QuestionJohn,
Hi, I have a 96 Disco SE7, has 125k on it. One morning cranked it up and it idled rough and seemed to be underpowered, like it was running on 6 cyl. Took it to a local shop and they of course dont have the correct Diagnostic tool to get codes for the Land Rover. He did check the fire to the coils and discovered that one coil has no fire, and I think its the coil that controls cyl 8 and cyl 5 .
He swapped with new coil, still no fire. He thinks it maybe a sensor or ECU, another tech I talked to thinks carbon build up may cause the valves to stick and therefore no fire will happen anyway. Is this a common occurence? I had just had an engine flush and oil change done 1 week prior to this, is there any rememdy like a fuel cleaner or what should I do? What is the price on a valve job?
AnswerHi John,
rare to find a coil problem. Coilpacks are a different type and they can break down but older coils are usually very reliable. A liquid leak is the usual fault.
It could be a problem with the wires, plugs or even the spark amplifier module (attached to distributor).
As for sticking exhaust valve preventing coil to spark...bullshit. Just another scam to drain your wallet.
Our older Disco I's can have the sticking exhaust valve BUT that engine keeps on working. A real work horse. The new Disco II engines are so dependent on the EMS and sensors that continued operation becomes very difficult.
I'm almost certain that firing will continue even if the valve sticks.
On your '96 do you have a coilpack or the older coil generator? Do you have a distributor? If you have a coilpack, you don't have a distributor. Newer Disco's have combined these two units into a 'coilpack' and all the sparkplug wires run from there.
If you have a coilpack, go to a local auto electrician shop and ask them to test your coilpack. A professional shop will be able to do this...even if its a LR Discovery.
If you have a distributor, it could be a problem with the cap or even the rotor. Two cyl. not firing could be caused by a crack in the cap or deposits on the rotor. You could pop the cap, clean off the deposit buildup on the points, buff up the rotor metal.
As for a valve job...I think the tech who suggest that is also giving you a snowjob. If you had sticking valve problems, you'd have noticed this long before now. You'd have noticed extreme loss of power while under load (climbing steep hills, towing, etc.) and a slow loss of power, perhaps even some misfires.
The engine flush intrigues me...did you happen to WASH the engine area? The spark amplifier module is very sensitive to moisture. If it got wet...it could cause this type of problem.
Lastly, don't bother to purchase additives for a sticking exhaust valve problem. In theory, additives are burned up by the intense heat of the combustion and nothing can survive to help an exhaust valve. So don't be fooled by those con artists who are only after your $2500 (valve job).
Best of luck,
JohnMc
