Uneven running / misfire on my patrol

[Osprey]

Hi,

My "new" 98 patrol 4.5 is running badly - feels like it is running on 4 or 5 cylinders, smells like the mixture is rich, loads of heat coming out through the gear change area. In short has the performance and response of a 3 legged dog.

A diagnostic test with nissan suggested a whole mountain load of possible causes - fuel filter, knock sensor, plugs, cables,..... on and on. They quouted 3500 to change them all.

Any suggestions or advice welcome - I am taking it back to Mr Rajan in Sanaya who will check and change them one by one but is it worth splashing out and changing the lot?

Thanks, Jeff.

[offie]

ok from my point of view, if this is your car and you want it to run properly then pay the price, then it is a one off and no more hands in pocket,

i had lee fixing my car in the desert on friday due to losing power lol but all it needed was the filter removed and sand removed,
pain to do but once dane car was fine,

as the saying goes you get what u pay for,

[JC]

Jeff try the MAF Mass Air Sensor these thing are know for failing it probably needs a clean out (sand in it)

[Osprey]

Thanks, will do - it had a bit of a misfire initially but is much worse now (could be full of sand). Am tempted to change the other bits as well - is it normal to have heat pumping out of the gearchange area, feels like someone has a coal fire burning under there? I know lots of cars have these mats/covers on that area but wonder if the car is OK, the temp sensor only started to register after 45 minutes off road, normally it just shows cold.

[ScaVenger]

would say check you saprk plug or ignition system as maybe one isnt working or getting an ignition. my opinion, if alot of heat, and not due to missing parts (heating insulators around gearbox,) check if gearbox oil level ok and if not been changed in a while. had extreme heat coming from my gearbox in landcruiser before, and turned out that gearbox was low on oil + needed to be changed.

[Lionbar]

Hi Butty Bach,

First and foremost, do the changes accordingly to price and likelyhood of failure.
The one thing that the agencies are not good at is diagnostic work, rather than actually taking the time to pin-point the problem, they change everything that might be even remotely connected.
Cleaning out the air filter with compressed air and the MAF sensor (with a mild electronics cleaning spray), changing the fuel filter and plugs are a good bet to start with, easy jobs. If that fails replace the plug wires, not sure abt the knock-sensor tho. All I know is that the MAF sensor from the stealership is 1300dhs and they only have 1 for a 98 model in UAE.
BTW, what fuel do you use?

Regarding the gearbox, as Scavenger stated, get the oil level and quality of the oil checked. If it is low, it'll run the gearbox hot, if it is old and goes to the consistency of water, it'll loose its cooling capacity. Does the box area get hot whilst it is in neutral or only when the box is under load (Drive or Reverse)? Are the gear changes smooth and consistant. If you put ur boot into it does it go to 5000 rpm before changes?

If the gear oil is old, then make a point that normally all the drivetrain oils are changed together, so its advisable to change both diffs and the low-range box at the same time.

Sanaiya has heaps of experienced mechanics who know their way round the engine bay of a Badrool with their eyes closed.

Keep us informed of how it all pans out.

Search http://www.patrol4x4.com, they have heaps of info available.

[tintin]

So you sold the jeep to get rid of the problems and now look, more problems. Old cars will do this, I agree with the others. Try cleaning the air filter out. Swap the plugs and cables and have the fluids changed. That way the smaller, less expensive problems are solved, and they are good then for about 25,000kms. Also, run some fuel injector cleaner through it once you have changed teh plugs, you may have a clogged injector or a blockage in the system somewhere.
Do you know when the last time the fuel filter(s)n was changed on it? May be a good idea to do them too! In other words mate, trial and error. Start small, get the little things done, then move onto the bigger problems! You may find it is just a bad plug, or it may be a faulty fuel injector. Enjoy, and let us know what it was, always good to have an outcome posted!

[PR]

Since it's a new car (for you) then start from the assumption that the previous owner did no maintenance work of any sort - and so you do a complete mechanical overhaul right from the start.

Spend the 3,500 dirhams happily, knowing they will save you $$$ and strife down the road.

Actually, 3,500 is waaaay too much for a complete overhaul!!! What are they changing, the gearbox???

Here's the deal: flush and replace all liquids, change all filters, check all rubber parts for cracks and flexibility (replace if any damage found) - that should cost less than 1k.

Do it yourself, if possible, as you'll learn how your truck works and see the condition of the parts for yourself.

Then go through all systems one by one, taking notes of any wear and tear for future replacement or prevention of greater damage. Keep the remaining 2,500 dhs for those that need attention, but don't hesitate to spend it.

The engine stumbling is either fuel or spark (or both) and it's probably a sensor that governs the fuel/air mixture, nothing more. The MAF mentioned above is promising. Have a look at the spark plugs and if they look fine, leave them (not all clogged with oil, or covered in dry soot, or steam-cleaned: just plain old spark-plug-colour tips). Same with the plug wires, if no cracks and they're nice and flexible don't worry about them for now.

Here's how to read spark plugs:

[Osprey]

Thanks for all the advice folks - just got new plugs and cables plus the air filter, sensors blown out with compressed air. It is better and has a bit of pick up but still not 100%. He did a compression test on all cylinders and reckons they are only on 70 instead of 120+ so this may be bad news. I'll try it out tomorrow again and keep changing the bit smentioned. The tick over is still wobbly but it does generally feel smoother and quiter than before. Two questions:

Is the MAF sensor actually stuck on to the fat air filter tube (small square Hitachi box) with 2 phillips screws?
If this is the beast, can I use carb cleaner spray on it?

Thanks again,
Jeff.

[PR]

Compression test is an accurate reading of the wear on engine combustion chambers so that is the baseline - in other words, anything you do to the engine externals will not change the fact that the piston rings are losing almost half of the compression, and are actually running at 58% capacity.

I'm afraid you need an engine rebuild, mate new rings, at the minimum, perhaps cylinder sleeves; maybe even pistons... could go as far down as replacing crankshaft bearings.

I would immediately stop any other work like renewing fluids, and the other bits mentioned, etc., because it's lost money on an engine running 70 psi instead of 120

Lesson learned, and next time the compression test comes before purchase The good part is you get basically brand-new engine internals, though, for a 98 Patrol to require an engine rebuild means it's been run real hard: that's a tough engine to wear down! Maybe have the compression test repeated to double-check the readings?

Sorry for the bad news, mate.

EDIT: and before launching into any engine rebuild, have someone check the gearbox as well, because wear in the engine usually means wear in the gears, too and you don't want to plonk down on the engine only to then find out the gearbox needs a rebuild as well. Mechanical parts wear out, especially when pushed hard, so quite frankly if you find a used car with heavy-use engine, you suspect all other mechanical parts have been subjected to the same strain.