cut off issue and mpg issue with 06 brm jetta

For the past 1.5-2 months car has been getting 35 mpg, before that I avg'd 42-44.
when it's been real hot and AC on level 4, car will cut off while in neutral, coasting to a light. it's done that 8-10 times in last month, REAL HOT and ac blasting is only way to recreate.
car threw a check engine light about 3 weeks ago, code was related to Throttle Body/Regulating Flap (BRM), took that part off and replaced it. light came on once and stayed for a couple of starts afterwards, then went away. replaced part 1 week after check engine light went off. it didn't seem to be in bad shape, but wanted a new one since it was only $129. thought it may be part of my cut off/crap mpg issue.
car has cut off twice since I changed that part.
changed tb in march but used both lock tools and ran fine for 2 months after that
looking for someone with vag com or vcds in richmond va now.
what should I look for?
thank you in advace!

No one at all got any advice?

Could it be a seizing a/c clutch...? When in netural, and at idle rpm, the engine isn't strong enough to turn the compressor...? Just a thought...


df

First thing to do with any diesel is to change filters. It solves a lot of problems and eliminates multiple possibilities.

Then the in-tank fuel pump. You need to know that it's working. VAGCOM will verify.

Obviously there could be other related fuel issues but I doubt it.

Next is air delivery. There have been some recent problems even with the newest ASV valves. Make absolutely sure there are no internal shorts in the unit. No continuity between the sensor and motor circuits and nothing between any of the conductors and the housing.

If you're suspicious of the ASV, just unplug it. You'll get a CEL but the car will run fine.

One other thought is your alternator. Heavy load in hot weather. Are you absolutely sure the bearings and clutch are working properly?

This isn't much help but I remember a MI owner last year who had the exact problem and we were stumped. However there were not codes set.

nord said:

First thing to do with any diesel is to change filters. It solves a lot of problems and eliminates multiple possibilities.

Then the in-tank fuel pump. You need to know that it's working. VAGCOM will verify.

Obviously there could be other related fuel issues but I doubt it.

Next is air delivery. There have been some recent problems even with the newest ASV valves. Make absolutely sure there are no internal shorts in the unit. No continuity between the sensor and motor circuits and nothing between any of the conductors and the housing.

If you're suspicious of the ASV, just unplug it. You'll get a CEL but the car will run fine.

One other thought is your alternator. Heavy load in hot weather. Are you absolutely sure the bearings and clutch are working properly?

Click to expand...

thanks for the tips yall. all filters were changed within the past 5 months.

I still need access to a vagcom or vcds in richmond area.

a little research and I found this:
First, make sure your torsion value is somewhere near '0.0'. -.5, somewhere about there. This in NOT engine timing, as that is automatically set by the ECU. It is CAM TIMING.

If you can read the label on the timing belt cover, there are some hand written numbers for what the torsion value was set at the factory. Torsion value can be checked by using the VCDS/ engine module/ block 4/ torsion value. We always recommend checking to see what the torsion value is prior to disassembly of the engine. If you change the setting and the reading does not change, you are in a cam position default mode and need to get your cam position sensor running. Check that all the fingers on the cam position sensor are straight.

Also check block 13 for injector balance. Numbers should be relatively close.

Check the EGR for sticking. Clean the valve if it is stuck. It should close under it's own power. Reinstall without putting the wiring harness on it. Try the engine again to see if it runs better. Reinstall the harness, try again. Bad? Replace EGR or leave unplugged until you can replace it. Fuel economy usually will suffer when EGR is inoperative.


My torsion setting is 0.0 as listed on tb cover

my 3 other tdi's never gave me any real probs, except my b4, only real prob I've had with all my tdi's, ended up being n75 valve/vacuum lines which I replaced, turbo was cutting off.

AC could be culprit. Not too sure how to test that other than turning it off for a full tank to see if mpg improves.

once again, thanks to all!!
will update once I get somewhere with all this. car still runs relatively fine, so I'm not super duper worried about it.

dieselfuel said:

Could it be a seizing a/c clutch...? When in netural, and at idle rpm, the engine isn't strong enough to turn the compressor...? Just a thought...


df

Click to expand...

do our cars have a traditional clutch on their AC pumps? because I thought we had a different kind of system.

did you try it with the flap disconnected? check engine will come on but it will be fine. i have vagcom if you want to come down to woodbridge...

well, it's def my AC at the heart of the problems! Blows fine, BUT has a problem!
mileage through a half tank is back to normal and runs super strong...
so, what could be the deal with the AC.... compressor, how in the hell can I test? Bearings, once again, how to test?
this sucks!
any advice or consolling words are appreciated!

I've been suffering with less than stellar economy for nearly the entire time i've had my car. Everything, EVERYTHING checks out but very recently since it's been getting cooler I've noticed with the AC off or in "econ" my economy via the MFD improves by quite a lot. I know the MFD is not 100% accurate but if nothing else it's a way to gauge economy from trip to trip and day to day.

While my actual economy is in the high 30s on a normal day with the AC running the MFD usually tells me right around 40. With the AC off or in "econ" The MFD tends to tell me around 46-48 mpg.

Since it's come up in this thread I think I'm going to try a tank of no AC, perhaps I'm having a similar issue as you are...

i use old fashioned method of figuring economy....
how much diesel pumped in, divided by miles driven, reset trip meter every tank fill.
yeah, my prob is def my AC, don't know how to test ... For some reason, AC is too much strain on my motor, and can cause stalls and cut offs!!
and hell if I'm taking her to the dealer for this!! a thousand some dollars later and who knows if I'd still have the prob or not!!!
oh well, at least it's almost fall!!