Hello Everyone,

I'm pretty stumped here. Disco II with 145K.

Let me preface my problems with the Maintenance that is done to the truck.

Head gasket done @ 115K. I've done quite a few of these and they always outlast the rest of the engine!
With the head gasket change, I did a valve job, replaced the valve guides, seals, and the valve springs (over half of the old springs were worn out)

I did plugs and wires a the same time. (champion plugs & STI 8mm wire)

@ 125K I replaced all 4 o2 Sensors

@ 140K I picked up a random misfire code and the 1590 code ( the 3 amigos showed up for the party also, * I don't really care to address them*)

I replaced the plugs and wires Again along with new Bosch coils.

Truck ran great for about 4500 miles and then CEL for random miss fires.

Then today on the way to Home Depot, all hell broke loose.

CEL stared flashing, you can feel the misfires, truck bucks slightly at part throttle, and run ok @ 50 -75% throttle.

Got home and read the codes

P0300 , P0301, P1300, P1319, P1590


I assumed the HG popped, It's never been low on water or over heated!!!

Compression test warm yielded 175-180 across the board

And the Chemical Exhaust gas test, proved there is no exhaust in the coolant!

Oh yes for the skeptics I run 93 OCT.


I'm thinking I've got bum wires ? Or maybe a fuel pump going out? Or how about a MAF ?


I hope I've provided enough info! Help me Save my Rover

 

MIsfires are frequently spark plug and wire related Wires would be a good place to start.

Other sensors as well, and you did mention the MAF. Cleaning the throttle body may provide some improvement, and some have cleaned the MAF (WHEN COLD, please) with CRC cleaner.

I am not suggesting you buy any parts, other than new wires, without more diagnosis.

 

So, have you tested the #1 plug and wire? this is no big issue, need to find what is causing the misfire on 1 and fix it, all the codes will go away except for the 1590.

 

Yea I tested it, Good resistance. plug looks like a plug that has been in for 5,000 miles.

Just don't understand why I've done plugs and wires twice now in roughly 50,000 miles?

 

Lets make this real simple.

Switch the plug with a plug from another cylinder. If your misfire moves, to the cylinder you swicthed it to, you plug is the problem. If not, move the wire to another cylinder and repeat. If still not your issue, you are gonna have to break out the digital multimeter to start the real fun parts.

 

Seems pretty 1,2,3 to me. Plug, wire, coil.