Digifant II - Q's

[mikinoz]

This one goes out to those that love Digifant (and those who don't but may be able to help).

You all know I have a 16V that has been converted from KJET to DIGI. Now I have had so many attempts at tuning this thing I feel like putting a spanner in the timing belt.

So this story goes as follows;

Since I have had the car the idle has been fast and fluctuates, and I have tried a few things and replaced some bits.

- air bypass screw o-ring
- vacuum hoses to the throttle body.

So the things that I have questions about are;

Vaccum lines - I have the following vacuum lines to the throttle body - 1. formerly from the airbox that has been replaced with a pod is the vacuum line to the FPR which heads to the front rhs vacuum spike on the t body. - 2. The other 2 spike are now interconnected and a line goes from these to the instrument cluster. These were formerly the vacuum to and from the carbon canister (that is not on this car).

My question is should the lines to and from the non existent carbon canister be linked together (as they would have been if the canister was still there) or should I have blocked them off entirely. What is the line to the instrument cluster for and what should be feeding to it? Should it be on the canister loop or the FPR loop, or should I just have it disconnected.

Timing - I looked at the timing today, I determined it was out... I read that Digifant wants TDC (or flywheel and bellhousing markers to align) at 2000-2500 rpm with CTS disconnected. It seemed that the car was a bit too far retarded so I lined them up. Yes, I used #1 cylinder for the timing light, which was the lead coming from the plug closest to the timing belt.

Fuel - So there is an adjustable fuel pressure reg on the car. I feel that this may be the weak point. The settings I have put in are 3.0 bar with vacuum line removed (2.5 attached). The issue is that the system is not holding pressure when the car is turned off so the FPR may be suspect.

I have also looked for vacuum leaks around the place but cannot see any that I am aware of. The ISV has been cleaned and I have tried 2 different units with similar results.

Any advice appreciated. If I cannot sort it out I am going to buy a BBM fuel rail with OEM FPR adaptor so I know that side of the engine is ok.

[Jmac]

Vac feed to the cluster is to the Map sensor in the cluster, this is for your MPG mate. I still think the system has leak back and not holding pressure on shut down. You need residual pressure. You would need to cycle the ign a few times to build that up before start up .if its leaking back, im sure it is. I reckon you could rig it up like the later Mk3 Tdi. This switches the glow plugs on when the doors are opened to lower the glow time. Wonder if you could through a relay of course rig it to prime the fuel pump and thus system when the door contact switch is activated. Then when you cyle the ign it burst the pump one more time and yeha, make sense???? Im sure that could be done

Jmac