Z3 idle issues and lumpy running and sudden rev loss...

[phb10186]

Happy new year all... its been a while, just been very busy at work etc etc, and dont really use the Z much anymore (well about once a week is a lot these days). So as opposed to 250 miles a week, I do perhaps 20 if I'm lucky... I've been spending my time getting my Direct Access bike test out the way... just got myself a Honda SH300i with ABS, really smart piece of kit - everyone should have one!

Back to the Z... the fault is basically lumpy idling pretty much all the time... with sudden loss of revs at idle, normally after selecting neutral after the revs have been at normal driving speeds.

Typical situations:

Revs drop when dipping the clutch to change from 3rd to 2nd to turn a corner. Same situation when parking and manouvering...

Seems to be worse on declining roads??? might just be in my head though.

Also the revs never seem to match when the 1st to 2nd change comes round, and I always get the jerk, the revs are always on the low side rather than too high.

Also pulling away is never smooth, as the natural gas to biting point balance seems to provide too little revs/ fuel... thats the best way I can describe it.

Cold starts seem OK, but the revs are all over the place, and when cold puck up can be terrible, and it kangaroos sometimes while in gear, so I have to give it more gas to compensate....

so it sounds like mixture, airbox sensor, idle control valve.... I really don't know what it could be. Will do a search too for more info.

In the old days it was always the idle control valve.... not too sure of the fuel setup on the newer cars.

All the faults are definately far worse i the cold weather, but I get the random rev dropping even when the car is at full operating temperature.

OK, just tested it a bit, if I get the car up to operating temperature, and then blip the throttle with some gas, when the pedal is released the revs fall past normal idle speed to about 2-300 and then rise again to normal idle again, it never used to do this... does this help?

Thanks for the help....

Ben

[phb10186]

After performing a search and looking through for a while. I think the coil pack's and sensors would be a good place to start.

I don't suppose anyone has a known working spare coil pack or any of the intake/ exhaust/ crank sensors that they could lend me to test out; I would be extremely grateful?

'98 Dual VANOS 2.8i manual.

PM me if anyone can help out. Thanks

-B

[tiger823]

Someone else on here has a similar problem and I suggest you check your vacum system for leaks/cracks in tubing and connectors.

[estocks]

Cheapest job first. Clean the ICV. Search for my photo guide.