Printable Version | Subscribe | Add to Favourites
New Topic New Poll New Reply
Author: Subject: DOHC Carb engine running poorly
Jon Bradbury

posted on 10/6/05 at 11:41 AM Reply With Quote
DOHC Carb engine running poorly

hi

Just got back from my pre SVA MOT and the engine has been misbehaving.

Basically it is running OK on full throttle but with moderate loads it cuts out momentarily before kicking in again. Holding the throttle about half way causes the engine to hunt in regular spurts, so it cuts out, then revs, then cuts out, then revs (and so on), with the frequency of each cycle being regular.

I think the ECU is trying to compensate for something, but I don't know what it is. It's similar to fuel starvation.

The kind of things I will check are

- air leakage on the inlet manifold
- blocked jet in the carb
- a blockage in the fuel system before the carb

Does anyone have any other ides? I couldn't get the emission test done because of this, it wouldn't hold steady idle or intermedite engine speed (2500 RPM was what the tester wanted).

All ideas welcome!

Thanks

JonB

PS, Apart from that the car performed well. Got up to 90mph on the dual carriageway <ahem> private road and it's going well (on full throttle). After getting the wheels aligned I have self centering too!

View User's Profile Visit User's Homepage View All Posts By User U2U Member
TTK77

posted on 10/6/05 at 12:12 PM Reply With Quote
Propably needs different kind of emulsion tubes.
To get more fuel to middle rpm's.
Which number tubes do you have in them?


[Edited on 10/6/05 by TTK77]





http://www.aar.fi

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
awinter

posted on 10/6/05 at 01:14 PM Reply With Quote
what carbs are you running?

Could you not richen up the idle mixture to increase the fueling on part throttle. Just a couple of turns of 4 screws on DCOE or DHLA carbs

View User's Profile View All Posts By User U2U Member
Jon Bradbury

posted on 10/6/05 at 01:27 PM Reply With Quote
It's a Weber 2V TLD, standard fitment to the Ford 8v DOHC engines (well the ones that aren't injection that is!).

I don't expect there's anything non stock about it as it came straight out of the donor with the engine as-is.

This problem manifests itself once the engine is warm, after a few miles.

[Edited on 10/6/05 by Jon Bradbury]

View User's Profile Visit User's Homepage View All Posts By User U2U Member
TTK77

posted on 10/6/05 at 01:38 PM Reply With Quote
My mistake...I read DCOE instead of DOHC. I thought you had twin webers...





http://www.aar.fi

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
Jon Bradbury

posted on 10/6/05 at 04:41 PM Reply With Quote
Not on that engine. No one makes a manifold for it
View User's Profile Visit User's Homepage View All Posts By User U2U Member
Jon Bradbury

posted on 10/6/05 at 04:42 PM Reply With Quote
quote:
Originally posted by awinter

Could you not richen up the idle mixture to increase the fueling on part throttle. Just a couple of turns of 4 screws on DCOE or DHLA carbs


Don't think I can be doing that as it's going for SVA next Thursday. Fiddling the mixture will spoil the CO2 + HC readings.

View User's Profile Visit User's Homepage View All Posts By User U2U Member
big_wasa

posted on 10/6/05 at 10:16 PM Reply With Quote
I had a Fiesta that would do that.It was just crap in the jets from me always running it with bugger all petrol...You used to have to pull the choke out to richen the mixture to get you home..

The carb on those is servo controled from the ecu,are they working ok? on mine it sticks from time to time and you have to dab the loud pedal

What air filter do you have, again I have this engine in my donor car and I fitted a piper cross jobie which leans it of a bit to much.Great induction sound from it

View User's Profile View All Posts By User U2U Member

New Topic New Poll New Reply


go to top






Website design and SEO by Studio Montage

All content © 2001-16 LocostBuilders. Reproduction prohibited
Opinions expressed in public posts are those of the author and do not necessarily represent
the views of other users or any member of the LocostBuilders team.
Running XMB 1.8 Partagium [© 2002 XMB Group] on Apache under CentOS Linux
Founded, built and operated by ChrisW.