Started playing with the ECU/ignition
Discussion
Just hooked up a few diagnostic LEDs.
http://youtu.be/lM_IB5t0CEM
As they seem to be working fine I'll be sticking them into the spare lamps in the instruments so I can see them all the time, but for now stuck to the windscreen.
The two on the left/lower show the injector banks and the two higher ones are high/low on the ignition.
I reproduced the cutting out fault turning right and the LED pattern didn't waver, so I suspect the ignition HT side now.
Quite a useful little tool I should have added this yonks ago.
http://youtu.be/lM_IB5t0CEM
As they seem to be working fine I'll be sticking them into the spare lamps in the instruments so I can see them all the time, but for now stuck to the windscreen.
The two on the left/lower show the injector banks and the two higher ones are high/low on the ignition.
I reproduced the cutting out fault turning right and the LED pattern didn't waver, so I suspect the ignition HT side now.
Quite a useful little tool I should have added this yonks ago.
Well so far I have changed:
Ignition leads including king lead
Rotor Arm (bling!)
Dizzy cap
Coil
Checked the ignition timing and advanced it a little
... and added a better earth to the coil than the standard "round bracket" which was quite corroded between coil and bracket. (None of this at great expense mind).
My tell-tale LEDs have shown steady patterns all through every misfire last week. The LEDs monitor the coil LT and the injector pulses. The engine still cuts out when I jink the car to the right.
Next on the list is checking/cleaning all the earth straps.
Ignition leads including king lead
Rotor Arm (bling!)
Dizzy cap
Coil
Checked the ignition timing and advanced it a little
... and added a better earth to the coil than the standard "round bracket" which was quite corroded between coil and bracket. (None of this at great expense mind).
My tell-tale LEDs have shown steady patterns all through every misfire last week. The LEDs monitor the coil LT and the injector pulses. The engine still cuts out when I jink the car to the right.
Next on the list is checking/cleaning all the earth straps.
No - I've tried that and also wiggling all the loom wires, battery leads etc.
Yes I have a spare magnetic lead clamp somewhere so I might try that first on the king lead and then on each plug lead to confirm ignition HT. But as the LT is pulsing it seems strange that the HT could disappear.
The fault itself "feels" like spark is gone because it's so sudden (both the off and the on afterwards) but I might try looking at the fuel pump connections too just in case.
Yes I have a spare magnetic lead clamp somewhere so I might try that first on the king lead and then on each plug lead to confirm ignition HT. But as the LT is pulsing it seems strange that the HT could disappear.
The fault itself "feels" like spark is gone because it's so sudden (both the off and the on afterwards) but I might try looking at the fuel pump connections too just in case.
OK here's the latest gen:
Cutting-out still happens when pulling right suddenly. But now it's getting worse with the odd burp on sudden throttle depression.
I made a magnetic clamp using a clip-on ferrite ring and around 20 turns of copper wire on it. This feeds a single transistor then an LED that I've tucked into a spare dash indicator hole - this picks up the pulse through whatever lead it's clipped around.
It shows the spark is constant all through the misfire at both the king lead and on other leads it's clipped to. So - it's ain't the spark.
I have already checked the throttle pot for smoothness so my next suspect is the AFM. As it's mounted across the bulkhead (i.e. transverse) on the 400SX I think the left->right jink might disturb the flap. So I will check it for smooth variation etc.
Cutting-out still happens when pulling right suddenly. But now it's getting worse with the odd burp on sudden throttle depression.
I made a magnetic clamp using a clip-on ferrite ring and around 20 turns of copper wire on it. This feeds a single transistor then an LED that I've tucked into a spare dash indicator hole - this picks up the pulse through whatever lead it's clipped around.
It shows the spark is constant all through the misfire at both the king lead and on other leads it's clipped to. So - it's ain't the spark.
I have already checked the throttle pot for smoothness so my next suspect is the AFM. As it's mounted across the bulkhead (i.e. transverse) on the 400SX I think the left->right jink might disturb the flap. So I will check it for smooth variation etc.
adam quantrill said:
I have already checked the throttle pot for smoothness so my next suspect is the AFM. As it's mounted across the bulkhead (i.e. transverse) on the 400SX I think the left->right jink might disturb the flap. So I will check it for smooth variation etc.
A multimeter with bar-graph function set to measure the AFM pot. wiper voltage might catch any spurious transients.Seems odd that you've had it all these years without issues though.
The track is fine - pushed the flap through the full range - no sudden jumps or open-circuit.
