5mt stall revisited.

[TomsSVX]

There is only one way to wire it. Did some thinking and after some serious talking about it at reading I realize why we are stalling. Ok, first when the automatic has the TC locked it will engine brake like an MT. If a person were to toss the car into neutral while engine braking liek this, the car should stall or come close to it(thanks Bill). This means that there is a cut in fuel or air to the engine that is electronically controlled on engine braking. Once the auto pops the lock on the TC(when brakes are activated) engine will no longer brake and the ECU will turn all things back to normal. The mt does not send any kind of signal to the engine so it runs by ECU function alone. In this fact when we engine brake(downshift) it is telling the ECU to cut fuel and/or air to the engine. Now since our clutches immediately allow the trans to free fromt he engine(unlike a TC) it will let the RPM's fall too quickly. SO what we need is a way to only be able to keep the ecu thinking it is constantly in gear except when we want to start it. any ideas please post em up but right now I gotta run.

Tom

[rmjjensen]

don't ground any wires to the ECU and it'll always be in drive, clutch in or out. You don't need any sort of trick to start the car, just wire in the NSS that connects the starter wire from the ignition to the starter solenoid. That's how mine is currently set up ....it rarely stalls, but that's rarely not never.

I still think using the engine torque control during shifts would help.

[TomsSVX]

it needs to be wired to drive all the time unless you are starting it. The best way to do this is to wire it so that when the shifter is actually in neutral the car reads it as such. The "in Gear" switch inside the trans is no help because it leaves an open circuit when it is in Neutral where we would need it to be closed. Subafreak recommended a relay to make this work but since I am not familiar with the functions of relays so maybe someone else could chime in and elaborate

Tom

[rmjjensen]

you can do it with a relay, I would recommend a solid state one or a transistor to convert the switch in the trans. I did this in my experiment to eliminate stall.

But you don't need to touch the ECU to get the car to start. All you need to do is turn the motor quick enough ...literally, and the ECU will see this by position sensors (crank/camshaft), pulse the injectors, give the motor fuel/air and viola ...she's running. There's no need to give the ECU an electrical start signal ....just the starter solenoid to turn the motor. I still have NOTHING connected to my ECU to trick the car into starting. Don't believe me? Put the key in the ignition, turn it to the ON position, go and jump +12V to the starter motor and watch the car start without touching the ECU. Same as when you push start a car via dumping the clutch.

Now, what I do recommend is using that switch in the Manual Trans to avoid a high idle. Via relay you can:

pin 85 -> +12V
pin 86 -> Switch off the NSS inside the trans to read ground ONLY when in gear
pin 30 -> Ground
pin 87a -> to the ECU nuetral pin input
pin 87 -> (No Connection)

Problem is with a standard relay it's ON everytime the car is in gear ....which is 90% of the time which means extra wear on the relay. Hence a simple transistor based design would be much better.

Happy hunting for a no stall solution ...it's quite a pain.

[TomsSVX]

But that doesn't allow cruise to shut off when you want it to. Basically I only want my car to think I am in neutral when the trans is in neutral. I can also wire the bottom switch on the clutch to work along with the trans to kick off cruise control. I don't have CC but for those that want to keep it that solution wouldn't work

Tom

[rmjjensen]

Use the relay AND the switch on the clutch. The clutch switch ONLY goes to the cruise control module as a kill just for cruise. The NSS on the trans would go to the ECU.

I can get you a diagram of the cruise module and tell you were exactly you should hook it up.

I don't use my cruise control either. It's annoying as it seems to function ON or OFF and doesn't smoothly engage the throttle.

[mbtoloczko]

Tom, have you talked to LAN to find out if he can make any mods to the ECU programming?

