1996 E38 Misfire/lumpy idol
Discussion
My new to me 96 740i 4.4 has a very lump idle/misfire.
It drives superbly and is fine while on the move but a lot but not all of the time at tickover it rocks from side to side and seems to misfire or run very rough.
I've had it serviced and changed the plugs and there's no mayo to be found, my garage dont know for sure but say it could be a coil pack on its way out but they are far from sure.
Any ideas what to try next?
It drives superbly and is fine while on the move but a lot but not all of the time at tickover it rocks from side to side and seems to misfire or run very rough.
I've had it serviced and changed the plugs and there's no mayo to be found, my garage dont know for sure but say it could be a coil pack on its way out but they are far from sure.
Any ideas what to try next?
Alistair H. said:
Surely not Nicasil problem?
Correct me...but is a 96 car a 4.4 and not a 4.0?
It sure sounds like Nicasil with the rocking issue.
answered my own questionCorrect me...but is a 96 car a 4.4 and not a 4.0?
It sure sounds like Nicasil with the rocking issue.
1996
1996 740iA 750i included Steptronic automatic transmission with manual shift mode.
728i and 735i were launched with traction control, ABS, alloy wheels, dual airbags, air-conditioning, leather upholstery, and electric front seats.
740i and 740iL upgraded from the M60 4.0 L to the M62 4.4 L V8 engine.
You'll be nikasil and vanos free at that age.
Your exact engine name is the M62B44, it was the M60 with nikasil, and the M62tu with vanos.
If you haven't already, check all your sparkplugs for oil leaking from the rocker cover gasket and drowning them, or if that has been done recently, check the injector wiring by pushing down on the wiring guides on each bank with the engine running and missing.
The injector plugs are all clipped into a rail, so it's hard to be sure if each one has individually clipped on properly.
Your exact engine name is the M62B44, it was the M60 with nikasil, and the M62tu with vanos.
If you haven't already, check all your sparkplugs for oil leaking from the rocker cover gasket and drowning them, or if that has been done recently, check the injector wiring by pushing down on the wiring guides on each bank with the engine running and missing.
The injector plugs are all clipped into a rail, so it's hard to be sure if each one has individually clipped on properly.
+1 on checking for oil in the spark plug wells from valve cover gaskets (easy job, btw). Replace teh gaskets, replace teh plugs, wipe clean teh coil silicone boots with alcohol and then use the very the merest wipe of silicone grease where they meet the plug insulator before refitting.
Also:
- undo and re-seat the connector to the MAF near the air filter.
- Have the spark plugs actually ever been changed?! Could just be worn out at 100K+miles without anyone ever looking at them (it happens!)
- Clean the idle air control valve on the front near the throttle body - 5-10mins with aerosol carb cleaner, then add a couple of drops of engine oil to lube the internal valve
-Clean the PCV valve on the rear of the manifold (- same aerosol, just more fiddly)
- Check and re-check for minor intake vacuum leaks, inc intake manifold to block (the gaskets can get leaky); check all vacuum lines and use the carb cleaner spray liberally on all joints - if the idle speed flares momentarily up you have a leak.
HTH.
Also:
- undo and re-seat the connector to the MAF near the air filter.
- Have the spark plugs actually ever been changed?! Could just be worn out at 100K+miles without anyone ever looking at them (it happens!)
- Clean the idle air control valve on the front near the throttle body - 5-10mins with aerosol carb cleaner, then add a couple of drops of engine oil to lube the internal valve
-Clean the PCV valve on the rear of the manifold (- same aerosol, just more fiddly)
- Check and re-check for minor intake vacuum leaks, inc intake manifold to block (the gaskets can get leaky); check all vacuum lines and use the carb cleaner spray liberally on all joints - if the idle speed flares momentarily up you have a leak.
HTH.
Gassing Station | BMW General | Top of Page | What's New | My Stuff