I purchased a 2000 Disco II is 119k on it. It had a bad water pump which caused the head gaskets to fail also. I replaced the whole upper gaskets set from head gaskets up, milled the heads, thermastat, valve job, new water pump, Bosch 4+ plugs, 8mm wires, oil/filter, air filter change. Seafoam in tank to stabilize since it has not been driven in a few months. Put it all back together today and it fired up but idiling rough and is showing a misfire on cylinders 4 and 6. The service engine light flashes until you get the RPMs up and keep them there for a few seconds, than it is just illuminated. What are some suggestions on what to check next. Thanks in advance.

 

Idle air control maybe?

Do you have access to a ODB-II device to pull the code?
________
Colorado dispensaries

 

Yeah it shows a 0304 and 0306. Cylinder 4 and cylinder 6 misfire. thought about coil pack but pulled the wire off the plug and there is a hot spark that jumps to the exhaust manifold, so I am getting spark. So I am wondering if the injectors are not giving enough fuel to cause a misfire. What do you think?

 

If you have good spark it has to be fuel. Or timing. hmmmm
________
NO2 VAPORIZER

 

I am going to check the injectors hopefully tomorrow. I do not believe the timing chain has ever been messed with and I think it would run a bit rougher if the timing was off but it is something to check if the injectors are working properly. I would think the valves may have a problem but I just had them finished and he put the new seats in that come with the HG set, so I hope that is not the problem. The machinest I take all my heads and stuff to is really good and has been doing it for over 30 years, so I think if there was something wrong there he would have noticed it. I feel confident that is not the problem but it is running like the cylinders are laging like a valve problem (hopefully it is the injectors). Thanks for the help I will let you know when I find something out. Anyone else have any ideas or ever had a problem like this with their rover?

 

I did a compression check on the cylinders and the 2 hole had about 140psi and the 4/6/8 had about 120 psi. I know there shouldn't be more than a 10% difference between cylinders which leaves me a bit below at 140 and 120. If I just did the GH and had the heads planed and valves done what do you think could be the next thing to check? Do you think with the heads being milled about 8 thousandth the rods could be too tight and causing the valves to stick open and leak a bit through?

 

Swap out those spark plugs and throw in some 'el cheapo copper plugs and see what happens.
Alot of people have reported mis fires after switching to the +4's.
If your coils are weak these plugs will bring that out because the +4's need more power than other plugs.
So a cheap way to rule this out is by using cheap cooper plugs, put them in, clear the codes, if it still runs rough then keep looking.

 

I will swap the plugs tomorrow and see what happens than if that doesn't work I was goin to change the coils and see what happens. I will let you know what happens tomorrow. Any idea on what could be causing the difference in compression? Thanks for helping, I am up for anything right now.

 

Are you having a loss of power too? I've just done exactly everything you've done except for the water pump, and I too was getting multiple cylinder misfires (4 to be exact) and even more codes then that. I couldn't really tell if they were misfiring or not, but I was having noticeable lack of power, inconsistent power, etc.

Turns out my MAF sensor is bad. Not sure if I killed it when I cleaned or what, but when I borrowed someone's MAF and air intake hose (mine was shabby and falling apart)...it purred at idle and showed more power then i've never experienced in my Disco (not saying much really).

 

I wouldnt worry about those compression numbers.
Stuck vales, slipped liner could all cause lower compression.
Unless the lower compression is on the cylinders that you are having problems with I def would not worry about them.