Freelander 1 K series misfire / cut out - SOLVED

Ok you k series experts !

First decent drive in the G4 today. Really pleased with the poly bushed suspension and new brakes.

About once a mile it misfires, like a jolt as it runs.

No fault codes but mysteriously it shows no misfire cyl 1 & 2 at idle but cyl 3 & 4 show "??"

Not sure what this means.

Any ideas from the K series fraternity??

Thanks

Is it a DIS or dizzy cap model? When were the plugs last changed? How old are the HT leads?
There are many items that can cause an occasional dropout, but they are almost always spark related.

Thanks.

No distributor. Plugs within 12 months and clean.
Springs on ht tweaked for good fit.

Might be a coil pack playing up.

Not sure what the ?? means when monitoring the misfire rate on pscan. Maybe philip can help ? @pscan.eu Please ??

Fitted 2 x brand new coil packs today.
Identical fault. I think misfire is misleading - it momentarily cuts when driving then runs ok again. No fault codes, no fault lights.

Feels like electrics as it comes and goes in a fraction of a second.

Still have misfire count as ?? on cylinder 3 and 4.

Also, compression test - cyl 1 - 175 PSI, cyl 2 - 155, cyl 3 - 155, cyl 4 175.

My gauge reads a bit high, but the difference is the key thing.

I can do a data log run but what to monitor ??

I'm not sure what the ?? is referring too, seems a strange thing to display.
So you've eliminated coil packs, leads and plugs.
Next would be injectors I guess. I'd be tempted to move their location, to see if the fault moves with them.

Compression on No2 and 3 is a bit low, especially if your gauge reads high.
The compression on a healthy 1.8k is normally around 170 to 175 PSI, and it shouldn't really be more than 15 PSI below 175. As you have 2 cylinders are 155, those could potentially cause misfires, but I'd expect to see them misfire all the time, and on cylinder 2 and 3, not 3 and 4.

More investigation is going to be needed.

Thanks. Not possible to see if the fault moves with injectors as I don't know whether it is 1 or more or which cylinders are playing up.

I do have a spare inlet manifold with injectors so could swap that.

I might do a Pscan data log run to try to ascertain whether fuel or electrics. No fault codes is not helping !!

Still no fault codes. What could make it hesitate and not provide a code?

Monitoring parameters looks fine.

Bit low on power but otherwise ok apart from the hesitation.

Any ideas ??

Low fuel pressure possibly.
If the filter hasn't been changed, it could be restricting the pressure available at the rail.

O.k. good idea. That will be next. Shame there is no pressure monitoring on the ecu.

andyfreelandy said:

O.k. good idea. That will be next. Shame there is no pressure monitoring on the ecu.

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No there's no active monitoring of rail pressure, but there is a pressure test port, where a pressure gauge can be connected.

Hey, I have read through your thread and it sounds like your having the exact same issue I had with my 1.8 petrol years ago. It turned out after plugs coil and leads that it was actually the lambda sensor causing it even although it appeared to switch correctly on live data.
To test it just unplug the number 1 lambda and go for a drive. If the fault disappears change the lambda sensor.
Most folks don’t know it but ngk and other manufacturers recommend that 4 wire lambdas are changed at 100,000 miles as they go bad and effect efficiency.

Thanks Ross. You might be on it..

The waveforms all looked good, no fault codes, no engine light.
Took the 1st O2 plug out, cleaned with electrical spray on both parts, reassembled and it hasn't coughed again since.

Will not mark up as resolved yet, but looks good so far. Wonder what happens not to log a code?
thanks again.

Yeah it won’t log a fault code as long as the ecu is receiving a lambda signal that’s within the accepted range. But it will run lean and misfire anyway as the air/fuel ratio is off. I always found with mine that when it missed baldy just flooring it would make it go as at full throttle the ecu ignores the lambda sensor and just gives it all the beans in open loop.

So the cutting out hasn't reappeared but engine light on a few times and P0170 Fuel trim code keeps coming back.

First O2 sensor playing up ???

Yeah it sounds like it. If you look at live data you’ll see the short and or long term fuel trims are going beyond the threshold to trigger the eml. Usually once the trims go over positive or negative 25/30 percent (depends on manufacturer) you’ll get that code. It’s another sign the no 1 lambda sensor is guffed.

No 1 will be over or under reporting leftover oxygen. I suspect it’s adding fuel with the trim due to a lean condition. You’ll likely see a disagreement between sensor 1 and 2, 1 may say it’s adding fuel trim but the second may show a lean condition. This would be more proof that no 1 is fubar.

To test no 1 response just watch live data and drive the system rich and lean. To drive the system rich turn your gas blow torch valve on and feed the gas (unlit) into the intake. You should see the fuel trims go way negative quickly as your providing unmetered fuel to the system. When you stop feeding gas it should go back to normal or whatever it’s current normal is. To drive the system lean just repeatedly pump the brake pedal and don’t stop. You’ll see the fuel trims quickly go positive. If it’s slow to respond or responds inappropriately then that’s more evidence it’s guffed.

There's only one O2 sensor used to monitor mixture on the 1.8K. The post cat O2 is used for cat efficiency monitoring only, and simply puts the MIL on if CAT efficiency is under a pre-set level.

My daughters Fiat 500 was suffering from a very strange fault, where there was a 10 second delay between the ECM making a mixture adjustment, and the O2 responding to that adjustment, which created a strange rich, lean, rich, lean cycle with a 10 second reaction between them. This caused the engine to increase power, then loose power each rich lean cycle. After lots of head scratching, it turned out that some in the past had replaced the CAT, and connected the pre-CAT and post-Cat sensors the wrong way round, so the ECM was trying to adjust the mixture based on what the O2 after the CAT was shouting.

Maybe this fault is something similar?

O2 sensor 1 doesn't look good !! Red trace. Green is post cat.

Long term fuel trim in red. Short term is green but hidden by blue and didn't move. Perhaps someone could explain the picture ? I blipped the throttle a couple of times. Short term trim was stuck !!

New upstream O2 sensor on order. Hopefully that will solve the lack of power and eml.

andyfreelandy said:

O2 sensor 1 doesn't look good !! Red trace. Green is post cat.View attachment 302788

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It's definitely not switching clean, so I'd be replacing that O2 sensor first.