Here we go. If i cold start a car it revs to 1.5k and then drops to 950 after 30min driving or so when in neutral at trafic lights it revs at 1.5k again and if i disconect iacv yellow plug and plug it back revs drop back to 950 for 30mins. Replaced iacv twice any ideas why ?

Could be the associated loom.

 

Use a suitable diagnostic tool to identify exactly what is happening when the issue occurs. Easiest & quickest way to solve a problem.

 

I take it the valve is adjusted correctly and not by ear.

When you unplug the aicv what do the revs drop to at idle?

When you unplug the aicv what do the revs drop to at idle?

 

950 it used to be auto that's why they are so high i guess

Could be the associated loom.

 

Use a suitable diagnostic tool to identify exactly what is happening when the issue occurs. Easiest & quickest way to solve a problem.

 

I take it the valve is adjusted correctly and not by ear.

 

It was adjusted on consult

The idle should be set without the aicv plug in using the idle screw and should be about 650rpm ie below what the ecu needs to see, then plug the plug back in and the ecu will take over the idle at about 750, but before you do that you need to make sure the TPS is at 0.44v closed throttle.

 

Once you have the revs settled, check with consult the aicv percentage, which should be around 15% at idle, adjusted with the idle screw.

If you have trouble getting the percentage or struggling with revs bouncing, then check your maf and on to check for air leaks.

 

Have you got the neutral switch wire connected to the ecu pin since you did the manual conversion?

Edited August 31, 201411 yr by groover

I never set it that way on a Zed, the less the loom is disturbed around that area the better for me.

 

By setting it initially via diagnostics, you just monitor how quickly the AAC % reaches the desired 15%. This way, you simply set it so it just drops to 15% after manually increasing the revs and letting them settle. The whole 650rpm on the tacho is probably just to ensure the AAC% will be >15% once the plug is reconnected. Kind of pointless really, but perfectly understandable in the days when diagnostic machines were main dealer only. Naturally, all this needs to be done when the car is up to temp and with all ancillaries switched off. The main thing is that the AAC just hits 15% at the desired idle RPM. If the rate of decrease is too high, the valve is too far open. Takes all of 3 minutes to get it spot-on and no messing around with connectors & clips :D

 

Couple of side notes:

AAC minimum on my own car is 17%, it never reaches 15% anymore.

For Auto-Manual converted cars, I always use a manual configuration file when mapping so as to avoid the +10° timing increase (idle & in gear condition) when the neutral switch has not been wired in. Idle RPM will increase if you're still using an Auto ECU and no neutral switch.

I have owned 2 Zeds, and driven another 2, and all 4 have always idled similar to this!

 

Current car is much better than the others but very occasionally when the car is idling it jumps to 1500 before coming back down again, can go for weeks without doing it.