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engine wont upshift or rev over 2500

B

bronc571

NAXJA Forum User
Location
mi
1996 xj 4.0, 4x4, auto. engine seems like its hitting a rev limiter at about 2800 rpms while under load. have to let off the accel to let it upshift. adjusted tv cable like the naxja forums suggested and nothing. pulled tcu fuse and no change. engine will rev in nuetral well over 3000. i replaced the tps a cpl yrs ago, and the jeep was not acting the way it is now. 3" lift 31 x 10.5 tires. ran this setup for a long time before any shifting issues. installed 34 tooth speedo gear to correct the speedo in january but did not have shifting issues after that. i have a obdII code 1493 which indicates batt temp sensor, and autozone readout also says possible bad ecm.
 
Check your fuel pressure.
 
replaced fuel filter, checked fuel pressure before replacement. 50 psi before and after. still the same
 
BIG OLE WELL DONE!! TO OP FOR PUTTING ALL THE INFO IN FIRST POST!!!
:party:

----------
Some where in the longago was something about a "limp home mode" which was just about what you have. Might search for that.
OR maybe someone remembers better than I !
 
I did rev engine while checking fuel pressure and stayed at 50 psi. I will try to find a vacuum gauge. thanks for the info about the cat, i didnt know that. OP? sorry im not a big poster in forums.
 
"Original Poster"
 
xj didnt act this way when the tps was bad before. i have no fsm. i thought i read 5 volts is acceptable for tps? sound right?
 
Approximately 5.0 reference (input) voltage; output voltage should be 83 percent of the reference voltage.
 
We have so many posters that fail to put even the most basic info that it is really needed to help. Like we can GUESS the year, engine,etc., etc.

Your post is a Excellent example of how to do it right -
THANKS!

------

Looked around in the FSM with no luck onthe 'limp home' mode. Guess its another vehicle.

Longshots-
-try unplugging and replugging the CPS and TPS connectors.
PCM also. (Temp sensor at thermostat)
-test battery volts at battery posts Engine on/off/reved.- the voltage regulator is in the PCM and that battery temperature sensor DOES effect charging. Jeeps do NOT like the 12 VDC being very far off.
(Instrument panel voltmeter is not accurate. Use a test multimeter)

Suggestion-
Save up and get a real Mopar FSM (Factory Service Manual)-EXACT YEAR ONLY!- 96 is diff from other years.. The others manuals are NOT worth having. A good Code scanner and multimeter too. When they save you from one dealer repair/tow they paid for themselves.

Good Luck,
Orange
 
orange said:
Longshots-
-try unplugging and replugging the CPS and TPS connectors.
PCM also. (Temp sensor at thermostat)
-test battery volts at battery posts Engine on/off/reved.- the voltage regulator is in the PCM and that battery temperature sensor DOES effect charging. Jeeps do NOT like the 12 VDC being very far off.
(Instrument panel voltmeter is not accurate. Use a test multimeter)


Good Luck,
Orange
Click to expand...

Be better to check for a bad cat first....if you don't have a vacuum gauge (I don't either) you can disconnect the exhaust anywhere UPSTREAM of the cat, I did this on mine and it worked fine, just don't over-rev it run it on the road that way, could risk burning a valve. BUT at least that would tell you if the cat is clogged!
 
Only About 5 minutes for "longshots". Narrows down a bunch.

Although the cat is probably next on list.

:cheers:
 
i think i have a bad head gasket. absolutley had no way out of it, but i HAD to run up the highway yesterday, and it overheated. stopped several times and thought to myself check the oil. its overfull by 1.5 qts. :-( bad head gasket could also suck air and engine would hit a wall under load. or if compression gases are goin into the crankcase the engine wldnt make power. any thoughts? im going to compression test each cyl today.
 
i had no clue it could be a bad head gasket untill it overheated on the highway :-( my bad!! do you think it cld be head gasket causing the engine to hit a wall under load?
 
You say the crankcase is 1.5 quarts overfull? Milkshake = oil + coolant? Does the oil smell like fuel?
 
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