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Piggyback pnp recommendations?
I am looking for simple pnp piggyback solution for a 94 Miata (STS na autox car) that would work with the stock injectors and sensors.
Would something like an emanage blue with a boomslang harness work? Are there better options? If the rules allowed it, I would just get an MSpnp2 but as it stands they are not legal for the class. |
how would an emanage blue be legal but not the MSPNP?
what are the rules especically, because I'd hate to recommend ANY piggyback. Even piggyback rides aren't that fun. |
I think the basic rule is that you can't add any more sensors (ie a MAP senor), you have to use the stock ones. So, on a 94 you could switch from MAP sensing to using a TPS (Alpha-N).
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does it still have to fit inside the stock case? i remember that being a thing too...I think someone had built some board over on m.net to run a ms v3.0 board inside the stock case with some nice pnp adapter running alpha-n.
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Rules have slightly changed for this year, in short:
Piggyback are now explicitly allowed but they also added that OBD communications port functionality must remain which is a problem for running any standalone in the OEM Ecu housing. 14.10 ENGINE AND DRIVETRAIN ... F.The engine management system parameters and operation may be modified only via the methods listed below. These allowances also apply to forced induction cars, except that no changes to standard boost levels, intercoolers, or boost controls are permitted. Boost changes indirectly resulting from allowed modifications are permissible, but directly altering or modifying the boost or turbo controls, either mechanically or electronically, is strictly prohibited. Traction control parameters may not be altered. Any OE OBD communications port functionality must remain. The Check Engine Light (CEL) or Malfunction Indicator Light (MIL) may be disabled via software. Alternate software maps which violate these restrictions may not be present during competition, regardless of activation. 1. Reprogrammed ECU (via hardware and/or software) may be used in the standard housing. Only the OE sensors may be used for engine mangement. 2. Supplementary (“Piggyback”) ECU may be used subject to the following restrictions: a. Connects between the standard ECU/PCM and its wiring harness only. b. Must be plug-compatible with the standard ECU/PCM (no splices). Electronic components may be installed in-line between an engine’s sensors and ECU. These components may alter the signal coming from the sensor in order to affect the ECU’s operation of engine management system. Example: fuel controllers that modify the signal coming from an airflow sensor. 4. Fuel pressure regulators may be replaced in lieu of electronic alterations to the fuel system. It is not permitted to electronically modify the fuel system AND replace a fuel pressure regulator.
5. Ignition timing may be set at any point on factory adjustable distributor ignition systems. 6. VTEC controllers and other devices may be used which alter the timing of factory standard electronic variable valve timing systems. |
parallel install a MS in this case, the only function the ECU will be in control of is the idle (if you want it to), CEL, and purge valve pretty much.
although it's technically not valid to the rules... so maybe something like the f/ic might be best... |
Though it would violate the spirit of the rule, a standalone, utilizing a patch loom so that it is installed between the stock ECU and the harness, would satisfy the letter of the rule. The way I read it anyway. There could be some further definitions of terms ("piggyback" for example) in the appendix but, for what you have there, I'd say a standalone is legal.
The SCCA is notorious for poorly written rules. When we were racing Improved Touring in the 90s, the SCCA wanted to allow "chips". They wrote the rule saying, basically, anything that fit inside the stock ECU case was legal. So guys were gutting the case and installing Motecs inside of them. Certainly violated the spirit of the rule but was ruled legal for years until the rule was finally changed. |
Originally Posted by C. Ludwig
(Post 883479)
Though it would violate the spirit of the rule, a standalone, utilizing a patch loom so that it is installed between the stock ECU and the harness, would satisfy the letter of the rule.
Must run in alpha-N mode (load is based off TPS). |
Would that work with a MSpnp2? Was told it couldn't read the MAF signal.
Any chance in seeing a pnp solution for that purpose from DIYAutoTune? |
On a 1994, you could run alpha-N easily enough since you have a real TPS.
It is possible to get an existing MSPNP to read the MAF signal, but the current firmware makes this a bit more difficult than running alpha-N. We've been discussing getting a better MAF code out with the firmware gurus. The MSPNP does have the hardware support for MAF input already; it's just that the current firmware does not handle MAFs in the most user friendly way. We'd rather come up with a way to Yunick the current rules with existing hardware than develop a purpose built ECU to get around the wording of the rules in a particular class. Not only is this a tiny niche market, it's a niche the SCCA could wipe out with a rules change next year - or worse, a rules clarification with a FasTrack bulletin if we got too creative. |
Actually was more thinking in the line of a custom harness for a MSpnp2 or even Microsquirt.
Like you said rules can be fickle and I'd rather not end up with an ECU I can't re-sell if need be. What's the downside of using alpha-N mode vs using the MAF signal? |
it would be easier and cheaper to build an MSI unit with the v2.2 or v3.0 mainboard and build a boomslang patch harness. i used to do them back in 2006. MS controls everything but the idle, and CEL pretty much.
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Originally Posted by Fabre
(Post 883688)
Actually was more thinking in the line of a custom harness for a MSpnp2 or even Microsquirt.
Like you said rules can be fickle and I'd rather not end up with an ECU I can't re-sell if need be. What's the downside of using alpha-N mode vs using the MAF signal? I was thinking just cut the ECU end off a junkyard harness, drill a hole in the top of the MSPNP case, and glue or duct tape the end of the harness inside the case. Then run it to the stock ECU. Meets the letter of the rule, at least... |
Originally Posted by Matt Cramer
(Post 883936)
Alpha-N mode is more likely to need retuning with new mods; that's its biggest drawback.
I was thinking just cut the ECU end off a junkyard harness, drill a hole in the top of the MSPNP case, and glue or duct tape the end of the harness inside the case. Then run it to the stock ECU. Meets the letter of the rule, at least... Any OE OBD communications port functionality must remain. |
there's no OBD communications port in a 90-93.
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I have a 94, anyway this also applies to the OBD connector under the hood.
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94 is still ODBI. and the diagnostics connector? i guess it can report back fault codes, bu ti mean whos going to plug something into it? OBD-I has no standardization to even plug some sort of device into something to read anything.
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Actually there is a Mazda tool that connects to it.
Anyway point is that connector needs to remain functional and it's fairly easy to check that it still returns error codes. |
1 Attachment(s)
so build a v3.0 board and call it a day.
I used to do them all the time in 2006: https://www.miataturbo.net/attachmen...ine=1338570983 |
Originally Posted by Fabre
(Post 884019)
Actually there is a Mazda tool that connects to it.
Anyway point is that connector needs to remain functional and it's fairly easy to check that it still returns error codes. |
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