freelander 1.8 (back again)

forgot to mention hc's 1186 ppm limit is 200

So it's running majorly rich. As I can't remember the original thread, I'll start with the basics. I'm guessing all the obvious things have already been replaced like plugs, and plug leads etc...? How long has the misfire been there? Since the head gasket was done? Is the misfire apparent through all the rev range, or more apparent at certain speeds (ie idle, 2-3k or so, full throttle)?

hi, yup all the obvious have been changed. it was misfiring before the hg was changed. it only misfires at idle, its fine through the gears/revving. no loss of power just at idle, need it sorting urgently only a couple of weeks to its mot. the only sensor we havent changed is cts.

has the lambda sensor been reconnected, likewise the coolant sensor, if they are connected have they been renewed. Have you had a head leakage test done since the repair

This sounds very strange. Going by the gas test results, I think we can safely say the fuel is getting into the cylinders, but just not getting burnt how it should.

I'm assuming the misfire is always on a certain cylinder? I was thinking that possibly low oil pressure and hydraulic lifter problems, but the compresstion test results would rule out that theory. And if it was something like a sticky valve, I'd expect the misfire to be more apparent the higher the revs.

Given the amount that's been changed, first thing I'd be inclined to do, would be a diagnostic data log to check that all the sensor values are valid (a sensor could be giving a spurious signal, but may still be within range so the ECU doesn't flag up any faults, but instead the engine just runs like a bag of s***). Then I'd be checking for faulty plugs/leads (it's not unknown for new ones to be faulty), preferably by using an inductive pick-up to compare values between cylinders. After that, it's into quite advanced diagnostics.

all connections have been remade. had leak tests done when it was compresion tested. I havent changed the lamda sensor due to its location as its very hard to get to. as i said the cts is the only sensor that hasnt been swapped. I wondered about the cts but the chap at the garage hasnt suspected it.

hi thanx for your help so far. I have a detailed diag list if you want me to post it (its a bit long)

FFS! With overfuelling like that it will soon (if not already) bugger the o2 sensor and cat! I wouldnt drive it until you can determin the cause else you will be facing even more big bills.

Firstly have the garage check the fuel pressure at the rail both with and without vacuum. I am not sure what the Freelander specs are off the top of my head, but 5psi more without vacuum. 55psi sounds abit high, but maybe ok.

Check there is no restriction to the return line. Check they have connected up the feed and return pipes correctly apres HG change. (i've seen this too!) Also check the vacuum sense hose isnt pissing fuel into the inlet manifold! I've seen split diaphragms allowing just this.

If all this checks out ok, see if you can manipulate the fuelling (with a

I would also be looking at the live data and seeing if the ECU is fuelling somewhere near correctly to the inputs its receiving- you can also see if any input sensors are telling porkies too.

To be honest, your second garage doesnt sound too hot either if they cannot determine why its running rich (not many causes!)

Tim.

The accepted way is to check the pressure *after* the regulator. What the pump is doing is largely irrelevant provided it is adequate.

asked the bloke at the garage to explain his diagnosis, he reckons the high hc's are due to lack of fuel not to much, he said if we can get the hc's down the rest will "fall in". The regulator is an intergral part of the fuel pump (all in the tank) two pipes run off one to the inlet and one to the charcoal canister. any thoughts (apart from burn it)

chunkybear via CarKB.com (u14753@uwe) gurgled happily, sounding much like they were saying :

My head hurts. How can "too little fuel" be causing it to run with excessively high hydrocarbons - that's unburnt fuel - in the exhaust?

thats what i thought. time for another switch me thinks. Might try another set of plugs although the ones fitted are new, i might have a duff un. currently using ngk platinums. would a different type of plug make a difference??

chunkybear via CarKB.com (u14753@uwe) gurgled happily, sounding much like they were saying :

No idea.

I presume (without going back through the thread) that you/they have done all the basics - that there's no inlet air or exhaust leaks. that the lambda sensor's been replaced, and that all fault codes have been read and cleared?

I'd really suspect the regulator. A lot of other stuff has been checked, so I'm wondering if the pressure is way too high = too much fuel.

would a lamda sensor have such a major effect on fueling? reading other threads suggests that it affects fueling by + - 10% could this be enough to cause a misfire? I'll get a garage to swap it, my boyfriend wont touch it! He says its a pig to get to with out stripping off the exhaust manifold.

What does it take to find somebody who knows what they're doing now adays? (that's a retorical question, so need to answer it, as I know quite well!)

First thing to establish, is the misfire constant on one cylinder? Check this by pulling of one HT lead at a time (using some insulated pliers!), and see if the engine tone changes. If there's no/little change, you've found the faulty cylinder. If the engine reacts the same for each HT lead, then there's not really a misfire as such, it's just running like a bag of s***.

If the misfire is on one cylinder alone, try swapping the plug with another cylinder and see if the misfire moves. If it does, the plug is faulty. If it doesn't, try swapping the leads around with another cylinder. If it moves, then the lead is faulty. If it doesn't move, then - At this point, the next step depends on if the engine uses a coil pack or distributor (I honestly have no idea, as I avoid K-series like the plaque). If it's a coil pack, it'll most likely be a wasted spark system. In which case swap the HT lead connections at the coil pack for it's complement cylinder (ie, 1 and 4 are on the same coil, and 2 and 3 are on the same coil). If the misfire now moves, then the coil is faulty. If it doesn't, then the fault lies with something else on that cylinder.

If it's not a coil pack, and it's a distributor, then check the cap very carefully. Look for any damage (cracks, chips, burn marks where it's been arcing), and give it a good clean, and make sure it's dry (10 minutes or so in a warm oven is ideal). If there's an improvement, then you've found the fault. If not, then it's a cylinder fault.

You also say the CTS hasn't been changed. Has anybody actually looked at a datalist readout of the sensor values? If not, find somebody who can do it. Any faulty sensor causing the engine to run this badly, should be blatantly obvious to anybody competent in using the diagnostic kit.

the garage checked pressure and it came out at 55 psi (3.8 bar). the haynes says 3.5 + - 0.2 bar. so looking at that it is a touch on the high side especially for a seven year old pump....

Did my post of last night appear in this thread yet?!?

tim. .

This is running much too *lean*, surely? Not rich?

If you could get a measure of the gases *before* the cat (or even in the tailpipe when it is cold-ish and the cat not working) that could be a useful diagnosis

Tony