HIGH IDLE, only in gear, fine in neutral

[bonga_msp]

Very weird problem.

Car idles fine in neutral.

With the clutch fully disengaged, putting the car into gear (any gear even reverse) will cause the IDLE to go up to about 1500-2000rpm and stay there, moving it back to neutral will cause it to go back down to 800rpm.

Ingear: High idle
Neutral: Normal idle

Any Ideas?

Thanks

[Stormtrooper77]

Hmm, you have bigger problems if you can put the car into gear with the clutch disengaged.

[Maxx Mazda]

I think he meant with the tranny disengaged?

[1moreMPH]

ah you know what he meant!
im not going to be much help here, but im interested -- subbing for an answer.

[BradC]

Very weird problem.

Car idles fine in neutral.

With the clutch fully disengaged, putting the car into gear (any gear even reverse) will cause the IDLE to go up to about 1500-2000rpm and stay there, moving it back to neutral will cause it to go back down to 800rpm.

Ingear: High idle
Neutral: Normal idle

Any Ideas?

Thanks

So, if your car is running...

Clutch in - tranny in neutral - normal
Clutch in - tranny in gear - high

correct?

Just slipping it into gear will jump your idle?

does clutch in or clutch out in N have any difference?

[Gasological]

Hrmm. I had my idle jump to 2k rpm after I added hardpipes and BOV, but that resolved itself within minutes. I figured it was the ECU learning the equipment.

[JRTritsch]

Perhaps a vac hose being pulled by the shifter? Weird.

Clutch-in, clutch out in neutral makes no difference?

[crashkelly]

Key ? = do you have mods?

[bonga_msp]

So, if your car is running...

Clutch in - tranny in neutral - normal
Clutch in - tranny in gear - high

correct?

Just slipping it into gear will jump your idle?

does clutch in or clutch out in N have any difference?

Yes, that's correct.
Clutch "in" or "out" makes no difference in neutral, idle is normal.

[bonga_msp]

Key ? = do you have mods?

Nothing new in the last year (this just started happening a week ago):
but for interests sake here are the mods
Injen Intake
Relocated MAF
BOV
Hardpipes
SMIC
3" Exhaust

I've taken apart all the intercooler piping and inspected MAF, all seem to be in good condition, no vacuum or boost leaks that i can find.

[xelderx]

There are two harness plugs that go into the tranny. Make sure they are both plugged in properly. If the one that tells the car when it's in nuetral is not functioning properly it will cause the ECU to do funny things with the idle. I had that happen after a motor swap where that was the one thing I forgot to plug in. Took about an hour to figure that one out.

[bonga_msp]

There are two harness plugs that go into the tranny. Make sure they are both plugged in properly. If the one that tells the car when it's in nuetral is not functioning properly it will cause the ECU to do funny things with the idle. I had that happen after a motor swap where that was the one thing I forgot to plug in. Took about an hour to figure that one out.

good thought, but it is definetly something being triggered once the Neutral Switch sensor is triggered, I need to find out what that switch talks to.

[bonga_msp]

Update:

I hooked the computer up to the car today, It looks like the Fuel System status is going from a Closed Loop (normal idle) to an Open Loop (Power enrichment) when the high idle is kicking in, almost like there is a load it's trying to compensate for, the weird thing is the "Calculated Load" doesn't really change when this is happening.

My next test will be to disable the Neutral Switch and see if it still happens.

[bonga_msp]

Update again:

Disconnected the Neutral Switch and the Computer stays in an Open Loop regardless of the gear or neutral, which seems normal from the other posts ive seen about people forgetting to connect it, which in turn causes high RPMS and poor idling.

Hooked it back up and I get the same results as before, Normal idle in neutral, high idle in gear and computer goes into Open Loop.

[1moreMPH]

this is still so far beyond my comprehension....

[thingie12345]

I just started having this problem myself..... It all started after I removed my interior to dynamat my car. I know everything is hooked back up the same way, I documented my tear down with pictures. Any updates on what could be causing this?

[bonga_msp]

Sorry for the lenthy delay in replay, no I never did. I actually still have the problem which I just recently discovered again. It must have been in hiding recently. I just did a spring tuneup, while doign that I reset the ECU and it's showing up again.

If you tore it down make sure that you hooked up the neutral sensor. I konw if that is not hooked up you get something simular to my problem where it seems to permantely idle high. That's not my problem though.