desperate - massive miss
Discussion
I'm desperate - a week long rally next week, 3 days in the workshop this week, and no solution!!
1996 4.0 Chimaera has just developed a massive miss that occurs occasionally – sometimes massive problem, sometimes minor, sometimes runs OK
Symptoms
- always runs OK with the accelerator well down
- under deceleration from any rev range – will sometimes have massive jolts, sometimes just a large miss. Often have to use clutch to avoid mechanical clangs
- stalls and nearly stalls sometimes at idle – next minute, no problem
Have done
- stepper motor cleaned & checked – but this should only affect the idle anyway, but problem also occurs at much higher revs than 1500
- have replaced distributor cap, rotor, igniter unit, leads, plugs
- trial replaced all other electrical items – complete distributor unit, coil, no resistor on plug leads
- compression OK
- empty fuel and checked = OK
- replaced fuel filter
- when its running OK – diagnostics OK – ie hydrocarbons etc
Other
- computer shows no faults other than some stepper motor issue. Not thought that this is the root cause because happens at all rev ranges
- when the igniter unit was replaced on Monday, car ran the best it ever has – more power everything. About 50 k’s later – went even worse than it had been. Igniter has since been trial replaced – but fault continued
From my perspective the “experts” are at their wits end. They all think that it is electrical. It seems to me that it is now likely to be something very subtle
I am about to check myself
- earth from motor to chassis – but starter motor / starting has never been a problem
- earthing of igniter unit – does anyone know anything about this unit???
If anyone can suggest anything at all – it would be hugely appreciated
1996 4.0 Chimaera has just developed a massive miss that occurs occasionally – sometimes massive problem, sometimes minor, sometimes runs OK
Symptoms
- always runs OK with the accelerator well down
- under deceleration from any rev range – will sometimes have massive jolts, sometimes just a large miss. Often have to use clutch to avoid mechanical clangs
- stalls and nearly stalls sometimes at idle – next minute, no problem
Have done
- stepper motor cleaned & checked – but this should only affect the idle anyway, but problem also occurs at much higher revs than 1500
- have replaced distributor cap, rotor, igniter unit, leads, plugs
- trial replaced all other electrical items – complete distributor unit, coil, no resistor on plug leads
- compression OK
- empty fuel and checked = OK
- replaced fuel filter
- when its running OK – diagnostics OK – ie hydrocarbons etc
Other
- computer shows no faults other than some stepper motor issue. Not thought that this is the root cause because happens at all rev ranges
- when the igniter unit was replaced on Monday, car ran the best it ever has – more power everything. About 50 k’s later – went even worse than it had been. Igniter has since been trial replaced – but fault continued
From my perspective the “experts” are at their wits end. They all think that it is electrical. It seems to me that it is now likely to be something very subtle
I am about to check myself
- earth from motor to chassis – but starter motor / starting has never been a problem
- earthing of igniter unit – does anyone know anything about this unit???
If anyone can suggest anything at all – it would be hugely appreciated
Thanks to everyone who helped on this. I couldn’t log on to here yesterday for some reason – so todays update!
It went OK all day yesterday after the various fixes. I could still detect the problem – don’t think it was my imagination – but severity so slow that it’s no problem
The earthing as per Seasider was I think the biggest single difference
I also checked every electrical connection I could find, and sprayed their contacts with contact cleaner – especially including the injectors
I re-routed all wiring to prevent any HT wiring touching any of the low voltage wiring – especially near any sensor wiring
One of the receptacles holding the little suppressers near the coil was not tight, and the suppresser spade terminal could move quite easily – I tightened that up
A huge thanks to everyone – and I would love to buy a beer for any of you if you come to Auckland at any time!
I was (probably still am) really stressing as we are about to start a week long Targa rally from Auckland to Wellington. About 650k of special / closed stages and 1400+ k’s of touring. 197 race cars, and 22 touring cars – I am touring this year
Some interesting drivers including Chris Amon out of retirement with Murray Walker of F1 fame as his co-driver
See more on www.targa.co.nz
Thanks guys!
It went OK all day yesterday after the various fixes. I could still detect the problem – don’t think it was my imagination – but severity so slow that it’s no problem
The earthing as per Seasider was I think the biggest single difference
I also checked every electrical connection I could find, and sprayed their contacts with contact cleaner – especially including the injectors
I re-routed all wiring to prevent any HT wiring touching any of the low voltage wiring – especially near any sensor wiring
One of the receptacles holding the little suppressers near the coil was not tight, and the suppresser spade terminal could move quite easily – I tightened that up
A huge thanks to everyone – and I would love to buy a beer for any of you if you come to Auckland at any time!
I was (probably still am) really stressing as we are about to start a week long Targa rally from Auckland to Wellington. About 650k of special / closed stages and 1400+ k’s of touring. 197 race cars, and 22 touring cars – I am touring this year
Some interesting drivers including Chris Amon out of retirement with Murray Walker of F1 fame as his co-driver
See more on www.targa.co.nz
Thanks guys!
Gassing Station | Chimaera | Top of Page | What's New | My Stuff