No acceleration/cruise control...Update: intake

[AVE_ENG]

2000 Jetta, 155,000kms, 5spd. Never had a CEL, and it gets Powerservice white every other tank.

It's got no giddy up in 4th and 5th gears at highway speeds, and the cruise control doesn't maintain speed on even slight inclines. I also have a hard time getting any power after 3000 rpms in any gear. Actually revving past 3000 in 1st is like braking.

Please give me some logical troubleshooting steps. Where to begin?

 

[DieselFumes]

Re: No acceleration in 5th, and cruise control sucks

Disconnect the MAF to see if it improves performance.

 

[JoeHafner]

Re: No acceleration in 5th, and cruise control sucks

Have a look also inside the EGR Valve and the intake manifold for oily soot build up which restricts airflow to the engine. This is very comon. Joe

 

[CraigSmith]

Re: No acceleration in 5th, and cruise control suc

If not MAF, could it be that the fuel filter is clogged?

 

[Dave_D]

Re: No acceleration in 5th, and cruise control suc

Also check the snow screen if it has one and has the air filter been changed at the proper interval?

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

Disconnect the MAF to see if it improves performance.

Can I drive extensively with it this way? Such as on my 80km commute home?

 

[jaydhall]

Re: No acceleration in 5th, and cruise control sucks

Yes. I have driven over 1500 miles this way. (MAF died on trip to California, of course.) And I REALLY think it is the MAF. When mine have gone out, the first thing I notice is the cruise not working.

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

I unplugged the MAF, and the only really noticeable effects were: a bit stronger torque in 1st and 2nd off the line, I can hear the turbo spool up sooner, 3000rpms still seems like a brick wall in 1st, no improvement in acceleration in 4th and 5th.

Maybe I need to do some more experimenting?

Could this have anything to do with the N75? Not sure where that is, but I keep seeing it mentioned.

 

[jaydhall]

Re: No acceleration in 5th, and cruise control sucks

Unplugging the MAF only helps the low end. I think you need a MAF. Try a friends or vag yours.

 

[spdrcr]

Re: No acceleration in 5th, and cruise control sucks

I had a bad MAF, but it didn't change much unplugging it and when we put a vag-com on it the requested and actual were pretty good. However when we swapped MAF's with a good running car it did the trick, so try to find someone who will let you try theirs to confirm. I'm betting that's the problem.

 

[TDIDarryl]

Re: No acceleration in 5th, and cruise control sucks

I had the exact same problem when my MAF went south. Unplugging the dead MAF gave no noticable impovement to me either.

I met up with a fellow TDIClubber and checked actual vs. specified air flow to determine that it actually was the mass airflow sensor, I replaced it with a Pierburg (at that time you need a second mortgage to buy a TDI MAF) and fixed the problem.

You can always sell the MAF in the classifieds if it isn't the MAF but I'm pretty sure that that's your problem.

Check with Guelph VW, they were really good about replacing my friends MAF under VW Goodwill at 100,000kms. Before you wheel in there though, and once you're sure that it is the MAF, pull over and unplug it (the MAF) to trigger a CEL to help the technician diagnose the problem.

Otherwise you'll pay a week's labour for the knuckleheads to figure it out. Nevermind the price of the new fuel pump, cruise control module, shocks, steering wheel, headlamp fluid they'll replace during the course of their diagnosis.

 

[craig01b]

Re: No acceleration in 5th, and cruise control sucks

Guelph VW wasn't nearly as nice with me....over 500$$$$$

I put a pierberg in. Works great.

Avery, send me a pm, I live nearby and have a vag com if you want to check it out....

Craig b

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

Thanks all. Craig, I'm gonna take you up on that.

Cheers.

 

[Wingnut]

Re: No acceleration in 5th, and cruise control sucks

The retail price at the dealer for a TDI MAF is now $112. So not nearly close to the $400 + it used to be

If you want to save a few more $$$, you can mail order one from Brian Harrison. Great guy to deal with and ships quickly.

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

Did some diagnosing today with the help of craig01b. 1st we VAG'd to check for codes and response levels of the MAF. There were no DTC's and MAF levels looked normal. So, we proceeded to swap my MAF with Craig's, a Pierburg.

No joy. There was still not enough juice coming in 3rd to 5th gear, and the turbo was unusually quiet. Went back to my MAF, and looked into turbo and wastegate regulator valve measurements.

My idle measured roughly: 900rpm, ~990mbar specified, ~985 actual, 24% (not sure what the % means, but it wasn't within the 45-95% range stated underneath in VAG-COM).

There's also a procedure to test the turbo at 3000rpm and WOT, so we gave this a try. The readings, (from my vague recollection) were low: ~1600mbar actual, and only ~36% MAP (?).

Could this mean a stuck actuator? Since no codes were thrown, I need a bit of guidance from here. After reading a few threads about VNT acuators, I checked mine from above. It was tight at first, but I got it to move freely. I greased it as best as I could with some PC Duron (all I had on hand). Next time I get under the car, I'll do a better job, but I think it's far from seized.

There's still a major power deficiency and the turbo is all but silent. I can only hear it slightly at higher rpms, but I sure don't feel boost.

Bad N75 maybe? And how come there were no codes?

edit: I forgot to mention that I measured resistance at the N75 connection, and it was 20 ohms on the dot.

ps - Thanks again Craig!

