88' Xjs Th400 mph per gear?
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#25
Definitely sounds like fuel then. Even though you recently changed the filter, if there was rust in the tank it can still plug a filter quickly. Filters last until they are plugged, that could be one tankful or a thousand depending on the fuel.
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if if it was the front ignition coil wouldn't it not even make it past like 3k rpm? I did new main coil, plugs, wires and cap. The only think I can think is that the centrifugal advance might be sticking and I know the vacuum advance is bad. Would that be the issue?
#31
#32
Join Date: Mar 2008
Location: Pacific Northwest USA
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BUT.....the 'bucked like a bronco' really rings a bell.
On my '88 XJS V12 (years ago) I had a severe case of bronco-itis. Under gentle acceleration it was fine. Under moderate or hard acceleration it would buck and carry on like crazy....almost violently.
Cutting to the chase it was in inlet (RH side) pressure regulator. I can't remember how I came to that determination but I remember a fair bit of hair pulling and I remember that eliminating it solved the problem!
Cheers
DD
#33
I didn't get much from the video
BUT.....the 'bucked like a bronco' really rings a bell.
On my '88 XJS V12 (years ago) I had a severe case of bronco-itis. Under gentle acceleration it was fine. Under moderate or hard acceleration it would buck and carry on like crazy....almost violently.
Cutting to the chase it was in inlet (RH side) pressure regulator. I can't remember how I came to that determination but I remember a fair bit of hair pulling and I remember that eliminating it solved the problem!
Cheers
DD
BUT.....the 'bucked like a bronco' really rings a bell.
On my '88 XJS V12 (years ago) I had a severe case of bronco-itis. Under gentle acceleration it was fine. Under moderate or hard acceleration it would buck and carry on like crazy....almost violently.
Cutting to the chase it was in inlet (RH side) pressure regulator. I can't remember how I came to that determination but I remember a fair bit of hair pulling and I remember that eliminating it solved the problem!
Cheers
DD
#34
#35
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,866
Received 10,920 Likes
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7,174 Posts
I can't think of any trans problem that would cause the engine to buck and carry on as you mentioned. That sounds like a fuel or ignition problem....and the transmission wouldn't have anything to do with that.
However....
It seems plausible to me that there might be some sort of transmission failure scenario that drags the engine to the point where it can't develop higher RPM. Some sort of torque converter failure perhaps? I'd think you be feeling other symptoms as well; some sort of weirdness in the transmission behavior.
Fix the bucking-like-a-bronco condition and then see how the transmission behaves.
Cheers
DD
#36
I can't think of any trans problem that would cause the engine to buck and carry on as you mentioned. That sounds like a fuel or ignition problem....and the transmission wouldn't have anything to do with that.
However....
It seems plausible to me that there might be some sort of transmission failure scenario that drags the engine to the point where it can't develop higher RPM. Some sort of torque converter failure perhaps? I'd think you be feeling other symptoms as well; some sort of weirdness in the transmission behavior.
Fix the bucking-like-a-bronco condition and then see how the transmission behaves.
Cheers
DD
However....
It seems plausible to me that there might be some sort of transmission failure scenario that drags the engine to the point where it can't develop higher RPM. Some sort of torque converter failure perhaps? I'd think you be feeling other symptoms as well; some sort of weirdness in the transmission behavior.
Fix the bucking-like-a-bronco condition and then see how the transmission behaves.
Cheers
DD
oh one thing though the trans when cold has a hell of a time wanting to reverse!
#37
If this is the original TH400 transmission, there is no converter lockup. I'm not aware of there being a locking converter for that transmission, I did look a while ago.
#38
#39
The TH400 never came from the factory with a lockup converter, there was someone modifying them.
Is the oil level in the trans correct, if so then I would drop the pan and check for debris in the pan, there is a magnet there to attract the metal debris, when I dropped mine the pan was full of sludge.
Is the oil level in the trans correct, if so then I would drop the pan and check for debris in the pan, there is a magnet there to attract the metal debris, when I dropped mine the pan was full of sludge.
#40
The TH400 never came from the factory with a lockup converter, there was someone modifying them.
Is the oil level in the trans correct, if so then I would drop the pan and check for debris in the pan, there is a magnet there to attract the metal debris, when I dropped mine the pan was full of sludge.
Is the oil level in the trans correct, if so then I would drop the pan and check for debris in the pan, there is a magnet there to attract the metal debris, when I dropped mine the pan was full of sludge.