Hi guys, thanks in advance for any advice!

My non-jag mechanic suspects an open and warped flap inside the mass airflow meter on my rebuilt bosch mass airflow meter.

does the flap typically warp, or might it be gunked up at the hinges, or something else...? Is it worth the effort for me to remove the unit and tinker with the flap and or the components under the black plastic square cover -- before i buy a rebuilt replacement ??- ($$ is tight post x-mas)

Car is running verrrry rich, hard to warm start,and stalls below 5-10,000 rpm unless i put it into neutral and rev it a bit to prevent stalling, car runs okay around town/highway when not idleing low at a stop light...

THANKS FOR ANY ADVICE

 

There is a thread (use search) about someone who took pics when fixing the AFM. I remember reading it and he said there is a switch inside the black box that sometimes goes bad and he zip tied it to make it work properly. I do not know if that is your problem, but worth a read.

Also, I suspect my AFM has a small issue as well. Car idles better at 17BTC when I open in slightly by hand. May be the opposite of your problem tho...

 

Not that mine is the final word, and we know "anything can happen", but a warped/sticking AFM flap isn't the usual failure mode on the AFMs....in fact, they don't fail all that often. When they DO give trouble is more commonly that the 'wiper" has worn a dead spot into the resistance track.

MUCH more common culprits for a rich running condition are the coolant temp sensor and fuel pressure...among other things.

It shouldn't be hard to find a good used AFM as opposed to a rebuilt unit.

Cheers
DD

 

Here's some info that might be of interest before buying anything:

http://www.jag-lovers.org/xjlovers/xjfaq/efirich.html

Cheers
DD

 

Check for vacuum leaks first. Very common and pretty easy to check.

There is an idle mixture adjustment screw on the airflow meter which may need adjustment. Usually this screw is hidden by a pressed in plug. You can read more about using an oxygen sensor reading as a guide to adjust the screw so it runs leaner at idle. It does not affect anything but idle.

Info in step 12 here: http://www.hiperformancestore.com/Ljetronic.htm

Research using L-Jetronic air flow meter adjustment idle mixture as keywords.

 

Heh heh. The picture you're using is MY old Ser III :-)


Cheers
DD

 

Everyone on the thread is correct.
My personal experience is a dirty MAF or fuel pressure regulator.
My fuel pressure regulator gave up and it flooded the engine badly. Your mechanic should be able to check that.
As for the MAF; an inexpensive check & fix is a can of throttle body cleaner.
I removed the air filter & canister then manually held the throttle open to prevent stalling as I spayed in the cleaner in. I took extra care to clean the MAF flap & hinge and was surprised to see (prior to cleaning) the gum build up on the flap.
While spraying in the cleaner, you will see a small amount of smoke from the exhaust as the cleaner passes through.
Try that & check for air leaks before spending $ to buy a new MAF unit.
Mine ran to 275,000 miles with regular maintenance; nothing else broke except the A/C, it kept running until the body rusted away.
Cheers

 

I save all the hot Jags I find for underhood reference. Maybe someday mine might look as good. Or at least it'll look correct!

 

I really miss that car. I hope to have another Ser III one day.

The car had 147k miles when that picture was taken. The new owner takes good care of it but hasn't kept up with the cosmetics.

Cheers
DD

 

Looks more like 47k, at least it is still on the road and not lost forever. Shame though that all your fastidious maintenance of cosmetics was neglected by the new owner.