Engine warms up and transmission stops working
#1
10-12-2015, 09:34 AM
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Engine warms up and transmission stops working
I have a 1998 XK8 convertible with 120K miles on it. Radiator blew up. Some coolant in the transmission. Replaced radiator with a brand new one. Also, drained and refilled transmission fluid twice. Card drives good for first 10-15 minutes, then the transmission goes limp... revs go up but no move. If you let the engine really cool down, at least an hour, then the car goes again for until it gets warm.. two more points: on higher gears (highway) the limp is less visible... also, when engine is hot, it smells like transmission fluid... Help!!! any ideas other than rebuilding transmission?
#2
10-12-2015, 10:35 AM
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#3
03-29-2020, 08:28 PM
Veteran Member
OK, I have finally resolved the original problem that I posted here way back in early 2018.
Checking the operation of the system's temp sensor as it warms up and plotting its resistance on a chart in order to compare it to the readings found in the shop manual, revealed to me that the existing temp sensor info being sent to the ECU was pretty much correct. Buy, well, in spite of those good findings, I still kept thinking that the sensor's resistance variation (drop) as the engine warms up is probably the most critical info for the ECU to keep the engine running as it should, so with that in mind (along with the sensor's cheap price) I decided to just buy me a sensor.
Well, I installed a brand new temp sensor and since that day I no longer experience any power/acceleration difference between running cold and running fully warmed up. Man, it has made so much difference that I still can't stop smiling when I accelerate. The only thing is that this was done during the cold(er) winter season, meaning that in summer, with a much hotter environment, I may just have the true final test, so I'll write another update here to confirm either way.
Of course, if I find initial acceleration to be too slow because of a bad temp sensor . . . I can always turn on my optional 0.5 seconds "burst" switch on my "Wizards of Nos" English N2O injection system and by the end of the initial 0.5 seconds injection has shut down and the engine has very quickly come up to its best normally aspirated power producing rpm's. From there everything is just normal but you have already left behind Mr BMW and Mr Audi...
Your XJ40 cars have the AJ6 engine, just like my '94 XJS. FYI here's another AJ6 engine with nitrous injection: https://forum.retro-rides.org/thread...trous-injected
Best regards,
Checking the operation of the system's temp sensor as it warms up and plotting its resistance on a chart in order to compare it to the readings found in the shop manual, revealed to me that the existing temp sensor info being sent to the ECU was pretty much correct. Buy, well, in spite of those good findings, I still kept thinking that the sensor's resistance variation (drop) as the engine warms up is probably the most critical info for the ECU to keep the engine running as it should, so with that in mind (along with the sensor's cheap price) I decided to just buy me a sensor.
Well, I installed a brand new temp sensor and since that day I no longer experience any power/acceleration difference between running cold and running fully warmed up. Man, it has made so much difference that I still can't stop smiling when I accelerate. The only thing is that this was done during the cold(er) winter season, meaning that in summer, with a much hotter environment, I may just have the true final test, so I'll write another update here to confirm either way.
Of course, if I find initial acceleration to be too slow because of a bad temp sensor . . . I can always turn on my optional 0.5 seconds "burst" switch on my "Wizards of Nos" English N2O injection system and by the end of the initial 0.5 seconds injection has shut down and the engine has very quickly come up to its best normally aspirated power producing rpm's. From there everything is just normal but you have already left behind Mr BMW and Mr Audi...
Your XJ40 cars have the AJ6 engine, just like my '94 XJS. FYI here's another AJ6 engine with nitrous injection: https://forum.retro-rides.org/thread...trous-injected
Best regards,
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