one for the doc??

[rob-bx16v]

Hi There,

Right where do i start? This evening i decided to put my new dizzy cap and rotor arm on followed by my new fuel rail,seals and serviced injectors on the 16v. All jobs done but the anoying thing is the car has a very SLIGHT missfire every now and agian. Now ive had this problem before and it was traced to the plug for the knock senser being pluged into the actuator!!! (that was done at the garage during the engine re-build) now since i have touched the injector loom it seems to have come back to haunt me. Now all the plugs were labled and put back in the right place checked and double checked. Theres no leaks from the injectors now but i did discover the inlet manifold nuts were a bit loose so they were tightened up, the earths for the injector loom were cleaned and put back in place. The dizzy cap and rotor arm have been checked and they are on properly. One thing i have solved now is the car ACTUALY ticks over now when warm and doesnt hunt like there was an air leak??. Looking at the inlet manifold it will have to come off again soon as its leaking oil from there and it will probably be re-sealed. So the question is why does it "MISS" every now and again?? Having taken it for a blast it doent half go with the new injectors in you can realy tell the difference . could anybody share any light on these tempremental engines Oh and the other thing is its leaking from the exhaust manifold at the mo quite bad but the "miss" has always been there when the manifold was sealed just not as bad as now

[rob-bx16v]

im that mithered ive just realised ive posted in the wrong section. can one of the mod,s put it in the technical section please. cheers rob

[docchevron]

hhhmmm,
well, without actually looking at the car and checking everything, it's hard to say whats causing the miss really.

They are very tetchy about air leaks though, and if the inlet manifold was insecure then that wont have helped.
A leak from the exhaust manifold wont help either, although that would usually just cause rough running rather than a miss.

I assume the plugs are in tip top condition and the leads show no sign of tracking??

The injector plugs must be PERFECTLY clean, and tight. It could just be that since they've been diturbed one is not contacting well enough and giving a high resistence. Although again, that would usually be more noticable under load / hard acceleration etc..

Is the coil in good condition? They can break down and take the ign amp with them.
Since yours has the knock sensor then you'll have the big round multiplug on the O/S wing. Take it apart (carefully) and make sure all the pins are bright and tight, bit fiddly, but can pay dividends.

ANY air leak anywhere between the AFM and combustion chamber will f^&k things up royally, so it's worth ensuring all the pipework is not split and clipped.

[rob-bx16v]

Been out in it this morning and between idle and 2000 rpm there is definitly a miss. It doesnt do it constantly just maby 2 or 3 minitues apart. I called in at the local exhaust place today and the cars booked in for a new sealing ring and bolts for the down pipe to exhaust manifold. Could it just be an air leak thats causing this?? Did have the knock sensor unbolted yesterday as i re-rooted the injector loom under the inlet manifold but it was cleaned and re-bolted back on. (strangely enough though my car had the wiring for the knock sensor when i bought it but did NOT have one fitted?? the plug was just dangling loose??) The only other thing i could do is posibly swap the ecu for a spare i have to see if that does anything. As im writing this now im fuming with it as you just cant do a job without somthing else going wrong. Im tempted to cut my losses bung it on e-bay and get a newer car you can just turn the key and go............. says it all realy

[docchevron]

We all get like that mate. I threaten mine with the scrapper every other day, although if it keeps rooting the way it is, I wont have a car left to scrap!

hhmm, if it's only every 2-3minutes I very much doubt it's an air leak on the induction side.
Sounds more like an electrical gremlin. I'd be very surprised if the ECU was causing the fault though.

Has your car got the multipin round plug behind the LHM tank? I'm assuming it has, so it should have the knock sensor, but interesting it wasn't fitted...

I assume the idle actuator is working correctly??

Also, does your have the K light, and if so, does it work??
Not all valvers used the K light, mine doesn't... and I know several others that dont. But could give us a clue!

[rob-bx16v]

Doc,

yes it does have the big connector by the lhm tank and all the wiring is there for the knock sensor. The idle actuator is not the original it was changed for one that was on my old 16v that was scrapped (e652 bfm) but it worked perfectly when taken from that car. Ive had the plugs out and they are all ok.. like new, The dizzy cap and rotor arm are brand new as well, My ecu was tried on my dads car and there was no fault to be found. K light wise my valver was built in 1991 orga 5338 and registered in 1992 and doesn have one??????. The symbol is present on the dash and ive even had the dash out and but a bulb in there to no avail. If it does have a k light its never worked in the period ive owned it yet my dads 16v rolled of the production line only a week later orga 5342 and his has a k light and knock sensor fitted witch makes me think someones been playing with the loom in the past ?????.

[rob-bx16v]

Also forgot to mention that it has a new coil on but ive also tried a brand new spare i carry with me so its not that. The ign amp has also been replaced but that was about 5 years ago again it was one that i took from my other valver before i scrapped it and it was a nearly new amp then since then i havent tried a spare because i cant find it. Ive also cleaned all the injector loom plugs up and re connected them to no avail.

[docchevron]

Ah, nope, yours wont have the K light. Bummer...

Ok, I'm sure they're fine, but do you know the condition of the hydraulic lifters??
A long shot really, I'm sure it's electrical.
Have you ever had the car on an ECU reader, preferablly one that gives real time??
Usually if the K light is not employed the socket doesn't work either...

At this stage I'd be tempted to check the resistances of the two earth wires as far back into the loom as you can..

[rob-bx16v]

Doc,

im almost sure now that its electrical. But yes the hydrolic lifters on mine are VERY worn and are VERY noisy also the cams are original but i didnt have them done as like i said i want a ported/cammed head so i dont want to spend the money on this head.

[rob-bx16v]

Problem solved.......... It turns out that i had put the white backing plate to the distributer on the wrong way round . The cap didnt fit properly and was not quite lined up with the rotor arm inside hence the miss.