Hanging/high idle manual tranny auto computer

[shr3dd3r 09]

I have been struggling with this problem for the better part of three months since I finished my v8 swap into my 2000 Ranger, and at this point I am grasping at straws for a solution. I used a v8, wiring harness, and auto computer from a 2000 mountaineer but I swapped in an m5r2 and bw4406 from an f-150.

I have had the pcm tuned several times and the driveability has improved dramatically. The truck drives great, but every time I step on the clutch or shift into neutral while coasting the rpms spike to 2,000, and when I come to a complete stop they drop to 1,500 and stay there. The idle speed is set at 850.

The only time it idles at 850 is when I first start it, but as soon as I start moving it behaves as I described above. It also seems like it's searching for idle speed even when it is idling in the 850 range. Below 1000 rpms it idles pretty rough but smooths out quickly at 1000. No vacuum leaks and the iac is functioning correctly.

With the iac unplugged it wants to die when i first start it but as soon as i start driving it will idle at 1500 just like before, but it won't spike up to 2000. The timing is completely electronic and for some reason the computer is not agreeing with its own settings.

My tuner said it is most likely just missing the load from the torque converter, and that he can't do anything more to it to help it. But I have a hard time swallowing that. I am tired of driving around in the city and burning my brakes up because it wants to pull itself 45 mph in 3rd gear with no gas. Aside from that it runs great and drives great on the highway with no mishaps.

All auto tranny codes/cel's have been programmed out. There has to be a way to get it to act like it has a manual transmission attached to it. Surely it's not impossible.

Can anyone direct me to a tuner that has done this in the past or can any of you help me with this? I am at the end of my rope.

 

[shr3dd3r 09]

Verified proper engine vacuum today. It is steady. There has to be somebody out there that can program my computer to work with a manual transmission. I know it's been done before, but I haven't found anyone that can do it right yet. I'd look into it myself if I had the software and a scan tool. Please help!

 

[kimcrwbr1]

I`m just thinking it has alot to do with the neutral safety switch does the increase in rpm happen when you shift it out of neutral. Ideally you want the rpm to rise when your letting off the clutch. have you tried manually pushing the throttle butterfly back when it is stuck on high idle. Is there any movement up and down on the throttle butterfly shaft maybe a sticky throttle cable or vacuum leak from butterfly shaft. Erratic like you say makes me think its a mechanical problem somewhere. Maybe the computer is seeing the clutch switch and saying WTF is this IDK. GL

 

[shr3dd3r 09]

I`m just thinking it has alot to do with the neutral safety switch does the increase in rpm happen when you shift it out of neutral. Ideally you want the rpm to rise when your letting off the clutch. have you tried manually pushing the throttle butterfly back when it is stuck on high idle. Is there any movement up and down on the throttle butterfly shaft maybe a sticky throttle cable or vacuum leak from butterfly shaft. Erratic like you say makes me think its a mechanical problem somewhere. Maybe the computer is seeing the clutch switch and saying WTF is this IDK. GL

Throttle cable isn't sticking, and no vacuum leaks. The idle speed will not drop below 1500 when driving no matter what I do. If i just start it and let it sit it will idle at 850 for a while and then jump to about 1100 or so and it will idle like that all day.

As soon as I drive it I start having the surge to 2000 and then drop to 1500 when stopped. Once I shift into neutral the rpms will sit at 2000 whether the clutch is depressed or not. The neutral safety switch is wired in right because I can't even start it unless the clutch is in, even if it is already in neutral.

 

[shr3dd3r 09]

This problem is absolutely driving me insane.

 

[shr3dd3r 09]

rpm increase when shifting out of neutral? I assume you mean sitting still? No it does not affect the idle. Everyone I have talked to seems to think it is solely a computer issue. Man I wish they made a 5.0 mountaineer with a manual tranny, I'd just have it flashed with a manual tune.

 

[shr3dd3r 09]

Replaced the IAC with a new one. Big surprise... it didn't affect anything. Here's what I have done in case this gives anyone any clues.

