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View Full Version : C20XE on Twin Webers - Misfire - Plz Help!


frank_dh
15-09-10, 07:54 PM
Hello,
I'm really needing some ideas on the long standing problem with my C20XE. I've taken some many routes only to hit brick walls, today I took the last route and hit yet another.
I'm running a C20XE on twin 45 Webers using the Webcon ignition system with a coil pack and ecu.
I have a pair of genuine Weber brand new out the box carbs.
There is a misfire on cyl 3 & 4.
All cylinders have spark, fuel, good compression on all four cylinders.
I've replaced the head gasket, had the head pressure tested and the valves lapped in.
Valve timing is correct. Pistons and bores are fine. Valves are straight. It has brand new plugs, also swapped around. The HT leads are on in the correct order.
I've swapped the carbs over left to right and it still misifres on 3 & 4.
It will genuinely run on two cylinders, ( 1 & 2 ), by removing the HT leads on 3 & 4 it makes no difference to the engine running and there is a strong spark from each lead.

I've put some pictures up just to show the set up.
Any help and ideas will be greatly appreciated.

Cheers, Frank

http://s910.photobucket.com/albums/ac305/djfrankly/?action=view&current=SDC11522.jpg

http://s910.photobucket.com/albums/ac305/djfrankly/?action=view&current=SDC11520.jpg

http://s910.photobucket.com/albums/ac305/djfrankly/?action=view&current=SDC11521.jpg
Cle
15-09-10, 07:57 PM
Not sure about engine problem but, if i see correctly i can see a bent shell soon
frank_dh
15-09-10, 08:11 PM
Bent shell?
Cle
15-09-10, 08:16 PM
Doesnt look like its been seam welded
Balley
15-09-10, 08:21 PM
Right so even if you swop the carbs it still misses on them cyclinders, and all 4 sparks are healthy and its sparking at the correct time!?
frank_dh
15-09-10, 08:25 PM
yep, Carbs swapped over, still misses on same cylinders. Brand new super4 plugs, swapped over from cyl to cyl, correct ignition timing straight from the coil pack,,,
frank_dh
15-09-10, 08:26 PM
Btw, Harry Hockley strengthening kit fitted
Balley
15-09-10, 08:29 PM
This is strange as we had a lad bring an let head in with the same problem at work, he never fixed it in the end, we also skimmed it and re seated valves etc..

dunno mate
frank_dh
15-09-10, 08:39 PM
Well, I'm not the first then! My head has been skimmed and valves lapped in. Compression is 10.9 - 12 bar across each cylinder.
John
15-09-10, 08:48 PM
Frank, is it possible to swap the carbs over? (ie side to side?) Any airleaks manifold to head/carb to manifold?

(cle, if you can't help, keep your trap shut!)
Cle
15-09-10, 08:49 PM
Frank, is it possible to swap the carbs over? (ie side to side?) Any airleaks manifold to head/carb to manifold?

(cle, if you can't help, keep your trap shut!)

blah blah i was merly pointing something out
John
15-09-10, 08:50 PM
blah blah i was merly pointing something out

Not very constructive though was it. :roll:
Damo
15-09-10, 08:56 PM
Frank, is it possible to swap the carbs over? (ie side to side?) Any airleaks manifold to head/carb to manifold?

(cle, if you can't help, keep your trap shut!)

Think he's mentioned he's done that in his first thread john and its still the same.

Frank, A silly suggestion tbh but have you connected the servo vachum hose as i forgot once and it caused similar problems for me.
Cle
15-09-10, 08:56 PM
Not very constructive though was it. :roll:

Well could of been if he drove it and then buckled shell lol
frank_dh
15-09-10, 08:56 PM
Yes John, I've swapped right to left, new inlet gasket, all put on clean during head gasket. Also checked servo pipe, no obvious problems. Induction from all four ram pipes. Seems to be strange problem :-(
John
15-09-10, 08:57 PM
Well could of been if he drove it and then buckled shell lol

oh yeah, silly me. :roll:

Sorry Frank i'd missed you swapped the carbs, do the plugs foul?
frank_dh
15-09-10, 08:58 PM
foul as in coke up or foul as in hit the piston?
John
15-09-10, 08:59 PM
Foul as in soot/oil up.
frank_dh
15-09-10, 09:01 PM
no, do seem damp though so definately fuel getting in. New plugs so hard to tell,,,
turnipheed
17-09-10, 04:42 PM
have you checked the inlet manifold for cracks/ poor welds ? what about the coil pack is it run from a stand alone ecu, if so is it programable? i had a mis on my 45 xe but it was a mix of leads and plugs but you have covered that,
mowgli
17-09-10, 05:00 PM
ht leads or coilpack.. you can often get a weak spark in the open air, but not in a high compression environment.
turnipheed
17-09-10, 05:07 PM
ht leads or coilpack.. you can often get a weak spark in the open air, but not in a high compression environment.

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