I'm stumped - ALH with issues...

[spiderb_151]

Greetings!

I need some help with an originally stock 2002 Jetta Wagon with a 5-speed I picked up recently. Needed a fuel pump - that was easy. It runs good but gets crappy mileage, it's stuck at 36 to 39 MPG depending on how hard you drive it. Here's what I've done to try and fix it:
1. Compression check - comes up to 550 PSI on all 4 quickly
2. Cleaned intake and leak tested
3. Installed new larger injectors w/ appropriate tune
4. Logged data, requested vs actuals for groups 1,3,4,8,11 match closely, it does over boost a bit before it settles down - typical from what I've read??
5. Replaced MAF, at idle it was reading 450, now 360 - didn't help but it smokes a tiny bit less at WOT now.
6. Advanced timing to the top line in VCDS
7. Set IQ to 5 via hammer mod - software is still at 32768, all other adaptations are stock
8. Tested needle lift sensor
9. Got a "low smoke" tune from tuner - didn't make any difference, same smoke and poor mileage
Long drives on the highway with the cruise set to 70 it can get 39.5. What else is likely the culprit?
Thanks

 

[Enabled]

It's manual, right?
Start looking for dragging calipers.

 

[spiderb_151]

Will check for hot wheels after the drive home. It rolls so easily when I push it I didn't suspect them. Thanks.

 

[dieselnuts]

Interested in where this goes. I'm in the same boat with my 2002 Jetta

 

[spiderb_151]

Initial temperature reading of the calipers when I got to work today showed the front left to be 5 F warmer than front right. This seems insignificant... any thoughts out there? I'll do a follow-up test this evening.

 

[speed185187]

What type and size of injectors do you have?

 

[IndigoBlueWagon]

Who installed the pump and timed the engine? Getting the engine set up right makes a big difference in FE. I'd also look at a boost log to see if your turbo is working properly and following the boost request.

 

[Nevada_TDI]

There should be more than one person with VCDS where you live that is willing to help, likely for little to no compensation. Or a six-pack. I'm just sayin'.

 

[A5INKY]

In addition to the things already offered, check you coolant temp with VCDS once warm. I see thermostats fail open or partially open all the time keeping the engine too cool. Car needs to get above 80C and stay there or fuel economy really suffers. Should stay closer to 90C.

 

[spiderb_151]

Speed: I have the same problem with stock and DLC 764 w/tune.
Indigo: I used a local shop (Dark Castle Motorsports) that's familiar with the process. Without specifics to check I don't know what to ask them but they seem to know what to do. I've spoken with them at length.
Nevada: I have VCDS
A5inky: I'll check, it does warm up quickly but at idle will come off the peg... You might have something!
Thanks guys!

 

[IndigoBlueWagon]

Hook up VCDS and look at timing in basic settings. Then look at it in measuring blocks. It should be the same. If it's not then the cam, crank, and IP may not be aligned.

 

[adjat84th]

A5inky: I'll check, it does warm up quickly but at idle will come off the peg... You might have something!
Thanks guys!

It should not come off of 190F at idle at your location. Mine did the very same thing (but in the winter), and it got me to replace my thermostat. This drastically shortened my warmup times and fuel economy came up a bit as well.

 

[Nevada_TDI]

The temperature gauge in our TDI's is more of an idiot gauge. Most engines when the hit 160F will read at 190F. The system is designed to be "vague"; if the temperature gauge was exact there would be too many owners calling the dealership due to the "wide temperature" swings on the gauge. VCDS is really the only accurate way to know the temperature of the engine/coolant.

 

[adjat84th]

^ This is correct. Meaning if it comes off the 190F mark, you're below 160F and thus likely stuck in the warmup enrichment cycle (injecting more fuel) by the ECU.

 

[spiderb_151]

Seems you guys are on to something. I logged engine temp on the way home tonight. Ambient temp was around 75, after driving on the highway at 80 for 10 min the engine was still not above 80 C. At 70 C the gauge showed full temp. I'll swap the thermostat in the morning!!

 

[turbovan+tdi]

Also swap the green temp sensor, they are known to fail too, cheap insurance and a 5 min job when doing the thermostat.

