'98 Disco Problem When Hot

[dnshiftbr]

I have a 98 Discovery Series II 50th anniversary edition with 150k miles, and it's latest twitch is a problem when it reaches normal operating temp. It revs and drives fine when it is started, but as it gets warm it starts to misfire more and more until it is at temp, then it wont rev above 2250 rpm. I replaced the TPS and have checked the MA, IAT, and the injectors, all of which seem to be ok. Any help would be great, also, no dummy light.

 

[joey]

Check fuel pressure... when was the last time you changed the fuel filter and major tune up.

 

[Disco Mike]

Possible fuel temp sensor but more then likely the XYX switch.

 

[dnshiftbr]

Fuel pressure was in spec, but i haven't checked the fuel temp sensor. When it reaches temp, its like its on a rev limiter at 2250-2500 rpm in neutral, a little lower in gear. Would the xyz or fuel temp cause this in park?

 

[dnshiftbr]

After looking through the manual again and comparing the symptoms to the normal operating conditions, I think I have it narrowed down to the four open loop sensors; crank, maf, iat and tps. I just replaced the tps, and the iat and maf seem ok, so I suspect the crank sensor. I'll through it on the scope and see what it says in the next day or so. A little comic relief also happened to me, my bmw lost it's idler pulley and thermostat yesterday. It's no fun driving with no power steering and no heat when it's 7 degrees out!