already been proven to be the Idle Air Control Valve (not sure if auxiliary or main) that can't open fast enough when the clutch is pushed in and the rpms start to fall. Someone in this forum removed their IACV but left it connected so as not to throw a code, then installed a non functioning valve in its place that always allowed enough air for idle. Boom. No more stalling.

We should be able to do the same thing, maybe with a cheap plumbing valve from home depot, just to make sure the engine doesn't choke when the throttle closes.

I'd love to tinker with this theory myself, but my 5mt swapped SVX just doesn't stall. No idea why but I'll take it