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Random misfire with lean codes

4K views 116 replies 6 participants last post by  iamthewalrus 
#1 ·
Hi

I only normally get a misfire when the engine is cold but when it was 18 degrees outside this morning I was surprised to get the misfire before I left the driveway. I had lean codes and sure enough I found dirt in the MAF sensor. Is this mix of misfire and lean together due to to anything serious I should look into? I'm going to clean the MAF later and see how it goes.
 
#2 ·
Hi,

I have cleaned the MAF sensor twice with appropriate cleaner, used a small paintbrush to get the fly out. Anyway, after vacuuming the filter and putting it all back together, despite the engine being hot as I just drove home, it ticked over a while then went to P1347 Manufacturer Control. I have had this code before, this I mistakenly took for random misfire is actually misfire on cylinder 3 with fuel cut off.

I have done no work on my car at all and it drove perfectly fine home yesterday, I have some fuel trims info in the pictures. I have the ongoing catalytic converter below efficiency, which I treat every ow and then with fuel system cleaner. Any advice gratefully received.
Measuring instrument Technology Electronic device Tool Electronics
Measuring instrument Electronic device Technology Tool Electronics
Electronic device Technology Measuring instrument Tool
 
#5 ·
I just had an idea so I disconnected the MAF sensor, went for a short drive, and when I set off the old paper flapping against the exhaust symptom was there pretty bad, the car sat on the driveway the last two hours so it cooled down a bit to the 10:30 position where 12 is running temperature. When I got back the flapping wasn't so bad but still there. I put the sensor back on, started the car and it took one minute of idle before it threw the code again. Looking at the notes I have on the car this code usually clears itself up. I have thrown in fuel system cleaner to see if it might be injector issue.
 
#6 ·
Sorry @iamthewalrus Your pics are honestly a bit disturbing! It looks like you have the diagnostic reader stuck between the cleft of your arsse?
But putting that behind us (no pun intended) can you not get INPA and the obd cable (and dis) these generic code readers are good at being generic! INPA is also not the perfect but at our level you can use it quite effectively.

shit in = shit out
 
#9 ·
Hello Clavurion,

Thank you for your response.

Rubber boots between MAF and throttle valve
ok easy to check I will dismantle, check and clean tomorrow night.

CCV, DISA valve
CCV was replaced about 5 years ago. I personally cleaned and checked the disa valve about 3 years ago, I also cleaned the ICV.

rubber plugs at the rear end of intake manifold.
I don't know which part you are referring to?
Thanks in advance.
 
#13 · (Edited)
If one cylinder is cut off is it OK to do a 50 mile journey at the weekend up the motorway?

I have used the gas a lot lately, is it possible to get the car to use the cylinder for the purpose of helping to get injector cleaner through it?

How long do spark plugs last for, the ones that also do lpg?
 
#25 ·
I dont know tbh, its pretty loud so could be from anywhere. Its just a gernal vibration sound, I promptly slowed down on both occasions to 60 and it went away. I do find it strange though the paper on exaust test was pretty bad for a hot engine, definitely something bad going on there.
 
#33 · (Edited)
But do you understand what I Am saying, it can't be leak issue from boot if it misfires with the maf disconnected. However I am still trying to work out what the other guy meant by "rubber plugs at the rear end of intake manifold. "

Injection coils 3+4 were replaced in March 2017, all spark plugs were replaced April 2016 too.
 
#36 · (Edited)
My car has a lot of bits missing and god only knows how the previous owner thought it was ok for this however I am now realising there is yet another bit possibly missing, I assumed that the intake boot that has a skrew in the F-Connector in the attached photo of my car was because they put in a replacement boot that was supposed to be in another car and put the screw in just to appropriate it. However upon looking at the below link which I found while I was searching for the intake plugs the clauvrion was referring to, I find that the F-Connector was supposed to go to some pipe:

It says on the page in reference to the F-Connector "small:Fuel filter, pressure regulator". My fuel pressure was checked the other year and it was considered ok so I presume nothing is wrong.

Later on in the page it says :

"So this answers the question why the vacuum port on the CCV is capped when used on the M54.

"So this answers the question why the vacuum port on the CCV is capped when used on the M54.

On some M52 engines the FPR was on the end of the fuel rail and the vacuum source was the nipple on the CCV. On the M54, the FPR is on the fuel filter. The second hose on the "F" connector supplies vacuum to the FPR.

I suspect the "L" connector was changed to an "F" connector on the M54. The vacuum port on the CCV was capped on the M54 because it is redundant. "

However I dont see the understanding behind that statement in the article.

Is it wrong I don't have a pipe connected to it? Multiple mechanics have seen this car over the last few years and no-one said anything.




270558
 
#37 ·
I have checked for vacuum leaks, I heard no change in the pitch but now I have found a new code. The MAF was unplugged and I had the p1347 but now I have? P0102

Mass or volume air flow A circuit low.

I presume that's purely because I disconnected the MAF.

"
What the P0102 code means
P0102 is the general code for a problem with the Mass Airflow (MAF) Sensor having a low voltage output to the Engine Control Unit (ECU)."
 
#46 ·
Oh bother. So they've put the LPG plumbing overtop the cam cover. Brake lines should not interfere with the cam cover - it's all the LPG stuff. Bother.

I don't even know what the slim box on the lower middle of this photo is - can only think this control the LPG injectors?
 
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