Revs at start-up and no power...

Hi all. I hate to start a new thread but after a week of searches here, trying several things suggested in the various threads I've read, I am nowhere with my results.

Subject car is my 2003 Jetta TDI ALH with 159,000 +/- miles. I drove about 50 miles and stopped in a restaurant for a bite to eat last week. When I got in the car to start and leave, the engine at start up revved up to about 1900 RPMs and I thought what the heck?! When I got out on the roadway I noticed low power, it was all I could do to get to 65 MPH. I hobbled home and started reading.

The engine check light never lit up. Before you ask what the DTCs were, I don't have a VAG-COM or code reader (yet). I was just trying to catch something simple first before I got into the big money stuff.

Foot off the throttle pedal, the engine only revs up at start when at operating temperature, but will rev up every time at start up. When cold, it starts normal and idles fine.

What I've done so far to fix the issue(s)... New fuel filter, new air filter, new engine coolant sensor (under thermostat housing), EGR delete kit, inspected intake for blockage (wet with oil and black gunk but wiped out with a carburetor cleaner soaked rag to bare aluminum), cleaned existing MAF sensor (test drove no improvement), installed MAF sensor off my running 2000 TDI (test drove no improvement), looked at O-ring on fuel shut off solenoid (test drove no improvement), installed fuel shut off solenoid from my running 2000 TDI (test drove no improvement), engine's vacuum pump is pulling 27 hg at furthest port (egr), pressure gauge shows about 19 psi boost under load returning to about 1 to 0 psi when let off throttle pedal, Turbo holds vacuum (the VVT actuator) and doesn't stick.

Timing belt was done at 100k miles.

I'm sorta new to these TDIs, but have been driving them since 2011. My 2000 has 339k miles and until I robbed parts from it, was still running fine.

I'm all ears to suggestions! Thanks

Are you sure that you have a 2004 with an ALH? Could you look at the tenth digit of the VIN and let us know what it is?

You mentioned pulling the fuel shut off solenoid, so I assume that it is an ALH, but is it a 2004?

Anyway, get the VAG on it and let's see what's going on.

I have read that the limp mode for a bad go pedal position sensor is a high idle.

Seems worth checking based on your symptoms though I'd have thought it would set the check engine light.

Seems to me the light should be on no matter what the cause if it's running that bad???

Thanks for the quick replies!

Duh, 2003... sorry.

VIN is 3VWSP69M63Mxxxxxx

I guess I should go ahead and get a VAG-COM ordered. There's the first 'big money' but the money it will save in time and aggravation will be made back several fold.


I kind of suspected the throttle position sensor from the beginning, but what I read up to this point pointed me everywhere else.


Just for further clarification, the check engine light comes on when I turn the key on and stays lit until I start the car. After started, it goes out like it normally does, so the bulb is not burnt out. This weekend I can swap out the throttle sensor from my running 2000 TDI. If that doesn't correct the issues, I'll order the VAG-COM and see what the ECM sees.

I see you've replaced a lot of components, how about the dumb stuff? Vacuum tubes, big pipe connections. Isn't there a coolant temp sensor behind the coolant glow plug?
Best clue I see is normal operation when cold.
You can stop by a parts place for a scan, it might help, be sure to record it exactly, it will help you determine if there read was good.

BobnOH said:

I see you've replaced a lot of components, how about the dumb stuff? Vacuum tubes, big pipe connections. Isn't there a coolant temp sensor behind the coolant glow plug?
Best clue I see is normal operation when cold.
You can stop by a parts place for a scan, it might help, be sure to record it exactly, it will help you determine if there read was good.

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Yes BobnOH, I did check the vacuum lines and the piping involving the turbo, sorry, should have mentioned these as well. I did replace the coolant sensor behind/below the vacuum pump (new, green for green), is there another?

What operates ''normal'' at first start up is the idle (no rev-up). there is no power when cold either. The car only has a touch of power at 1/8 inch (3 ~ 4 mm for the metric guys), of pedal pushing. I can manage to get it to 80 mph driving in this manner, but it's slower than granny leaving a green light at take off.


*** Update ***

I changed out the diesel throttle pedal assembly from a known running TDI and no change.

*************

Off to find someone with a code reader. I am totally stumped!

So it's low power all the time. The codes will help, but there certainly are some simple things you can check. Drive with MAF unplugged. Watch the actuator when the car is started, it should move over. Try going thru the low power link in my signature, it's a lot, but may give you some ideas.

Thanks Bob, I had actually read through your links and tried a lot of those simple tests. I have driven with the MAF unplugged (plug just after air filter), no improvement. Took MAF off my 2000 and installed on this one, no change. I'm pretty sure the vanes aren't sticking (used a mighty-vac, pulled vacuum and lever did a full pull, held vacuum and returned fully when released without hang-up or noise).

Bottom line is I have to buy a Ross Vag-com. I bought a cheap E-bay one that doesn't work at all (wasted $13+). It's just $220 is hard to cough up at the moment. The local Advance Auto Parts store here stopped code reading and I don't want to waste $90 on a generic code reader they sell that probably won't go into as depth (I know it won't) as I need it to go.

What's the history with this car?

How long does the high-idle go before settling down (what happens to make it settle down)?

UhOh said:

What's the history with this car?

How long does the high-idle go before settling down (what happens to make it settle down)?

