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Discussion Starter #1
Hey everyone,
Here's my problem with a 2000 NB 1.8t APH engine, 140K miles. It's been maintained very well over the years, it still looks good and runs good....most of the time. it's become a battle to the end, either it or me is gonna walk away from this!

Sorry for the long windedness, but I know there will be questions and ideas.....I wrote here before in 2009 and have tried all things I've seen on here since including: Coil packs, dealer plugs, MAF sensor, Crankshaft position sensor, Oxygen sensor, fuel pump and relay, EGR valve, all vacuum lines are new, diverter valve...even found the MAF connector disintigrating and replaced it a few weeks back...evidently the dealer did it once already years ago and did a lousy job leaving exposed wiring etc.........I replaced that mess as well....injectors professionally cleaned by local reliable shop....running good fuel........no codes.....no stored codes at all...Dealer mechanics had it for a week, driving it home with a laptop attached......countless hours spent looking for cracked hoses, leaks, loose wiring....etc....

Every time I found a reason to replace an item listed above with a OH man that's got to be it.....often due to finding broken wires, bad connections...even a code or two a few years back.


Under no load driving conditions, I have this intermittent problem. Let me put emphasis on intermittent.

The ECU wants to make unnecessary or at least un-needed fuel adjustments causing the engine to noticably shudder or kind of jerk slightly so whoever is along feels like a bobble head.....Not hard like its missing......just enough to drive a man insane over time.....I can duplicate the symptoms exactly by rapidly pumping slightly on the gas pedal while driving.

I live in a county with emissions testing required, it passes with flying colors.

This only happens on flat pavement, at any constant speed, cruise on or off it doesn't matter. starting up a hill or letting off the gas stops the problem immediately stops.

when it's cold before the coolant temp sensor actuates.......the problem never occurs....it has to be in closed loop to do it.......

Again, no codes, nothing.....not a one.....it's been to the dealer for countless hours of diagnostics, they shrug their shoulders and say........hmmmmmmm........local mechanics have done the same thing......

So, I research and study and every few weeks or months convince myself or find something that causes me to replace another item............the bug is 12 years old, so every item I replace I say.....what the heck it was old anyway.......

Anyone ever had this type of issue? anyone? ever? Throw out an opinion...I would appreciate any idea.

Thanks
 

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Quick question. Is your car a 5 Speed or an Automatic?

Also did you ever check the hose coming off the Turbo going into the metal charge pipe. That hose has slid off slightly once in my case and I had similar symptoms. Popped it back on and no more issues.

If that's not it it could be a faulty N75 valve.
You also mentioned that it did throw a code once or twice. What was that code? Also were those readings taken with a VAG com/VCDS software or a generic
OBDII reader?

Did you try and run the car without the MAF sensor connector attached? Any change?
Did you ever swap out the coolant sensor for a new one? They can cause problems as well.
I know these things can be very frustrating to diagnose.
Hope you find out the problem soon.
 

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Discussion Starter #3
its a 5 speed........the code it threw a few years back was oxygen sensor, we switched that and it went away....The dealer got it to blip a code on the N75 and changed it....didn't help...

I was thinking the coolant sensor is cheap and would be next...

the trouble with that darn turbo area is it's buried and I can't see it very well.......

I touched the wire on the crank sensor and it came off in my hand........thought that was it........but nope.....

yes, trouble seems to remain with the MAF disconnected......although it seemed to get better after I messed with the connector and put it back on..........so I found it all broken with bare wires........made it some what better.....but still there.......last time it did it I stopped and messed with the wiring and connector......didn't change a thing....its funny, I find something odd....think that's it and then it rears its ugly head again....

its almost entertaining now........I refuse to let it beat me.......

the codes were checked at the dealer and a local place....I can only assume the dealer was the real deal.....local guys who knows........I did just ordered a hand held vag-com for my own experiments.......I just got it emission tested today.....and no codes were on there readout listed for stored trouble codes either........

thanks for the input.....
 

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Hmmm, Very strange. Those connectors should break that easily. Do you live in a very Dry climate? Seems all your parts are dry rotted.
I would still check the Turbo hose coming off the Turbo and going to the Metal Charge pipe. It's a bit tricky but it can be done.
And yes do get a new Coolant sensor. I am amazed that they haven't replaced that part yet. That is a very common part known for failure which can cause the issues you describe.

Here is a Genuine VW unit for under 20 bucks. (Dealer charges almost 50)
Volkswagen New Beetle 1.8T > Search > Coolant Sensor > ES#264174 Coolant Temperature Sensor With O-Ring & Clip - 4 Pin - 078919501CKT

Or if you don't like you can give a much cheaper version a try.
Volkswagen New Beetle 1.8T > Search > Coolant Sensor > ES#2535452 Coolant Temperature Sensor With O-Ring & Clip - 4 Pin - 059919501AKTU

I used the cheaper one and it works fine. ;)
 

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Discussion Starter #5
one other tidbit......the MAF sensor is new and from ECS tuning......it looks exactly like the original.....it was on while at the Dealer and I told the mechanic......he said he tested it and it was well within tolerance......so for grins I have switched back and forth between the old and new MAF and the problems is the same either way.......
 

