Bad tick over

[Anonymous]

My gf has got a 91 GSI, which still isn?t running right, I have fully serviced the engine new plugs leads etc, yet it still does not tick over right. When the car is cold, it ticks over fine but when its just starting to warm up, the revs slowly drop to about 500. But when it?s fully heated up its ok, but even if its hot, when you have the lights on the revs still drop slowly to 500. Any ideas anyone?

[Anonymous]

battery??!?! alternator? i dont really know!

[-flash.gif-]

[Anonymous]

If you've got Bosch injection could it be the water temperature sensor or idle control valve??
Don't really know myself but there's an interesting article in Total Vauxhall (09-01 with Dec. Burkes Nova in) all about various injection problems that should help you sort it.

[Anonymous]

The 3.1 doesn't have an idle control valve as such - well mine doesn't.

I have a similar problem with my GSi (posted before), although its only really a problem when the weather is cold. My car also seems to over fuel on cold mornings :( FSE related methinks!!

If its not something servicing related and the fuel pump is kicking out a good pressure then..

I have this theory that the idle dropping is caused by the ECU software switching from open loop idle control to closed loop control too early. That is, it switches from its internal cold starting routine to warm running. I think the amount of adjustment the ECU has for fuelling when in closed loop running is limited hence the poor idle. What's it like when you go to restart the car as semi-warm? Mines cack for the first few minutes. Pretty fecking annoying!!

Now the next question (if what I am saying isn't a total load of rubbish) is what causes the ECU to do this?? Its either gonna be a temp sensor somewhere (water one replaced), the A/F meter (has a temp sensor in too) maybe as this controls fuelling (replaced with no difference) or perhaps some other gremlin in the system. Oh, I also replaced the *supplementary air valve* (this lets air by pass the throttle butterfly when running choke) made no difference really.

I have not had the time or will to find this other gremlin. Its either gotta be wiring somewhere...or maybe somehting internal to the injection ECU. Maybe the throtlle housing just needs a good cleaning.

I have forced the ECU to run in its 'get you to the nearest garage asap' - lol - mode by disconnecting the throttle switch etc etc but this made no difference - actually I can't remember if that did make a difference...hmm give that a go see what it does. Maybe the RPM sits high or something---can't remember.

Aside from that I am stumped - I have spoken/emailed lots and lots of Bosch/ECU specialists and none of them can really diagnose it - without spending a mint byu having your motor with them for a day or two...

Letme know if you find anything else out.

Ben.

[Anonymous]

Thanks for the info, im going to try changing the thermostat as it runs alot colder than my 1.6 carbed engine. If that doesn't help then im going to tinker with the idle cut off valve. Will let you know what happens, better work GF getting pissed off with it! Cheers Tony.

[Anonymous]

Sorry not the idle cut off valve, the coasting air valve. Too many valves and switches for my liking. What you need are some carbs.

[Anonymous]

Oh yeah, I had a play with that too...didn't make much difference either.

Ben.

[Anonymous]

It's all sorted :D After changing the thermostat, cleaned the hole injection system, sorted the supplementary air valve. It ran alot better, but the revs still slowly dropped from a 1000 to 500, so i ajusted the coasting air valve buy unscrewing it quite a few turns. Now even with the lights heater etc all on it idles perfect. Also when you retsart it from warm it settle straight away, without having to rev it!! Girl friend want to be pleased. So i surgest you have a look at the supplementary air valve and test it. And ajust the coasting air valve. Let me know what happens

[Anonymous]

Hmmm...maybe I didn't unscrew it enough...I'll give it some more turns, lol.

Cheers. Ben.

[Anonymous]

Interesting post lads - should help sum peeps. Cheers:)