Mk4 Golf 1.9 TDI PD 130 (ASZ) - Low MPG and high-end power

Jakeswagen

Member
Joined
Jul 27, 2018
Location
South-West, UK
TDI
VW Golf Mk4 1.9 TDI PD130 ASZ
Hi all,
My first post here - Been reading lots of posts from here in my research and finally signed up, glad to be here!

Quick bit of background - I'm now on my third Mk4 Golf PD130 in 7 years. The first one I picked up after selling my 1.8t GTi - Loved the Mk4 platform but wanted better fuel economy as was driving long distances for work, picked up the PD130 and was amazed at amount of torque it offers in every gear, and just all-round driving experience in general. I eventually sold it on for one reason or another but we still have 2 PD130's in the household, one is the mrs' and I've recently picked up another for myself.

My new Golf is great, low mileage for the year (114k) and really good condition. However one thing really bugging me is my average MPG reading has been over 30% lower than my previous Golf with exactly the same driving style and driving routes, coupled with noticeable turbo lag and also lack of power in gears 3-6 from around 2200rpm.
I drive sensibly but not like a grandad - I like to get up to speed quickly where is safe/ possible and then cruise, so go through the gears changing up around 2200-2500rpm, letting the turbo work and provide a good driving experience.

However...when I do drive like a grandad, which is usually on the way to work (stuck behind a grandad!) - I'm changing up the gears at a lower rpm/ not using the turbo, and my mpg results are high and as should be expected with this engine. Therefore I'm fairly certain the low mpg and power is a turbo related fault. Anyway...more info below...

I read an article over on myturbodiesel about low-power causes then decided to get a VCDS license to start running some tests. I have provided the results at the bottom of this post but also here is some more useful information to consider:

Mecanical profile of the car:

All done during my ownership within last 500 miles:
- Contitech timing belt + Meyle HD metal impeller water pump.
- Contitech auxillary belt + Febi tensioner.
- Full service: 5w40 Quantum Platinum oil, Oil Filter, Air Filter, Fuel Filter - All OEM items.
- Coolant temp sensor + thermostat / Coolant flush + new G13 coolant - All OEM.

Other points of interest:
- Clutch + DMF changed @ 87k (no record of brand)
- No fault codes.
- The car is not going into limp mode.
- No smoke when driving or idling.
- Idle is not rough.
- Tyre pressures correct.
- Brakes recently changed and are not binding.
- Car starts and shuts-off perfectly - Ruling out anti-shudder valve issues?

Test Results:

Temperatures from cold-start - Logged using block 007 -


Air Flow (MAF) - Logged using block 003 -


Boost Pressure (MAP) - Logged using block 011 -

Chart 1


Chart 2


....I also did a log for Injection Quantity using block 13 - I let the car idle for a minute or so then worked out the average deviation across that timescale, results are:

13, 1, Injection Quantity, Deviation Cyl. 1. -0.45 mg/str
13, 2, Injection Quantity, Deviation Cyl. 2. -0.13 mg/str
13, 3, Injection Quantity, Deviation Cyl. 3. -0.26 mg/str
13, 4, Injection Quantity, Deviation Cyl. 4. +0.84 mg/str

Cylinder 4 reached as high as +0.96 mg/str during this test. Could this relate to lower MPG? I read a thread on another forum where a guy had cylinder 4 at ~1.2mg/str - He did a diesel purge then posted the results after, the reading had gone down to around 0.6mg/str but he said there was no noticeable improvement in mpg or power, just said the smoothness of the idle was improved.

Since looking at the results of this test I wondered about possible cam wear issues. Looked back through the service history and was gutted to find that the garage that the previous owner took the car to has used 5w30 semi-synthetic oil for the last 2 services....NOT the VW spec 5w40 fully synth as we all know should be used! There was 2 oil changes with this oil and it was used over approx 30k miles... I then took the rocker cover off to inspect the cam lobes/ chamfer and the lifters but thankfully all checked out ok, no wear whatsoever.

Anyway.... I haven't checked for any boost leaks yet. Could the turbo lag and low MPG be caused by a leak?

Invested alot of time and thought into this so far and really want to find the root cause of this issue....help!

Thanks all in advance!

Jake.
 
Last edited:

WildChild80

Veteran Member
Joined
May 30, 2016
Location
Nashville, AR
TDI
2001 Jetta TDI 2000 Jetta TDI 2000 New Beetle TDI ALL 5 speeds
I know comparing an issue from a VE to a PD usually is pointless but check your cam timing...my first VE cam lock tool wasn't spot on and when I locked the cam at zero with a different lock tool I found my crank timing wasn't at zero.

I experienced very high torque down low crazy boost spikes after horrible boost lag and by 4k RPM it was barely making power. My fuel economy was down from what it is now. It pulls past 5k now with a more gradual power increase.