 

[GoFaster]

Re: No acceleration in 5th, and cruise control sucks

See if there's vacuum being supplied to the hose that leads to the VNT mechanism. You don't need to disconnect anything to do this. If you reach your fingers way down behind the engine, you can put them on the linkage for the VNT. Get someone to start the engine while you have your finger on it, to see if it moves. (BE CAREFUL - but it is possible to do this without getting your finger squashed.) If it doesn't move, disconnect the hose and find out if there's vacuum being supplied. No? Disconnect vacuum supply to N75 and see if there's vacuum with the engine running. Yes? N75 is bad. No? There's a leak or a wrongly connected hose somewhere.

 

[Northman]

Re: No acceleration in 5th, and cruise control sucks

I just went through the whole routine that you did on my 2000 with 160Km. Had a little peek in the egr with the pipe off and looked not too bad. Finally pulled the egr off and couldn't believe my eyes. The intake was practically closed right off with soot. I couldn't even get a small screwdriver through. Took me about 8 hrs to dismantle and clean using info from this site and now all is well and I have an extra MAF if I ever need one. Good luck on this I know how frustrating this is.

 

[craig01b]

Re: No acceleration in 5th, and cruise control sucks

Avery....no simple fix here, keep looking, I am off next week Monday thru thursday....lube that n75 rod, and I am off next week again.. We can do the clean out, and print out the mod for egr....we can twiddle with the vag com next week.

CB

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

OK - I took the EGR off just for kicks. Low and behold....

I don't know if this is my only problem, but it's a problem for sure. I guess I'll be reading lots of 'How To Clean Intake' posts tonight. Ughh.

 

[craig01b]

Re: No acceleration in 5th, and cruise control sucks

Holy mess batman.....

Would explain a few things...happy digging.

Craig

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

Well I'm in the midst of my intake cleaning weekend. It kind of became a coolant flush at the same time since a lot spilled out of the exhaust cooler before I could stop it. Not much warning about this in other posts.
Damn some of those manifold bolts took forever to get out.

This job sucks.

Question, is the EGR piston supposed to be free moving when it's all cleaned and everything? Mine isn't, and I don't have a vacuum vessel to test it. Could it be broken? Could I be so lucky?

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

WOOHOO the job's done. I have all the power back and it revs like a madman in any gear. Cruise control is no longer laboured either.

I sure hope I never have to do THAT again. Craig - need your help to do the EGR mod, if that really helps. I would also like to experiment with disabling the EGR since mine is a MY2000, rumour has it that no engine codes will be thrown.

 

[Wingnut]

Re: No acceleration in 5th, and cruise control sucks

Glad you got it done. But if you ever have to do the job again, there is no need to remove the EGR cooler. I just tie it up out of the way with some wire. No fluid loss and the job goes quicker that way.

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

I only disconnected the rear hose, but yes, I can now see how unnecessary that was. I also removed the heat shield, which was pretty straight forward and gave me a chance to wire brush the rust off.

 

[karlb13]

Re: No acceleration in 5th, and cruise control sucks

I am having the exact same problem as you described... but... I cleaned the intake and nothing improved. I was a bit disappointed to see mine wasn't nearly as gummed up. Sooooo... I am not sure where to go from here. I wish the CEL would appear to point me in a direction. Driving isnt nearly as fun. Maybe the MAF I guess...

Anyone have a VAGCOM on the central coast of CA? I am near San Luis Obispo.

 

[AVE_ENG]

Re: No acceleration in 5th, and cruise control sucks

A VAGCOM will surely help you determine if it's the MAF. You may also want to dig around with the turbo actuator valve N75, and check vacuum lines. Do some searches on these, there're lots of topics related to lack of boost.

 

[karlb13]

Re: No acceleration in 5th, and cruise control sucks

Yeah, I did the check where I stuck my arm behind the engine, had the wife start the car and the actuator moved, so I figured all was well with that.
I am sort of going through the list of possibilities and trying to eliminate everything before I purchase the MAF.

 

[weedeater]

Re: No acceleration in 5th, and cruise control sucks

When it happened to me, it was a vacuum leak. a hose fell off from the vacuum resevoir.

 

[karlb13]

Re: No acceleration in 5th, and cruise control sucks

Update!
Ok, I never found anyone around me that had a computer setup and my car was so slow, so I finally gave in and took it to the dealer.
[After cleaning the intake manifold, changing fuel and air filter and snow screen, checking vacuum hoses, cleaning and greasing the maf contacts etc... I finally thought "Well it must be the MAF gone bad." Soooo, I could have just tried buying a MAF and installing it... but i didnt.

Long story short, the dealer diagnosed it and agreed it was the MAF. I had them install a new one, and my Beetle is back to life! hooray!

For information: ~$250 when all was said and done out the door. ($85 of which was diagnosis!) The MAF was surprisingly reasonable at $77.

Note: They said you need a computer setup to "match" the computer and the MAF so if I had installed the MAF myself, it wouldnt have worked right. I dont think that is true...?

In any case, they fixed me up and it didnt cost too terribly much.

 

[paramedick]

Re: No acceleration in 5th, and cruise control sucks

Let's see. The MAF costs a max of $80. Disconnect wiring and corrugated tube to air intake. 2 phillips screws to R&R. Hook wiringand corrugated tubing back up. 10 minutes, tops.

Yup, the dealer took your measure and laid one on you. Absolutely NO computer matching of MAF and ECU.

Sorry.