Went to the dyno..
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Went to the dyno..
And had a intresting problem. The car won't rev past 5500 and stay clean, it will go past but it stumbles and the logs show it going up and down in rpm but slowly up.
AFRs were 10.5-11.2, I was kind of focusing on the RPM problem more than making the AFRs perfect, had 17deg timing and saw almost 9psi of boost.
Made 540 / 557 and 512 / 601, very disapointing numbers but the power is still going way up when it hits our problem RPM so I think once I get that resolved things will go better.
LTLHOMER had the same problem on his car and it was a crank pickup wheel issue, but if anyone has suggestions on things to try before that let me know!
AFRs were 10.5-11.2, I was kind of focusing on the RPM problem more than making the AFRs perfect, had 17deg timing and saw almost 9psi of boost.
Made 540 / 557 and 512 / 601, very disapointing numbers but the power is still going way up when it hits our problem RPM so I think once I get that resolved things will go better.
LTLHOMER had the same problem on his car and it was a crank pickup wheel issue, but if anyone has suggestions on things to try before that let me know!
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Did you have the cam sync override on or off? If you have it off (aka won't override) it should hit the certain rpm, resync itself, and then hit it again and again almost like a rev limiter. Mine was on so it would just hit the certain rpm, lose cam sync and die.
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Any video? Or any logs?
LTLHOMER@aol.com
The a/f wouldn't be the cause...I've run mine from 9.5 to 12.5 and it rpm's exactly the same.
LTLHOMER@aol.com
The a/f wouldn't be the cause...I've run mine from 9.5 to 12.5 and it rpm's exactly the same.
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Originally Posted by Pro Stock John
Plug gap?
Type of coils?
BS3?
Cam
Valvesprings, open & closed spring pressure?
Stock pcm gone?
Type of coils?
BS3?
Cam
Valvesprings, open & closed spring pressure?
Stock pcm gone?
Coils : Stock
BS3 : Yes
Cam : Small
Springs : Huge
Pcm : Gone
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Originally Posted by LTLHOMER
Send those logs over. LTLHOMER@aol.com
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ltlhomer, can you describe in more detail the cam sync error, what happens when the error reports on a log, and what the cam sync override does, and what the car should do when you select override?
i was talking to john about this myself last night cuz i get a backfire now and then, he had me check to log cam sync error and it is hitting when i get the backfire. so he mentioned to try selecting the synch override or advancing the cam?
my chain was more slack than i thought it would be when i changed cams last week also fwiw
i was talking to john about this myself last night cuz i get a backfire now and then, he had me check to log cam sync error and it is hitting when i get the backfire. so he mentioned to try selecting the synch override or advancing the cam?
my chain was more slack than i thought it would be when i changed cams last week also fwiw
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Originally Posted by MIGHTYMOUSE
also, what did your external crank sensor have to do with correcting cam synch error?
If cam sync override is on, it will continue as if the cam sync was not lost so if cam sync really wasn't lost, it would continue on its merry way. I've heard of a few instances of this...has to do with how close the falling edge of the cam and crank sensors are to eachother (COP value). If cam sync was lost, it will be off 15 degrees per tooth it missed and eventually just shut down since it will be adding fuel and sparking somewhere it's not supposed to be (that's what mine did). This is why John was asking about you advancing the cam because that will increase the angle between the cam and crank falling edges.
If cam sync override is off, it will rev down a little from the rpm where it loses sync in order for it to resync itself, and then either keep hitting that same point and repeating or just rev through that point without issue. That's what mine did when we turned it off...it would hit 6700, come down to 6300 or so, and go back up like a rev limiter.
I can go into more depth when I get back from my interview, but that's the 2-minute version and probably has some mistakes.
As far as the log goes, if you log cam sync, you can see a spike in the graph when it loses sync. It will go back to zero when it resyncs itself and usually takes <0.10 seconds. If you send me your logs I can take a look since I've seen pretty much everything in relation to the cam sync stuff.
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Originally Posted by MIGHTYMOUSE
ltlhomer, can you describe in more detail the cam sync error, what happens when the error reports on a log, and what the cam sync override does, and what the car should do when you select override?
i was talking to john about this myself last night cuz i get a backfire now and then, he had me check to log cam sync error and it is hitting when i get the backfire. so he mentioned to try selecting the synch override or advancing the cam?
i was talking to john about this myself last night cuz i get a backfire now and then, he had me check to log cam sync error and it is hitting when i get the backfire. so he mentioned to try selecting the synch override or advancing the cam?
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Originally Posted by 67Firebird455
That is nuts... I am curious to see what it is... I know the backfire he's referring to... Strange that it revs slowly. What is the timing like on the log?