Persistant missfire is driving me mad

[dan71westy]

Hi there. I have a problem thats driving me mental. I have recently rebuilt the engine in my van and fitted a 1641cc bore kit. The week before i rebuilt the motor i had a missfire start (its only ever missfired when the points have worn out). Its still the same after. Its running twin Dell'Orto34 carbs, Pertronics Ignitor breakerless ignition and Pertronics flame thrower coil, ceramic mondo exhaust. Its had new plugs, leads, dizzy cap, rotor arm. I removed ignitor and refitted points and condenser and its still exactly the same. Have now refitted ignitor kit, still the same. Adjusted tappets and its still the same. Piston rings are seated correctly and in the correct orientation, Im at my wits end with the bus now. Anybody got any ideas?

Im supposed to be taking the bus to Scotland on July 24th and its fast approaching now.

 

[aogrady]

Hi!

Have you put another coil on? I have seen posts on vzi regarding problems with the flame thrower coil. A post suggested using a Lucas DLB105 sport coil, 17 quid or thereabouts

http://www.minisport.com/acatalog/info_DLB105.html" onclick="window.open(this.href);return false;

Maybe you can borrow a coil to try?

Alistair

 

[dan71westy]

Also tried a brand new Bosch Blue and still the same. Im really hoping it hasnt got a kippered valve or seat. Really dont want to pull the engine out again.

 

[mk2matt]

to stop points wearing out on the cam of the dizzy grease the cam up and makes it not stick or wear too quickly

had this prob on the bus and the beetle

good luck dude

 

[ProfessorWheeto]

Is it a constant or intermittent miss? Is it on the power or on the over run?

Is the exhaust fitted and sealed up correctly?

 

[dan71westy]

Its constant from startup on the power. re hung the exhaust 3 weeks ago when engine went back in with a good quality fitting kit. No leaks. Ran lovely for about an hour but not properly since.

 

[mjknight71]

.....I was going to suggest, since you feel it maybe a valve to wet and dry compression test it to see if something shows up....

......but then I thought 'can you wet compression test a flat4 engine' :? now I have just confused myself! :roll:

Pull a lead off each cylinder and maybe isolate which one it is that is missing?

 

[ProfessorWheeto]

Double check your plugs?

Had a constant misfire on mine that turned out to be dirty plugs. Guess your carbs to be set too rich, but not sure if they could foul up the plugs in an hour?

 

[VWAIRCOOLED]

Did you take all the valves out and re seat them whan you had it apart?

I would pull a lead off each cylinder as mjknight71 says and try and work out which one isn't working properly and go from there.

 

[dan71westy]

I should have done but i didnt reseat them. Cant even turn the key in the ignition now. I love these old vws!

 

[VWAIRCOOLED]

Maybe thats the cause of the misfire,the ignition switch has burnt out ?

 

[muntz70]

Just had a friend with a similar problem and we found that one of the intake gaskets was the cause.

...my 2 cents.

 

[dan71westy]

WAHOO Sucess at last. Had a dodgy spark plug coupled with a dodgy lead. (both were quality Brand New Bosch items!!) I had reset the valve clearences before running the motor so soon as it had run everything settled down a bit therefore tappets needed adjustment again.
New ignition barrel fitted after idiot mechanic forced it with the wrong key now for the dreaded MOT on monday!

Cheers for your help guys.

 

[VWAIRCOOLED]

Well done dude,good luck with the MOT