[TomsSVX]

yeah, but he said he could only control fuel timing. He said there was too much encrypting to get to the actual data that controls the IAC

Tom

[Dessertrunner]

I have been thinking about this issue and wonder if the stalling is caused by the fact that the airbypass value is trying to reduce the high idle by pulling it back, example is when you rev the engine the idle drops to 1,500-2,000 then slowly comes back to 700. I think the car has a idle problem and the ECU is working its butt off trying to get the revs down which it does but has done it in such a way that that the car has no power left. To support this arguement when I pull away in low rev's (below 2,500) the ECU is going crazy trying to get the engine to run right and you can feel the car surging etc. I feel for half my cars life even with the Auto it had high idel problems. We need to find out why the cars run rough at low revs and how to get then to go straight to 700 RPM when you lift the foot from the throtle. My plan if I get time before I go away is to disconnect and block each of the hoses supply air after the throtle body including the ECG and find out which is the problem, If you block the air bypass hose the car won't idle but it revs and is far more responisive to the peddle.
So in simple terms fix idle then see if the stall goes away I am not convinced that special relay etc or grounding ECU is the answer as my idle was screwed before I changed the gearbox.
Tony

[Matthewmongan]

i have the same problem with my auto that desertrunner is explaining. its alsmost as if it missfires from 2500-3000 when the tq converter is locked.

[Beav]

If that's the case why not cut the brake signal to the ECU and feed IGN + on the ckt to the ECU? (don't want the brake lights always 'ON') Or wire the inhibitor harness to show manual 2 to the ECU - no lockup in 1 & 2.

[oab_au]

This problem of the manual stalling has been a real bug. So I decided to start from
scratch, and look at the problem.

The Idle speed is controlled by the ECU by adjusting the Idle air By-pass solenoid valve.
This valve is an electromagnetic solenoid that is operated by a Duty Cycle, the same as
the rest of the gear box, power steering, Air conditioning, EGR, and Canister Purge
control solenoids. The valve is held in the open position by a spring, and the ECU applies
a Duty Cycle to pull the valve up to reduce the amount of air that is passed by the closed
throttle, to control the idle rpm.

The By-pass valve here.


The good book tells us that the ECU uses inputs from; Throttle sensor, No. 1&2 crank
sensors, water temp sensor, Park/Neutral switches and the Vehicle speed sensor 2.
The way the ECU controls the Idle speed, is to read the engine rpm from the crank angle
sensors, compare this against the rpm that is written in the “look up tables”. The ECU
then sends the necessary Duty Cycle to the By-pass solenoid to bring the idle rpm, in line
with the “written” rpm.

To see what goes wrong with idle when the manual is fitted, we must first understand
how the by-pass valve operates with the auto fitted. The prime input to control the valve
is the throttle sensor, as when the ‘closed throttle signal’ is received by the ECU, the
engine rpm will have to be controlled by the by-pass valve. Input from the Water temp
sensor, will cause a higher rpm, as will the Air con, and the Park signal. These speed
increases are produced by the ECU, so they are set value speeds, so that the ECU can
increase the speed, before turning on the AC or selecting a gear. This prevents the sudden
drop in speed, that has to be recovered by opening the idle valve a bit more. Other
happenings that would cause a drop in the idle speed, like the alternator, power steering,
and the brake booster, would be covered by the feedback loop of ‘ check rpm, check
tables, send correction to idle valve’.

Looking at how it would have to operate on the road. When you first start the engine the
valve would be open, as the engine runs the valve would start closing, till the ‘tabled’
speed was achieved. You pull it into gear, the valve opens the ‘tabled’ amount, to
maintain the speed. You push the throttle to go, the closed throttle signal has gone, so
there is no need for the idle valve to control the engine speed, it is allowed to return to the
fully open position. The same happens when it is idling and you just rev it up a bit, as
soon as the ‘closed throttle’ is lost, the valve is returned to full open, you let it the
throttle come back to idle, the closed throttle signal returns and the valve is pulled back
up, to bring the last few hundred rpm down to a smooth idle. That’s why the rpm never
drops down quickly to the idle speed, its always gently ‘lowered down’ to idle.

To prevent the idle valve from operating every time you back off for a corner, the vehicle
speed sensor, signals that the car is in gear and moving, so there is no need to respond to
the closed throttle signal, while it is where, the valve just stays in the fully open position.

With such a fool proof system, why does it stall? When the auto is removed, the inhibitor
switch is removed also, so the Park/Neutral signal is not sent to the ECU. With neither
connected, the ECU assumes that the transmission is it gear, so it sends the valve the
speed up signal, the result is a high idle. If we ground the N, the ECU assumes that the
box is it Neutral and sets a normal idle speed, but tends to stall when slowing or stopping.

