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so, Ive had an issue with my ze since i dropped it in about 9 months ago. I can seem to get it to idle anywhere near 700RPM, usually its at about 1200RPM and randomly, it will idle at 700RPM until i drive it to the next light and then it will idle at whatever it likes. The other issue is that when the motor is fully warm or after Ive given it a bit of s---, it rev's up and down between 1000RPM and about 1500 RPM. As soon as it hits 1500RPM it drops to 800RPM and repeats itself. The only way i can get it to idle is if i press the gas peddle multiple time, but as soon as i stop, i returns to searching for idle.

Here's what I've tried:

Different throttle-body (including TPS sensor)
looked for vacuum leaks
changed CAI (in-case of possible leaks)
played with the idler screw ( i can screw it completely closed and the car does the same thing or will rev higher if i un-screw it)

Specs:
96 MX-3 GS OBDII
KLZE w/ K31 Cams
CAI
Pacesetters
2.5" SS mandrel bent
no ignition mods
Throttle body coolant bypassed

engine codes :
EGR codes associated with no EGR equipment hooked up
sometimes MAP / BARO code but very rarely

Video:



any help would be greatly appreciated

soooo have you cleared your codes with the code reader? Have you tried resetting the ecu?

Try all these steps
http://www.mx-3.com/manuals/photo.php?f ... F2-104.gif
http://www.mx-3.com/manuals/photo.php?f ... F2-152.gif
http://www.mx-3.com/manuals/photo.php?f ... F2-153.gif

this might sound silly, but have you tried making sure your battery cables were tight? mine did the same thing when i bought it and bugged the hell outta me. then one day i went to disconnect the cable and it wasnt tightened at all. ran perfectly after that. ive also heard around here that due to the location of some coolant temp sensor if your coolant is low or has air bubbles it can make the idle go wacky as well.

thanks for all the replies guys, ill be taking a look into those possibilities today or so and ill left you know of the outcome

RS_OBD'oh_2 wrote:soooo have you cleared your codes with the code reader? Have you tried resetting the ecu?

and yes, i have cleared all my codes every time Ive had any codes other then the EGR codes

Ok, you said you played with the idle screw. You have to have TEN and Grd jumped to adjust that. It usually starts at around 3 turns out. Reset that first and set it so the engine idles at 650 rpm then when out of diag mode it'll jump to 700. Turn the screw in until the engine idle starts to die then turn the screw out till it just reaches 650 but not past that or your engine could run sluggish. I also assume your running a KL02 VAF right.

I just noticed this, (Throttle body coolant bypassed) why did you bypass this? We need this in Canada, it gets cold here and the engine needs a higher idle during warm up. Reconnect this and see what happens.

I agree with dan. The coolant lines through the TB control what is called the BAC valve, which is a thermostat for air. cold = extra air passage, hot = thermostat style valve closes extra air passage.

Since you've screwed with the idle screw, and the IAC valve has its limits, the car is probably pissed at you because its so far out of whack it actually can't correct your shady mechanic skills.

spray all your vacuum lines, TB gasket and IM gaskets with some brake clean and see if the rpm goes up?

well, finally got to messing around with the ze last night.

I jumped TEN and GND together and set the idler screw and it idled at about 750RPM for quite some time, but after my 10 min commute home, it was still doing the same bouncing revs thing.

I didn't get a chance to re-connect the coolant lines to the throttle body but the car does idle properly more often at least

As for the vacuum leak possibility, i went through all the lines again thoroughly and still came up with nothing .

I'm going to try a JE50 VAF (not sure why i have a KL02 on there in the first place) and set my TPS properly and see what that does for me.

Possibly a different ECU as well since i sometimes get a MAP / BARO Circuit malfunction, which im told is an ecu problem :S