The mk2 escort with cosworth turbo engine is coming out the garage after winter and took it for a drive today. I have an issue where it runs ok at idle and revving it on the drive and driving steady. But when I put my foot down it intermittently misses and splutters and pops. I had a leaking injector into the manifold and wiggled it and stopped leaking but this fault is as if the injector doesn't keep up when accelerating.
any ideas?
Have you replaces the phase sensor and crank sensor since you have owned it? that would be my first port of call, along with a new set of plugs.
Cossie misfire chasing can be a nightmare
plugs and plug gaps are first place id start
Not changed these but it revs fine even up to 5k rpm if I take it up steady it just seems to be when u give it some. Been through 2 sets of plugs recently. They do seem to get coked up quickly.Originally Posted by Bloomers
Lower your gaps a little, mine used to blow out the spark when the boost came on quickly and strong.
What to? And how is this done? Never heard of doing this before. Thought they would be set right if they are the plugs for the car.
Thanks
I'd say fuel pump due to it happening underload. What pump are you running and what condition is the wiring supplying it?
They're a bastard for trying to tracing misfires though so it could be loads of other stuff.
I'd get that leaking injector sorted though too before it goes up in smoke!!
it was common to reduce plug gaps to avoid blowingthe spark out, particulary if running raised boost, if it misses but is ok if you lift and then boot it again its well worth trying smaller plug gaps i found 0.020 to 0.022" good
check the manual for the correct gap. 071 plugs, i have 0.7 mm in my head, but i dont know why. plug wont nessersarily be right for every application out the box.
good point on the pump, check the voltage isn't dropping off under load, that could reduce fuel pressure
It's the 044 fuel pump. I'm certain that's OK as it's an instant thing when I plant my foot. I have the 071 plugs. Would you recommend reducing the gaps on these or try different plugs.
something to add is that my map sensor is mounted on its side. I have been told it may not function this way and needs to be up upwards like it comes in the Sierra cosworth. Is this true and could it cause an issue?
Right,
I Tried a spare set of 071 plugs that I gapped to 0.6mm and fired up smooth. Runs responsive and doesn't miss a beat now. This will now be the 2nd time I have had to do this but it has worked. I noticed the plugs were coked up a lot this my be due to starting it cold and it over fueling until it warms up and I noticed plug 2 was wet. By changing the plugs it runs nice and smooth. Is this an issue with the cheap 071 plugs I'm using and I should try some iridium ones or is there an over fueling fault that causes the plugs to Coke up. Compresion test fine.
I'd look at fuelling. Mine used to happy run 365hp at 30psi using 071's. just used to change them every service. used iridium once, but they never made a difference to anything.
If you have 1 wet plug, no missing and good even compression, I'd be looking at a fault with that injector. if its worn or dribbling a bit, you might be overfuelling a single pot.
right, just been having a look and I'm even more confused now. The plug on cylinder 2 is wet so as you suggested it may be a leaking injector. So I swapped injector 2 with 1 hoping the wet plug would be on cylinder one but the wet plug is still 2. I ran it and it's running on 3 cylinders so pulled the lead of 2nd plug and runs the same and checked for spark and looks good.
Like I said, after driving about 500m it clears and runs fine. No idea what this could be as its on the same cylinder which compression tests out ok, good spark, injector changed :/
Is your dizzy cap and rotor arm ok? I used you burn them out fairly regular. If the terminal for number 2 is worse than the others, you could visually get a reasonable spark, but it may not be as strong when under load or running
dizzy cap and rotor arm where brand new about 300 miles ago. I will how ever take them off to check and reconnect. The only thing I haven't changed is the ht leads as I would have thought it either works or it doesn't and like I said, after driving 500m it clears and runs fine and continues to run fine.
Thanks
Right, have done a cold compression test on all 4 cylinders and have found the following: cylinders 1,3 and 4 all give a reading between 135 and 140 but cylinder 2 gives a higher reading of about 155 and if I continue to crank it, it goes up to 180 and holds there. Surely this is not right? What is it indicating is wrong? Or could this reading be due to carbon build up from misfiring?
thanks
Last edited by Jon_d_h; 02-03-2016 at 18:20.
do the compression test again on a warm engine, the first three look low, the last lloks high, it could be high because the oil rings are not doing there job, or theres loads of oil going down the guides and that oil is giving compression ring a better seal than if it were dry
thanks, the reason I did it cold was because I only seem to get the misfire when it's cold. I assume that the cylinder is is carboned up due to the last times I have been running it it's been misfiring. I will how ever do the compression test again warm but it runs fine when warm. I read 140 psi is the readings I should be getting.
thanks
Think I have found the fault. Where the ht leads connect to the dizzy cap the one for cylinder 2 was loose. Have removed the dizzy and the leads and no of them really connect to the cap well. Even when pushed on tight they manage to find their way loose again. Are there different connectors on the ht leads or dizzy caps?
not heard of that before. have you tried a different cap?
No the cap is reasonably new. I thought this solved the issue but seems I still have a mis under load. It idles ok now since reconnecting the lead but I have removed the leads and cap to terminate them all better. Also, is it possible to get an intermittant fault with a ht lead? I might be worth replacing them all. I'm not sure if the mis is related to my previous mid fire or is something completely different now.
my leads kept coming loose so i used cable ties to secure them in the cap, haven't had a problem with misfires since, also a group a coil might help if you are on a standard one.
iv had the same problem, changed ignition amplifier and sorted for a time, it could be over boosting? try amil valve
Had this on mine on boost seemed to be dodgy Ht leads
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Rev counter made mine misfire :-) strange
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