Hi all,

i went to move my xj6 after it hadnt been started in a few months and she certainly isnt ruining like she use to. it seems its drastically overfueling. i have checked the resistance across the colant temp sensor, seems in spec. unplugged the cold start injector and looked for obvious vacuum leaks and checked all the fuses i could find.
it idles ok but when you rev it it just misses like a dog and spurts out a whole heap of smoke. if you push the air flow sensor so its a little leaner its fine but i cant get enough tension on the spring so it act normal, besides then it wouldnt idle.

could what is it likely to be? im thinking airflow sensor might be past it as the top was off and had a bit of moisture get in.

thanks jay

 

That's opposite of what should happen.

Pushing the air meter flap will enrichen the mixture unless the throttle is opened at the same time. Opening the air meter flap signals that more air is entering the engine and the ECU will command more fuel. But....unless the throttle is opened at the same time then there *isn't* more air entering the engine and the extra fuel will over fuel the engine





Not quite sure what you're saying here





Mositure in the AFM doesn't sound good at all

Is this problem sensitive to coolant temperature?

Cheers
DD

 

if it were a vacuum leak as you said ide expect it needing richer mixture but thats not the case. its just running way to rich under acceleration. at idle its lean enough, to the point where it just runs smooth but as soon as you accelerate it sucks the flap back too much and makes it too rich. by push the sensor i meant push the flap closed more.

what i have to do is open the accelerator then manually push the slider in the afm back to get it to lean out enough to run. there is clouds of black smoke as well.

ive checked the cold start injector system and the temp sensor closest to the back of the engine and it checks out fine according to the specs in the book. it seems to have happened after replacing the fuel filter and after the afm got wet. ive cleaned the afm traces so it should be ok but i probably should also clean the contacts that go the the center of the slider as well. could it be the fuel pressure is not regulating properly, whats the best way to test?

any ideas? might be easier for you to start from the start so i can run through everything to make sure i haven't missed anything.

thanks allot,
jay

 

Yes! Only way to test to to use a fuel pressure gauge.

You could pull the vacuum hose off the regulator and examine for signs of raw fuel.....that condemns a regulator immediately. However, lack of raw fuel doesn't prove that it is regulating pressure properly




You covered the bases pretty well. The AFM remains suspect but I don't know of DIY test to check opeartion. Most swap in a "known good" replacement when other possibilities are exhausted

There is a "double fueling" fault that you might want to consider although the symptom usually occurs only for a couple minutes when cold. Here's the info:
XJ 6 Series III 4.2 - Cold Start EFI Overfuelling

And here's some general reading on rich mixtures but I don't think anyhting new will be revealed:
XJ6 Series - EFI Rich Mixture

Cheers
DD

thanks allot,
jay[/QUOTE]

 

one thing im going to check is the resistance to the coolant temp sensor at the ecu as i suppose there may be a large resistance in the cabling. suppose i better do it for all the wires to the afm ect

ill let you know how i go

thanks,
jay

 

Good idea.

Before crawling into the boot, though, carefully examine the connector at the sensor itself, if you haven't already done so. Problems there are much more common than further down the line.

Cheers
DD