I have a 96 Dico. It starts good but starts miss firing the first mile you drive. New plugs and wires have not done any thing to solve the problem. New air filter and still nothing. It runs rich enough to flood out plugs almost. No codes returned as fault except missfire. Ok anyone with ideas? What are you calling the bonnet switch? Thank you

 

timing off? all the sensors check out ok?

 

Have a look at your upstream O2 sensors, that's where i would start.

 

Maybe the air intake? Does it have a mass air sensor?

 

well bboat. Most of the stuff with running rich has been covered, but check the air filter/ air intake sensors. they may not show up on the diagnostics. as being the problem, the fuel pump and injector, and injector rail pressures may not be right. Hope it helps, gotta love a rover. duboff

 

How do you check the sensors? I have checked the fuel pressure and it is good. I was wondering if the ECU would run in default and not give a service engine lite? It is very hard to find any information on the systems.
Thanks

 

Is there any way to test them when I remove them?

 

The ecu is a maybe, generally speaking the ecu will give a show anything and it will show even when no problem exists. some local parts stores have the correct link to do the diagnostics. they may be able to help. as far as information, the shop manual, the electrical manual, are both good things to have. If you have the ability to check the sensors it can be done with a multimeter. you do need the electrial manual to do it. It works by checking to see if the circuits are not shorted out. Most of the sensors have no servicable parts and just have to be replaced. If you can do a wet and dry compression test on the cylinders do one. It is not a big deal to do. Most auto repair manual will walk you through it. Haynes also has a manual for discos. It is easier to use, but not as complete. The reason for the test is to determine if the cylinder pressures are the same give or take 10psi. It can help determine if the valves or rings are causing a problem. That is about all I can think of, off the top of my head. I will take a look at my books and see if anything else pops up. Hope it helps, gotta love a rover. duboff

 

I have a ODBII Scanner Computer and fuel pressure checker. I have purchesed the Haynes manual but it doesnt cover 4.0 engine. I also have a multi meter.
Now I need the information to be able to understand to test the sensors.
Thanks

 

No sensor will do that. What misfire codes are you getting ?