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flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
Those logs look like a possible vacuum leak to my untrained eye.
Test the various suspects and/or just replace the vacuum hoses.
 

Jakeswagen

Member
Joined
Jul 27, 2018
Location
South-West, UK
TDI
VW Golf Mk4 1.9 TDI PD130 ASZ
I know comparing an issue from a VE to a PD usually is pointless but check your cam timing...my first VE cam lock tool wasn't spot on and when I locked the cam at zero with a different lock tool I found my crank timing wasn't at zero.

I experienced very high torque down low crazy boost spikes after horrible boost lag and by 4k RPM it was barely making power. My fuel economy was down from what it is now. It pulls past 5k now with a more gradual power increase.

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Hey man thanks for the reply!

We've checked this out already as have seen this issue mentioned alot! Can confirm the timing is correct. The symptoms are similar just not quite to the same magnitude as yours!
 

Jakeswagen

Member
Joined
Jul 27, 2018
Location
South-West, UK
TDI
VW Golf Mk4 1.9 TDI PD130 ASZ
Those logs look like a possible vacuum leak to my untrained eye.
Test the various suspects and/or just replace the vacuum hoses.
Cheers flee - A leak was my main suspicion so that gives me some confidence! We're planning to do a boost leak test today if the rain stops so will post the results as soon as they're in
 

WildChild80

Veteran Member
Joined
May 30, 2016
Location
Nashville, AR
TDI
2001 Jetta TDI 2000 Jetta TDI 2000 New Beetle TDI ALL 5 speeds
Hey man thanks for the reply!

We've checked this out already as have seen this issue mentioned alot! Can confirm the timing is correct. The symptoms are similar just not quite to the same magnitude as yours!
My 2001 was more of a basket case when I bought it, after replacing the turbo for vane issues and oil consumption there were vacuum issues...the saga went on for a little while. Now I think my vacuum pump is getting tired and not making much at idle now

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Jakeswagen

Member
Joined
Jul 27, 2018
Location
South-West, UK
TDI
VW Golf Mk4 1.9 TDI PD130 ASZ
Those logs look like a possible vacuum leak to my untrained eye.
Test the various suspects and/or just replace the vacuum hoses.
So we did a boost leak test yesterday - No issues found.

To test we simply put some bin liner over the air intake and clamped it with the spring clamp - Took the PCV hose off and injected the air from the inlet as can be seen in the picture below.

Obviously this was only done with 5psi as to not damage any seals etc but was pretty conclusive that there's no boost leak, as the bag expanded and held the air.

So one thing I was thinking when doing this test - This isn't testing the vaccum lines around the N75 valve etc is it? As I believe they're solenoid operated. Do I need to run another test to check these out? We've just done a visual inspection on the vaccum lines so far and all seem to be fine.

Any ideas on how to do a vaccum test if this boost leak test doesn't cover it?

Cheers

 

flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
Testing for vacuum leaks is step one for aging TDI's. Step 2 is replacing vacuum hoses.
The various procedures are well documented in many discussions so start reading.
A vacuum pump with a gauge is a very useful tool for testing the various components.
You might as well check the turbo actuator function and smoothness while you're at it.
I'm assuming you've made sure that there are no restrictions in the intake also.
 
Last edited:

Jakeswagen

Member
Joined
Jul 27, 2018
Location
South-West, UK
TDI
VW Golf Mk4 1.9 TDI PD130 ASZ

Jakeswagen

Member
Joined
Jul 27, 2018
Location
South-West, UK
TDI
VW Golf Mk4 1.9 TDI PD130 ASZ
Drove the car back from work last night then opened up VCDS on the drive at idle. Block 004 doesn't specify Torsion Value? See below, it's marked as Synchro angle....any ideas on this?
Ok I've done some more research and found that Synchro angle = Torsion value.

..so I took this log after a 20 minute run when the car was up to temperature and then sat on the drive idling. The torsion value reading was flicking from 1.6 to 2.2 constantly, back and forth.

As the reading is within the -3 to +3 tolerance is it still a possible problem? Should I try to adjust this, and what to? Or should I be looking elsewhere for the cause of my low power and low mpg issues?

Thanks!
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Daughters car, 2005 Golf TDI Mine, all 5 spds
Try bumping it down to 0.0 , be careful a very very minute adjustment can move the torsion several degrees.
 

Jakeswagen

Member
Joined
Jul 27, 2018
Location
South-West, UK
TDI
VW Golf Mk4 1.9 TDI PD130 ASZ
Try bumping it down to 0.0 , be careful a very very minute adjustment can move the torsion several degrees.
I'll get around to testing this at some point next week and post the results.

Checked the torsion setting on the other PD130 in our household and it flickers between 0.0 and -0.5 - It definitely feels like it has more low down torque, whilst only minute it's still very noticeable during normal every day driving.
 
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