Hello Forum People

I have reviewed the forum's threads regarding misfires, however looking for advice regarding next steps in my diagnosis. Vehicle is a 2002 Land Rover Range Rover P38 with 120,000 miles, experiencing MIsfire codes; PO300 and PO303. Replaced Coil Pak's, spark plugs, plug wires, cleaned MAF sensor, all o2 sensors (it's been a couple of years since replaced) and both SAI Control Valves. Tested ignition system by spraying water in dark, coil output and finally spark plug in-line tester, all passed. Since the ignition seems to working correctly next phase will be fuel delivery, my question is recommendations regarding fuel system troubleshooting starting with cheapest components first. If I was just getting error code for the number 3 cylinder I would assume a bad fuel injector, however I'm also getting a random misfire code which leads me to believe there could be an issue affecting all cylinders. When first starting, engine runs smooth until warm once operating temp is reached cylinder 3 begins to misfire which continues when driving with poor performance and CEL flashing. Would appreciate help with fuel system testing recommendations.

Best
Ernie

 

Welcome to the forum!

I'm no expert but I'd say start by visually inspecting the combustion chamber of #3. How does the plug look? dry or fouled? fouled with fuel or coolant if fouled?

That answer will eliminate or confirm a cracked block behind 3 if you do or do not find coolant.

Once that is eliminated then on to fuel issues... Could be an injector or an injector O ring problem. Lots of thread in the D2 section here about those issues.

Good Luck!

 

You could also try posting this on the D2 part of the site. As it’s an engine/engine electronics issue it will be pretty similar to the D2 and there are a lot more viewers in that part of the site.

 

Ever figure this out? We may have a similar problem

 

Still #3 is misfiring, just finished replacing fuel injectors, spark plugs/wires, new coil pack, new O2 sensors, MAF, performed compression test tested 170, inserted spark tester number three was strong. Idols seems relatively smooth but when placed in gear misfire becomes more pronounced. Looking for recommendations on next step.

 

Still working on cyl 3 misfire, purchased new injectors before installing check resistance of old injectors which was 14.5ohms new injectors showing 15.5ohms. Injector part number ERR6600 however I find a large difference in prices from $127.00 for a set of 8 to $864.00 for a set. Can anyone explain why such a cost difference between ERR6600's part number. What is the manufacture and part number for recommended injectors? Could the different ohms create misfires?

Thanks
Bolte

 

The O rings are more likely to cause misfires, or a clogged jet. You can test the spray pattern of the old ones when removed. IDK about price.

 

As stated in my thread, I have a 2002 range rover p38, Still #3 is misfiring, just finished replacing fuel injectors, spark plugs/wires, new coil pack, new O2 sensors, MAF, performed compression test tested 170, inserted spark tester number three was strong. Idols seems relatively smooth but when placed in gear misfire becomes more pronounced. Looking for recommendations on next step.

Starting to suspect a bad valve or head gasket, does anyone know symptoms associated with a bad valve/head gasket or a way to diagnose without removing engine top end?

Thanks Ernie