XJS V12 Marelli Engine Cuts Out at 7000 RPM in 2nd Gear
#1
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Hi Guys
Got an unusual problem (at least for me)
Everything's is ok when I am in drive but when accelerating in 2nd at around 7,000 RPM the Engine seems to cut out and pull up but if I put her back in drive then She runs as normal
Any Ideas?
Got an unusual problem (at least for me)
Everything's is ok when I am in drive but when accelerating in 2nd at around 7,000 RPM the Engine seems to cut out and pull up but if I put her back in drive then She runs as normal
Any Ideas?
#2
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orangeblossom (08-24-2020)
#3
#4
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orangeblossom (08-24-2020)
#5
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The GM400 will automatically shift into second from first, even if first is selected using the stick, at about 5,400 rpm. If second is held on the stick the box will never go into third.
OB, What i meant was, did you really mean 7,000 rpm? I would have thought 5,000 was more like it!
OB, What i meant was, did you really mean 7,000 rpm? I would have thought 5,000 was more like it!
Last edited by Greg in France; 08-25-2020 at 01:38 AM.
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#6
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Hi Greg
Perhaps I didn't explain that very well
When the Car is in drive She runs perfect regardless of top speed but there are some very twisty roads where I like to Manually put and leave the Shifter in (2) instead of (D) where regardless of the gear changes that happen inside the gearbox, when the Shifter is moved Manually from (D) to (2) and left in (2)
When the Revs have gone up to around 7,000 rpm
That is when the Engine starts to Stutter and Shake like it is misfiring and that is when I put her back in (D) and then continue the rest of the journey in (D)
This has only recently started to happen, as before I could drive around with the Shifter in (2) for as longs as I wanted without any problem
Perhaps I didn't explain that very well
When the Car is in drive She runs perfect regardless of top speed but there are some very twisty roads where I like to Manually put and leave the Shifter in (2) instead of (D) where regardless of the gear changes that happen inside the gearbox, when the Shifter is moved Manually from (D) to (2) and left in (2)
When the Revs have gone up to around 7,000 rpm
That is when the Engine starts to Stutter and Shake like it is misfiring and that is when I put her back in (D) and then continue the rest of the journey in (D)
This has only recently started to happen, as before I could drive around with the Shifter in (2) for as longs as I wanted without any problem
#7
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Hi Vancouver
When the Shifter is in (2) and left in (2) the engine starts to Stutter and Shake at around 7,000 rpm which has never happened before, so not sure what could be wrong
Where it really sounds just as if it is about to Stall, so at that point I change into drive to avoid any damage
When the Shifter is in (2) and left in (2) the engine starts to Stutter and Shake at around 7,000 rpm which has never happened before, so not sure what could be wrong
Where it really sounds just as if it is about to Stall, so at that point I change into drive to avoid any damage
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#8
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#9
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I'm slightly confused as well. On my car at least, 7,000 rpm is the absolute top, well into the red zone (starts at 6500 rpm). Even in second I've never been able to get close before running out of road on any twisties. On the straight, she'd be doing instant-licence-losing speeds at 7,000 rpm, assuming I ever got that high. I have to be really pushing her to break 5,000.
Reference thread HERE.
Reference thread HERE.
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#10
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#11
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Greg in France (08-25-2020)
#12
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4000 rpm makes a big difference. Then I'd start to suspect something in the ignition, likely a coil.
Try the same experiment in first gear and see if you have the same misfire at 4000rpm in first. Also see if you can vary the load while holding the revs in the band you were experiencing the stutter, that will help determine if it's spark or fuel.
Try the same experiment in first gear and see if you have the same misfire at 4000rpm in first. Also see if you can vary the load while holding the revs in the band you were experiencing the stutter, that will help determine if it's spark or fuel.
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orangeblossom (08-24-2020)
#13
#14
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#15
#16
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#17
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full overhaul nowwwwwwwww.
I recently picked up some 10mm leads from a UK supplier they seem nice, havnt installed yet. Like some people here will suggest getting thick magnecor or other heavy duty racing spec cables will last a life time. If u need marelli amps I can give you the #part number for exact equivelent parts... It beats the $450/ea for 'original' vs these which were 30ish each?
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#18
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This reminds me of the description of the effects of an Italian tune up in Kirby Palm's book. Obviously, make sure the car is in good condition before trying this, but it could explain what you experienced.
People think I’m makin’ this stuff up about the Italian Tune-Up. Bill de Creeft provides a quote from a British car magazine after the HE engine came out: “...if one runs the car for not less than a working week of relatively gentle driving, typically commuting with no longer journeys between, then, once properly warm, accelerates flat out, the engine goes through a period between 4500 and 5000 rpm of loud detonation accompanied by pale but noticeable exhaust smoke. You learn, after the first rather frightening occasion, to keep your foot down regardless, to accelerate through the knocking which, together with the smoke, stops and doesn't return until after the next period of town running. Jaguar,and Michael May, say that in gentle driving or with a lot of cold starts and short journeys combustion deposits build up in the head and on the valves. On hard acceleration these deposits heat up and burn, causing detonation but clearing, as they burn off into smoke. Jaguar says that in tests they conducted before the engine's launch (in July'81) in which such deposit-induced detonation was sustained artificially for long periods of hard running, showed no sign of piston or head damage.”
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#19
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Hi garethashenden
That description sounds exactly like what I am experiencing with loud detonation noises in that rev range although it also feels like my Car is misfiring in between 4000-5000 rpm but only when accelerating hard in (2) on the Shifter
It never happens when the Shifter is in (D) but then of course the revs are that much lower
That description sounds exactly like what I am experiencing with loud detonation noises in that rev range although it also feels like my Car is misfiring in between 4000-5000 rpm but only when accelerating hard in (2) on the Shifter
It never happens when the Shifter is in (D) but then of course the revs are that much lower
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AceVentura (08-27-2020)
#20