 

[Ganoid]

I'd swap the sensor first. The sensor has 2 elements so its not uncommon to have the gauge read correct but the vcds (ecu) reads cold (this was my issue). My friends car was different his gauge was reading cold but the vcds was correct. When I changed mine the car got much smoother I suspect due to the ecu having the correct temp reading. I always change the thermostat while Im in there for the timing belt.

edit... don't forget to purchase the little plastic clip when you get the sensor.

 

[spiderb_151]

First I checked timing in Basic and Measure Blocks and they match. Then I finally got the thermostat swapped - big improvement. On a 120 mile test hop it got 45 MPG instead of 36! So now how to I get to 50+?

 

[runonbeer]

Drive slower

 

[aja8888]

Adding to Robbie's on target solution, you can install a taller 5th gear, add air to the tires (not to exceed rating on tires), wax the car, remove the side mirrors and the antenna, coast down hills, and remove the back seat and spare tire to reduce weight.

(I'm bored today)

 

[spiderb_151]

I hear you guys and understand the points . Based on what I read here the ALH with bigger injectors and tune can break 50 on the highway. Just trying to make sure I've checked everything and it's right before I swap this engine into a Golf (this car is a beater!!) I already have. Thanks for your help getting here!!

 

[Nevada_TDI]

Many here will say, "Your fuel economy is controlled by your right foot." While that statement is very applicable it isn't always that easy. On the freeway with the cruise control on 50 mpg is very reachable. With a Stage 3 tune and .205 nozzles, I got 52mpg at 75 MPH using the cruise control.

 

[spiderb_151]

Many here will say, "Your fuel economy is controlled by your right foot." While that statement is very applicable it isn't always that easy. On the freeway with the cruise control on 50 mpg is very reachable. With a Stage 3 tune and .205 nozzles, I got 52mpg at 75 MPH using the cruise control.

That's all I'm getting at!! I figure 50 is reasonable from what I've read here and maybe I can do slightly better under good circumstances and when I don't abuse WOT! Thanks, we'll see how a full tank goes

 

[spiderb_151]

I spoke too soon. I've put 3 tanks on the car since the last post with mileage ranging from 36 to 39. The car does miss at idle a little which is weird but timing looks great when data logging, not sure what else to check. What else can I check to solve this?

 

[turbovan+tdi]

I spoke too soon. I've put 3 tanks on the car since the last post with mileage ranging from 36 to 39. The car does miss at idle a little which is weird but timing looks great when data logging, not sure what else to check. What else can I check to solve this?

If its missing at idle, and everything is good, your IQ is probably too low, you need VCDS to adjust it, that will also affect mpg.

 

[spiderb_151]

I've checked this a few times and found that it jumps all over. Ranges from 4.4 to 5. I had set it to 5 and noticed it had moved but I've never seen it flickering between a range of values. Bad fuel pump?

 

[IndigoBlueWagon]

In your first post you wrote that you replaced the pump. Where did it come from?

 

[TDIJetta99]

Camshaft timing also has a profound affect on fuel economy but there's no way to check it with VCDS on an ALH..

The camshaft locking plate always has a little bit of "slop" when in place.. I have found to get the best economy, you want to have the camshaft on the advanced end of this "slop".. It's not much, only 1-2 degrees, but it seems to make a difference.

Also regarding operating temperature.. The hotter you can get it to run (to a point) the better it will run and it will return better fuel economy. I like to use the 92C thermostat listed for a 2000 Cabrio 2.0 at my local Napa.. They have a Behr brand and a Calorstat brand so no chinese garbage.. They'll run 92-95C (198-204F) according to VCDS and my Torque app.

 

[spiderb_151]

Indigo: I sent it to DFIS in Portland and had them do a full rebuild, bot just worn parts.

99: I have quick warm-up and operate at 92+ . I don't know about the mechanical timing since I bought it as is. Is there a way to check easily or do I just need to do the timing belt install process?

 

[turbovan+tdi]

Also regarding operating temperature.. The hotter you can get it to run (to a point) the better it will run and it will return better fuel economy. I like to use the 92C thermostat listed for a 2000 Cabrio 2.0 at my local Napa.. They have a Behr brand and a Calorstat brand so no chinese garbage.. They'll run 92-95C (198-204F) according to VCDS and my Torque app.

Great info,