The FFS crew is at it again....
06-20-2011, 04:21 PM
#44
This post will probably get deleted, but whatever:
http://forum.miata.net/vb/showthread...72#post5228072
http://forum.miata.net/vb/showthread...72#post5228072
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06-20-2011, 05:53 PM
#55
It has all the earmarks of belt slip except he is making the proper boost.
It has all the earmarks of the loose alternater pivot bolt (Ground return for the alternater) except he checked it and it is tight.
It has all the earmarks of a slipping clutch except, if it was slipping that bad, you would smell it, wouldn't you? Still a possibility.
If it had enough knock to pull enough timing to lose 30WHP, pistons would be popping out of the hood and compression is still 180-200 across the board. Not knock.
It could still be ignition as misfires will produce the same peaky Isosceles triangles as knock. Typically, however, knock and misfires show lean on the wideband even though there is excess fuel in both cases because there is also excess air and the wideband reads O2, not fuel. In his case, the A/F reads at 12, more or less. Possibilities: Bad coils, low voltage to the coils, bad ground to the coils, bad wire(s).
It has all the earmarks of bad cam timing. It has been checked but we are still waiting for pictures. I have seen those marks misinterpreted numerous times. Still a possibility.
I brought up the voltage/alternater/bolt problem because we had one several years ago and the curves looked near identical to his. The pivot bolt for the alternater is the ground return for the alternater. Found the problem by driving the car home from the dyno at night. When you would get on it hard, the lights would also dim. Tightened the bolt and regained the missing 30WHP. I lean heavily to a bad ground or other loss of voltage to the ignition. it is not a fuel issue as he has confirmed that A/F is adjustable and both extra injectors are working properly. It is those Isosceles triangles that are the giveaway to being ignition. As they are typically either knock or misfires and he has no knock, .........................
A bad/stuffed cat typically shows three symptoms. Knock, higher boost than expected and loss of power. He has no knock, boost is at or slightly lower than expected. He has only loss of power. I seriously doubt the cat.
It has all the earmarks of the loose alternater pivot bolt (Ground return for the alternater) except he checked it and it is tight.
It has all the earmarks of a slipping clutch except, if it was slipping that bad, you would smell it, wouldn't you? Still a possibility.
If it had enough knock to pull enough timing to lose 30WHP, pistons would be popping out of the hood and compression is still 180-200 across the board. Not knock.
It could still be ignition as misfires will produce the same peaky Isosceles triangles as knock. Typically, however, knock and misfires show lean on the wideband even though there is excess fuel in both cases because there is also excess air and the wideband reads O2, not fuel. In his case, the A/F reads at 12, more or less. Possibilities: Bad coils, low voltage to the coils, bad ground to the coils, bad wire(s).
It has all the earmarks of bad cam timing. It has been checked but we are still waiting for pictures. I have seen those marks misinterpreted numerous times. Still a possibility.
I brought up the voltage/alternater/bolt problem because we had one several years ago and the curves looked near identical to his. The pivot bolt for the alternater is the ground return for the alternater. Found the problem by driving the car home from the dyno at night. When you would get on it hard, the lights would also dim. Tightened the bolt and regained the missing 30WHP. I lean heavily to a bad ground or other loss of voltage to the ignition. it is not a fuel issue as he has confirmed that A/F is adjustable and both extra injectors are working properly. It is those Isosceles triangles that are the giveaway to being ignition. As they are typically either knock or misfires and he has no knock, .........................
A bad/stuffed cat typically shows three symptoms. Knock, higher boost than expected and loss of power. He has no knock, boost is at or slightly lower than expected. He has only loss of power. I seriously doubt the cat.
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