Hey folks, like many my old landy has the “misfire” of doom. Its a freelander 1 td4 on an 04 plate. It’s a daily driven project I’ve been working on for years and have made a lot of progress with. So now I wanna tackle the misfire which has confused and plagued many for years.

I am a qualified mechanic and mot tester so should be able to solve this, as long as it doesn’t come down to needing to observe sensor or other waveforms with a scope as I don’t have access to one just now.

First I just wanna brainstorm and create a “get started list” which I thought I would share on here and get the opinions of some other td4 folk. I already have a number of things in mind which could be causing this.

Just to clarify I have run my freelander with and without the egr delete, with and without the crank case filter delete/mod, with and without the Ron box and also replaced my injectors with a known good set. None of this made a difference to the misfire.

It happens roughly between 2,000rpm and just under 3,000 rpm I would say, my engine does this cold or hot, although its worse when it’s cold and more noticeable, let it warm up for five min and it’s a lot better. Also my misfire isn’t that bad, when stationary and holding 2-3k rpm you just feel the little wobble/kick of the miss and you see an appearance of blue ish smoke from exhaust that isn’t there at the higher or lower rpm’s. When driving the miss isn’t really noticeable.

My suspicion is that it just isn’t managing to either measure air coming in properly at all rpms or is failing to inject the correct amount of fuel at the right pressure in that rpm range. It isn’t unusual for a sensor to fail in one area of its operating range but to work fine in others.

Obviously I’m gonna start with observing live data to see if anything obvious jumps out at me. This could be caused by many things so time to build a list of things to check. If anyone has an ideas and input for this please share, I will share my results as I go with you folks.

Gonna look at;

fuel rail pressure sensor and wiring,
hp pump suction valve (check resistance),
may also try to measure fuel pressure (low side), does anyone know if the low pressure pump operates at a set single speed or is it variable in any way?
I also wanna check the injector coil resistance and also injector loom resistance and load testing.
Also the crank sensor id like to resistance check.
Also I’m aware the fault only happens at certain rpm, which means likely the fault only happens under those exact conditions which may make it difficult to test some items.

Anything else I should add here folks?

If you read to the end, thanks. I tried to keep it short.

Cheers

Hmm, this looks rather complicated to me.

The only thing I would add to your get started list is coffee, lots of it.

It’s been a while since I had a Td4, but they are often reported doing that (mine did). No particular solution as far as I’m aware. You could just ignore it.

guineafowl21 said:

It’s been a while since I had a Td4, but they are often reported doing that (mine did). No particular solution as far as I’m aware. You could just ignore it.

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Yeah, to be honest it isn’t really a big problem so to speak, the car drives fine and passes emissions with ease.
It’s just annoying that it does it when it shouldn’t. As it has plagued many for years and has never been solved, I thought I’d use my knowledge and experience to take it on while I have some spare time for the next few weeks and see if I can resolve it and potentially share my findings to help others.
I do have access to a bunch of rather expensive diagnostics which may help.
So I’m gonna have a bash and see what I find.

I've a hunch that it's related to the breather, but sold mine before I could test my theory. I can to this conclusion because I'd checked or replaced everything else on the engine except the turbo.
My plan was to plug the breather connection to the turbo intake hose, and vent the breather to the atmosphere.

So mine used to have it and it did get on my nerves, but I got used to it. Funnily enough though, I can't remember when it last did it, so much so I'd completely forgotten that it was a thing until Ross posted this thread.

Nodge68 said:

I've a hunch that it's related to the breather, but sold mine before I could test my theory. I can to this conclusion because I'd checked or replaced everything else on the engine except the turbo.
My plan was to plug the breather connection to the turbo intake hose, and vent the breather to the atmosphere.

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Hi nodge, you could well be right there and it’s worth checking out. My suspicion that makes me think you could be right is the appearance of the blue ish smoke which is usually oil related. I may give your plan a go. I noticed an unclamped hose at the back of the head about 1.5 inches in diameter roughly, its is elbow shaped 90 degree, is that the one?

Ross Tait said:

Hi nodge, you could well be right there and it’s worth checking out. My suspicion that makes me think you could be right is the appearance of the blue ish smoke which is usually oil related. I may give your plan a go. I noticed an unclamped hose at the back of the head about 1.5 inches in diameter roughly, its is elbow shaped 90 degree, is that the one?

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I also came to the same blue is burning oil conclusion. Also when an engine is running at high RPM off load, the proportion of blow-by gas and oil mist is higher in relation to clean air than when the engine is loaded. Also a good amount of blow-by gas is CO2, along with oil mist, CO2 isn't combustible, which could account for the misfire and oil mist accounts for the blue smoke.

There is a hose which connects the breather from the cam cover to the turbo feed hose. To test my theory, this hose needs disconnecting from the turbo feed hose, but the turbo feed also needs plugging, or the MAF signal will be incorrect.
It's something that I just never got round to testing on mine.

Nodge68 said:

I also came to the same blue is burning oil conclusion. Also when an engine is running at high RPM off load, the proportion of blow-by gas and oil mist is higher in relation to clean air than when the engine is loaded. Also a good amount of blow-by gas is CO2, along with oil mist, CO2 isn't combustible, which could account for the misfire and oil mist accounts for the blue smoke.

There is a hose which connects the breather from the cam cover to the turbo feed hose. To test my theory, this hose needs disconnecting from the turbo feed hose, but the turbo feed also needs plugging, or the MAF signal will be incorrect.
It's something that I just never got round to testing on mine.

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Hi, yeah that’s the hose I was thinking of. I guess the quick cowboy way to check it would be to pull the hose out the cam cover and use the long nose locking pliers to clamp the thing shut, leaving the crank to vent straight into the engine bay. The only problem with this idea is the loss of vacuum from the turbo inlet will effect the crank case depression limiter valve as it needs that to function according the rave manual system description and operation. Guess I could just try and see what effect that may have anyway.

In my experience, the crankcase valve clogs with goop anyway, so seldom works. I'd do the clamp thing as a test. It's only when holding it at 2k off load that the issue appears, so you'll be able to keep an eye on the engine.

Nodge68 said:

In my experience, the crankcase valve clogs with goop anyway, so seldom works. I'd do the clamp thing as a test. It's only when holding it at 2k off load that the issue appears, so you'll be able to keep an eye on the engine.

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Yeah I’m gonna give that a shot soon as the weather clears up here.