GOLF MK4 GTI -Intriguing Problems- Please help diagnose

[JNS83]

Hi all,

A quick introduction, I am new to this forum and a relatively new Golf owner (1 year). I drive a 2004 MK4 GTI (Drive by cable) that has done roughly 80K and has a APR chip. Here are the problems.

Problem 1: Air Conditioner (Climate control)
A few weeks ago, the aircond stoped blowing cool air when the car was stationary or driving slowly. On the freeway, it worked fine. Took it to my mechanic in Burwood, they said the air con fan was broken and so was the aircon module. Replaced both. $1000 later, the problem is still there. On the freeway, the cool air comes through and the climate control starts to regulate however, when I am in traffic or going slow, it doesn't work. The mechanic now seem to think it is a fuse problem however can't seem to locate the fuse? They will try again when they re-open on Monday.

Problem 2: jerking/power cut of between 2K-3K rpm
The car seems to lose power between 2K-3K rpm. The jerking/power cut seems to get worse over time and the car is becoming sluggish. My mechanic seems to think the Electronic Control Module (ECM) is giving way.Apart Another expensive piece to change without knowing the actual problem.


Has anybody experienced the above problems before? Is there a chance that the problems are related? any help would be much appreciated.

[kaneda]

I would start with a new mechanic .

[RolfGolf]

Just wondering if you've had your car scanned for fault codes - is it a VW mechanic you're taking it to?

[JustCruisn]

I would start with a new mechanic .

x2
Look here for a list of reputable service providers
http://www.vwwatercooled.org.au/f12/...ead-11511.html

[WhO]

x3

There really isn't as much guess work in cars these days as the cars computer can often tell you whats going wrong, just you need the right tool to scan it. That said there really is no excuse for a mechanic not to have the appropriate scan gear considering it can be had for very little these days!

A mate of mine with a A3 was having issues with it stalling, running poorly, randomly not starting etc. Nearly 1.5k, a couple weeks later and a bunch of replaced parts later the issue was still there. He then took it to a mechanic with the right equipment, 10 minutes and it was diagnosed and the same day it was running like new....

I highly doubt your ECU is ****ting itself, most likely a sensor gone somewhere, something a simple fault scan would likely show up.

RE the aircon, when you turn it on are the fans turning on? Is it cold briefly when first turned on but doesnt stay cold, can you hear the compressor kicking in? Does your car overheat in traffic at all?

Since its working when your moving im thinking the fans aren't working thus the system overheats quickly when stationary and shuts down. Potentially your car has suffered from the known problem with the Mk4 fans where the low speed resistor fails leaving the fans to only pulse at off or High. This can eventually blow the fuse for the fans leaving you with no fans at all. I believe the fuse is ontop of the battery in the little fuse box, its a 40A strip fuse i think. If thats blown and your mechanic couldn't find it.... dont bother going back there... The only other fuse location i believe is the fusebox in the cabin.

Actually just noticed you mention your fans have been replaced? If thats the case the fans should no longer be an issue, first port of call, check the fuse ontop of the battery.

[JNS83]

All, Thank you for the great responses. Below is are a few more points:

RolfGolf: The mechanic is a reputable VW specialist is Burwood (Any guesses?). Again, I will give them a bit more time to asses but will not spend any more $ until they are certain of the issue. It has been through a scan and no faults have come up.

X3: The fans turn on periodically. They spin mostly on the freeway/going fast (hence cold air comes through). When stationary, there is no overheating. I will check the fuse box and the 40A Strip fuse.

I still don't know if the aircon issue is related to the jerking issue/power loss. The car also not idles at about 500rpm when I start the car. It has a low toned whining. Again, I don't dont this is the ICM issue as previously diagnosed by the mechanic.

A little bit more of background. About 4 weeks ago, the car battery died. Had it

Another bit of background: About 4 weeks ago the APR chip got installed. It was brilliant for 2 weeks until the battery died. Had it replaced, and this is when all the problems started. Could the chip be messing things up? Could the change of battery caused any other issues?

Again, thank you all for the consultation. It is much appreciated.

[Manaz]

A VW specialist who can't locate the fuse for the fans on a Mk4? Doesn't sound like much of a specialist to me. The fans are known to have failures, as are the fuses in top of the battery box...

[Ideo]

A friend had the issue with the ECM. Was told he needed to replace it.

We spent a saturday morning looking over it on his driveway, and it ended up being a loose connection at the back of the ECM that needed reconnecting.

[McDub]

Problem 2: jerking/power cut of between 2K-3K rpm
The car seems to lose power between 2K-3K rpm. The jerking/power cut seems to get worse over time and the car is becoming sluggish. My mechanic seems to think the Electronic Control Module (ECM) is giving way.Apart Another expensive piece to change without knowing the actual problem.

ECM? you talking about the ECU or the ICM? the ICM (ignition control module) is only about $160

[brodzta_GTI]

Id definatly check fuses first.. if the ac doesn't work at idle but fine at speed there's a air flow issue..and vw ac systems won't work if the fans don't turn on.. as for the engine issue.. it could be the tune, coils, the altitude sensor, maf sensor.. u need someone that understands the systems to properly diagnose the issue..not just someone who connects a scan tool, doesn't see any faults and says " no faults, no issues" try taking it to a dealership, they have the correct tooling, knowledge, experience and the ability to speak directly to vw Australia if they require further technical assistance