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Discussion Starter · #1 ·
Help! We've had the car for about 10 years and haven't drove it much in the last 2 years but it was running great when we stopped driving it.
We're pretty stumped and have searched for many hours trying to find what's wrong with my kid's bug
99 VW Bug 2.0L gas 4speed auto trans. When the engine is cold everything runs great, trans shifts up and down fine, but after it warm's up and the cold light goes off it will struggle shifting. It wont shift into 2nd unless I let off the gas for a second and then it shifts into 2nd. Increasing the speed it wont shift from 2nd to 3rd unless I put it into neutral, let off the gas till it idles, and then give it gas again and then its shifted to 3rd gear.
There's no codes that show up and we've replaced temperature sensor and we did a check where we disconnected the forward O2 sensor.
Transmission fluid and filter has been changed and filled to proper level while running at around 100F.
The car isn't overheating and overflow is full. We checked most of the vacuum lines except the one next to the spark plugs.

Thanks for any ideas
 

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What scan tool; are you using? A VW specific type; like VCDS by Ross Tech, can read transmission related codes and view live data. This might give you a clue; as to what is going on, the shift solenoids sticking and worn valve bodies, are the most common fault but there could be other internal issues or external problems, like wiring harness failures, plugs, etc.


01M diagnostic videos:

 

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Discussion Starter · #3 ·
What scan tool; are you using? A VW specific type; like VCDS by Ross Tech, can read transmission related codes and view live data. This might give you a clue; as to what is going on, the shift solenoids sticking and worn valve bodies, are the most common fault but there could be other internal issues or external problems, like wiring harness failures, plugs, etc.


01M diagnostic videos:

Thanks for the reply, we checked it with our ross tech VCDS scanner and are able to read transmission codes. We had a knock sensor code which turned out to be the plug not plugged in all the way.
We also went to a shop to double check our scanner where the guy said his scanner was a $10k scanner and he checked everything and found no fault codes.
Curious on why it would shift perfectly while cold.
 

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Do a full autoscan with VCDS and post anything you find.

For sticking shift solenoids; they can work fine when cold and then, heat expands the metal, then they can start sticking.


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Discussion Starter · #6 ·
Hi, bug still running not running right! and NO CODES.

Runs perfect for 1st 5 minutes when cold light is on.; then gradually has less and less power and after 15 minutes, it will barely make it up a hill. (I think this is why it wasn't shifting correctly.. If I pop it in to neutral and back to drive, it always shifts).
Tested fuel pressure and fuel volume, as per manual and both are ok.
Changed fuel pressure regulator because it fell apart when taking it out - new Bausch.
< I am an Old street rod builder, SBC I can handle, this bug is eating me up, lol.

I have searched and read sooo many threads.

Things I HAVE changed.
Wires and plugs - about 10 years and 2,000 miles ago
Recently changed - oil and filter, trans oil and filter, gas filter, temp sending unit, fuel pressure regulator

Possible? reasons for no power with no codes?

Things I HAVEN'T changed:
MAP sensor, knock sensors, ignition coils, Cat convertor,

All help or ideas would be greatly appreciated.. I hate being a parts changer, but I am getting desperate..:unsure:
 

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You have VCDS; did you do a full autos-scan and review the results?

Please posit; if you find any thing.

I would be checking things like the maf sensor and fuel trims, etc. and these are when the engine is running (live data).


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For the testing results; can you post the specific data and that will help us, help you.

As tot the current history, of the vehicle and when the car wasn’t driven much or was dormant for two years. Did battery die (?); you can sometimes lose the throttle body settings and the throttle body can be dirty, which can make rhe car run poorly.



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As to maf testing and a poorly running 2.0L; here is a recent discussion, where we worked through troubleshooting things and found a maf issue, among other things causing a drivability issue.

 

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Discussion Starter · #12 ·
Whoa! thanks for all the replies!. lots for me to do and test. :)
I tried to do the full scan, but the 7th number in the vin was not listed as one i could choose, so i just picked VW Beetle. I will do it again tomorrow and report where it stopped and what it said.

The Battery was 'deader than doorknob for quiet a while.. so prob lost all settings, then that battery went bad, now has new battery, again.

It runs sooo good for about 5 minutes when cold, and every time I fix something, I think 'I got it fixed!' lol.. but sadly, no...
 

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Discussion Starter · #14 ·
Hi, I have been working on the bug.. unfortunately no change..

Soo, I cant do an auto scan since I have what you call the 'cheap Chinese cable', but I can scan each module individually.. no codes.
I took the bug to a garage last week where the guy said his scanner cost $10k and it would find codes if the bug ever set one... no codes

I cleaned the throttle body and re-set the throttle body.
I can't get to block 32 or 33 with my cable.
I found this MAF testing procedure Part 1 -VW Mass Air Flow (MAF) Sensor Test (5 Wire Type) and will do this when I can get some help.
I am leaning towards replacing the MAF sensor, only one I have found so far was on ebay and used..
Anyone know of a place to buy one reasonable?

I am still baffled as to why it runs perfect when cold, then no power when it warms up, and why no one here seems to know why this is happening, and why there is no codes..

In my many hours of reading threads, someone said that the water temp sending unit <I replaced this with a Bosch>, and the forward O2 sensor does not send info to the computer when cold.. true? any other sending units do this too?

I will see if my friend in Houston will mail/loan me his scanner if it will do the bug.. If not, I will try and find a garage locally here in Colorado that has a Ross Tec that will do an Auto Scan for me.

Thanks!

Me 2 baffled ;)
 

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Discussion Starter · #15 ·
Seems 2 codes have now popped up..PO300 and 301.. guess I will look at the coil packs and wires and plugs.. I replaced these ~12 years ago and about 10,000 miles.
At least a got a couple of codes, lol
 

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As to checking the maf and fuel trims; you could probably rent a scan tool from a auto parts store or buy a cheap vag scanner or even a cheap wireless elm327 would be helpful. Then, you could view live data; refer to the discussion, i linked to above, to see what is considered normal readings at idle and in 2nd gear @ WOT (wide open throttle).

A affordable oem Bosch maf; can be purchased, at places like autohausaz and fcpeuro. Refer to the discussion;!for more details.


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As to the misfires; it seems to be specific, to cylinder #1? So, check the spark plug, wires, injector, compression, etc.

A common problem, is the coil pack; may develop a crack and cause arcing, grounding out, misfires.

Here are some testing techniques; using a spray bottle:



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