Mk4 Tdi issue

[James Spagnuola]

Hello after doing so much research and not finding much help I’m here my 2001 tdi is having issues and idk where else to look to start off my obd2 is have a (linking error) also the car starts right up every morning and runs fine till I get to work shut it off try to re start it and it starts then stalls for a few times then will re start after trying it a bunch of times Iv tired both keys the immobilizer light goes right off after ignition is turned on. When car stalls it sounds like a old vacume when shutting it off as well Thought maybe injection pump but changed it still having issues any help would be great thanks!

 

[STDOUBT]

I don't know the solution since it never plagued me, but this sounds like the "hot start" issue.
A well-known issue. Here's a thread to get you going. The answer is on this site somewhere.

Hard to start when hot issue.....

My '99 A4 Jetta has been hard to start when hot since I bought the car. This is my third VW diesel and I thought that this car would operate like the others. I was used to putting the key in the ignition and b-a-r-e-l-y turning the key to have the 'beast' start. The timing is good, nothing...

forums.tdiclub.com

Also, VCDS would be a smart move since generic OBD scanners can never tell the whole story on these cars.

 

[James Spagnuola]

Not sure if it will connect the car with it having the linking error I took the radio out unplugged it still nothing changed the 109 relay still nothing

 

[Mongler98]

So. The only way to do this cheaply (not throwing pointless parts at the problem with no idea of what the issue is) is to fix the obd2
I have had issues with the link as well.
1. Proper vagcom cable. No ebay knockoff stuff ok!
2. Make sure the obd2 harness is not tapped into by anythjng else. For instance, I used a scangauge II and I used a obd2 splitter. I can scan codes with a generic scanner obd2 tool and use the scangauge at the same time but ots hit or miss and my vagcom cable will not work unless the scangauge II is unplugged. So make sure no one has messed with it like that.
3. Their are a good handful of codes your car will store that will not trigger a check engine light. And using vcds to look at the fueling and timing would be a big help. A log would be awesome as well.


What comes to mind

Hot start issues (things warm up and are worse) like a fuel line with a crack in it that only showes up when it's hot enough.

Timing. Just for kicks, put the timing belt and sprockets at tdc and see if anything is not aligning up. Check the health of the belt too. No visible issues or missing teeth. These belts are really only good for 5 years or like 80k miles. Whatever comes first and any little bit if diesel or oil spray that gets on them kills them. I don't want to worry you but it kinda sounds like the crank sprocket walk issues. Only way to tell other than pulling it off is to check with vcds.

I know it sounds noobish but check your battery too. Same with your wire harness for wearing areas or areas that move too much that could break a wire.

Honestly your goal here is to fix the obd2 otherwise you are chasing a rabbit you wont catch with out a lot of luck.

 

[BobnOH]

Could be a sticking anti-shudder valve.

......................................snip........................................Thought maybe injection pump but changed it still having issues any help would be great thanks!

Wow!

 

[Mongler98]

im fairly sure OP means pick up pump. but the IP. you don't just replace an IP so nonchalantly, especially if you can not use the OBDII port on the car. im 99% sure he meant the intank pickup pump.

 

[James Spagnuola]

No just the injection pump on the motor

 

[STDOUBT]

Sounds like you can afford VCDS!

 

[Mongler98]

No just the injection pump on the motor

oh dear lord.
stop throwing parts at it please. fix what's wrong with it. how much was your replacement pump and where did it come from? it might be worse than the one you "had" if you still even have the original pump. if you cheaped out on this, you could have a serious issue on your hands very soon. otherwise i would advise you to sell the car and move on. the car cant be worth more than the parts you have already replaced and if your unwilling to do things "sensibly" then i'm afraid you would save money by not fixing it and moving on.


so moving forward, you have your task. FIX your OBD2 and go buy a used old type VAG-COM cable and move on with diagnosing it.

Also how the freak did you replace the pump with no VCDS? i bet you marked the belt and prayed a prayer and just put it back together didn't you!

 

[James Spagnuola]

This is only the 5th tdi Iv done along with my buddy’s 3 other tdi projects but price isn’t a big deal I wanted a bigger pump for the things I’m doing with it anyways.. But will the vag-com even hook up to it Even tho every scan tool in tried comes up with (linking error). The cars never going anywhere seeing 2 years later I haven't put nothing but fuel and oil in the car the issues it’s having now is the only ones it’s had so trowing new parts at it Doesn't bother me just trying to fix it

 

[James Spagnuola]

How do I fix the OBD2 when everything I have looked up for it having linking errors Iv done and non of them fixed it

 

[Mongler98]

I told you. It could be a wiring issue and you need vcds and a proper cable. Get the cable first. If it works, good. The ebay fake cables you have to hack the software and they usually do have connection issues.

 

[STDOUBT]

Come to think of it, aren't there rare cases the ECU starts to fail out and one of the symptoms
is the hot-no-start?
James, does your OBD work fine on other cars?

 

[James Spagnuola]

So tonight we hooked it to vcds and even that wouldn’t connect checked all fuses there all good now I’m stumped and it’s not a hot-no-start cuz I started it drove down the road to my buddy’s (3 mins) from me and shut the car off it did the start stalls for a while till I got it to start

 

[AndyBees]

The OBD Port (the outlet itself) is poorly mounted in about every VW product made to date. So, I'd start right there to make sure all the wires are in place. One of them could be out of it's socket.

