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Discussion Starter · #1 ·
Good day fellow Van lovers,

I need some cleverness from you.
For a few years now my bus would go into limp mode under hard acceleration with load(pulling caravan), but not frequently. It would do it once or twice a year and I read on the forum it has to do with the turbo actuator that gets sticky and does not want to allow the turbo to boost fully then causing the engine to go into limb mode. It is now doing this more frequently and is doing something new. When going out on the open road and accelerating normally it feels as if the bus is hesitating, if that makes sense and this only happens when it is busy getting to temperature.
I suspect the turbo, but do not want to replace the turbo if not the fault.
Please help me out here.
 

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Hi,

have you tried cleaning or replacing the MAF and MAP sensors, this may help.

I recently had the same sort of symptom, and it was sorted with a new turbo..

good luck
 

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That sounds exactly like over-boost limp mode due to a sticking VNT on the turbo.
Before wasting any money, get the fault codes read.
 

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Discussion Starter · #4 ·
That sounds exactly like over-boost limp mode due to a sticking VNT on the turbo.
Before wasting any money, get the fault codes read.
I wish i could, but for some reason above my understanding my van refuses to connect to the scanner. Not even VW's pc wants to pair with it.
 

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Discussion Starter · #5 ·
I have made notes of the symptoms it is exhibiting.

The problem of the "hesitation" is only present under the following conditions:
1. Between 2200rpm - 2800rpm
2. Engine Temp: 70 degrees C - 85 degrees C

She run normal under and over the above rev range and then cold and/or at 90 degrees (normal operating temp)

This is really baffling me and i do not want to start replacing components left, right and centre.

Any help will be greatly appreciated.
 

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I'd start with getting to the bottom of why the ECU cannot be accessed with any diagnostic equipment. Can you connect to any ECU's in the van?
 

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Discussion Starter · #7 ·
Update on the hesitation story:
I had the turbo removed and cleaned, the sandblasted the casings and cleaned all the carbon off and reassembled and tuned the turbo. Made a difference in how the power is delivered. Much smoother than what it was.
But the hesitation is still there, it feels a little lighter than it was prior, but still there.

I spoke to someone else regarding the problem and he believes the problem is electronic. I mentioned to him that problem is only present at a specific temperature range and that towards the last 1/4 of 2020 i had the temp sensor on the block of the van replaced as the temp was shooting up and down the whole time. The temp gauge is now correct, but can the temp sensor be the incorrect one for the vehicle and would an incorrect reading to the ECU have an effect on the running of the vehicle?

Thank you in advance for your assistance.
 

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The correct part number for the G62 should be 070919501D. My original (2004) was the same number with an A suffix instead of D which is an updated version of the same part.

You could do with getting some logs done with VCDS. You can log the output of both the G62 (the sensor you had changed) and the coolant temp reported by the radiator outlet sensor (G83) from cold to see if anything is happening when the fault starts/ends.

In VCDS Group 011 shows these two sensors. You have to join up the two traces on this graph in your head because I knocked the cable out for a while, but basically the first log shows before the stat opens and the second (right hand) log shows after. The difference between the G62 and G83 is how efficient the radiator is.



Does yours have the original cam? How many miles do you have on it now?
 

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Discussion Starter · #9 ·
The correct part number for the G62 should be 070919501D. My original (2004) was the same number with an A suffix instead of D which is an updated version of the same part.

You could do with getting some logs done with VCDS. You can log the output of both the G62 (the sensor you had changed) and the coolant temp reported by the radiator outlet sensor (G83) from cold to see if anything is happening when the fault starts/ends.

In VCDS Group 011 shows these two sensors. You have to join up the two traces on this graph in your head because I knocked the cable out for a while, but basically the first log shows before the stat opens and the second (right hand) log shows after. The difference between the G62 and G83 is how efficient the radiator is.



Does yours have the original cam? How many miles do you have on it now?
My van still has the original cam as far as i know and has 155 300miles (250 000km) on the clock.
 

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Many 2.5's have had a new cam by 155k but not all. The cam is a bit of a pain to check because to get the rocker cover off it's bumper off and front panel forward or free the engine from its mountings to move it to allow room.

In the early stages of cam and follower wear there can be no symptoms except a very slight loss of performance. Most people don't notice on the 174 because they are pretty quick anyway. When the cam wear get serious the classic loud thumping/knocking/popping back through the inlet starts. This can vary in the early stages from knocking only with a cold engine only but silent when warm and knocking all the time.

I think I would try and check everything else more accessible first. I think you will struggle unless you have access to diagnostics though. I think I would start with eliminating the basics, so a new fuel filter and check the fuel flow from the low pressure pump. Make sure there is no restriction in either the intake or the exhaust/cat.
 

