Misfire cylinder 2 & 3

[GJC]

2000 Disco II, p1300, p0302 & p0303.
New plug wires, plugs ( Champion) and coil packs.
Even change injectors 2 & 3.
Tightened up lower intake manifold.
Heads were redone and new head gaskets.
Does not burn any coolant and runs at normal temperature.
Even installed new Bosch O2 sensors and cleaned MAS.
Did I miss something?

 

[LRDONE]

Dead misfires? You should check the injectors wiring along with the wiring to the coil packs and confirm you have spark with a spark light. A least that's where I'd start considering what's been done.

 

[GJC]

2000 Disco II, p1300, p0302 & p0303.
New plug wires, plugs ( Champion) and coil packs.
Even change injectors 2 & 3.
Tightened up lower intake manifold.
Heads were redone and new head gaskets.
Does not burn any coolant and runs at normal temperature.
Even installed new Bosch O2 sensors and cleaned MAS.
Did I miss something?

 

[GJC]

Yes, I forgot to mention that I do have spark.

 

[LRDONE]

Okay well having spark is good. lol you could use a noid light to make sure each injector is getting signal. Noid lights can be bought for pretty cheap unless you'd rather probe the harness. Either way, eliminate the possibility of a harness issue to the injectors.

 

[pinkytoe69]

Does the misfire happen only at startup?

 

[GJC]

It's most noticeable after it warms up, and then the codes come back.

 

[GJC]

Although today it was rough right from the start, and CEL came on almost immediately.

 

[Bumsnatch]

It’s almost like that crack in the windshield every disco in Wisconsin has. The motor is based on 50 year old Buick so maybe your lifters aren’t getting enough pressure? CEL right away eh?

 

[JohnB]

So no mis-fire before you put the rebuilt heads on? If so then I would do a compression test. Double check where you plugged the plug wires into the coil packs. Maybe mixed them up.

 

[rovercanus]

 

[discostew]

That makes it easy. Because it'sq so hard to get at the coil end of the plugwire, I take them off at the plugs and measure resistance thru both wires and the coil. so since your misfires are on 3 & 2 just go there. A plug wire on either one of those coils can cause a misfire on both cylinders. If I remember correctly both wires and the coil on those longer ones will be about 32K ohms