my engine in my nova just wont idle!

ive taken the idle speed control valve off and cleaned that up. it seams to be working fine!

the TPS is giving the right voltage reading on full throttle. but nothing anywhere else in the rev range.

i have been told that on my engine its more of a tp switch rather than a sensor. but i thought there should be a small voltage reading when the throttle is close. (like about 0.5v)

when i unplug the tps it dosnt make a difference to how the car runs at all.
to me that would indicate that its not doing what it should be as it dosnt mater if its there or not.


when u start the car it starts every time. but the revs just drop and it dies.
it runs ok when you rev it. but does back fire a bit and generally pops and bangs a bit.

if i run it up for a while and get it warm then it does try to idle. but not very well. its drops very low and the pickes its self up to just over 1k. then drops and picks it self back up. etc etc.


i unplugged the air flow sensor and this caused it to sit at about 3k. it didnt climb and fall, and dosnt die. just sits there.



any thoughts would be great as i just dont know what to do any more.
i dont have mates with the same engine to swop bits about with to eliminate things from the problem, so im hoping to find it before replaceing bits that are not broken.

its a 2ltr 16v red top engine. (c20xe)


cheers guys

 

anyone got any ideas?

dont say your all scared of letting another nova out on the roads upsetting the rs crew.


please dont take that the wrong way and tell me to fook off to the vauxhall forum.
ive been on there all weekend anyway but with no luck still.

 

Chip-3dr is the best person to ask. I think he's the man in the know

Maybe change the title to FAO Chip or sommat might help.

 

did someone say nova?????


only joking!!!! yeah mate, ask Chip....he knows all to know with that engine!!!

 

Have you wired the management light in?


TBH it sounds like some sort of air leak possibly after the flow meter making it go very lean, do you have a wideband you could confirm that with?

Different revisions of the ECU have different TPS units, some are (like you have been told) basically just a switch, others are more like the cossie type in terms of being variable resistance.

If all else fails, then as a temporary measure just adjust the throttle cable so it holds the butterfly open, that should keep it running long enough for you to take it somewhere with the correct equipment to look at it.

 

As chip said mate, get your ecu light working for sure.

I'm still thinking it might be that fuel tank vent valve, get an ecu light wired and you'll know much more,

pops and bangs though doesn't seem likely if it is just that, stick up what fault codes you have when you flash the codes out

 

sorry to be dumb, but how do i wire up the ecu light?

is it just a 12v lamp i need?
am i right in thinking i use pin 6 on the green plug that on the ecu loom coming through into the car? the brown and blue cable??

do i connect the live side of the lamp onto that and the other side just down to earth?

when does it flash up the fault codes?
when running or just when the ignitions on?

is there anything i can do to bypass the fuel tank vent valve?
like i said in the pm mate, one of the inlets into the valve was broken (the one that the pipe from the inlet manifold goes to)
the other side of the valave has a pipe the runs across the fuel rail to the drivers side and then just to atmosphere.

would it make any difference if i unplugged that vavle?

thinking about it now it could well be this thats the problem as that had broken. and could of just been knocked when doing the water pipes or something. but nothing else has been touched.

are the expensive to buy, as if they are not i'll try and get one asap and see if it fixes it.


chip:
i did try adjusting the throttle cable to keep it running, but it dosnt keep it running untill about 3k or so.

i dont have any sort of equipment that i could check fuel pressure or anything with.

cheers for the advice.

do you know if any of the parts that have been mentioned are cheap?

i dont mind spending money on it, but dont want to if they are really expensive and might be the wrong bits.
but if they are cheap i'll just get them incase as it cant hurt to replace bits can it.

 

id search for a air leak mate,,,,,,,,, might be worth unbolting things and then refitting em again so to speak, may iron out a few things

but i know that air meters dont like leaks and that makes the car go a little silly


or could maybe be te cold start on the car, how is that controlled on it too as you say when warm it trys to work

 

it tries when warm, but is defo still not right. it still backfires and stuff.

i'll have to see if i can some spare parts or something to start eliminateing stuff

 

I cant remember what wires are which colour for the bulb, ask on migweb.
But basically there should be a plug, you just put a bulb between the two pins on it, it should come on solid when you turn the ignition on and go off when you start the engine if its working normally.
Then there is another plug that you short two pins on to get it to flash the codes.

No point anyone guessing at anything till you have flashed the codes out of it.

 

ok, cheers mate!

i'll get on there now and find out how to wire it all up.

 

Cool, i notice you are only in london anyway, if you get really stuck i can probably lend you a hand.

Air leak is still one of the favourites though, espeically based on what you are saying about not idling below 3K etc

 

ps

Check the rubber hose that joins to the SFi box and folds back on itself, they go for a past time.

 

im kind of on the borders of london and essex. a small place called chingford incase youve heard of it.

do u mean the rubber hose that goes from the bottom of the sfi box to the icv?

 

Not that one, i meant the huge fecker that goes from the sfi box to the airflow memter and wraps back on itself, they crack on the folds.

