1.8t - Car randomly stutters under light load

[kendog]

For anyone that is curious about the boost leak tester... This is hooked up to my bike pump, but you could also get an attachment to hook up to a spare tyre, or even change the nozzle to fit onto a compressor...

Looks great! Do you have a pic of all the individual parts you got from bunnings to make it? Did you block the other end going into the throttle body too?

Also, I have a spare SMIC after just installing my FMIC..

PS - That Wiring/Plug goes to nothing on my GTI/1.8T too..

[Sirocco20348]

Looks great! Do you have a pic of all the individual parts you got from bunnings to make it? Did you block the other end going into the throttle body too?

Also, I have a spare SMIC after just installing my FMIC..

PS - That Wiring/Plug goes to nothing on my GTI/1.8T too..

Thanks for the heads up on that wiring plug, I was trawling etka last night going insane. Ill just let it hang.

I can take close up pics of it tonight, but honestly it is not very sophisticated.

- 50mm threaded piece of PVC (Thread goes about half way down)
- 50mm matching threaded cap
- 1x Air connector of choice, I used a schrauder bike valve which required me to use a 8.5mm drill bit to drill a hole. (Exact fitment). I left the harder more durable piece of rubber around the base of the valve.
- 1x roll of plumbers tape to wrap around the main thread of the 50mm threaded cap.
- Glue the valve onto the threaded cap with loctite, cold weld, whatever you like, aslong as it does not leak. (i used loctite on this occasion.

• Insert the newly constructed boost leak tester into the intake pipe.
• Remove the PCV valve from the TIP and plumb the hole with something. (I used a c02 canister as in picture). If you dont do this, apparently it pushes oil into the TIP and you will be blowing smoke afterwards.
• Remove the oil cap from the top of the engine.

No need to block off anywhere else. Start pumping with your bike pipe and listen for the dreaded hissing noises haha

If using a compressor start at 5 psi, because its pretty darn obvious when you have a leak. If its ok at 5psi, then keep raising it up to what is normal boost for your engine. If its holding that pressure fairly well, then you should be all good!

I used this page and youtube video for inspiration...

Stealth 316 - Intake pressure tester
http://www.google.com.au/url?sa=t&rc...55819444,d.dGI

[Sirocco20348]

Thanks for letting me know about your spare intercooler. I repaired mine last night with some epoxy weld, but if it doesn't work properly I will give you a PM and we can work out a deal. I haven't tested mine yet lol, apparently this epoxy weld is good for 4500psi.. so i don't think 20psi should be a problem. Will let you know.

[Sirocco20348]

Ok so I have ...
- Fixed known boost leaks
- Replaced rubber vacuum hoses around the engine, including the small one that goes to the fuel pressure regulator.

The car pulls very hard now, but every now and again I still feel a random stutter or jolt while under light load. No where near as bad as before thou.

I will have to drive it more this week to confirm that it is still there. Thanks for all your recommendations.

Out of curiostiy what are the symptoms of a failing fuel pump? Do they die slowly... or just die?

Ps. Just to add something funny/amusing for others, but not for me.... The c02 canister I was using to plug that hole, slipped down into the Turbo Intake Pipe. I nearly cried. But after a trip to Jaycar and Bunnings I had an earth magnet attached to a drain cleaner probe, and fished it out haha What a crap time that was...

[Sirocco20348]

Hey guys, I need some more brainstorming as the problem still persists.

As mentioned before, I have fixed all boost leaks and replaced the rubber hose from the plenum to the fuel pressure regulator.

Today I cleaned the MAF with MAF sensor cleaner and changed the air filter. Did not solve the problem.

I then unplugged the MAF plug, and the problem still persists. So I am pretty sure its not the MAF.

This problem is starting to wear me down a little as I just do not know what to try next.

Any other people experience this problem? Or suggestions?

[Sirocco20348]

Ok I just used vagcom to read engine codes... none were there. No CEL's.

I did a throttle body adaptation and took the car for a drive... it felt better but the car had a throaty noise to ?

It stuttered less... no where near as bad as before?

Just going back on the ignition control module... are symptoms of this failing usually of a more intense nature?

[h100vw]

Ok I just used vagcom to read engine codes... none were there. No CEL's.

I did a throttle body adaptation and took the car for a drive... it felt better but the car had a throaty noise to ?

It stuttered less... no where near as bad as before?

Just going back on the ignition control module... are symptoms of this failing usually of a more intense nature?

ICMs just quit usually. Plug gaps all the same and not too big. Compression test, dodgy valve/burnt seat?

Gavin

[Sirocco20348]

ICMs just quit usually. Plug gaps all the same and not too big. Compression test, dodgy valve/burnt seat?

Gavin

Hey Gav, Thanks for the reply.

I installed new plugs (gapped to 0.28mm) before the track day last month, and I didn't have any problems.

Actually maybe I should elaborate more on my boost leak test situation.

I fixed the hole in the inter cooler and replaced the hose that goes from the plenum to the pcv valve?

When I went to use my bike pump again to compress, The hissing noises were gone from the intercooler and pipe.... but I could not for the life of me build pressure.... should I be able to build up even the smallest amount of pressure with a two handed floor mounted bike pump?

With the oil cap off, I could hear a hissing noise coming from within the block? But I dismissed that as in the video link I posted, they said that some air will go through the block. Is this a concern?

[h100vw]

Hey Gav, Thanks for the reply.

I installed new plugs (gapped to 0.28mm) before the track day last month, and I didn't have any problems.

Actually maybe I should elaborate more on my boost leak test situation.

I fixed the hole in the inter cooler and replaced the hose that goes from the plenum to the pcv valve?

When I went to use my bike pump again to compress, The hissing noises were gone from the intercooler and pipe.... but I could not for the life of me build pressure.... should I be able to build up even the smallest amount of pressure with a two handed floor mounted bike pump?

With the oil cap off, I could hear a hissing noise coming from within the block? But I dismissed that as in the video link I posted, they said that some air will go through the block. Is this a concern?

If you don't block it at the throttle body, there'll always be air escaping through one of the cylinders. The smoke machine is good as you can see it and chose whether it should be there or not.

I would cap smaller sections and when you are happy join them together again.

Gavin

[Sirocco20348]

I just thought I would keep this updated...

Since I have the piratebay vagcom... I thought I would verify my results by taking the car to Gareth at Northside Euros in Mitchell and have him run the official vagcom.

He had the same results. No engine fault codes, and from the ecu point of the view, the car is in good condition.

Maf. 02 sensors, throttle body adaptation are all good.

I decided to swap out the fuel filter this afternoon. The stuttering/misfiring has become less frequent, but is still there and very annoying.

Some hills while on cruise control, would cause misfiring, while others did not. It is really sporadic.

No stuttering under full boost at all.

I will follow up with further boost leak testing.

I still have half a tank of fuel left.. I am wondering if the fuel is crap... highly unlikely but still plays on my mind.