My 91 volvo 940 seems like it wasn't hitting on all 4 cylinders so I took the spark plugs out 1 at a time, checked the gap and put the wire back on with the plug on the manifold to see if the plug sparked every time when I ran it. All 4 plugs would spark when I ran it. What do I do now? Could this problem be that maybe not all 4 injectors are firing?
My 940 Seems Like It'S Not Hitting On All 4 Cylinders.
Started by slashmaster, Mar 20 2010 11:44 PM
2 replies to this topic
#2
Three Fat Tigers
-
- Moderator
-
- 1,752 posts
RWD Moderator
Posted 21 March 2010 - 03:58 AM
Turbo or not? Regina or Bosch? Regina has a LARGE square ignition coil on the front of the left strut tower, Bosch has a small cylindrical coil behind the right strut tower.
→1st: check for any stored ODB1 codes
http://www.brickboar...ineOBDCodes.htm
→You might try unplugging each injector one at a time while it's running and see if you can tell which cylinder is at fault. With all injectors unplugged, measure ohms between the terminals, all should read the same. If a turbo, inspect the injector resistor pack, resistance to all 4 terminals should be the same. For reference:
http://www.threefatt...sistorPack2.jpg
→Assuming Bosch fuel-ignition system: Make sure all connections to the ignition coil are in good order. Inspect the red-white wire; very often the coil wire will arch to this wire right at the coil and burn through the red-white wire insulation. Also inspect the coil wire for evidence of arching to the AC dryer bottle. If found, try to arrange the wires to achieve maximum clearance. Measure between the #15 (+) terminal and a good ground point on the body (ignition on), should read the same as at the battery. For reference:
http://www.threefatt...Volvo/Coil1.jpg
http://www.threefatt...Volvo/Coil2.jpg
→Try swapping the radio suppression relay for the pusher fan relay.
On the turbo: http://www.threefatt...e/Volvo/RSR.jpg
→Remove and inspect the cap and rotor, clean the terminals with a dremel+carbon steel brush bit.
→Spray carb cleaner around the injectors where the fit into the cylinder head, and around the intake manifold gasket while at idle. Any change in idle speed indicates an intake leak.
Otherwise might be an injector, cap, rotor, coil wire, spark plug wire, or even a bad spark plug, or O2 sensor. I had an issue on my '94 940T where it would miss under boost, turned out to be a defective cap AND rotor, both, bosch parts, went bad after only 10k miles.
→1st: check for any stored ODB1 codes
http://www.brickboar...ineOBDCodes.htm
→You might try unplugging each injector one at a time while it's running and see if you can tell which cylinder is at fault. With all injectors unplugged, measure ohms between the terminals, all should read the same. If a turbo, inspect the injector resistor pack, resistance to all 4 terminals should be the same. For reference:
http://www.threefatt...sistorPack2.jpg
→Assuming Bosch fuel-ignition system: Make sure all connections to the ignition coil are in good order. Inspect the red-white wire; very often the coil wire will arch to this wire right at the coil and burn through the red-white wire insulation. Also inspect the coil wire for evidence of arching to the AC dryer bottle. If found, try to arrange the wires to achieve maximum clearance. Measure between the #15 (+) terminal and a good ground point on the body (ignition on), should read the same as at the battery. For reference:
http://www.threefatt...Volvo/Coil1.jpg
http://www.threefatt...Volvo/Coil2.jpg
→Try swapping the radio suppression relay for the pusher fan relay.
On the turbo: http://www.threefatt...e/Volvo/RSR.jpg
→Remove and inspect the cap and rotor, clean the terminals with a dremel+carbon steel brush bit.
→Spray carb cleaner around the injectors where the fit into the cylinder head, and around the intake manifold gasket while at idle. Any change in idle speed indicates an intake leak.
Otherwise might be an injector, cap, rotor, coil wire, spark plug wire, or even a bad spark plug, or O2 sensor. I had an issue on my '94 940T where it would miss under boost, turned out to be a defective cap AND rotor, both, bosch parts, went bad after only 10k miles.
#3
slashmaster
-
- Members
-
- 55 posts
Level 1 Member
Posted 24 March 2010 - 05:40 PM
Thanks Three Fat Tigers! I didn't really explain the situation well. At first it was idling poorly but ran on all 4 cylinders so I checked the plugs and when I put them back it ran much worse like it didn't run on all 4. This is a twin cam so some oil was leaking into the spark plug holes when I took the plugs out, oil must have gotten in the gap of one so made it run worse. Anyway the oil must have burned away because it runs on all 4 cylinders now but still runs poorly at idle. The more accesories I turn on the poorer and lower the idle speed gets. Could this be a bad alternator?Turbo or not? Regina or Bosch? Regina has a LARGE square ignition coil on the front of the left strut tower, Bosch has a small cylindrical coil behind the right strut tower.
→1st: check for any stored ODB1 codes
http://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm
→You might try unplugging each injector one at a time while it's running and see if you can tell which cylinder is at fault. With all injectors unplugged, measure ohms between the terminals, all should read the same. If a turbo, inspect the injector resistor pack, resistance to all 4 terminals should be the same. For reference:
http://www.threefattigers.com/Protocore/Volvo/VolvoResistorPack2.jpg
→Assuming Bosch fuel-ignition system: Make sure all connections to the ignition coil are in good order. Inspect the red-white wire; very often the coil wire will arch to this wire right at the coil and burn through the red-white wire insulation. Also inspect the coil wire for evidence of arching to the AC dryer bottle. If found, try to arrange the wires to achieve maximum clearance. Measure between the #15 (+) terminal and a good ground point on the body (ignition on), should read the same as at the battery. For reference:
http://www.threefattigers.com/Protocore/Volvo/Coil1.jpg
http://www.threefattigers.com/Protocore/Volvo/Coil2.jpg
→Try swapping the radio suppression relay for the pusher fan relay.
On the turbo: http://www.threefatt...e/Volvo/RSR.jpg
→Remove and inspect the cap and rotor, clean the terminals with a dremel+carbon steel brush bit.
→Spray carb cleaner around the injectors where the fit into the cylinder head, and around the intake manifold gasket while at idle. Any change in idle speed indicates an intake leak.
Otherwise might be an injector, cap, rotor, coil wire, spark plug wire, or even a bad spark plug, or O2 sensor. I had an issue on my '94 940T where it would miss under boost, turned out to be a defective cap AND rotor, both, bosch parts, went bad after only 10k miles.
Oh yeah, forgot to answer your questions, not a turbo and has the round ignition coil so guess it must be a Bosch if that makes a difference. Did they have OBD in 1991?