Incidentally I found out that the Blue (U) wire starts at about 3.2V (flap shut) then drops to 0 as the flap opens.
I can't reproduce the problem except on the open road when changing lanes. This even rules out a rolling road (unless you know of a 2-lane one!)
It seems worse when it's hot (in case that's a clue).
I may get an inverter and a logic analyser/MSO onto it next!
Incidentally I found out that the Blue (U) wire starts at about 3.2V (flap shut) then drops to 0 as the flap opens.
I can't reproduce the problem except on the open road when changing lanes. This even rules out a rolling road (unless you know of a 2-lane one!)
It seems worse when it's hot (in case that's a clue).
I may get an inverter and a logic analyser/MSO onto it next!
rev-erend said:
Given the age of the car - it could well be a wire that is partially cut through.
I have a mate who does a lot of disnostics for garages that cannot find issues like this and often traced to wires with unsupported spans, cables through bulk heads etc..
I was thinking this also...Have you checked to see if the ECU plug is pushed in tight..Or could it be a wire under the dash that is getting caught every time you turn right...Just seems strange that it only happens when turning right..Delilah used to sometimes cut out when turning left and that was due to the battery being un-secured and the earth lead a tad loose...ZigaI have a mate who does a lot of disnostics for garages that cannot find issues like this and often traced to wires with unsupported spans, cables through bulk heads etc..
pretty neat
Make sure you don't rear end the bu66er in front
(watching them)
The default answer to cutting out on turning is of course extra load on power steering.
Due either to fubard pump, low fluid, or seized ball joints.
As I'm typing I realise you may not have power steering. Doh.
If you feel it is really cutting out and not just stalling I would look at the disable wire on your alarm, this may have been run on its own, in perhaps not the best route, and is probably not protected like the original wiring.
Make sure you don't rear end the bu66er in front
(watching them)The default answer to cutting out on turning is of course extra load on power steering.
Due either to fubard pump, low fluid, or seized ball joints.
As I'm typing I realise you may not have power steering. Doh.
If you feel it is really cutting out and not just stalling I would look at the disable wire on your alarm, this may have been run on its own, in perhaps not the best route, and is probably not protected like the original wiring.
adam quantrill said:
The track is fine - pushed the flap through the full range - no sudden jumps or open-circuit.
Incidentally I found out that the Blue (U) wire starts at about 3.2V (flap shut) then drops to 0 as the flap opens.
I can't reproduce the problem except on the open road when changing lanes. This even rules out a rolling road (unless you know of a 2-lane one!)
It seems worse when it's hot (in case that's a clue).
I may get an inverter and a logic analyser/MSO onto it next!
You could practise your lane swopping on some of those dead straight fenland roads (I think you are near Cambridge?) Incidentally I found out that the Blue (U) wire starts at about 3.2V (flap shut) then drops to 0 as the flap opens.
I can't reproduce the problem except on the open road when changing lanes. This even rules out a rolling road (unless you know of a 2-lane one!)
It seems worse when it's hot (in case that's a clue).
I may get an inverter and a logic analyser/MSO onto it next!
Thanks for the ideas - yes a bad wire is foremost in my mind but on the other hand I've been wiggling the loom and connections and it doesn't cut out sitting on the drive. The ECU is plugged in OK too.
Not the PAS because I can "turn right" when stationary just on idle....
I have plenty of roads to/from work to test this out with - it will cut out momentarily when moving from lane 1 to lane 2 on dual carriageway/motorway (if you do it sharply).
Not the PAS because I can "turn right" when stationary just on idle....
I have plenty of roads to/from work to test this out with - it will cut out momentarily when moving from lane 1 to lane 2 on dual carriageway/motorway (if you do it sharply).
Turning right suddenly sends the fuel in the tank crashing to the left and sudden braking can have a simillar effect. Are you sure it's not fuel starvation? Park the car banked steeply at an angle to the left, to give the effect of turning sudden right and let the engine idle. See if that has any effect. These cars respond to fuel starvation almost instantaneously.
Tony.TCB
Tony.TCB
As I recall, Adam's diagnostic equipment shows continuing spark (but is it adequate and at the right time?) and continuing operation of injectors (but for what duration and at what pressure?).
Eliminate the potential sloshing fuel issue by filling the tank?
Fortunately, the fault is getting worse so it will be easier to fix when it breaks down completely, unless that happens immediately in front of a lorry on the A14
Eliminate the potential sloshing fuel issue by filling the tank?
Fortunately, the fault is getting worse so it will be easier to fix when it breaks down completely, unless that happens immediately in front of a lorry on the A14
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