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A lot of people blame the MAF and most of the time it is something totally unrelated. But it's an easy part to replace so people just swap it out and hope for the best.
 

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Discussion Starter #7
I'm one of those people........I blamed the MAF.....however I have a spare now........and I didn't get Boned by the dealer for the cost of it..........so.......I feel ok with it....HA!
 

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Discussion Starter #8
I just looked......those hoses all seem to be ok........from what I can see and feel.......

I ordered a coolant temp sensor.......what do I have to lose....

I thought that sensor was on or off........I figured it worked because the blue cold light on the dash would go off after the car warmed up........but again its a cheap part and gives me another item to eliminate........

Oh.........and no, I live in the midwest..not that dry.....humid......I just figured the MAF connector dry rotted due to age......I haven't noticed any other disintigrating connectors.........
 

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Discussion Starter #10
Yea, the real bummer is nothing is failing......just nuisance symptoms........I look forward to a component failure.....so I can actually find and fix the problem....
 

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What a nightmare. Keep on plugging at it, you're bound to find it sooner later. You are definitely in the right spot, I can tell you, this place is great.

Sent from my ZTE-Z990G using AutoGuide.Com Free App
 

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I just looked......those hoses all seem to be ok........from what I can see and feel.......

I ordered a coolant temp sensor.......what do I have to lose....

I thought that sensor was on or off........I figured it worked because the blue cold light on the dash would go off after the car warmed up........but again its a cheap part and gives me another item to eliminate........

Oh.........and no, I live in the midwest..not that dry.....humid......I just figured the MAF connector dry rotted due to age......I haven't noticed any other disintigrating connectors.........
Where in the Midwest? I am in Indianapolis . If you are not too far perhaps we can get together and both have a look?
 

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Cup- 2k New Beetle GLS/ 'Chino- 13 Beetle 2.5
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Here are my two SWAG'es ...

1) ... check your compression
2) ... check the Secondary Air Pump Valve
:lol:
Haven't heard the term SWAG, since my days in tech school, circa 1983.


Sent from my SGH-T679 using AutoGuide App
 

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Discussion Starter #15
appreciate all the SWAG's.....I will get the compression tested.....luckily got a mechanic in the family with a lift etc......gives us bonding time HA!.....

secondary air pump valve - should'nt a faulty valve throw a code?.....

let me ask this?........I did put an after market front O2 sensor on it a few years back.....it cured the code....but do ya think.....this could be the culprit?.......some say after market O2 sensors are trouble.......I'm beginning to think most everything aftermarket is trouble......its got to be some little thing like this sensor causing this fluctuation in fuel/air mix.....

this is a good site.....I've spent hours reading on here....
 

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oh Sorry Indy.........I'm fairly close to St Louis......

its funny......if nothing else.....I feel like I can actually carry on a conversation regarding emissions and closed loop systems after messing around under the hood all this time.....

truthfully......its kinda enjoyable.....other than the fact I can't fix it.......HA!
 

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appreciate all the SWAG's.....I will get the compression tested.....luckily got a mechanic in the family with a lift etc......gives us bonding time HA!.....

secondary air pump valve - should'nt a faulty valve throw a code?.....

let me ask this?........I did put an after market front O2 sensor on it a few years back.....it cured the code....but do ya think.....this could be the culprit?.......some say after market O2 sensors are trouble.......I'm beginning to think most everything aftermarket is trouble......its got to be some little thing like this sensor causing this fluctuation in fuel/air mix.....

this is a good site.....I've spent hours reading on here....
It definitely could be it... I wouldn't use an aftermarket primary 02 sensor.

When my OEM one failed, I don't believe it ever threw a code but once.. My fuel trims were wacky though not wacky enough to trigger a code. It will only throw a code once it reaches a certain threshold, so maybe your aftermarket one isn't reading right but it's not bad enough to throw a code.

Are you using vag com to check for codes? Sorry if you already mentioned this lol
 

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Discussion Starter #18
I just got a new maxscan vagcom today in the mail..haven't played with it yet....it's cold out there.

I did get it emissions tested yesterday and there were no stored codes at all....

I think I will break down and change that 02 sensor.....you think the ECS versions saying "genuine replacement part" really is?.......the dealer just reminds me of my Harley parts counter........they are proud of their parts and it shows in the prices.....
 

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oh Sorry Indy.........I'm fairly close to St Louis......

its funny......if nothing else.....I feel like I can actually carry on a conversation regarding emissions and closed loop systems after messing around under the hood all this time.....

truthfully......its kinda enjoyable.....other than the fact I can't fix it.......HA!
Have you ever checked the Catalytic converter?
Did you also change the post cat O2 or just the pre O2?
 

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I just got a new maxscan vagcom today in the mail..haven't played with it yet....it's cold out there.

I did get it emissions tested yesterday and there were no stored codes at all....

I think I will break down and change that 02 sensor.....you think the ECS versions saying "genuine replacement part" really is?.......the dealer just reminds me of my Harley parts counter........they are proud of their parts and it shows in the prices.....
Well before you replace anything else I'd do more diagnosing..

um, what is maxscan vagcom?

Also, I'm not sure about this, but emissions testing doesn't test all of VW's modules does it? AFAIK they check readiness.. but I dunno how all that works.. Oklahoma doesn't do emissions and I'm catless :p
 
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