 

have you checked the throttle body inlet for leaks? common problem on C20 XE's, not sure if its got an EGR valve same as the X16 XE this might also be causing problems? my Gsi had a massive idling problem, would bounce from 1k to 3k consistently then stall when slowing down, i changed iacv, blanked EGR valve off and changed throttle body inlet and still had the same problem so ended up getting shot of it cos spent too much money on sensors

Sarah

try migweb theyre usually very clued up on XE novas anyway

 

that looks to be in pretty good nick. i havnt actually taken it off and checked for cracks though. i'll do that.

i'll get the ecu light done asap and get some details off that.
hopefully it will give a better idea.

 

They always look fine till you take them off

 

What have you done with the SFI box? Cut and shut? Check for leaks there too. Also have to screws that hold it down got rubber washers underneath?

 

hopefully he left it in tact and drifted the thin bulkhead back to clear it, like i did on the red one Rich had off me.

Thats the proper way to do it

 

Got any fault codes yet ?

Out of interest you didnt remove the throttle body from the manifold did you ?

A guy I just finished a conversion for had removed his, not sealed it back on and my god was it causing problems, maybe would of helped if he had of mentioned that he had done that ! tried loads of sensors with no luck as well

Chip - do you know if all xe's ran a fuel tank vent valve ? as coem to think about it this guys didnt have one !

 

XE's dont all run a vent valve, im positive that mk2 astras dont have such a thing in the first place for example.

 

Aint MiG being muchg help mate? Ill pop over if you need a hand with anything? Or ill steal a Haynes manuel for you

Let me know

 

a haynes manual for a 1990 astra would be rather handy if halfords are giving them away

 

gonna pop round in a minute and attempt to wire up the ecu light. i'll post up the results when i get back. any advice on wiring it up?

i havent thouched the throttle body or manifold, especially not since it was running right

 

Surely an H plate astra doesnt have a tank vent valve? :O

 

i was just after one in general for reference. i dont even know what car my engine came out of.

 

I cant remember off the top of my head which wire does what.

I wired in the tech plug though and just bridged the correct pins out to flash the codes

I know for sure that a cavalier and calibra both had tank vent valves, judging on what you said by PM yours has got one, It should be attached to the 2 studs of the inlet manifold (master cylinder side)

Got any brake cleaner, if so have a good spray about !

James

 

mine does have waht u described. it is secured using the last 2 inlet manifold bolts. i'll take a pic when im round there and post it up. ive got some wd40 so i'll have a spray with that.

ive got some info off mig that i found but its a bit vague.
hopefully i'll be back in a few hours with some more info for u to process.

 

ok so im back now.

firstly i'll say how i connected the ecu light up.
the brown and blue to the neg of a lamp, and a 12v live from the battery to the pos of the lamp.
the brown and white cable i shorted to earth.

when i started the car it flashed once.

still the same problems (no idle)

the only time the lamp did anything but flash once was when the battery died. the light flashed everytime the engine tried to turn over.

the lamp didnt come on at any other time.


this is the valve mentioned earlier.



it seams to be working ok. when i tried to blow through it you couldnt. i put a small pin down the hole that you connect to the inlet manifold and pushed a button, this opens the valve and you can then blow air through it.
i checked the pipe going to the inlet manifold and that seams all ok.


chip i took the large black hose going from the air flow meter to the sfi box and it was slightly worn in places but no holes. just a few very thin cracks.

only other thing i noticed was the fuel pump was slightly noisy when it over runs after the engine dies. it aint got much petrol in it, but there is definately some in there as if i rev the car it will run as long as i want it to.

im going to try and find out what the flash of the lamp means now.

 

i just went on topbuzz. i realise what i have just said above is useless to anyone.

not sure what im doing wrong. really need some one on mig help me out with wiring up this light.

chip if ur bored for 2 minutes would u mind sticking up a post on mig just asking how its done as im sure you'll get a reply.

ive got a small black and green plug coming through into the car from the engine bay on the ecu loom. it all comes from the bunch of cables that go to the ecu, and also the fuel pump cable.

i just need to know what cables from these plugs i need to use, and what to do with them.

if not i'll keep waiting till some one helps me out on there.

hopefully more info tomorrow if i can get back round there and i know what cables to use.

 

just found this:



if anyone has wired up an ecu light on an xe before maybe this will jog your memories as to what i need to do.

like i said above i was told to short the brown/white to earth.

and the brown/blue was a switched earth.


im thinking now maybe i link the brown/white and the brown yellow out.

but thats just a guess.

i'll put this pic up on mig as well.


i just wanna get out there and start annoying scoobies.

 

right ive sorted it.

sorry for wasteing ur time. but it was the brake servo pipe was disconnected.

i removed it when i was doing the heater matrix pipes and forgot to put it back!

its idleing fine now. but its still backfireing a bit when u rev it. got a feeling its where ive played with the throttle stop and things whilst trying to make it idle.

im gonna wire up the ecu light still just incase there are any faults.

cheers again guys!

 

at least it's something simple... we all forget bits like that from time to time (worse one i did was forget to put the oil feed pipe back on one of my turbos... that cost a small fortune )

 

Told you it was that all along........

 

maybe i should take ur name for a while.
that was a full on skool boi!

 

does that mean your almost done now

 

yeah, just gotta bleed brakes. tidy all the wiring up and find out what sensor is the oil pressure sendor for the gague, and what is the oil pressure warning light.

and then get all the crap out the back of it and rob a bank to pay for the insurance, mot and tax