Any 2nd Gen ECU Mods?

Eagle7

Eagle7

New member
I know the rev limiter needs to be dealt with, but does anybody use an aftermarket ECU or any other kind of ECU mods?
I dynoed my car this week, and the A/F mixture is all over the place (always lean). Seems like just boosting the fuel pressure will move the curve, but not change the shape much. How do I flatten it out?

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Marty Doane
ITS RX-7 #13
CenDiv WMR
 
Yikes - looks like the M4 is what I would need, and it retails for "only" $1840. I'll check with SS, but I don't think that'll be arriving on my doorstep any time soon.

Thanks Andy,

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Marty Doane
ITS RX-7 #13
CenDiv WMR
 
I thought both 2G EFI systems ran to rich at high rpm and had to be leaned for power. If you really are to lean, look for any fuel system related problems that would show up as a flow restriction during high flow conditions, fuel pump, filter, etc.. You may also be able to see this in the AFR as a function of rpm, or by running with a pressure gauge and seeing if you are loosing fuel pressure at high rpm.
 
I have logged and dynoed my A/F ratios on an S5 setup. With 40psi of fuel pressure mixtures over 5000rpm are in the 12:1 range. Leaning the mixture with the fuel pressure regulator to the point that A/F ratios approach 14:1 makes for a very lean (~17:1) condition below 5000rpm. That in and of itself isn't so much of a concern because we're all really only focusing on that 5000-8000+rpm range anyway. The big finding on the dyno however was that the power gain was very minor over 5000rpm when leaning the mixture out and the losses below 5000rpm where the ratios were lean was considerable.

The real gain in a custom ECU may lie in the ability to tweak the timing?

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Chris Ludwig
08 ITS RX7 CenDiv
 
There are a lot of possibilities that I've been thinking about, most of which will be addressed over the winter.
1) The dyno shop couldn't get my O2 sensor out to put his dyno sensor in, so he put it in the tail pipe. Said it should be close, but not close enough to tune from.
2) I've never checked the flow through my injectors.
3) I'm running a stock fuel pump and regulator.
4) This engine had about 140K on it when went untouched into the race car last year.

Measured A/F spikes to 15.0 at 3800, about 14.2 from 4000 to about 5500, dips to 13.4 at 6600, then back up to 13.8.

I'm building up an S5 engine this winter, and will dyno-tune it in the spring.

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Marty Doane
ITS RX-7 #13
CenDiv WMR
 
How can there even BE a MOTEC solution? Are you saying SS shoehorns a Motec ECU in the stock case and uses the stock wiring connectors?



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Paul D'Angelo
73 ITS CENDIV
Indy Region
http://www.iridiumracing.com
Header3.jpg
 
Originally posted by paulydee:
How can there even BE a MOTEC solution? Are you saying SS shoehorns a Motec ECU in the stock case and uses the stock wiring connectors?
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sad isn't it
dick
 
Why's it sad? It's legal as far as I can tell. Paul and I discussed this earlier in the year. The same idea went through my head when the rule was announced.

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Chris Ludwig
08 ITS RX7 CenDiv
 
I have no question about it's legality. It is just I wish it was not a direction that IT had to go. I do not know how it could have been prevented but I find it sad that the only way to go is a $2000 icu. It is sad that the effect of the rule limiting you to a stock ecu case and wiring had this result.
dick
 
That's what we get when there is no practical way to police a "stock" ECU rule. While many cars can be chipped, our’s cannot, hence the resulting open ECU rule. It's not desirable, but it is fair.
 
Were any of the ITAC members on this forum on the comm. when the rule was changed? Why did you include the words "or replace?" It was one thing to allow mods to the stock ECU but quite another to allow completely new ones inside the box. How was that deemed "consistent with class philosophy?"
 
Originally posted by ITSRX7:
I was not. I personally hate the rule and would love the chance to put the genie back in the bottle.
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I hear ya. I hate rules creep in IT. I have plates for my car for when I need to take it to a local shop. I still have a driver's window and working door locks so I can lock it up at night when it can't be in a garage.

If porting and fuel testing are enforceable, then why not the ECU? Just put an inspection hole in the cover of the box. At least then it would have to *look* stock.

Some people will always spend to the limit of the rules. Stock = cheap. I think this rule should be fixed.
 
My car was also lean at high RPM, even with fuel pressure set in the 40's. Had my fuel injectors cleaned, and now I actually have to turn down the fuel pressure.
 
Marty, back to the issue, as Karl noted, if you are so lean you are loosing power, something is probably not right. Once you get this fixed, you will find that leaning the top end a bit will add 5-10Hp.

I don't think there is any way to police electronics, aside from handing out sealed units, which is only practical in single engine racing series. Even post run dynoing can easily be fooled.
 
Can a Mega Squirt system be built to fit inside the stock case - and with wires that plug into the stock harness? It's the cheapest system I've found - and seems to be used by other racers as well as on modified street cars.
 
I have seen the MegaSquirt installed in the stock ecu case and connecting to the stock wiring. If you didn't cut a hole for the DB9 plug and the LEDS, no one would even know it was there. With the current MegaSquirt you would have to run a distibuter though (if you wanted to keep everything hidden). AFAIK the MegaSquirt II should be able to control the ignition as well, and I think it is in final testing right now. Personally, I am waiting for the UltraMegaSquirt to be finished (the MegaSquirt II is an integral step towards UMS).

For anyone interested: http://www.msefi.com
There are several people with MS's in FCs.
 
Originally posted by DAharon:
I have seen the MegaSquirt installed in the stock ecu case and connecting to the stock wiring. If you didn't cut a hole for the DB9 plug and the LEDS, no one would even know it was there. With the current MegaSquirt you would have to run a distibuter though (if you wanted to keep everything hidden). AFAIK the MegaSquirt II should be able to control the ignition as well, and I think it is in final testing right now. Personally, I am waiting for the UltraMegaSquirt to be finished (the MegaSquirt II is an integral step towards UMS).

For anyone interested: http://www.msefi.com
There are several people with MS's in FCs.
Click to expand...
AFAIK the MS includes (and requires) a MAP sensor, which the FC does not have (has MAF instead). The recommended MS configuration has a vacuum hose running to the MAP sensor on the circuit board (not IT legal, nor would a remote mounted MAP sensor be). Do you know if there's a way to use the MS with an ITS legal FC?

Thanks,

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Marty Doane
ITS RX-7 #13
CenDiv WMR
 
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