Idle symptoms + lower dyno #'s... Head related???
05-27-2005, 05:55 AM
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Idle symptoms + lower dyno #'s... Head related??? Ok, first for the list of mods related to the area so you know what I'm dealing with, and this is all on a 98 formula M6
CHS Stage II Heads 2.02/1.57 milled .030
TSP Camshaft 231/237 .598/.595
Hardened pushrods (7.35")
Patriot Performance Dual Valve Springs
My symptoms...
1100-1200 rpm idle all the time
Really sluggish low end rpm climb
the car won't idle with the A/C turned on
It is cold blooded on startup, and I have to keep it running for about half a minute.
low rpm stumble (mainly noticeable around 2000 rpm when you just rev the car while in neutral)
The car also dynoed 403 hp/ 376 tq. when it was dyno tuned at MTI.
Now I have been told that this could be compression related or tune related. When MTI tuned it they suspected maybe a compression problem causing the sluggish acceleration and low dyno number. It has new rings and everything, so MTI suggested that maybe the valves were letting something through.
Here is a copy of the dynosheet also, so you can see rpm and power relation:
What do you guys think my problem could be?
CHS Stage II Heads 2.02/1.57 milled .030
TSP Camshaft 231/237 .598/.595
Hardened pushrods (7.35")
Patriot Performance Dual Valve Springs
My symptoms...
1100-1200 rpm idle all the time
Really sluggish low end rpm climb
the car won't idle with the A/C turned on
It is cold blooded on startup, and I have to keep it running for about half a minute.
low rpm stumble (mainly noticeable around 2000 rpm when you just rev the car while in neutral)
The car also dynoed 403 hp/ 376 tq. when it was dyno tuned at MTI.
Now I have been told that this could be compression related or tune related. When MTI tuned it they suspected maybe a compression problem causing the sluggish acceleration and low dyno number. It has new rings and everything, so MTI suggested that maybe the valves were letting something through.
Here is a copy of the dynosheet also, so you can see rpm and power relation:
What do you guys think my problem could be?
Last edited by sfriesen; 05-27-2005 at 06:51 PM.
05-27-2005, 09:45 AM
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honestly sounds like a tuning issue, i used to have the same problem and went in for another tune, and it fixed my problems with my old cam/stall. How long ago was your tune? and is the person who tuned it reliable?
05-27-2005, 10:15 AM
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sounds like your tune sucks. did the installers seal the rocker studs when they were installed?
you should dyno more than that w/the 231/237 and heads, imho.
you should dyno more than that w/the 231/237 and heads, imho.
05-27-2005, 02:40 PM
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I figured it should put down more, when I read about guys with just a cam putting down the same numbers...
Motorsports Technologies Inc. out of Texas did the tune, and I haven't heard much bad about them...
Motorsports Technologies Inc. out of Texas did the tune, and I haven't heard much bad about them...
05-28-2005, 12:45 PM
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I would start with a compression and leak down test to rule out mechanical problems. If it is not mechanical then your tune is definately off. I would think 900-950 would be easily doable. Did they drill the tb idle hole bigger, or open the adjustment screw for the tb blade to get it to idle that high. I just tuned a FM13 cam only at 900 rpm idle, and it is rock solid. May even run it back to 850 rpm.
