mk2 gti wont run :(

hi people i am converting my 1.6 carb to a 1.8 8v gti when i first installed all the engine etc it fired up first time and run brilliantly then after about 30 mins it would start to missfire i would rev it and it would clear itself out i just put it down to not being run.

i have come to start the car yesterday and it started fine then missfired as usual but when i accelerated it wouldnt , no matter how much throttle i put on it would not rev up then it cut out and wouldnt restart.

i have come to it today and i will start but only run on the fuel in the line then cut out again i have to turn the ignition key back and forward so the pumps prime the injectors then it will fire up but again cut out after 2-3 seconds .

it is really annoying me and i need help please lol i have fitted a 16v high pressure fuel pump if thats relevent .

cheers ben

 

Did you fit the intank pump / sender unit from the 16v aswell?
This in tank pump lifts fuel out of the tank into the fuel bath that the injection pump sits in. The injection pump on its own will struggle to lift fuel from the tank.
Is the 8v K jet or Digifant injection? They run at different pressures.

 

hi i fitted an 8v lif pump and its digi

 

just got it started i found out that the air flow sensor wasnt plugged in ( my bad ) it ran mint cold but asoon as the engine started to heat up it started missfiring again and cut out and now wont start again i think its the coil breaking down any ideas guys?

 

assuming youve gone through rubjonny faq and checked dizzy cap/rotor arm/leads + changed blue temp sensor.. would guess its more to do with fueling than ignition with it getting worse as engine warms up (although coil heating up/breaking down does also make sense)

worth checking the vac line from the fpr goes to the outlet nearest passenger side on throttle body. also if youve got an ohmmeter you could also check resistances for air temp sensor in filter housing (as per graph in haynes)

 

iv checked all the vac lines and changed a few suspicious ones but nothing i have bought a new temp sensor so wil be fitting it tommorow and seeing but if that doesnt work will check the air flow cheers will update on the progress when i have done these things

 

i have done these things and still nothing, the air flow has tested allright, i took the plugs out they were cacked in petrol it is overfueling i have no ideas

 

i have done these things and still the problem continues it is overfueling the plugs stank of fuel when i pulled them out , i couldnt even get it started today

 

Have you put the correct connectors on each temp sensor?? the one for the ecu and the one for the gauge?? I'm not sure but I think you may be able to put them on the wrong sensor which will send the wrong signal to the ecu... You can also adjust the co (petrol ) on the maf .. I think you screw it in to lean it off but the car needs to be running to do this.. How long has it been running for in total??? Is the coolant circulating? It maybe worth checking all the plugs are on the correct sensors

 

yes i have put all the plugs on the correct sensors this was one of the first things i checked lol i have had it running about 5 times and everytime it has cut out just before running temp so dont even know if my stat opens

and i have allready changed the earth to the stud on the rear bell housing bolt.

i managed to get it statred this morning after flattening 3 batteries but it only stayed running for qbout 3 seconds enough to use the fuel in the line up .. my head is boggled lmao

 

i have just checked autodata and the 8v engine fuel pressure should be 3 bar were as the 16v should be 4.5 bar as i have fitted the 16v pump to a 8v engine is this the problem?

 

have allready changed the vac pipes to the fpr and cheers at least that means i dont have to buy another fuel pump lol

 

i have just thought of another possibility ... crank position sensor (hall effect sensor) inside the dissy does anyone know of any common faults with these ?

 

pretty sure they either work or they dont.. though worth checking wires round plug. when it cuts out do you know if youve still got a spark?

have you tried leaning it off a load on afm? haynes and elsawin say turning screw clockwise leans it off but iirc theyre both wrong and its actually other way round! ie unscrewing it leans the engine off. this makes more sense (to me anyway) as the more you unscrew it, the more air is able to bypass the afm flap.. less movement of afm flap means less fuel.

 

yes i still have a spark it not brilliantly strong but should be enough to start it .

will try leaning the mixture off, not sure if it going to work though as the engine was running when i removed it from the other car about a year ago. will let you know how it goes

 

Hi mate. You can try leaning off mixture but for it not to run it would have to be so far out that i cant see that being your problem. As you have just done the conversion im assuming the new engine and all bits and pieces were sitting around for a while. I had a problem with my golf that sounds very similar to yours after it sat for a couple of months. It turned out to be the Air Flow Meter. Have you checked that the flap moves freely. It should feel smooth and return back to start position quickly. Even if does it could still be that. I spoke to a friend who works at a vw breakers yard, he said these are the most likely cause. I paid 30 for a second hand one which cured the problem. Hope this helps. Good luck mate

 

i leaned it right off as far as it could go and it fired up eventualy and it ran the best since i have had it but yet again when it got hot it started miss firing and it cut out you can actually hear each cylinder dropping off. i have allready looked at the airflow meter it moved freely and i have done a rwsistance check across the terminals moving the flap to make sure it flucuates etc the terminals on the plug are abit corroded but nothing serious cheer sfor the input though mate , i removed my induction pipe and looked inside my throttle body and it is cacked up with a gooey substance so i removed the breather pipe to my rocker cover and it had the dreaded mayo substance coating the inside and abit on the oil filler too i think i am scrapping the bottom of the barrel here but is it possible for the head gasket to be gone/faulty causing low pressure in the cylinders when it gets hot and expands causing it to missfire and eventually cut out? it only had it done 11,000 miles ago