S-afc and n/a ecu controlling boost and igntion, some Q's...
#1
S-afc and n/a ecu controlling boost and igntion, some Q's...
Mike(j9fd3s) and I have been talking about this all day....
How does the stock ecu adjust the timing when you make fuel corrections with the s-afc? Since the igintion is based on rpms and load, and the s-afc manipulates the MAF(load), which would make the ecu think the maf is +- close or open. Then the ecu would change the timing, thinking its under +- load. So whats the deal? Either n/a or t2 ecu....
Another Question, If you turboed and n/a motor, could you use the stock n/a ecu with a piggy back? Just change the pressure(map) sensor? Or would u need the t2 ecu? and is the n/a ecu's map just a piece of the t2s map? ( -15 to 0 pressure)?...
The reason are one, we love talking about this all day,we been yappin about igintion split too , and I might be turboing and n/a in the future, on a budget until he has enough funds to do it right(standalone ems and rebuilt t2 motor).. so in the meantime we would be boosting an n/a motor, and using a piggy back, most likley the popular s-afc.
How does the stock ecu adjust the timing when you make fuel corrections with the s-afc? Since the igintion is based on rpms and load, and the s-afc manipulates the MAF(load), which would make the ecu think the maf is +- close or open. Then the ecu would change the timing, thinking its under +- load. So whats the deal? Either n/a or t2 ecu....
Another Question, If you turboed and n/a motor, could you use the stock n/a ecu with a piggy back? Just change the pressure(map) sensor? Or would u need the t2 ecu? and is the n/a ecu's map just a piece of the t2s map? ( -15 to 0 pressure)?...
The reason are one, we love talking about this all day,we been yappin about igintion split too , and I might be turboing and n/a in the future, on a budget until he has enough funds to do it right(standalone ems and rebuilt t2 motor).. so in the meantime we would be boosting an n/a motor, and using a piggy back, most likley the popular s-afc.
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yeah if you have big negative corrections it should advance the timing too, food for thought
mike
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Re: S-afc and n/a ecu controlling boost and igntion, some Q's...
Originally posted by 1Revvin7
Mike(j9fd3s) and I have been talking about this all day....
How does the stock ecu adjust the timing when you make fuel corrections with the s-afc? Since the igintion is based on rpms and load, and the s-afc manipulates the MAF(load), which would make the ecu think the maf is +- close or open. Then the ecu would change the timing, thinking its under +- load. So whats the deal? Either n/a or t2 ecu....
Mike(j9fd3s) and I have been talking about this all day....
How does the stock ecu adjust the timing when you make fuel corrections with the s-afc? Since the igintion is based on rpms and load, and the s-afc manipulates the MAF(load), which would make the ecu think the maf is +- close or open. Then the ecu would change the timing, thinking its under +- load. So whats the deal? Either n/a or t2 ecu....
Another Question, If you turboed and n/a motor, could you use the stock n/a ecu with a piggy back?
Just change the pressure(map) sensor? Or would u need the t2 ecu? and is the n/a ecu's map just a piece of the t2s map? ( -15 to 0 pressure)?...
#5
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Re: S-afc and n/a ecu controlling boost and igntion, some Q's...
I have done some limited testing of 2nd gen ignition timing, and have found no signs of timing changes with AFM movement.
My testing was performed at idle, by simply swinging the door of the afm to the fully open position and watching the timing light. No change in ignition timing was noted. This test was repeated with the OEM map sensor hose disconnected (and vacuum leak plugged), with the same results.
I'm running the Megasquirt standalone ecu, and am still using the stock ecu to control ignition. I would like to repeat the above tests at elevated engine speeds as well, but need a couple more hands! My gut feel is that afm sensor data is used to calculate injector duty cycle only, and the map sensor is the basis for ignition timing.
Perhaps someone else has a more definitive answer? No use repeating tests if the answer is out there...
Roger.
[QUOTE]Originally posted by 1Revvin7
How does the stock ecu adjust the timing when you make fuel corrections with the s-afc? Since the igintion is based on rpms and load, and the s-afc manipulates the MAF(load), which would make the ecu think the maf is +- close or open. Then the ecu would change the timing, thinking its under +- load. So whats the deal? Either n/a or t2 ecu....
My testing was performed at idle, by simply swinging the door of the afm to the fully open position and watching the timing light. No change in ignition timing was noted. This test was repeated with the OEM map sensor hose disconnected (and vacuum leak plugged), with the same results.
I'm running the Megasquirt standalone ecu, and am still using the stock ecu to control ignition. I would like to repeat the above tests at elevated engine speeds as well, but need a couple more hands! My gut feel is that afm sensor data is used to calculate injector duty cycle only, and the map sensor is the basis for ignition timing.
Perhaps someone else has a more definitive answer? No use repeating tests if the answer is out there...
Roger.
[QUOTE]Originally posted by 1Revvin7
How does the stock ecu adjust the timing when you make fuel corrections with the s-afc? Since the igintion is based on rpms and load, and the s-afc manipulates the MAF(load), which would make the ecu think the maf is +- close or open. Then the ecu would change the timing, thinking its under +- load. So whats the deal? Either n/a or t2 ecu....
