another m42 misfire...update

[///digitalme]

So I have been dealing with a misfire rough idle,
I have replaced icv, afm, water pump, thermostat, mess under the intake, intake boot, vacuum hoses, o2 sensor, fuel pump, and recently I got my valve cover and plugs replaced at a shop. Thats when I noticed a rough idle, and has been misfiring more often..it was misfiring before but not as often.I have checked and rechecked and today I found a stripped bolt on the valve cover near the half moon... could that be causing my rough idle and misfire? I have swapped good igntion wires with no difference...

[jrobie79]

http://www.e30tech.com/forum/showthread.php?t=105848

also maybe the FPR?

[///digitalme]

Update: got a compression test done
..
Compression was 180psi on all 4 cylinders
Didnt do a leakdow. Because it was a lot more money...
Is 180 good for an m42?

[jntar]

Yes 180 is fine

[uturn]

Smoke test? Correct plugs? Tried pulling spark plug wires one at a time to see if there's any changes to the engine idle? Don't get shocked! Did someone change the fuel injectors? Should be yellow tops. I've seen people do the mess under the intake conversion and not use properly sized hoses or kinked hoses.

[uturn]

Also this one.

http://www.r3vlimited.com/board/showthread.php?t=329750

[///digitalme]

I used bosch 4417 platinum from pelican...I have tried disconnecting each wire...every time I disconnect one the idle changes and runs rough and shakes...I havent checked the injectors. How can I check them?

[///digitalme]

Mess under the intake was done a bout a year ago used new hoses and didnt have this problem until the valve cover and spark plugs. Because one of the spark plug holes has oil in it.

[///digitalme]

Quick question...I noticed what seems to be a leak either upper oil pan gasket or rear main seal...I replaced the rear main seal I havent replaced the upper oil pan gasket...could that leak cause oil pressure loss???

[bmwman91]

How bad of a leak? A little weepage, especially if you run synthetic oil, is typical. If it is a huge leak, then maybe that could cause a vacuum leak.

I have tested for vacuum leaks with a bike pump and duct tape. Basically I unplug the PCV system and hook the pump up to the valve cover and put maybe 5PSI into it to see how things behave. You will lose a little air around the rings, but it could help uncover a bigger leak. Similarly, for the intake side I hook the pump up and block off one of the ICV hoses to see how things go. I had to move the crank a bit to make sure that none of the cylinders had intake & exhaust valves in the overlap phase since the air would just go out the exhaust.

[rikaro]

I don't know if you have the problem resolved yet but I've recently changed to 4417 bosch spark plugs and they didn't even start the car on mine. 1991 318is as well.

[roguetoaster]

I don't know if you have the problem resolved yet but I've recently changed to 4417 bosch spark plugs and they didn't even start the car on mine. 1991 318is as well.

I doubt that a plug change would cause a no start. Be sure you didn't mix up the wires.

BTW, NGKs or Bosch Silvers are the plugs you want. Hotter or colder as needed of course.

[rikaro]

I doubt that a plug change would cause a no start. Be sure you didn't mix up the wires.

BTW, NGKs or Bosch Silvers are the plugs you want. Hotter or colder as needed of course.

May be it's something with my car then. I am sure the firing order is correct. Put my old plugs back and it started again

[///digitalme]

Resolved my problem

After having replaced a lot of things I didnt touch the valve cover gasket as I found out it was not leaking. So I drove the car for a few days and it I parked for a few hours and it wouldnt start. I hit the fuel pump and it started. So I replaced the fuel pump( new 300 something dollars) now its working fine. I do need new wires though.