Misfire on pulling right
Discussion
Well the misfire on the 400SX is worse again and seems to manifest itself when moving right - e.g. changing lanes, or pulling out to overtake.
Symptoms are a complete loss of power for about a second, and if I don't lift off, a misfire.
So to my mind it could either be a loss of fuel pressure/injection, or a loss of ignition. To that end I tried wiggling the wires about last night when I got home but no effect. Also I tried yanking the wheel around on the drive - no change.
I am also thinking slightly about fuel pickup but right now there's full tanks so there should be little effect from fuel sloshing from side to side, and besides when it does run out of fuel it doesn't misfire, it's better behaved. Also it doesn't get worse when the tanks run low.
As per my previous thread all the trumpets are now stuck down fast, which was my previous problem, which did seem to help when it was first done a year ago but not this time around.
I also wonder if the flapper could be affected by the lunge to the right - it is oriented left/right across the bulkhead rather than front/back - but it's always been in this position so that's not such a good theory.
Symptoms are a complete loss of power for about a second, and if I don't lift off, a misfire.
So to my mind it could either be a loss of fuel pressure/injection, or a loss of ignition. To that end I tried wiggling the wires about last night when I got home but no effect. Also I tried yanking the wheel around on the drive - no change.
I am also thinking slightly about fuel pickup but right now there's full tanks so there should be little effect from fuel sloshing from side to side, and besides when it does run out of fuel it doesn't misfire, it's better behaved. Also it doesn't get worse when the tanks run low.
As per my previous thread all the trumpets are now stuck down fast, which was my previous problem, which did seem to help when it was first done a year ago but not this time around.
I also wonder if the flapper could be affected by the lunge to the right - it is oriented left/right across the bulkhead rather than front/back - but it's always been in this position so that's not such a good theory.
If you drive like you did on the day you passed your driving test, there should be no problems;-) or it could be the engine timing or timing related. When changing lane suddenly or overtaking, the engine is under load and it sounds like that's when the problem occurs. I have had a few bangers in my time (not that I'm saying your car is a banger) and messed around with engine timing. Your symptoms sound very similar. Each day on my way to college I would alter the timing and on a section of road which was my testing track I would do the necessary tests of accelerating, decelerating,overtaking and lane changing until I got it right. I would very seldom get to college on time which is why it took me two years to complete each year of my course.
Tony. TCB.
Tony. TCB.
Adam, if the lunge to the right also occurs during an acceleration then the engine lump, rotating as it tries to do against the rubber engine mounts, may be causing your main air inlet tract to stretch/compress when it pulls/pushes against the AFM which is normally fixed to the body of the car.
If that exposes and allows an otherwise insignificant air leak to upset the richer mixture needed to make the acceleration/pass/lunge.
Weakened mixture means a sudden loss of available torque just when you need it most!
If it does not do the same when lunging to the left, then the above suggestions still holds good because the opposite G forces do not expose an existing air leak issue in the same way. QED!
If that exposes and allows an otherwise insignificant air leak to upset the richer mixture needed to make the acceleration/pass/lunge.
Weakened mixture means a sudden loss of available torque just when you need it most!
If it does not do the same when lunging to the left, then the above suggestions still holds good because the opposite G forces do not expose an existing air leak issue in the same way. QED!
I had a strange problem that also manifested itself with the symptoms you describe. was even left stranded on a right bend when the car suddenly cut all together.
My issue was traced to a wife that had worn through on top of the engine where the injector wires were moving slightly and had worn though to the point where one was earthing to the engine and causing a misfire and eventually stopped me dead (eventually it blew a fuse).
Wrapped the wire in electrical tape and installed a sheath made of bike innertube to insulate them.
Never happened again
My issue was traced to a wife that had worn through on top of the engine where the injector wires were moving slightly and had worn though to the point where one was earthing to the engine and causing a misfire and eventually stopped me dead (eventually it blew a fuse).
Wrapped the wire in electrical tape and installed a sheath made of bike innertube to insulate them.
Never happened again
JVaughan said:
I had a strange problem that also manifested itself with the symptoms you describe. was even left stranded on a right bend when the car suddenly cut all together.
My issue was traced to a wife that had worn through on top of the engine Never happened again
Very strange that I bet it went a bit silent when she wore through My issue was traced to a wife that had worn through on top of the engine Never happened again
I once had a misfire /engine cutting out when going around tight r/h bends. Eventually traced it to a loose earth lead on the rear near side of the engine. I'd had the engine out for a clutch change and the mechanic had forgotten to tighten it up. On another car I had a misfire and cured it by pulling the loom slightly where it comes out of the bulhead into the engine bay.
