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[Nickbat]

Over the last couple of days a cold start has resulted in the car ticking over as if it's running on "full choke". A lot of engine vibration and smelly exhaust - but still running on all cylinders. When I give the throttle some wellie, it clears up and is largely fine thereafter until I leave the engine to get cold again. Swapped the ICV with a spare I had and the problem remains. I am suspecting lambda sensor but haven't had time to do a paperclip check yet. Any other thoughts on what the problem could be?    

[Marks DTM Calib]

Well you can forget lambda sensor as that does bugger all until it gets very hot.....

Next time its cold, place your foot flat on the throttle (to the floor) and crank it over a few times......then try starting as normal..........

[Kevin Wood]

I would be surprised if it was the Lambda sensor. They are normally not active at idle RPM and normally not until the engine is warmed up either. I would also be surprised if the Lambda sensor has enough authority to pull the engine that rich without triggering a fault code - but I may be wrong.

On the contrary it could be the Lambda sensor that pulls the fuelling back to sensible levels when it starts behaving so I might be tempted to look at the devices affecting open-loop fuelling (MAF sensor, intake air temperature, coolant temperature, throttle pot, induction leaks, etc.)

Kevin

[Nickbat]

Thanks guys.

Mark, I'll try what you suggested right now.

[Nickbat]

Well you can forget lambda sensor as that does bugger all until it gets very hot.....

Next time its cold, place your foot flat on the throttle (to the floor) and crank it over a few times......then try starting as normal..........

OK, Mark, put my foot to the floor and it burtst into life without the earlier problem. What does this point to? Throttle flap sticking??

[Marks DTM Calib]

One or more injectors leaking neat fuel into the inlet when stood over night.....start car and you get a pool of fuel drawn into the cylidners and a period of poor starting/rough running....use full throttle and you get much more air and the injectors do not fire (on an injection engine, the injectors do not fire at WOT when cranking)....the result is that it clears the inlet of the fuel first......

[Nickbat]

Cheers, Mark.

Can I carry on with this leaking injector, or will it need repairing? Obviously the car is worth little, so I don't want a major expense.

Hoping to chop it in for a newer one this year.

[Marks DTM Calib]

Just keep using the trick above....you might want to try a good dose of Injector cleaner in the fuel....

[Matchless]

Injector cleaner might fix it but it usually only gives temporary improvement and it gets expensive if you keep using it. Try Forte Flush, available on t'internet for £5 delivered, add one bottle to half a tank and run to empty.
You could get another inlet manifold and injectors from a breaker (several being broken on here at present) or if you are only going to keep it for a short time then try giving it a little bit of throttle as it is cranking (say 1/4) rather than full throttle as Mark suggested. The extra air should ensure a quick start and its a bit kinder on the rest of the engine.

[Kevin Wood]

Removal and ultrasonic cleaning followed by inspection of the flow pattern and testing of the flow rate is the only real way to revive dirty injectors, IME. I've never noticed any difference following use of a fuel additive although it might help in an extreme case such as this where an injector is potentially not sealing.

There are a couple of places who offer a good cleaning service by post but it's doubtful if it's worth the effort or the expense on a car that is moving on soon.

Kevin

[TheBoy]

I would get a 2nd hand injector rail/inlet from someone who's breaking one...

[Nickbat]

I'll try the injector cleaner first and see how that goes (I've got a bottle in the garden shed).

Thanks for advice about a secondhand injector rail - as a last resort, that may be the way to go.

In the meantime, I think I'll play this one by ear, as they say.

[Nickbat]

BTW, whenever I think about jobs like getting a secondhand injector rail, the biggest problem that comes to mind is not fitting it, but queuing up at the Vx dealer to get replacement O rings for the plenum (and, if required, those red injector bridge seal thingies). Is there an aftermarket  for seals like these? I seem to recall that I saw a box of automotive O rings in Halfords the other day.

[TheBoy]

BTW, whenever I think about jobs like getting a secondhand injector rail, the biggest problem that comes to mind is not fitting it, but queuing up at the Vx dealer to get replacement O rings for the plenum (and, if required, those red injector bridge seal thingies). Is there an aftermarket  for seals like these? I seem to recall that I saw a box of automotive O rings in Halfords the other day.

I'd stick to dealer for plenum O rings.

Invariably, the red ones are OK to reuse