Can anyone help?
Discussion
I have a misfire problem with my 400SE.
No ordinary misfire this one!
She ticks over fine. If I apply the throttle gently she will run through the rev range sweetly but if I boot it she misfires between 2500 & 3000 revs. Once you get the 3200 revs she picks up and the misfire dissappears.
The misfire is through the inlet, you can clearly hear it in the plenum.
The things we have eliminated so far (mainly through exchanging with known working parts) are as follows:-
Ignition -
Plugs, leads, dizzie & cap, coil,throttle sensor,airmeter/ hotwire unit, ECU, ignition amplifier, temp sensor, stepper motor, timing
Fuel -
Pump (fuel pressure fine & increases when you blip the loud pedal), fuel relays, injectors
Currently we have run out of ideas.
Surely this can only be a fuel/ignition issue but this only occurs when you put your foot down, in other conditions the running is unaffected.
We have thought about valve spring or oil pressure to a follower but again this would be evident all the time.
Has any one had this problem or has an idea where to go next?
Beer tokens at the Wedgefest if you can help.
Brian
No ordinary misfire this one!
She ticks over fine. If I apply the throttle gently she will run through the rev range sweetly but if I boot it she misfires between 2500 & 3000 revs. Once you get the 3200 revs she picks up and the misfire dissappears.
The misfire is through the inlet, you can clearly hear it in the plenum.
The things we have eliminated so far (mainly through exchanging with known working parts) are as follows:-
Ignition -
Plugs, leads, dizzie & cap, coil,throttle sensor,airmeter/ hotwire unit, ECU, ignition amplifier, temp sensor, stepper motor, timing
Fuel -
Pump (fuel pressure fine & increases when you blip the loud pedal), fuel relays, injectors
Currently we have run out of ideas.
Surely this can only be a fuel/ignition issue but this only occurs when you put your foot down, in other conditions the running is unaffected.
We have thought about valve spring or oil pressure to a follower but again this would be evident all the time.
Has any one had this problem or has an idea where to go next?
Beer tokens at the Wedgefest if you can help.
Brian
Edited by Hormone on Thursday 20th March 12:18
Brain,
As Dicky says - it would be wise to check the throttle pot voltage at idle is correct and the afm voltage too.
Also check any wires for frays and brakages - the LT wires to the coil and cables to the ignition powerpack are famous for this. Also check the injector earth at the back of the engine block.
After that - I would check the timing and the exhaust gas reading (co, nox, hc etc).
As Dicky says - it would be wise to check the throttle pot voltage at idle is correct and the afm voltage too.
Also check any wires for frays and brakages - the LT wires to the coil and cables to the ignition powerpack are famous for this. Also check the injector earth at the back of the engine block.
After that - I would check the timing and the exhaust gas reading (co, nox, hc etc).
dickymint said:
Is this whilst stationary or when driving or both? You seem to have covered most things eh. Have you checked for air leaks? Swapped the resistor pack? Maybe She just needs the base idle and throttle pot adjusted from scratch.
Hi DickyIt does it stationary as well as on the move.
Bu55ered if I know what it is.
Hope you are ok & the job is still good.
Brian
rev-erend said:
Brain,
As Dicky says - it would be wise to check the throttle pot voltage at idle is correct and the afm voltage too.
Also check any wires for frays and brakages - the LT wires to the coil and cables to the ignition powerpack are famous for this. Also check the injector earth at the back of the engine block.
After that - I would check the timing and the exhaust gas reading (co, nox, hc etc).
Haven't checked the gasses but tried the rest.As Dicky says - it would be wise to check the throttle pot voltage at idle is correct and the afm voltage too.
Also check any wires for frays and brakages - the LT wires to the coil and cables to the ignition powerpack are famous for this. Also check the injector earth at the back of the engine block.
After that - I would check the timing and the exhaust gas reading (co, nox, hc etc).
Thanks Alan
cuneus said:
Thanks I will wade through when I go a mo.Sounds like a cam lobe to me.
Usually the rear ones go first. Disconnect one or other rear injectors (try the driver's side one first) and go for a drive. Your power will be down but if the problem goes away then that's a strong pointer.
Next step will be to take the rocker cover off and see if the valve is lifting OK on the corresponding cylinder.
Usually the rear ones go first. Disconnect one or other rear injectors (try the driver's side one first) and go for a drive. Your power will be down but if the problem goes away then that's a strong pointer.
Next step will be to take the rocker cover off and see if the valve is lifting OK on the corresponding cylinder.
rev-erend said:
leorest said:
rev-erend said:
An alternative method it to check the temp with a digital temp lazer guage on the exhaust headers..
Maplin are selling these cheap at the moment.Can we have a link and price !
£50
Edited by cuneus on Friday 21st March 23:22
cuneus said:
rev-erend said:
leorest said:
rev-erend said:
An alternative method it to check the temp with a digital temp lazer guage on the exhaust headers..
Maplin are selling these cheap at the moment.Can we have a link and price !
£50
Edited by cuneus on Friday 21st March 23:22
Got mine as one of me leaving presents from LG. Strangely enough it had to be calibrated the week we shut the factory 
cuneus said:
rev-erend said:
leorest said:
rev-erend said:
An alternative method it to check the temp with a digital temp lazer guage on the exhaust headers..
Maplin are selling these cheap at the moment.Can we have a link and price !
£50
Edited by cuneus on Friday 21st March 23:22
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