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Discussion Starter · #11 ·
Update:
I am going to send the van in for the harness to the injectors to be redone, it seems that these wires that run in the head in the oil get a bit heat treated and then start to fail. Was told it is a common problem with these types of VW.
For good measure i chucked in a can of injector clearer in the tank (strong mix) to see if it might easy the problem. It did do something, after about 20km the van felt like it was not running on all the cylinders, it was "misfiring". I switched it off and started up immediately and she ran like the clappers. Took it right back for a diagnostic to see the fault codes and she stored 2x codes - 18075/P1667 Valve for pump - Jet: Cylinder 2 (N241) electrical malfunction and 16683/P0299/000665 Boost Pressure Regulation: Control Range Not Reached. We cleared the codes and she has been driving still, the hesitation still there and after this a distinct ticking sound that i can only describe as possibly being injector 2 making a noise?
When the loom gets replaced, i am planning on inspecting the cam and rollers/rocker/lifters and will also remove the injectors to have them tested.

Any thoughts???
 

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Discussion Starter · #12 ·
Update:
Harness replaced, Injectors reconditioned, Camshaft replaced, with cam bearing and lifters as well as water pump.
Van started up and sounded fine, but when they started it up the next day is struggled to start. Sounds like it is not getting diesel, swings fast and then splutters into action and sometimes dies. Drove it down the road and does not have power.
They tore it down again and they are saying there is something wrong with the camshaft. The gears are not lining up.
192115


192116

May i have your thoughts?
 

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There seems to be 2 problems with cam timing on this engine -
1. The cam is put in 180 degrees out with respect to the cam sensor timing disc, the engine will run with the cam sensor disconnected.
2. The cam is 1/2 a tooth out because the gear backlash hasn't been set properly.
 

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Discussion Starter · #14 ·
Good day,
The new cam was removed and they measured it against the old cam and found that the new one is shorter than the old one. I exchanged the cam for another one and they fitted it back into the vehicle and she starts fine this time and pulls well.

BUT...... the original problem still exists. Misfire,misfire misfire under load. We suspect the rebuilt injector harness to be at fault hence i have ordered a new one from VW.
While we are waiting on this to arrive they also found that the exhaust manifold is cracked and leaking. So the van is now being treated to a custom made exhaust manifold.

I trust and hope that these corrections will fix the problem.

If anyone has any thoughts, please do share.
 

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Discussion Starter · #15 ·
Update:

The repair centre managed to sort the misfire out, the van starts fine and sound good, but does not seem to boost correctly.
Van feels weak and does not pull like it should.
Weird things is that no error codes are registering.

Does anyone have any thoughts? Would appreciate the help.
 

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Hi did you ever get to the bottom of this?

I have a 53 plate 174 AXE which is down on power. Starts fine but just feels like it's low on power.

Engine was rebuilt 10k miles ago but didn't require a cam. Engine has just had a new cam shaft due to a lifter seizing and causing the old one to snap, New MAF, New Tandem Pump, Injectors all tested and passed their test. Injector loom replaced 18 months ago.

No sign of Exhaust manifold being cracked and turbo seems to be boosting ok.

Was thinking could it be the throttle pedal as have read this can be faulty not sending the requested values to the ECU correctly to tell the injectors to put the correct fuel in.

I'm starting to get to a point where I don't know what else to do.

Jamie
 

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Was thinking could it be the throttle pedal as have read this can be faulty not sending the requested values to the ECU correctly to tell the injectors to put the correct fuel in.
The throttle position sender should be pretty easy to check with a diagnostic tool like VCDS - it should show you in real time what the values are, so you can see if it's failing to register movement at any point in its travel.

However, IIRC they have a built-in checking system (I can vaguely recall that there are actually two separate pots that operate in opposite directions, so one goes up in value while the other goes down?) which means that if there is a significant error it should generate a fault code.
 

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The throttle position sender should be pretty easy to check with a diagnostic tool like VCDS - it should show you in real time what the values are, so you can see if it's failing to register movement at any point in its travel.

However, IIRC they have a built-in checking system (I can vaguely recall that there are actually two separate pots that operate in opposite directions, so one goes up in value while the other goes down?) which means that if there is a significant error it should generate a fault code.
Hi

Thanks for the reply.

I'll get my vcds connected and take a look.

Any idea what the values should be?

I've changed so much on this van I'm well over what it's worth but I loved it when it ran with the correct power I can't stop fixing it now. Especially after the engine rebuild.

Jamie
 

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The TPS as viewed in VCDS should transition smoothly from 0% to 100%.
It's unlikely to be the TPS, as these are very reliable, try doing some live date runs with VCDS, particularly requested vs actual MAF, and boost.
 

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The TPS as viewed in VCDS should transition smoothly from 0% to 100%.
It's unlikely to be the TPS, as these are very reliable, try doing some live date runs with VCDS, particularly requested vs actual MAF, and boost.
Thank you bluezie.

I'll check it over today. My friends garage said he thought the TPS may be faulty as he was only seeing 0 to 80% on a full transition of the throttle. Will double check this today.

Jamie
 
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