Power FC Timing help...
04-13-07, 04:19 PM
#1
Timing help...
Working with my first PFC/Datalogit. Guy brings the car in last year and wants it installed and tuned. Didn't really have any problems other than figuring out how to make the 850 primarys work. Thank you RX7 Club. 
Put what I thought was a conservative road tune on it and he drove it for several months without issue. About 6 weeks ago he decided he wanted to put it on the dyno and have the tuned tweaked.
He's running stock twins and we're limiting max boost to 14 psi. The original tune had 11* advance @ 14 psi, 10* split, and 11:1 a/f ratios.
On the dyno I first played with the fuel and leveled out some minor bumps but stayed at 11:1 under boost. We started out at 12 psi and were planning on moving back up to 14 psi. We made right at 300 whp at 12 psi with the original timing map. I decided to bump the timing up to 13* leading @ 12psi with the same 10* split. We lost the engine at around 4500. Lost the rear seal. There is not a fuel problem, nothing else seemed out of the ordinary. I wasn't shooting for the moon. I was very puzzled.
I went back and looked at the datalogs and found a big abnormality. When looking at the regular timing datalog it showed numbers exactly as they were programmed. Nothing out of the ordinary. When I looked at the "advanced" timing log it showed numbers about 5* higher than what was programmed. My 13* logged at 18*. Hmmm...
Fast forward...I got a new engine together and fired it for the first time yesterday. One of the first things I did was to check the timing to see if it was synching up with what was programmed. At idle it's programmed for 10-12* BTDC leading. The timing light and the "advance" log is showing -5* (5* ATDC). I haven't done anything else with the car yet because I'm now very apprehensive about why I'm not getting the timing numbers that are programmed into the timing tables. Idle timing control was turned off BTW. With idle timing control on the timing at idle is more advanced (closer to TDC) but still not the 10-12* that's in the table.
I've heard some people say they get different knock values between normal and advanced and have never heard an explanation as to why. Can someone explain what is going on here? How do I get the timing table to jive with the actual advance?
Put what I thought was a conservative road tune on it and he drove it for several months without issue. About 6 weeks ago he decided he wanted to put it on the dyno and have the tuned tweaked.He's running stock twins and we're limiting max boost to 14 psi. The original tune had 11* advance @ 14 psi, 10* split, and 11:1 a/f ratios.
On the dyno I first played with the fuel and leveled out some minor bumps but stayed at 11:1 under boost. We started out at 12 psi and were planning on moving back up to 14 psi. We made right at 300 whp at 12 psi with the original timing map. I decided to bump the timing up to 13* leading @ 12psi with the same 10* split. We lost the engine at around 4500. Lost the rear seal. There is not a fuel problem, nothing else seemed out of the ordinary. I wasn't shooting for the moon. I was very puzzled.
I went back and looked at the datalogs and found a big abnormality. When looking at the regular timing datalog it showed numbers exactly as they were programmed. Nothing out of the ordinary. When I looked at the "advanced" timing log it showed numbers about 5* higher than what was programmed. My 13* logged at 18*. Hmmm...
Fast forward...I got a new engine together and fired it for the first time yesterday. One of the first things I did was to check the timing to see if it was synching up with what was programmed. At idle it's programmed for 10-12* BTDC leading. The timing light and the "advance" log is showing -5* (5* ATDC). I haven't done anything else with the car yet because I'm now very apprehensive about why I'm not getting the timing numbers that are programmed into the timing tables. Idle timing control was turned off BTW. With idle timing control on the timing at idle is more advanced (closer to TDC) but still not the 10-12* that's in the table.
I've heard some people say they get different knock values between normal and advanced and have never heard an explanation as to why. Can someone explain what is going on here? How do I get the timing table to jive with the actual advance?
04-13-07, 06:06 PM
#2
Eye In The Sky
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You need to buy my PFC/DL tuning notes where this and much more are explained.
Including how the PFC bumps timing up by 2 degrees by about 5200 rpm.
Maximum timing is not important, but where it occurs is important and at what boost. I made 350rwhp at 15 psi with a max advance of 23 IGL but that is at 8000rpm, not at 6000 rpm where max torque will occur.
Attach the bad map in zipped format with a list of all the mods for a quick analysis.
PM me if you are interested in the tuning notes package.
Including how the PFC bumps timing up by 2 degrees by about 5200 rpm.
Maximum timing is not important, but where it occurs is important and at what boost. I made 350rwhp at 15 psi with a max advance of 23 IGL but that is at 8000rpm, not at 6000 rpm where max torque will occur.
Attach the bad map in zipped format with a list of all the mods for a quick analysis.
PM me if you are interested in the tuning notes package.
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