Xj help
 

Hi any mechanical people out there.

how do i know if my 4.0 is running lean, reason i ask is it is getting hot, however, only when under load towing, it will sit in traffic, idle and all is ok, however towing uphill and it gets hot.

Just replaced radiator, thermostat, water pump, hoses and coolant, new plugs, leads, rotor button and distributor cap, changed oil and filter.

had thoughts it was a head gasket, however, no obvious bubbles in radiator, no coolant smell from exhaust and as said can sit in traffic or idle in driveway for 20mins and just moves between about 91 and 93 degrees.

after speaking with an old school mechanic who said it could be running lean that would make it run hot and especially under load.

supposed to be heading away on trip on saturday maybe not now

Post update? If so, fuel map can't really be changed or adjusted as it does so on the fly. You could reset it back to defaults and it will re-learn, disconnect positive terminal to ground or negative terminal (use jumper cable if it doesn't quite reach) and try key to start a couple of times and/or flash headlights on/off couple of times. Which fuel do you typically use?


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Thanks for your quick response.

Post update 1999 - use 91 unleaded

not sure i know what you mean, if i disconnect the positive terminal and hold that to ground how can i flash headlights or try to start it, won't it need power?

i am just a little confused.

appreciate the help just not sure i know what to do, could it be one of my sensors that may have computer leaning it out?

it has me baffled, just not sure i want to head off to lake eyre with potentially blown head gasket or some other issue that may leave me stranded

Yeah. Reset your engine computer as per what is said in the stickies and see how you go.

What do you call hot? It's normal for pretty much anything to run hotter towing a load up Hill, I've towed very heavy loads with temp gauge showing 110 without problems, turn air con off if worried, probably should be running after market trans cooler if towing a lot

Hi guys,

thanks for the info, will reset the computer in the morning.

Glenn, i would not worry at 110 however, it got to about 122, by time i was able to pull over the pressure was causing it to blow past radiator cap, i thought it should have just gone to the overflow bottle, but there was spray on the air box,
so way too hot.

No blockage in the overflow hose?
How's the compression?
Spark plugs gapped correctly?
I too would reset the computer....