Major miss-fire when hot
Discussion
My chim 450 has just started to exhibit a major miss-fire (signified by major loss of revs and stuttering) when the engine has thoroughly warmed up (after 15-20 mins of urban traffic).
Idle is fine (if perhaps a little low)
Constant throttle load is not too bad (though it is a bit lumpy)
Major problem is under acceleration between 1K - 3K - very rough running and miss-fires.
All goes away again when engine cold and restarted.
I've had a quick check of the forums and it is booked in to Offords next week but I was just wondering what the likly cause could be:
a) stepper motor (but idle is OK)
b) coil breaking down (wouldn't this be all the time?)
c) ignition amplifier
d) lamba sensor dead
e) ECU dead/dying (but won't this happen all the time?)
f) leads breaking down when hot
Any ideas gratefully received.
FG
Idle is fine (if perhaps a little low)
Constant throttle load is not too bad (though it is a bit lumpy)
Major problem is under acceleration between 1K - 3K - very rough running and miss-fires.
All goes away again when engine cold and restarted.
I've had a quick check of the forums and it is booked in to Offords next week but I was just wondering what the likly cause could be:
a) stepper motor (but idle is OK)
b) coil breaking down (wouldn't this be all the time?)
c) ignition amplifier
d) lamba sensor dead
e) ECU dead/dying (but won't this happen all the time?)
f) leads breaking down when hot
Any ideas gratefully received.
FG
cheers guys, I'll try the hot at night bit and look for sparks.
Interstingly the bu$$er did something different on the way home...
engine cold, started OK.
3 mins later (not quite 1.5 miles and engine not hot) cough, cough, splutter, die.
engine turned over but could not sustain any revs.
tried 3 times to restart (creating traffic jam in Cambridge at 5PM
) and on third time it started fine, picked up OK and never missed another beat in the 15 miles home.
could this be fueling related? crap in petrol, dodgy connection to the fuel pump, fuel pump relay on the way out.
confused of Cambridge
Interstingly the bu$$er did something different on the way home...
engine cold, started OK.
3 mins later (not quite 1.5 miles and engine not hot) cough, cough, splutter, die.
engine turned over but could not sustain any revs.
tried 3 times to restart (creating traffic jam in Cambridge at 5PM
) and on third time it started fine, picked up OK and never missed another beat in the 15 miles home. could this be fueling related? crap in petrol, dodgy connection to the fuel pump, fuel pump relay on the way out.
confused of Cambridge
AH Ha! Had the exact symptoms last year. With mine I found a badly corroded fuse holder was the problem.
expose the fuse box. Have a look for a fuse holder which is hanging free. on mine this had got damp from the carpet and the contacts had changed into a corroded black mess (fuse itself was fine so it only showed when I removed the fuse. A new holder was 99p & took 10 min to fit. been fine since. Mine used to start to mis fire then pick up then just die. It wouldnt start for 10 min then it would be fine until the next episode.
Hope your problem is as easy to fix.
Pete
expose the fuse box. Have a look for a fuse holder which is hanging free. on mine this had got damp from the carpet and the contacts had changed into a corroded black mess (fuse itself was fine so it only showed when I removed the fuse. A new holder was 99p & took 10 min to fit. been fine since. Mine used to start to mis fire then pick up then just die. It wouldnt start for 10 min then it would be fine until the next episode.
Hope your problem is as easy to fix.
Pete
poorpeet said:
AH Ha! Had the exact symptoms last year. With mine I found a badly corroded fuse holder was the problem.
expose the fuse box. Have a look for a fuse holder which is hanging free. on mine this had got damp from the carpet and the contacts had changed into a corroded black mess (fuse itself was fine so it only showed when I removed the fuse. A new holder was 99p & took 10 min to fit. been fine since. Mine used to start to mis fire then pick up then just die. It wouldnt start for 10 min then it would be fine until the next episode.
Hope your problem is as easy to fix.
Pete
no hanging free fuse holder in mine (dontcha just love the standard build of Tivs
) - checked all the relays and fuse connections all seem OK - and the fusebox area is a dry as a bone. Were the symptoms that it would sort of fire when you were cranking it, and just about keep running at a very low and eratic tickover as long as you kept off the throttle, but cut out as soon as you touched the throttle? In this case you have no fuel pressure, most likely because of an electrical problem. Time to find the delay, fuses, inertia cut-out, cnnector at the fuel pump and see whether there is any obvious fault with any of them. If not then change the fuel pump relay just in case, because they're notorious for causing intermittant problems when they start to fail.
Thanks for the replies folks.
Diagnosis at Offords suggested the coil and ingnition amplifier.
These have been swapped and so far (touches lareg piece of wood) the car is running like a dream - pulling much stronger than it used to as well.
lets hope this has cured it and I'm not just in a good part of the intermittent cycle!
FG
Diagnosis at Offords suggested the coil and ingnition amplifier.
These have been swapped and so far (touches lareg piece of wood) the car is running like a dream - pulling much stronger than it used to as well.
lets hope this has cured it and I'm not just in a good part of the intermittent cycle!
FG
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