1. Replaced IAC.
2. Removed EGR from tune.
3. All plugs and wires are brand new.
4. Idle screw is set so that the TPS voltage is at 0.96V at closed throttle.
5. Automatic transmission functions and CEL's deleted from tune.
6. Idle speed is set at 850 in the tune.
7. Engine holds steady vacuum at idle.

Truck will start and idle rough at 850 then increase to 1200 and idle smoothly.

When driving the rpms spike to 2000 with clutch depressed or in neutral and fall to 1500 only when at a complete stop. Always a very slow return to idle when revving. After several minutes of idling the rpms will steady out at 1200.

Here is what is even more strange.... I took the old IAC off and rplaced it with a small piece of sheet metal to completely seal off the passageways. It's harder to start like this, but after driving for a bit it will STILL idle at 1500 even at closed throttle but it won't spike up to 2000 with the clutch depressed. How is that even possible if it has no vacuum leak? I'm beginning to think it is possessed. Any clues? Anyone?

 

[alwaysFlOoReD]

I don't know enough about these systems to give a definite answer, but I feel it has something to do with the computer not getting the signals it is expecting from the various trans sensors.
Good luck,

Richard

 

[shr3dd3r 09]

That's what I don't understand. According to the tuner all of those signals were deleted. Unless some were missed. In any case I need to find someone else who can take a look at the tune that is on it and see what they say. Any ideas who I could talk to?

 

[dangerranger83]

Maybe stuff being deleted wasn't the fix for the problem, maybe instead the stuff needed a bypass such as being fooled it was getting the correct signals.

Sent from my A500 using Tapatalk 2

 

[shr3dd3r 09]

Maybe stuff being deleted wasn't the fix for the problem, maybe instead the stuff needed a bypass such as being fooled it was getting the correct signals.

Sent from my A500 using Tapatalk 2

I was wondering that myself. I sent a long email describing my problem in detail to SCT technical support, since I have one of their chips installed in it. We'll see if they can assist.

I also stopped by a Ford dealership and asked their senior technician about it. He said if all the auto transmission functions have been removed and it is still having the hanging idle problem, then it is most likely the IAC valve.

So I replaced it and nothing changed. I am wondering now if the IAC transfer function needs to be adjusted in the tune.

Also the last time I drove it with a scanner plugged in, it said it was in first gear all the time and not neutral like I thought. But I can still start it with the clutch pedal depressed. I don't know if thinking it's in first gear is messing with the idle speed or not. Again I'm just grasping at straws...

 

[dangerranger83]

It will mess with it. It thinks it has to elevate the idle due to being in gear when it's not. All in all, it's not right still, needs to think it's in neutral.

Sent from my rooted SPH-D710 using Tapatalk 2

 

[1mean02hd]

Your PCM obviously still thinks there's 4R70W behind it. The tell tale was that when you have the scanner plugged in, it thinks it's always in 1st gear in the auto trans. I think you really need to find someone else to tune out the transmission parameters from the PCM. Obviously "deleting" trans functions didn't do it. It's still looking for inputs from the transmission.

 

[Teddyzee]

IAC unplugged, what it your idle speed?
Just double checking to see if the base idle has ever been set (with the screw), I don't recall what you did before.
It is normal for the idle to go quite high, but it should settle after a few seconds once you come to a stop.
I believe I mentioned before that I deleted the IAC in my Mustang (4.6, OBDII) and set the idle at 650 rpm with the screw, as the high idle drove me nuts.

 

[shr3dd3r 09]

IAC unplugged, what it your idle speed?
Just double checking to see if the base idle has ever been set (with the screw), I don't recall what you did before.
It is normal for the idle to go quite high, but it should settle after a few seconds once you come to a stop.
I believe I mentioned before that I deleted the IAC in my Mustang (4.6, OBDII) and set the idle at 650 rpm with the screw, as the high idle drove me nuts.

If I unplug the IAC while it's running nothing will happen and it will continue idling at 1500 rpms. With it unplugged it won't spike up to 2000 when I hit the clutch, but will instead settle at 1500. If I unplug it and then start it up it will idle rough at about 500 before slowly picking up to about 1000. If I start driving it, after a bit it will idle at 1500 from then on and will never drop below that.