my idle is dodgy

[dangermousegsi]

ive got a 91 spec nova gsi an recentley it has started to idle very badly, it starts fine but when i slow down for a junction/roundabout/traffic lites etc it nearly stalls an the revs hover at bout 700 then it will rise to 900/1000 then drop again any ideas? ive just had a new fuel pump and relay so that shouldnt be the cause an i cant think of any other obvious reasons help! :| :? :( :cry:

[carltoncrazy]

ive got a smialr problem wiv my mk1 sr.
when i put the brakes on the engine revs rise

[vastre]

I have the same problem with my 91 Gsi, the car will idle ok then all of a sudden the revs will drop to 6 or 700 and stay there, when i blip the throttle they will go up to about 1200 for a while then settle back to 900, then drop sometimes back to 700. I think its either low fuel pressure or a faulty water temperature senor as this would cause rich mixture, but i also still get 45-47 mpg on a run so i dont see how it can be that. :?

[Rich Dale]

The water temp sensor can also cause week mixture if faulty.......mine was buggered on my GTE causing it to refuse to start and run correctly in cold weather....mixture too week at start-up.

I don't think the problem is caused by that though.....even when mine was buggered, it ran and idled fine once the engine was up to the normal operating temperature.
They can do strange things though.....if it's working intermittently, I suppose it could alter the mixture randomly causing the problem?
It could also be a dodgy air-flow meter or a whole host of other things!

The sensor is only around ?20 so worth buying to try it....mine was ?20.27 inc VAT to be exact.
Part number 90510183 for the GTE

[vastre]

Thanks for that info, i think i'll get one like you say anyway, i have an ohmmeter and don't seam to get the readings it says in the haynes manual. I was thinking maybe air flow meter or maybe a dodgey hose somewhere, but i have checked all them andeven bought a new coasting air valve because that needed replacing too.

[Dicko]

leaking seal on the brake servo hose if ya brakes effct it.
on the gsi it may be fualty idle valve, or 1 of then very thin pipes split/loose

[carltoncrazy]

so when i jus push the brakes and leave it for a min or so,the engine raises,so thats a knacked seal?
coz it stops fine,

[vastre]

I think i have found the problem with mine, its the throttle switch sensor i think, when the car is running high idle and i push on the connector to the throttle switch the revs drop, then when i let go they go back up again. I think i will have to buy a new one ?30! :o or will one fit off any car of that period as the ones on Astras look the same?

Anybody know? the part no. on it must be a bosch one as it doesn't look like the 902 xxx xxx x etc. found on other vauxhall parts i have seen.

[carltoncrazy]

yes astra wil fit

[dErZ1]

The water temp sensor can also cause week mixture if faulty.......mine was buggered on my GTE causing it to refuse to start and run correctly in cold weather....mixture too week at start-up.



I have a 1.4sr which is a bit iffy when starting could this be due to the water temp sensor or is it the termostat( if seems to work the thermostat coz the needle goes up and down!)

:?: :?:

[Rich Dale]

Is your 1.4 SR injected?

If so then maybe.....if it's carbed, then it won't have one!

It basically works like an auto-choke.......makes the mixture richer for cold starting, then weakens it off as the engine temp rises.

[Davo]

timing sounds out slightly to me

[idontknowimaduck]

What about the auto choke ??

[neiloakley]

anyone though about checking the idle speed adjuster? just a thought. It is the bit on top that looks like a fuel filter and it joins to the inlet manifold in two places. If it needs replacing, vaux will charge the earth. Best off going to the scrappy.