Try jacking up the driver's side to simulate turning right - or it could be a short due to the position of the steering wheel so try putting the front wheels on slippery magazines and turn the steering (with the engine running).
Do you have an electronic rev-limiter fitted, check the connections to the coil - this could be causing a cut-out now and then.
Russ
Do you have an electronic rev-limiter fitted, check the connections to the coil - this could be causing a cut-out now and then.
Russ
Adam, bearing in mind other suggestions regarding chafing wires and loose earth connections, it's possible you have an intermittent ignition fault when lunging to the right.
If so, you can test for intermittancy with a simple set up of bulbs and wires (which will be familiar to some) that came to light from a famous member on this forum. I took the liberty of reworking it and bunged on my web pages in amongst some other stuff.
Intermittent Ignition Faults are hard to find, often unseen in static tests, in which case try this dynamic test to view the primary side in action. Rig up two 4/5 watt, 12 volt bulbs (or better, two 2V, 15mA LED's + 680 ohm resistors) each connected between coil positive and coil negative to earth. Mark the bulbs “POS” and “NEG” and route the wires safely to the cabin. Keep them clear of hot/moving parts.
• Start the engine and observe that “POS”, sensing the ignition input voltage is permanently on, and “NEG”, sensing the pulsed voltage across the ignition amplifier flickers in sympathy with engine rpm, or is dimly lit (LED's flicker better). Now drive the car and have a helper note what happens when the engine misbehaves. If “POS” and “NEG” go out together there is an open circuit interruption of the 12 v feed such as a faulty wire/ignition switch, or a short on the same circuit due to burned insulation.
• If “NEG” comes on full, the amplifier or its associated wiring or earth contact has failed in open circuit mode or, the pulsed input from the pick-up coil to the amplifier from the dizzy has failed or the associated wiring is faulty/shorting to earth or (unlikely) the coil has failed in a short circuit mode.
• If “NEG” goes out, the amplifier has temporarily failed in short circuit mode due to excess internal heat or the local wiring is shorting to earth or the coil has failed in open circuit mode due to insulation breakdown or internal heat.
• If “POS” stays lit and “NEG” show signs of flickering instability, not sympathetic with engine rpm, then the amplifier or its connections are on the blink.
• If neither “POS” nor “NEG” change their behaviour, then the intermittency is not in the primary side so attention must revert to the secondary side high tension components.
The tests will locate faulty components as well as faulty wiring - more likely if earth or chafing problems exist.
If so, you can test for intermittancy with a simple set up of bulbs and wires (which will be familiar to some) that came to light from a famous member on this forum. I took the liberty of reworking it and bunged on my web pages in amongst some other stuff.
Intermittent Ignition Faults are hard to find, often unseen in static tests, in which case try this dynamic test to view the primary side in action. Rig up two 4/5 watt, 12 volt bulbs (or better, two 2V, 15mA LED's + 680 ohm resistors) each connected between coil positive and coil negative to earth. Mark the bulbs “POS” and “NEG” and route the wires safely to the cabin. Keep them clear of hot/moving parts.
• Start the engine and observe that “POS”, sensing the ignition input voltage is permanently on, and “NEG”, sensing the pulsed voltage across the ignition amplifier flickers in sympathy with engine rpm, or is dimly lit (LED's flicker better). Now drive the car and have a helper note what happens when the engine misbehaves. If “POS” and “NEG” go out together there is an open circuit interruption of the 12 v feed such as a faulty wire/ignition switch, or a short on the same circuit due to burned insulation.
• If “NEG” comes on full, the amplifier or its associated wiring or earth contact has failed in open circuit mode or, the pulsed input from the pick-up coil to the amplifier from the dizzy has failed or the associated wiring is faulty/shorting to earth or (unlikely) the coil has failed in a short circuit mode.
• If “NEG” goes out, the amplifier has temporarily failed in short circuit mode due to excess internal heat or the local wiring is shorting to earth or the coil has failed in open circuit mode due to insulation breakdown or internal heat.
• If “POS” stays lit and “NEG” show signs of flickering instability, not sympathetic with engine rpm, then the amplifier or its connections are on the blink.
• If neither “POS” nor “NEG” change their behaviour, then the intermittency is not in the primary side so attention must revert to the secondary side high tension components.
The tests will locate faulty components as well as faulty wiring - more likely if earth or chafing problems exist.
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