Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Andys VXR on 15 December 2011, 18:11:31
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My revs are still not dropping inbetween gear change so if its doing 3 to 4000 revs and i change gear or come to a stop thats where they stay ( using gears to bring them down). Now ive done what some members said and thats clean all breathers out and throttle body. Ive got two codes come up which are 0120 and 0220 both throttle related what else can i do to fix this .
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Checked for vacuum leaks ? Checked the throttle butterflies are fully closing ?
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Looking at those codes - could be throttle potentiometer or something related to it at fault.Either have a tech2 session or replace it ?
Maybe someone more knowledgeable on electrical matters may have some more detailed/ accurate answers. :-\
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how do i check the butterflys when on my drive at a stand still i can rev it and its fine only seems to happen when driving. ive checked breather pipes they seem ok
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sorry im a bit daft whats a tech2 session and replace what
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Tech2 is the GM diagnostics kit.A few people on here have them.Replacement - possibly throttle potentiometer,but best to get diagnosis really before throwing parts at it to try to find a cure. :y
If the butterflies are opening/closing ok when its revved up at standstill,then presumably they are ok. :-\
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have you checked if all plugs wires are conected properly
there is a conector at the front of the plenum this controls your revs
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Needs tech 2 to diagnose either throttle motor or pedal switch for the drive by wire.
Tech 2 being Vauxhall dialectic computer, which can activate various electric components remotely. Fairly sure there's a test for drive by wire throttle.
If I had to guess I'd go for pedal switch, although didn't you say pedal trick was not working at one point...?
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yes thats right but then i said i had plenium of so plugs were disconected because i was a burk . These were the codes after everything back together
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Servo to plenum hose securely fastened and airtight?
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So codes could be historic then, could be an air leak as Rob suggests. Check your work. Is everything connected? Plenum seated correctly. Etc.
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this was also happening before i took plenium of to clean all breather pipes
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Difficult over split threads mate...
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Did you clear the codes at any point? We need to establish if they are current or from turning ignition on with dbw plug disconnected.
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Yes i cleared the codes with my little code reader but done the pedal trick after that and no codes are you saying take the wire of the throttle body
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Right, so there are currently no codes via pedal trick? If no codes it should have a constantly flashing car/spanner light. Ie more than 10 flashes constant spacing between each flash.
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yes thats right
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If the codes mentioned earlier are still present then it needs diagnosis to find exactly where the problem lies imo.
If the codes are old or now cleared I would suspect a vacuum leak of some kind.
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Ok, so your codes are no longer present, therefor the ecu is currently not aware of a drive by wire problem. Yet still have high rpm. This suggests you have an air leak!
Afaik dbw throttle fails with no response or a limp mode anyway. Although no direct personal experience with that issue. ...?
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This was only yesterday so ill try it again in the morning after a little drive and see if the codes are back. Hang on ill go out there now and try again be back in ten
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Bloody hell thats cold out there right no codes so ECU not picking up anything
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Inlet air leak somewhere then.
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So whats the best way to find out where from and are you say it could be inlet manifold the plate between manifold and heads or plenium
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Spray some carb/injection cleaner (or similar) at the possible areas (only very small squirts at a time) and if the revs rise when you squirt it at one particular spot,then youve found the area of the leak. :y
Keep it away from exhaust manifold area if possible. Potential for fire risk if your not careful ;)
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Ok will do in morning but did you you say theres a chance of fire mmmm sounding good at the moment oh ok i wont give up yet ill post tomorrow to let you know how i got on thanks for the help
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Never heard of a car catching fire using this method,but its a flammable liquid and theres hot things under the bonnet so best to be careful. ;)
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I havnt had time today to spray around the engine but ive been thinking all day if it was an air leak why would it hold the revs at where ever they are on the rev counter. If im doing 2 3 4000rpm would an air leak hold the revs there surely it needs fuel to make it run faster. I might not be looking at the bigger picture here but if you could make a car rev just on air it would be great. When i start car on drive i can rev it as much as i like and revs dont stick it seems to be only when driving.
