1st Cylinder misfire problem
Thread Starter
Newbie
Joined: Mar 2020
Posts: 3
Likes: 0
2011 ML350 Bluetec
1st Cylinder misfire problem
2011 ML350 Bluetec
76,000 mileage
My car started misfiring while idling when it warms up. I was not getting any engine codes at all which meant I drove it a bit not more than 500 miles. After long and and difficult diagnosis I found out that my injector was bad. I replaced the injector and recoded it.
The misfiring didn’t go away which caused me to look for other reasons. So I ended up doing a compression test via glow plug and found that all my cylinders were within spec of 23-25 bars compression except cylinder 1 which was at 9.5 bars. But it was on and off sometimes I wouldn’t get any compression at all.
which lead me to near full engine rebuilt. Leaky intake valve was found and got resurfaced and the leak seemed to be gone.
All the appropriate gaskets and seals were replaced even the piston rings. Everything was cleaned. Piston was in good shape, and so was the cylinder head.
Once the engine was put together it was tested off the car and compression was steady and within spec on all cylinders. Car started up fine but again after about 5 min running first cylinder started misfiring.
After another compression test, cylinder is once again at 50% and off and on, at times no compression at all.
any ideas? I’m close to having a late summer bonfire with the car.
76,000 mileage
My car started misfiring while idling when it warms up. I was not getting any engine codes at all which meant I drove it a bit not more than 500 miles. After long and and difficult diagnosis I found out that my injector was bad. I replaced the injector and recoded it.
The misfiring didn’t go away which caused me to look for other reasons. So I ended up doing a compression test via glow plug and found that all my cylinders were within spec of 23-25 bars compression except cylinder 1 which was at 9.5 bars. But it was on and off sometimes I wouldn’t get any compression at all.
which lead me to near full engine rebuilt. Leaky intake valve was found and got resurfaced and the leak seemed to be gone.
All the appropriate gaskets and seals were replaced even the piston rings. Everything was cleaned. Piston was in good shape, and so was the cylinder head.
Once the engine was put together it was tested off the car and compression was steady and within spec on all cylinders. Car started up fine but again after about 5 min running first cylinder started misfiring.
After another compression test, cylinder is once again at 50% and off and on, at times no compression at all.
any ideas? I’m close to having a late summer bonfire with the car.
Senior Member
Joined: Jan 2013
Posts: 305
Likes: 42
W211 E320 Diesel OM642
Putting the cylinder 1 @TDC and pressurizing it via the glow plug port would tell you where compression loss is occurring. I would also scope that cylinder as you never know what you'll find. There are some inexpensive android mini camera options.
not having sds xentry myself, I can't say if there are any test you can run but if i recall, there is a smoothness run test that you could try.
not having sds xentry myself, I can't say if there are any test you can run but if i recall, there is a smoothness run test that you could try.