What I think is happening, when the Neutral pin is grounded the idle is good but when
you are driving, and close the throttle the ECU is trying to control the idle speed down to
the ‘tabled’ speed, as it has been told “its in Neutral”. So it keeps closing the By-pass
valve, till it is fully closed. When we push the clutch in to stop, the engine speed now
drops like a stone, the valve was fully closed and has to open, to save the stall, too
slow,,,,,,,,, engine stalls.

What we have to do, is to simulate the auto procedure as far as possible. We have to tell
the ECU that the car is it gear and moving, so that it won’t keep trying to set the idle
speed every time the throttle is closed. If it is in gear and moving the presence of the
signal from the vehicle speed sensor, will prevent the By-pass valve from closing and it
will be fully open when we push the clutch in to stop. This will have the engine running
at high idle speed, dropping as the By-pass valve closes to set the idle speed.

This will stop the stall as it does when neither the P or N are not connected, but we are
left with the high idle speed that the ECU sets when the auto is in gear. I think what is
needed is a ground signal from the gear box, to the Park pin, when it is in Neutral and a
ground signal from the clutch switch when it is pushed, . With this arrangement, when we
start the car, it is in Park, we push the clutch down, pull it into gear, still idles OK, let the
clutch out and the Park pin is now open circuit, the ECU thinks it is in gear so the idle
By-pass valve is left in the open position, ready to control the idle speed as soon as the
clutch is pushed in to stop, and the idle speed settles down to a normal idle.

To connect it up, a relay with normally open contacts is needed, and can be connected
like this.


Alternatively a change over relay with two poles could be used, with one pole switching
the ground to the park pin, and the other switching the ground to the Cruse Control to turn
it off, when park is selected, by pushing the clutch in.

What do you reckon, do the job OK,?

Harvey.

[shotgunslade]

Harvey:

I believe your analysis is consistent with a phenomenon that I have observed in my 5MT. If I am at fairly high rpm's in 2nd gear say 4500 or so and I lift off the throttle completely, initially, my car slows uniformly under engine braking. At some point, however, something changes, and the car lurches very slightly, and the drag from the engine becomes slightly greater. I believe that if I were to push down the clutch pedal immediately after that that lurch the car would stall. If I were to push down the clutch before that lurch, the car won't stall. Don't know exactly where this point is, but is probably around 2500 rpm. On the other hand, if I blip the throttle slightly immediately after I push down the clutch, even if it is at a relatively low rpm, the car doesn't stall.

[TomsSVX]

I have been playing with my stall issue lately. Thinking like an Automatic I have been driving like it was one. When the TC locks up in an Auto it will downshift the trans until about 2.5k or when the brakes are applied in which case the TC freewheels. This is the function the ECU was made to work with. Since many of us with standard transmissions are downshifting and revmatching our downshifts, the ECU has no freaking idea of whats going on and is using the IAC to cut all air from the engine to lower the RPM's. So, in short, the best way to avoid the 5mt stall is to drive like it's and auto. In 6th or 5th gear when you reach about 2500 rpm while downshifting put the trans in neutral and let off the clutch pedal and just use the brakes. This way, it should not stall. In short, unless you are not comming to a full stop, don't downshift. I know it will eat brakes a little faster but it may be worth it for some people, I mean starters are more than brakes

Tom

[oab_au]

Originally Posted by shotgunslade

Harvey:

I believe your analysis is consistent with a phenomenon that I have observed in my 5MT. If I am at fairly high rpm's in 2nd gear say 4500 or so and I lift off the throttle completely, initially, my car slows uniformly under engine braking. At some point, however, something changes, and the car lurches very slightly, and the drag from the engine becomes slightly greater. I believe that if I were to push down the clutch pedal immediately after that that lurch the car would stall. If I were to push down the clutch before that lurch, the car won't stall. Don't know exactly where this point is, but is probably around 2500 rpm. On the other hand, if I blip the throttle slightly immediately after I push down the clutch, even if it is at a relatively low rpm, the car doesn't stall.

How is yours connected, grounded Neutral pin? or no connection?

Harvey.