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When you induce extra air AFTER the MAF, then the O2 sensors will sense a "weak" mixture and command more fuel from the ECU by adjusting the "fuel trim" upwards, so the RPM will rise.
This will increase the vaccuum, suck in more air through your leak, run lean again so the fuel trim will be increased again, so the rpm will rise a bit more .. it will continue this until a balanced point is reached and the rpm will stabilise high.
Sometimes the increase in fuel trim /rpm causes the mixture to "normalise" and the fuel trim backs off, the rpm drops, the mixture goes lean, the fuel trim increases, the rpm rises etc etc etc thus giving a "hunting" effect.
All caused by an inwards(vaccuum) leak.
As said, a light spray around with carb cleaner, when the engine note changes there is the vac leak.
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Right ive sprayed everywhere with the carb cleaner small amounts and bucket loads and no change in engine notes. I cant work out why i can rev it as hard as i like out on the drive and the revs sit lovely dont get stuck and goes back to normal as it should it only happens when im driving it. I might go and get myself a 1.3 mk1 escort so therers only a set of points 4 leads and a thimble for a carb done the problem is they a worth a small fortune now.
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Yes i cleared the codes with my little code reader but done the pedal trick after that and no codes are you saying take the wire of the throttle body
Can your code reader show 'live readings'?
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No its only a £100 argos RAC one
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Yes i cleared the codes with my little code reader but done the pedal trick after that and no codes are you saying take the wire of the throttle body
Can your code reader show 'live readings'?
That's a pity.
My thinking is that 4000rpm would require a big air leak. If it is unmetered air then I am surprised that the engine starts (though maybe it isn't as big an issue for fuel injection as it would be for carburettors :-\)
If you can get live readings you would be able to see what the ecu thinks the throttle pedal and throttle body positions are and see how much air is going through the mass flow meter.
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Has anyone played with the throttle bodies at any time ?? Just wondering if you have a sticking throttle plate that moves OK on big throttle movements - revving it hard on the drive - but sticks on small movements when driving ??
There is a "how to" on cleaning/setting up the throttle bodies .. might be worth a look ??
http://www.omegaowners.com/forum/index.php?topic=90624.0
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It's just strange that the ecu hasn't stored any faults, as andy H says It must be a big leak to cause such a difference in rpm, I would check the icv, in case for some reason it was sticking in the higher rev range than lower.
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As a thought, are both the intake elbows from the first multiram to the throttle body :-\ They can be a bit of a pig to refit :-\
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It's just strange that the ecu hasn't stored any faults, as andy H says It must be a big leak to cause such a difference in rpm, I would check the icv, in case for some reason it was sticking in the higher rev range than lower.
3.2 is DBW (drive by wire) so there is no separate ICV. The ECU maintains idle speed by controlling the throttle position directly.
From the limited diagnostic info we have so far it points to the throttle butterflies not closing but whether this is because the throttle motor is faulty, the throttle body is faulty or the ECU is holding them open because it is getting duff sensor input is anybodys guess.
I haven't mentioned a vacuum leak because a vacuum leak big enough to hold the revs at 4000rpm should trivial to find.............
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It's just strange that the ecu hasn't stored any faults, as andy H says It must be a big leak to cause such a difference in rpm, I would check the icv, in case for some reason it was sticking in the higher rev range than lower.
3.2 is DBW (drive by wire) so there is no separate ICV. The ECU maintains idle speed by controlling the throttle position directly.
From the limited diagnostic info we have so far it points to the throttle butterflies not closing but whether this is because the throttle motor is faulty, the throttle body is faulty or the ECU is holding them open because it is getting duff sensor input is anybodys guess.
I haven't mentioned a vacuum leak because a vacuum leak big enough to hold the revs at 4000rpm should trivial to find.............
IIRC the plug to the throttle body can be a bit tempramental. Might pay to unplug it, blast it with an air line/air duster, refit it and secure it tight with a cable tie :y
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I think im going to try and get another throttle body just for the hell of it. I started it today and its fine revving it on drive but soon as you drive it the revs are getting stuck. They slightly go up and then it takes a very very long time for them to come down aaaarrrrr its got to be something to do with throttle body hasnt it
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Always just before Christmas ::)
bump