Tanked fuel economy. 2 VCDS charts. Any ideas?

[cfc1016]

I have a 2003 Wagon 01M (auto). I have had tanking fuel economy lately - sub 30mpg tanking. I had a new head installed/TB change recently, due to an on-start (not in-motion) timing belt failure, by a trusted mechanic in the area (forum recommendation) and things started to go south. The car is running well, but economy is tanking like crazy. Shifts are delayed too, and rough, just like they were before the last time I cleaned my MAF sensor. That was after I ignorantly ran a K&N air filter for a couple thousand miles.

He told me I had a crack in my intercooler and a faulty EGR. I replaced both.

Replacement intercooler is Part #- 1J0145803G
Original intercooler is Part # 1J0145803S
Replacement MAP sensor is Part # 0281002177
Original MAP sensor is Part # 0281002399
Replacement EGR is Part # 045131501L - same as original.

I cleaned the MAF sensor thoroughly with aerosol MAF cleaner. No noticeable change in shifting or fuel economy.

I poured UV-luminescent dye in my fuel at ~1/2 tank to try and find any leaks. No joy.

Air filter is ~25k miles/10 months old.

I ran a few rolling logs of EGR and MAF Actual/MAF Specified and graphed them. Does anyone see anything here that tells them something? Anyone have a suggestion of something else I should log/chart? Forgive the erratic RPM. I had someone else driving the car while I ran the logging.

I'm planning on buying a new MAF sensor next week, unless someone tells me something better to do. Thanks for reading.

 

[greengeeker]

Where is your static and dynamic timing?

How about a log of your torque converter lockup state (TCC)? (coolairvw has a couple good threads on how to log this)

 

[UhOh]

What was your typical fuel mileage BEFORE the TB failure? And, were there any transmission issues before the TB failure?

As greengeeker suggests, I'd look to check timing and TCC.

 

[oilhammer]

Were the rods checked while the head was off? Sometimes they can bend with a valve-piston contact and cause lower compression than it should have. Also, was the correct thickness head gasket used? And obviously check the timing, and you may look through my sticky in the fuel economy section for some other things to check.

 

[cfc1016]

Where is your static and dynamic timing?

How about a log of your torque converter lockup state (TCC)? (coolairvw has a couple good threads on how to log this)

Those are the static timing. It consistently hopped between 63/64. I'm not sure how to check dynamic timing - I'm new to VCDS - and couldn't pin down instructions for it in the VCDS manual. If you would be so kind as to instruct me on how to log that, I would be happy to.

I also have an ALH beetle. I swapped the [updated style - Part # 0281002757] MAF sensor from it into the jetta and ran another log. Here is the chart from that. Readings of MAF Specified vs MAF Actual look far less disparate in this one, atleast to my untrained eye...

I found coolairvw's '01M part3' and '01M part2' threads, but couldn't quite figure out from them how to log the torque converter clutch state. Can you help? Again, I'm new to VCDS, so my VAGCOM Fu is weak, to use the parlance of our times.

 

[cfc1016]

What was your typical fuel mileage BEFORE the TB failure? And, were there any transmission issues before the TB failure?

As greengeeker suggests, I'd look to check timing and TCC.

For mostly-city-driving fillups, I was averaging somewhere around 34-36. Mixed-city-and-highway (city plus drives up and down the eastern Appalachian ridge -very hilly) I was averaging about 35-39.

The only transmission issues I ever had, similar to the ones I've had lately, were before I A. performed a full auto trans servicing (filter, fluid, gaskets) and B. got rid of the BS k&n filter and cleaned my MAF.

 

[cfc1016]

Were the rods checked while the head was off? Sometimes they can bend with a valve-piston contact and cause lower compression than it should have. Also, was the correct thickness head gasket used? And obviously check the timing, and you may look through my sticky in the fuel economy section for some other things to check.

I don't know for certain. I will have to consult the mechanic on that one.

 

[BobnOH]

You could also run a compression test.