Zetec woes... Help !

[B@man]

The 16v Stylus is giving me a headache....

Here's the saga...

The car is fitted with a 115ps Silver top Zetec, with Dunnel 3D management & twin 40 DCOE's and has done approx 8500 trouble free miles since it was built.

Earlier in the year I started to get fuel appearing on the tops of the carb's, I traced this to split o'rings on the pump jet covers, then the brake light switch failed so I had to take the carbs off to get at the switch. So while the carb's where off I stripped them down, cleaned all the chokes / jet's etc and rebuilt them using a couple of weber service kits. The Carbs had a LOT of brown rusty goop in the bottom cover which I cleaned out, as this is the forth car that the carbs have been on I am fairly sure that the goop has been there since the Stylus was built. I checked the filter in the red top pump & it's clean which seems to confirm this. And I fitted a new cam belt at the same time.

Anyhow back to the plot, after the rebuild I re balanced the carbs, set the idle mixture and the car ran OK apart from a slight flat spot at approx 2000 RPM it ran OK (maybe the goop was doing something ?)

Three weeks later the thing is now running like a tractor, it's backfiring, spitting back through the the inlet and is all but un-drivable. It will idle but as soon as you open the throttle it coughs splutters pops and F$%ts....

So far :

Removed and cleaned plugs - ALL BLACK !
Checked float height - OK
Swapped out coil pack - No Change
Check connections to coil pack - OK
Checked spark at all 4 pots - Good spark at each cyl
Disconnected throttle pot - Same problem even when running 2D
Removed both carbs, fitted new MISAB plates and thackery washers
Refitted carbs, rebalanced + checked for leaks using carb cleaner
Before taking the carbs off Cyl one was spitting back, afterwards with the new MISAB plates cyl 4 is spitting back, I don't understand this ?

Back to square one, it will idle with occasional spitting back / backfiring, increasing the revs from idle to progression then onto the main circuit makes the problem worse, so if there is a problem with the carbs it's effecting both idle and main circuits ?

To Do :
Compression test
Replace plugs
Check Fuel pressure from regulator
Try another CAS (Crank Angle Sensor)
Check Cam timing has not slipped (Unlikely without a bang ?)
Put it back in the garage and forget about it......

Any other ideas ?

I've read about sticking valves on early silver tops ? This is a 97 lump and has 0W30 Fully synthetic oil, engine only has 20K since new and the problem does not seem any better worse when the engine is cold or hot so this seems unlikely ?

Anyone had a similar problem ?

[MJG280]

I had the spitting back on a cologne 2.8 eventually I thought of sticking valve, applied Halfords finest tin of cleaner additive and 15 minutes later perfect. Well as perfect as a 2.8 cologne is ever going to be. I had assumed that a sticking valve would just be short of a power but obviously the combustion was competing with something somewhere at revs.

A few weeks later the day car had a noisy tappet so back to Halfords and sorted

[B@man]

Thanks for that.

Hopefully the compression test should show something wrong if valves aren't closing properly, I read somewhere that 0W30 is actually thicker than 5W40 that is specified for this engine, engine ran fine for years on Mobil 1.

I've arranged to borrow a compression tester on Sunday so hopefully I'll fins something, I hope it's as simple as changing the oil !

[anonymous-user]

I had a 2L Zetec in my Tiger and initially it behaved as your does - idled OK but any throttle application would cause it to cough, splutter, backfire and most likely stall.

It just needed the carbs to be setup correctly (Weber 45s) - turned out they had the wrong jets and emulsion tubes, once they were swapped and the carbs' airflows were balanced it ran perfectly.

[B@man]

After much mucking about, I have eventually fixed the problem - 2 duff plugs !

Note to all: don't try to clean platinum plugs, bin 'em and fit new ones !

[singlecoil]

Bike carbs of various types are now highly thought of for the Zetec, Webers are becoming comparatively rare. A set off a 600cc bike seem to be ideal. Might be worth considering if you get any problems with the Webers

[B@man]

Hi SC,

I've heard good things about bogg bros bike carb conversions, however the DCOE's are now singing in tune again so hopefully that will be end of the popping and farting. Just need to get a few small cosmetic jobs done over the winter and it will be in the classifieds in spring.

Time for something with the same number of valves but double the cylinders (& Power)