#7
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Will do... If you've got some specific rpm/map points of interest, send them to me.
Given that I am running a standalone fuel controller on an otherwise stock vehicle (strange, I admit), it's a good opportunity to test the oem system. With an extra set of hands I can hold the engine at a specific rpm, apply vacuum (or pressure) to the oem map sensor, swing the afm door, and read ignition timing. If I do a more detailed test I'll try to mark out the pulley in 5 degree increments or so.
Just thinking... If the function of the stock 2nd gen ecu was better understood, it could be used as a retrofit to 1st gen cars as a distributorless igntion controller. T2 ecus could be used to provide DIS and boost retard for those turbo 1st gen cars running standalone fuel controllers. Hmmm....
Given that I am running a standalone fuel controller on an otherwise stock vehicle (strange, I admit), it's a good opportunity to test the oem system. With an extra set of hands I can hold the engine at a specific rpm, apply vacuum (or pressure) to the oem map sensor, swing the afm door, and read ignition timing. If I do a more detailed test I'll try to mark out the pulley in 5 degree increments or so.
Just thinking... If the function of the stock 2nd gen ecu was better understood, it could be used as a retrofit to 1st gen cars as a distributorless igntion controller. T2 ecus could be used to provide DIS and boost retard for those turbo 1st gen cars running standalone fuel controllers. Hmmm....
Originally posted by 1Revvin7
Thxs for the replies guys. Interesting... Renns if you ever do get the results let everyone know.
Thxs for the replies guys. Interesting... Renns if you ever do get the results let everyone know.
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hmm well i know someone who has tested stock ecu's and the afm and boost sensor effect the fuel (www.16paws.com), we know its not the tps though the s4 doesnt have a full range one
mike
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If the AFM acutally has a say in how the ECU sets the ignition timing and your SAFC manipulates that data, I would guess that richening a range with the SAFC would bring a small retardation of timing, assuming the ECU retards timing under increased load. However, if the ECU sets timing based on the MAP sensor, nevermind.
#11
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hmm well i know someone who has tested stock ecu's and the afm and boost sensor effect the fuel (www.16paws.com), we know its not the tps though the s4 doesnt have a full range one
If the AFM acutally has a say in how the ECU sets the ignition timing and your SAFC manipulates that data, I would guess that richening a range with the SAFC would bring a small retardation of timing, assuming the ECU retards timing under increased load. However, if the ECU sets timing based on the MAP sensor, nevermind.
Roger.
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I was in the process of putting a second gen ECU and cas in a 82RX at one time. I got the car running but noticed it seemed doggy. I got a timing lite out and rev'd the engine. The timing did not advance. So I added the tps of the 82 to the ECU and then the timing advanced and the car ran a lot better.. So....I'm not saying the tps does all the timing, just some of it anyway. At least at the beginning of acceleration.
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Originally posted by renns
Above is true until the user swaps in larger injectors, and uses the safc to correct fuel mapping. Negative corrections could potentially result in timing advance, as Mike said earlier in this thread.
Roger.
Above is true until the user swaps in larger injectors, and uses the safc to correct fuel mapping. Negative corrections could potentially result in timing advance, as Mike said earlier in this thread.
Roger.
mike
#14
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Originally posted by HAILERS
I was in the process of putting a second gen ECU and cas in a 82RX at one time. I got the car running but noticed it seemed doggy. I got a timing lite out and rev'd the engine. The timing did not advance. So I added the tps of the 82 to the ECU and then the timing advanced and the car ran a lot better.. So....I'm not saying the tps does all the timing, just some of it anyway. At least at the beginning of acceleration.
I was in the process of putting a second gen ECU and cas in a 82RX at one time. I got the car running but noticed it seemed doggy. I got a timing lite out and rev'd the engine. The timing did not advance. So I added the tps of the 82 to the ECU and then the timing advanced and the car ran a lot better.. So....I'm not saying the tps does all the timing, just some of it anyway. At least at the beginning of acceleration.
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No, never got to rig the pressure/boost sensor up. A salvage 87tuboii car came into my life and the project got dropped. 82 finally got sold off a couple of weeks ago. Toooooo many cars. Spend your whole life just getting inspections, plates etc for 'em.
#18
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Originally posted by Aaron Cake
I gave you the answer. The AFM reading does not effect timing. It is based upon manifold vacuum and throttle position.
I gave you the answer. The AFM reading does not effect timing. It is based upon manifold vacuum and throttle position.
I am not certain exactly how the S-AFC effects timing. HOWEVER, it is my GUESS that the ECU sets timing according to TPS value and boost/pressure sensor reading. I would imagine that AFM (the RX-7 does NOT have a MAF) reading has very little to do with timing.
This subject is of interest to me, as I'll be experimenting with MegaJolt, the ignition controller companion to my Megasquirt efi controller soon. Having access to REAL DATA from the oem setup would be helpful. I have enough spare bits laying about that I could cobble up a system in my basement and do some detailed testing. Heck, it's too cold to do much outside anyways.
Roger
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