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Car has ran flawlessly up to now. I bought it with 128,000 miles on odometer. It has 163,000 on it now. Changed oil every 5000 miles with T6 Rotella full synthetic. It revs up like you blipped the diesel pedal at start-up (up to 1900 rpm and back to idle) after it's at operating temperature. It does it everytime. It is repeatable. Thought maybe the cat was clogged, but plenty of exhaust blows out the tail pipe. When cold, it starts and idles fine. No power over 1/4'' of throttle pedal push whether cold or hot.

There is a sweet spot at about 1/8'' to 1/4'' pedal pressing when driving. Beyond that, (1/4'' pedal to full throttle), it is as if you let off the pedal and it returned to idle. Been driving it this way for 1,100 miles. I need to go to work and don't have time to really tear into it further. using only that much pedal, my mileage has gone to slightly over 50 mpg, was around 47 mpg beforehand. I drive 90 miles one way each day (180 round trip). Where this Jetta costs me like $7 a day in fuel, my diesel truck costs $26 a day. When my current job location finishes up and I'm back to a 45 mile trip, I will look into it or take it to the dealer if I need to leave it and drive my truck. I'm kind of rolling the dice. the equipment to diagnose it will cost a good $250. Dealer will probably charge me $125 just to look at it. I just don't trust they will properly find the problem.

Just installed a new Bosch fuel shut off valve and no change. Still revs up like you blipped the throttle at start up and still no power. I'm starting to suspect it has a dead cylinder. Everything else is new related to the high revs at startup threads I have read. I know of no competent dealers around me to trust to look at it. I don't want some wrench jockey throwing parts at it until they happen to fix it, (bad turbo! oh that didn't fix it, now what?), lol, I can do that.

Trusted TDI mechanics in Maryland

http://forums.tdiclub.com/member.php?u=16069

And the trusted TDI mechanics link

https://docs.google.com/document/d/1Lucw8ALCkLtt79MMw9JOG1E_dX57-raBhbhIFdtHnEQ/mobilebasic?hl=en_US

Without scanning for codes it's hard to say.
Maybe a local parts store can do a free scan?
I'm starting to wonder about N108 (injection quantity or such).

Last thought.
Check for bad grounds or frayed wires for the harness that feeds the injector pump.
Not the 1 power feed wire, multi wire plug on the side.

Need to stop messing and guessing and get this car scanned.

Thanks for the replies... My local parts store said they don't scan anymore. Apparently they rather sell a generic scanner to me. The trusted mechanics list has one for maryland, the link to his website is dead and an email was sent.

I followed the wiring and see an extra wire going to the fuel shut off solenoid. it goes to a small box on the firewall as if there is a break in the original wire. I disconnected it and the car would not start. reconnected it and all is fine.

I will try to go to one of the competent mechanics on the list even if I have to drive deep into Pennsylvania to find one. I'm wasting everyone's time posting my problems here. Just thought I'd catch something simple by asking.

I had this same symptom when my injection pump was going out, I didnt have vcds at the time and only had a generic reader that I was able to get codes off of. Vcds is so invaluable, if you plan on keeping the car for a while you should invest in one.

Sorry for joining in late. One of the things that killed a lot of power in my 01 was leaves, goo and acorns built up on the snow screen. Look in the tube between the air box and and the left headlight. Mine was completely clogged. The trap door worked but i'm sure it does not allow for efficient air flow. It only takes about 10 minutes to clean with a philips head and 10mm wrench.

I just went through similar symptoms, and my pump is junk. Out of nowhere i somehow got some water in my fuel which ended up in the filter and thereby got into the pump. I got no codes at all in the beginning, just "dead pedal" that would (in the beginning) go away but I still had no real power above 3000 RPM, and now just doesn't even start. After a couple of phone calls to the guys at DFIS in Portland, and nothing but good reports from the guys here at TDIClub regarding DFIS, I mailed my pump off this morning to them, they will call me with the diagnosis this coming week. Whatever it costs, it will be less than buying a new pump from Bosch, and if I have any questions I have someone I can talk to directly to get some answers. I will keep you all posted.

Nevada_TDI said:

I mailed my pump off this morning to them, they will call me with the diagnosis this coming week.

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I read the injectors should be rebuilt around 150K miles.
Did you ask them if they should be done also?
Don't know the mileage on yours.

At 150k miles, most here would suggest having your injectors rebuilt. It is also possible that the nozzles have worn out of spec and should also be replaced. A set of one size bigger than stock nozzles will improve power and FE if you are gentle on the throttle and the cost should not be prohibitive. My nozzles were rebuilt by DBW 60,000 miles ago, but now that my car is down, I will call him to see how busy he is.

I know this is an old one, but I'm having the same symptoms. Did you figure it out?

According to records, DieselDay hasn't been seen since 2017. What codes are you getting?
It's long, but you can try the low power thread in my signature.

I had code P1537 for N109 solenoid. I replaced it and it was better for one test drive, then it went back to no power above maybe 1/4 to 1/3 pedal. And when I started the car it revved up, then back down to a normal idle.

Codes are just clues for troubleshooting, not directions to just replace named parts. Often it's just the wiring/connects.
Here are a couple that list solutions
ALH Start-up High rev? | TDIClub Forums
3000rpm rev at hot start | TDIClub Forums
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