Hi, have 2001 Daimler Xj 4.0 V8, car was standing for a while and alternator and pully sized, had these replaced and now struggling to get the car to run well.
starts fine and idels, though a little lumpy. Will drive fine as long as I press the accelerator lightly, and will run up to 70 mph, but if I press the accelerator a little to much engine dies, let go accelerator and runs fine again.

Engine light co.es on with lean mixture in bank 1 and 2, and misfire.

Cleaned MAF sensors, replaced crankshaft sensor( had this code also previously now gone), fuel pump replaced, new fuel filter, new air filter, new plugs, put in injector cleaner.

Read it might be a dirty throttle body, not checked that yet, have ordered a new maf sensor, anyone got any other ideas that it may be?

Thanks.

 

You may have serious air leak, Check the air intake tube for cracks, various vacuum lines. It may be necessary to do a smoke test.

 

I would clean the throttle bore and plate; check for leaks; run another can of fuel system cleaner; check for excess accelerator cable; clean the part load valve.

Once upon a time, a friend and I tuned his 59 Chevy six cylinder (I did the ignition, and tuned the carb, he did the plugs, air and in-line fuel filter); ran like a top for a few miles, then half way up Loveland Pass -- '66 before the Interstate -- it started to cut out and would not accelerate, then died. (I had redone the main metering valve for high altitude). Popping the hood, I quickly noted that the arrow on the new fuel filter was pointing to the rear . . . . it happens!

 

Depending on how many misfires you have, it could go into Restricted Performance, which limits the engine to 3,000 rpms. Sometimes the RP won't show up in the message bar. I had that happen a couple of times when the alternator was on its way out and not producing enough voltage to run the electronics.

 

Almost sounds like a bad spot in the tps.

How many miles?
How long was it sitting?
Was it sitting outside the whole time when not being used?
Do you know why it was taken off the road?

 

Got a new alternator, it does go into restricted performance, though even once i cleared everything and no engine light it still wont rev high, i can cruise upto 70 mph going through the gears at 2 to 3k rpm.

 

just over 110k, was working fine, just off the road as had no use for it, outside covered up for about 4 years and inside for two years, was turned over every month though the last year it wasnt. Alternator and pensioners sized up. They were replaced.

 

Does the engine misfire at upper rpm’s or does the engine want to die down like fuel cutoff?

 

Looks like fuel starvation. Since you have new pump and filter, another possibility is the fuel pressure regulator. I would connect a fuel pressure gauge and see what happens to the fuel pressure when the engine is revved.