Reply With Quotethe new bosch spark plugs maybe mucking things up, have you tried the old spark plugs?
Major Contributor
having engine issues (M30)
Recent adjustments/mods:
Miller MAF & Chip
Adjusted valve clearance (cold engine)
New Spark Plugs (Bosch Platinum)
When I first put in the MAF and Chip I had an issue of the car not starting, i thought it would eventually start because i did everything according to the manual. So I attempted to start the car many times. I found that a spacer had slipped under the board causing it not to start. 2 days later i do the valve adjustment. I noticed the smell of gasoline but i thought i was just imagining it. a week later, being this weekend. A friend confirmed that i wasn't imagining it. On the drive back home from his house my car has been misfiring causing a very rough idle when in R or D and not so much in P. So today i did an oil change, i noticed the oil wasn't as thick as it usually is, not good. So i thought maybe the misfiring is somehow related to this but after the new oil and filter i have the same problem. i checked the spark plugs and they all seem fine, except for one the color seems just a tad bit different from the others. my valves still tick as usuall after the adjustment...
What can be causing this misfiring?
yes, im using 93 octane, right now im on empty but it started when i was at a quarter of a tank of gas left.
2 Grand Master
the new bosch spark plugs maybe mucking things up, have you tried the old spark plugs?
Big, Big Time Poster
If it doesn't improve after you change the plugs back, I would get a spark checker and see what each plug wire shows. If that's OK, I would check the fuel pressure to see if you have enough pressure. I've had the same situation on another BMW model and it was the plugs. Even though they were fairly new, I flooded the car and it wouldn't start until I changed the plugs. On my 535i, I had a dying fuel pump do what you describe.
1990 535im 421,000 miles, 1987 325is, 1989 325is, 1990 m3, 1991 318is, 2001 X5 3.0
Major Contributor
Update:
-Filled tank with 93 Octane Fuel (no improvement)
-Put old spark plugs back in (no improvement)
-Put AFM and Stock Chip back in (no improvement, other than less power)
I also had changed the throttle body gasket before this sputtering, pinging began. I dont know if that would affect anything.
How about a fuel filter? I have a new one but haven't put it in yet.
Other than that, fuel pressure regulator and/or injectors could be the cause?
3 Grand Master
Check all the vacuum lines in and adround the manifold, something may have gotten busted or loose.Originally Posted by ///Sniper535
Vee ave vays of dealing vid your kind...........
Grand Master
+1. Also check the intake track clamps past the MAF.
Is the check engine light on? If the car has a fueling problem (lean/rich) and is out of spec, the CE light will trip.
What codes do you get if you do a stomp test?
You say it's pinging? That typically due to running lean. You'd run lean if you had a massive air leak past the MAF/AFM. Check the work you did around the throttle body to make sure all the seals are tight and correct.
Be sure to look at the ICV to manifold hose (the big one in the middle of the manifold) and the manifold to brake booster hose. Carefully examine the brake booster check valve to make sure it's not cracked and leaking.
Check the throttle position sensor wiring and sensor too. You had to have that all apart and may have a connection problem or wire break or something.
Bellevue WA
90 535iM - not much stock remains. 3.7 liters, ported head, cammed, 3.73 diffy, M5 brakes, MAFed, yadda yadda yadda
86 Porsche 951 - Track Toy
Super Moderator
Same as Jeff and Bob.... go back to the original thing you did the throttle body gasket and check that over for vacum leaks and all the hoses near it....thin diluted oil could be gasoline getting into the crankcase from a leaking injector but that would not cause the pinging which is as Jeff said typically caused by a lean condition such as an air leak.
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