F reg GTi DX- Random Holding back total loss of engine power

F Reg Gti 8v Cabriolet DX engine

Totally standard
-1 immobiliser
-1 redundant alarm

Symptoms
-Randomly the car will hold back and the revs will drop, no power. then it will magically come back to life.
-Not like a missfire which chugs along, this is total loss of engine power, with no real reason.
-Seems to happen more when im about to slow down and changing gears, thus the car cuts out completely and the dash lights flash (battery) pump can be heard running for a second.
-hold back like a missfire when pushed under load at times.
-Seems to be at its worst when the car is HOT and stand still or in slow moving traffic
when the above the case, the car struggles to start as soon as you move it starts playing up and then does on you.

So far i have checked:
-In tank lift pump - replaced with another unit
-Outer tank pump- replaced with another unit.
-new fuel filter
-checked in the tank

-Replaced ignition coil -replaced with another unit.
-ignition module-  -replaced with another unit.
-directed coil to battery
-HT leads
-distributor cap and arm, even replaced the dizzy

checked all connections and plugs.
checked all breather pipes

im at a loss to what is wrong with the car. i know it need s tune up, i have checked the TDC settings and they are fine. the ide screw is also slightly open.

but i cannot get the car setup until i isolate the problem.

any suggestions.??
 

does the car start fine, no slow start issues… any smells on starting, as you said it needs a tune, what is making you say that…? A bit concerning on the cutting out issue, something electrical shorting or relay? or fuel pressure… i'm sure rubjonny mark1gls & Briano1234 can help you with this…  

Deandubya said

does the car start fine, no slow start issues… any smells on starting, as you said it needs a tune, what is making you say that…? A bit concerning on the cutting out issue, something electrical shorting or relay? or fuel pressure… i'm sure rubjonny mark1gls & Briano1234 can help you with this…  

The immobiliser is set on the fuel pump, so it doesnt prime on start up, but it starts ok.

The reason i know it needs a tune is that its not running spritely, especially when thensecond chamber opens up on the throttle. plus when warm it idles just over 1000rpm.

No smoking or rattles etc. mixture may be out but im going to get it set up, ideally want to eliminate this issue before all that.

rubjonny has advised to direct the coil to the battery to eliminate ignition feed cut , but that didnt make any difference.

I'm really at a loss.

could be the alarm/immobiliser wiring where its tapped in, or the units themselves starting to fail

Deandubya said

does the car start fine, no slow start issues… any smells on starting, as you said it needs a tune, what is making you say that…? A bit concerning on the cutting out issue, something electrical shorting or relay? or fuel pressure… i'm sure rubjonny mark1gls & Briano1234 can help you with this…  

I'm not sure I should be mentioned in the same paragraph as these 2 legends of the VW world..

Does sound like some sort of electrical problem if it's just happens all of a sudden?
rubjonny and Briano1234 are your electrical guys…

When you do get to set up the car make sure you are running it on super unleaded as I found my car runs smother and pulls better on it.  

So this still isnt sorted!

Took the WUR off and checked it inside and it was spotless!! Put it all back together and still same issue.

Set the timing and dizzy to TDC and adusted the idle screw.

Let the car start and it was ok but not smooth.

Kept it stationanry and waited for it to warm up completely and thats when it cuts out!
Fan kicks in but car stalls and dash lights come on.

Kept starting it to hear if the lift pump or outer pump were the culprits, but you can hear them running even after the engine dies….

Not sure what to try next..

Thank you to all who replied and assisted!!!!

The problem was ELECTRICAL!!! Turned out to be the existing Autowatch immobiliser!

Who ever fitted it or messed with it bypassed a wire from the internal fuse box to the outer pin of the fuel pump relay!

Rewired it to run through the fuse box and the car does not cut out or splutter! it was preventing the right amount of current to the fuelling.

car now idles at 900rpm.

c11rgd said

F Reg Gti 8v Cabriolet DX engine

Totally standard
-1 immobiliser
-1 redundant alarm

Symptoms
-Randomly the car will hold back and the revs will drop, no power. then it will magically come back to life.
-Not like a missfire which chugs along, this is total loss of engine power, with no real reason.
-Seems to happen more when im about to slow down and changing gears, thus the car cuts out completely and the dash lights flash (battery) pump can be heard running for a second.
-hold back like a missfire when pushed under load at times.
-Seems to be at its worst when the car is HOT and stand still or in slow moving traffic
when the above the case, the car struggles to start as soon as you move it starts playing up and then does on you.

So far i have checked:
-In tank lift pump - replaced with another unit
-Outer tank pump- replaced with another unit.
-new fuel filter
-checked in the tank

-Replaced ignition coil -replaced with another unit.
-ignition module-  -replaced with another unit.
-directed coil to battery
-HT leads
-distributor cap and arm, even replaced the dizzy

checked all connections and plugs.
checked all breather pipes

im at a loss to what is wrong with the car. i know it need s tune up, i have checked the TDC settings and they are fine. the ide screw is also slightly open.

but i cannot get the car setup until i isolate the problem.

any suggestions.??
 

   Metering head plunger sticking?