Discussion
I have just had my turbos replaced but the car still runs like sh$te. I get boost now but it cuts out when it's cold and stutters at about 2000rpm. There has been a lot of mention about plug gaps; I have NGK BR7EFS fitted. Can someone tell me what the gap should be and how you get to the rear ones? Getting a bit desperate as I have a rally to go to on Sunday, won't be the same in a Saab!
I dont bother removing the throttle body, just remove the intake pipe, unplug the sensors, two hoses to remove near the IC box, undo the 8 bolts with 8mm socket, and tilt the hole thing on its side towards the rear window to rest, you will need a special deep plug socket to get to the plugs though, its the small size i forget exactly the socket size, 14mm?
Make sure you put the coils back on in the correct order and be careful not to drop anything down the air holes into the engine, i always like to tape them over while working.
I think the plug gap should be 30 thou but i would get a mechanic to gap them properly...but you need to change the plugs, the BR7EFS are a twin spark plug they are no good for our cars, you need the BR7EF or the Bosch HR6DC
Make sure you put the coils back on in the correct order and be careful not to drop anything down the air holes into the engine, i always like to tape them over while working.
I think the plug gap should be 30 thou but i would get a mechanic to gap them properly...but you need to change the plugs, the BR7EFS are a twin spark plug they are no good for our cars, you need the BR7EF or the Bosch HR6DC
I'm not expert on plug gaps, but my understanding is the gapping depends on plug, and possibly more so on how fuel/air density between the gap, and fuel type. Higher air density = greater electical resistance between the plug gap. Missing under heavy load and wide throttle generally means too wide a gap (spark isn't happening due to high resistance across the gap).
Depending on your engine load at 2000 rpm, a wide gap could be your problem. What's your throttle and manifold pressure when the stutter occurs, WoodenHorse?
I recently joined PistonHeads, and have been a NobleForums member for a couple years. Don't know what gapping should be for your plugs, but for what it's worth:
o 1g Racing's recommended plug and gap for the twin-tubo M400 was 0.35" with Motocraft AGSF32N 7D plugs.
o However, threads on NobleForums, suggest a different plug and gap, and suggest that fuel is a consideration. One of RickyB's (Turbohoses) posts suggested a 0.032" for 91octane fuel, and 0.028" for 100+octane race fuel. I think it's true that TH customers generally have higher boost tunes.
o Other posts on NobleForums recommend a NGK tr6 plug.
That's the plug I use in my M400 with a 0.032 gap for street use, and I regap to 0.028 when I can afford race fuel at the track. I recently noticed a slight slight hesitation somewhere around 2000 when I slowly increase engine speed at no load (neutral with clutch in). But I don't experience any hesitation or missing on the road over the full boost range.
Hope this info helps.
Depending on your engine load at 2000 rpm, a wide gap could be your problem. What's your throttle and manifold pressure when the stutter occurs, WoodenHorse?
I recently joined PistonHeads, and have been a NobleForums member for a couple years. Don't know what gapping should be for your plugs, but for what it's worth:
o 1g Racing's recommended plug and gap for the twin-tubo M400 was 0.35" with Motocraft AGSF32N 7D plugs.
o However, threads on NobleForums, suggest a different plug and gap, and suggest that fuel is a consideration. One of RickyB's (Turbohoses) posts suggested a 0.032" for 91octane fuel, and 0.028" for 100+octane race fuel. I think it's true that TH customers generally have higher boost tunes.
o Other posts on NobleForums recommend a NGK tr6 plug.
That's the plug I use in my M400 with a 0.032 gap for street use, and I regap to 0.028 when I can afford race fuel at the track. I recently noticed a slight slight hesitation somewhere around 2000 when I slowly increase engine speed at no load (neutral with clutch in). But I don't experience any hesitation or missing on the road over the full boost range.
Hope this info helps.
I also noticed in the manual that if one of the vacuum pipes with a 90 degree Ben is pushed on too far it causes sensor issues. I noticed that mine was right on as far as it could go. Plan is to change the plugs, set to the correct gap and keep my fingers crossed! Might pop into the factory tomorrow lunch time to get e correct settings as it's only about 3 miles from work.
Good news is I have managed to get all 6 plugs out will little issue.
Thanks for the advice everyone.
Good news is I have managed to get all 6 plugs out will little issue.
Thanks for the advice everyone.
[quote=Wooden Horse]I also noticed in the manual that if one of the vacuum pipes with a 90 degree Ben is pushed on too far it causes sensor issues. I noticed that mine was right on as far as it could go.
[quote]
Then you have found the problem..
..
if it is pushed on too far that it blocks the vacuum pipe... which messes with the Map sensor and the fuel pressure..etc..there will be lots of compensation going on.
Still change the plugs though as you will not be getting good combustion with the twin spark, as all it does it takes one strong spark and splits it into two weak sparks...definately no good for turbo applications...
[quote]
Then you have found the problem..
.. if it is pushed on too far that it blocks the vacuum pipe... which messes with the Map sensor and the fuel pressure..etc..there will be lots of compensation going on.Still change the plugs though as you will not be getting good combustion with the twin spark, as all it does it takes one strong spark and splits it into two weak sparks...definately no good for turbo applications...
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