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Discussion Starter #1
Hey all, just bought a 2002 TDI Jetta for my daughter's first car. Have some experience with diesels, albeit along the 7.3 Powerstroke vein. Heard good things about the TDI, car seemed like a good price for Alaska, and I can't stomach the thought of a Prius in the driveway, even with gas at near $5.

However, even though it ran fairly well on the test drive (wasn't sure what to expect from a 1.9), the thing has turned into a pig in only a couple days. Won't get out of its own way, WON'T pull a hill, and just generally a pain in the a double snakes.

Reading through everybody's posts just as soon as I can; hopefully I'll find something that cures the problem. I probably won't be doing much beyond minor maintenance on this thing due to a busted-up body and patience factor, so any help/recommendations would be helpful.

Thanks all! Look forward to reading and interacting.
 

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Have you looked in FAQ mk4 section low power, scan for codes. It could be something as simple as a bad MAF or fuel filter. But again looking in the FAQ will narrow it down, good maintenance section as well.
 

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I have been tearing that section apart...

I'd hate to rip the intake off, but that may be what has to happen. I did perfprm some of the MAF tests, and while unplugging the harness made absolutely no difference, the engine will rev to the limiter in neutral, but only interemittently. Sometimes she will, sometimes not. Will always make it to the 4500 range, just not always higher. Yesterday added a pint of Sea Foam to a topped-off tank (she got a little smoky this morning upon start-up, figured that would be the additive); today's task is replacing the fuel filter (maybe a fuel supply problem?), probably replacing the MAF (only one I can find up here sub-$250 is from O'Reilly's...is that going to be an issue? It's definitely not a Bosch part, it's the "lifetime warranty" knockoff), and trying my best to look for leaks.

Took the car to the military base and one of the mechanics scanned the codes. Found #1 glow plug fault and an overboost fault. He cleared both codes and we took it out for a spin, but nothing changed. Didn't re-scan, so not sure if the codes showed back up again. I can't remember the actual code numbers, just read the text.

What are the turbos supposed to sound like on these little guys? When the 7.3 kicks in, you hear it and feel it, no doubt it's working (nice to have the boost/EGT gauge for visual verification...hehe). When the Jetta is parked next to the ruck and I have the door open, I THINK I can hear a little turbo whistle on rev-up, but it's very quiet. What am I looking for in sound/feel on what I assume to be a stock, high mileage TDI?

Well, better get after it, wish me luck and I'll keep you posted.
 

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IMHO, have a genuine Bosch MAF shipped instead, these things are sensitive enough already and someone else said that a genuine Bosch fixed their problem. The overboost fault sounds like something related to turbo control. could be vac lines, solenoid, wiring, vnt actuator, or internal sticking turbo. Take a look at the VNT actuator adjustment FAQ article to isolate it.

Low power is not related to glow plugs, you may just need a new harness or glow plugs, or even just cleaning of the contacts.
 

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Installed a new fuel filter, then made a run to German Steel here in Anchorage. They put the Ross-Tech (no charge! Thanks, James!!!) on it and found the following:

P1570 - Engine start blocked by immobilizer---intermittent
P0102 - Mass Air Flow Sensor (G70): Signal too low
P0671 - Cylinder 1 glow plug circuit (Q10): Electrical fault

Not sure what the 1570 is, never had a problem with it starting. Seems like I've read someting on here about the 0102, so I'll be reading some more, and the 0671 I'm not too worried about since, as you pointed out chitty, it wouldn't contribute to the issues I'm having. Well, not concerned until winter hits anyways, then it might be something to get fixed unless I want the daughter to walk for 8 months. hmmm.....

I will look for the Bosche MAF, though, thanks. Actually have made an appt to take her back to GS later this afternoon just to have someone who knows what they're doing put eyes on the whole car and let me know what should get done first. There are some chassis and brake things happening, doesn't feel critical, but I'd like to be sure.
 

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On the MAF, I would first try cleaning it with some electric spray cleaner (most auto parts stores should carry some, some might even say MAF cleaner). After a while they tend to get dirty and cause the car to get very sluggish. Pull it out, spray all the metal parts of MAF really well, you can't use too much, make sure you get the little straw in there and spray it down as good as you can, and give it a try. As long as the MAF isn't actually bad, I bet this will fix it.

You will need to get a secure Torx wrench to pull it off. I can't remember what size off hand but if you go to an auto parts store they should have a simple set of them that has the secure Torx on one side and normal Torx on another (looks like a round allen wrench but with the star shaped Torx on both ends). Something like this set. Just make sure one of the sides has a small hole in the middle, that is the "secure" part of it.

My TDI was extremely sluggish when I bought it, but didn't know it. I just figured 90 hp wouldn't feel all that quick but I let a friend drive it that had driven other TDI's and he told me it wasn't running right at all. Another friend that specializes in VW's told me to clean the MAF. Did that, put it back in and it was a new car right away.

For whatever reason a lot of the newer MAF's seem to do this. Had a 2000 Toyota MR2 Spyder that had the dirty MAF issue, an '08 Mazda CX-7, etc. I've decided to clean the MAF at every oil change, since the interval is pretty long on these. It will do wonders as long as your MAF isn't actually bad.
 

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The Good, the Bad and the Ugly:

The Good:
Did the MAF-cleaning thing (thanks MAchZ), unfortunmately no real difference. Purchased/installed new MAF and the car actually felt like a turbo-charged diesel! The difference was very noticeable.

The Bad:
Hit the highway and nailed it. The car leaped to 80 then hit what I'm guessing is "limp mode". Everything was back to pre-MAF replacement status. Got off the highway, turned off the ignition, re-started and I had power. Most hills it'll pull hard until I get the accelerator past about half way, then drop into limp. Re-start sets it back to good, and it stays ok as long as I baby the go pedal. It wants to run, I can tell. Is there an accelerator sensor that does this?

The Ugly:
Oh yeah, that's me.
 

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The only accelerator sensors that I can think of off the top of my head is the speedometer, engine speed sensor, and accelerator pedal.

On the bright side, now that you're limping it should have thrown a new code. The usual suspects are the vac line or turbo control system. Take a look at the VNT actuator FAQ article on how to isolate any possible problems with this system.
 

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I'll have the codes looked at again tomorrow, and I'm curretnly reading the boost leak test procedures...guess I'll have to break down and buy a cable if we're keeping this car. Seems to have too much potential to abandon it at this point. Even with all the touble, to include me mashing the pedal far more than usual, the thing looks like it's getting in the 35-40MPG range. SUCK IT, Prius!
 

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map sensor

If you change map sensor and no difference chances are broken wire close to the connector you need a scanner to see if you have a reading on the map sensor clear code when fix if you get over boost some times turbo gets sticky from lack of use if all systems check out ok you can try getting the car hot and slowly day by day bring the rpms higher to try and free it up won't happen over night try to keep it from throwing the code shift at 3k rpm for a week when car is hot hold to the floor threw the gears not to pass 3k rpm after that to 3.5 for another week and so on it came back for me may not work for all of them but worth a shot
 
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