The OBD port has 16 sockets, however, only 8 of them are used. The Black Plastic Port has very tiny numbers by each socket. You'll need excellent light and eyesight to see them...... trust me, the numbers are there!

Socket numbers (socket is my term)
1. Is made hot by the ignition from Fuse #7 (black/blue wire)
2. no use
3. no use
4. Ground
5. Ground
6. To the Cluster, T32a/27, Green side (CAN Data Hi Bus) (orange/black wire)
7. To the Cluster, T32/25, Blue side (Data Link Connector, K Wire) (grey/white wire) (SEE NOTE BELOW)
8. thru 12 have no use
13. Wire goes to the White Connector at 10w/1 at or near the fuse/relay panel but goes no further (dead-end) (wire color unknown by me)
14. To the Cluster T32a/28, Green side (CAN Data Lo-Bus) (orange/brown wire)
15. no use
16. Is hot (12 volts) from Fuse # 12 (always hot) (red/white wire)

Note: The K-wire from socket #7 goes to Splice A76 in the Radio wiring harness. One branch from the splice goes to T6/3 on the Radio Connector Plug. The other branch from the splice goes to the Cluster at T32/25, Blue side. (wire color stays the same in both directions on at the splice, grey/white)

If I am not mistaken, seems I read in one of the OPs posts that the Radio had been removed ......... maybe that is a hint.

Hope this helps... (let me know, as I will send you an invoice....

 

[Mongler98]

Come to think of it, aren't there rare cases the ECU starts to fail out and one of the symptoms
is the hot-no-start?
James, does your OBD work fine on other cars?

ECUs on these generations are extreemly rare to fail especially with heat issues. A few have died in the past but as far as i have ever found, no its either good or dead. Id it is the ecu, its the connection or between it and the whatever that is bad.
The hot no start issues with the ecus usually are from the connections workjng them selves loos. The entire reason most cables on computers had screws on them, same with the locking hardware on the harness.

Chances of having a failing ecu is about as likly as finding one of these cars in mint condition with less than 10k miles . Its out there. But yea, good luck!

 

[AndyBees]

OP, give us an update!

 

[James Spagnuola]

OP, give us an update!

Sorry I was on early re reading what you posted checked everything and still nothing I’m mind blown to what it is

 

[JETaah]

Hello after doing so much research and not finding much help I’m here my 2001 tdi is having issues and idk where else to look to start off my obd2 is have a (linking error) also the car starts right up every morning and runs fine till I get to work shut it off try to re start it and it starts then stalls for a few times then will re start after trying it a bunch of times Iv tired both keys the immobilizer light goes right off after ignition is turned on. When car stalls it sounds like a old vacume when shutting it off as well Thought maybe injection pump but changed it still having issues any help would be great thanks!

The vacuum sound is possibly the N75 valve bleeding off the vacuum from the system.
If you have an aftermarket radio it may be interfering with the ability to establish contact to the OBD. Try taking it out of the picture and see if it makes the difference.

Ross-Tech: VCDS: Afterrmarket Radio Problem

 

[James Spagnuola]

The vacuum sound is possibly the N75 valve bleeding off the vacuum from the system.
If you have an aftermarket radio it may be interfering with the ability to establish contact to the OBD. Try taking it out of the picture and see if it makes the difference.

Ross-Tech: VCDS: Afterrmarket Radio Problem

I did Iv removed the radio checked every fuse the 109 relay everything and still nothing

 

[James Spagnuola]

What ever the issue is is the issue of both linking error and start and stall cuz it did it all at once the day it happend I got in the car that morning drove to work an hr there then worked all day then started right up at work drove all the way home an hr then stoped at advance auto came back out side and then the car wouldnt hooked scanner up to it got the linking error and the start then stall start then stall I did it like 10times then it started dosnt matter if the cars cold or hot it will do it after the first start up in the morning fires right up but if I shut it off after then it starts then stalls.

 

[BobnOH]

Well if a VCDS won't connect, you needs to track down and test all the electrics involved. See Post #15

 

[AndyBees]

Of the 498 Views this Thread has had to date, I bet the info I posted at #15 has been copied several times for future use. Why, because it is good info. I installed an 02 ALH engine in an 84 Vanagon, including the Jetta Cluster, OBD port, Accelerator, ECU, Relays, Custom Fuse Panel, Brake Switch, Clutch Switch, Starter Switch at Clutch Pedal, and all the bells and whistles possible. So, I know the electrical components quite well (been there and done that).

No, I didn't pull that info from my head. I pulled it from the "manual" I put together as my project unfolded. It has been tested and proven (Example: Two trips to Alaska with the beast).......... over 80k miles on it since August 2012. (see my signature below)

Now, as BobnOH said, go back and look at Post 15. Copy and paste the narrative. Sort it out on a piece of paper so that you understand it. Then, test each of those circuits. If you do not "fix" the OBD Port issue, you will never solve your problem(s).

It is just fine to come back here and ask more questions ... tell us what you found, tell us what you don't know, tell us your frustrations. But, keep in mind, you are in control on your end. This is the best automotive forum on the Internet.

 

[James Spagnuola]

Took the car apart and come to find out my cluster is bad.

 

[AndyBees]

Thanks for the follow-up!

Just curious if there were any other noticeable problems with the Cluster?