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[feeutfo]

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.

[Andys VXR]

yes thats right

[albitz]

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.

[feeutfo]

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.     ...?

[Andys VXR]

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

[Andys VXR]

Bloody hell thats cold out there right no codes so ECU not picking up anything

[feeutfo]

Inlet air leak somewhere then.

[Andys VXR]

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

[albitz]

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.

Keep it away from exhaust manifold area if possible. Potential for fire risk if your not careful

[Andys VXR]

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

[albitz]

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.

[Andys VXR]

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.

[Entwood]

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.

[Andys VXR]

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.

[Andy H]

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'?