Bought used 03 Disco SE7 last August. 3 months ago I started getting a shutter on cold start if I didn't let the cold idle come down(not sure if that is even normal).

It was registering a Cylinder 4 misfire. I put new plugs in(Autolite Double Platinum, part number APP3923). Same result. I went to local certified Land Rover mechanic and he put in wires(Balden Premium 7mm SAE Class F KI). The problem is still happening, but only if I start it and go(press in the brake and put it in gear which drops the idle). I doesn't register a check engine Cylinder 4 misfire if I let it warm up.

The light will even go away on its own if I let it warm up every morning.

I took it to the local dealer. They put it on the computer, saw 2 misfires in Cylinder 2 and 4. They said they shut it down, claimed the connectors had gotten loose and "tightened" them and seated them properly. They started it again and claimed the problem went away while recommending new plugs and wires. I argued with them and wanted them to check out other things, they refused. They claimed no reason to test anything else, the misfire was gone. I told them it is just warm now and it would happen again.

Anyway, I have lost my battle(and wasted $120) with them and the next morning, as I predicted, same old misfire. I am at a loss, are my plugs and wires really the issue or am I looking at something else? What can I test before dropping even more money on this issue?

 

Platinums dont seem to work well in the trucks unless you got the +4s. I would recommend switching to the magnacor 8mm wires, and bosch +4 plugs. Also, how many miles are on the truck? Are you getting any lean codes or o2 sensor codes? I know that my front o2 sensors are causing me some issues aswell. Might be something else to check out

 

89K miles, not other codes. I get the 3 Amigos randomly, but that will be another search and find task I am sure.

Can I change the one problem plug on Cylinder 4 to see if that is really the cause?

 

Have you been having to add coolant, does this only happen on your first start in the morning and do you get any white smoke, maybe sweat smelling like coolant?

 

I have added some coolant, but nothing consistent. Haven't seen white smoke, although its hard to tell in the mornings sometimes from exhaust. I don't really know. I hadn't been paying attention to it until now. I am learning as I go here.

This happens anytime that the engine does a cold start idle(1.5 RPMs(20-30 seconds), then drops to 1 RPM) and I interrupt it by applying the brakes and putting it in gear. I have also had it happen a few times without the cold idle but again only if I don't give it little time to warm up(less than 30 seconds or so).

Also, this just happened one day. It wasn't progressive, one day it just showed up.

 

It appears to have some oil on the end, should it? If not, what does this mean? I put the OEM Champion I saved back in to test some cold starts with today. I have attached some pictures of the new Autolite plug I removed.