MR2 Owners Club

Just picked up a rev2 turbo few days ago. Its had a freshly built engine and I'm currently doing the run in miles (300ish so far). I'm wondering is the mines ecu a bad idea since its freshly built? With it being plug and play I can't be too sure exactly what it does and if its risking the engine again. Anyone any ideas on this? I searched but saw conflicting opinions. Its got 3" from turbo back, c26 hybrid, bigger injectors, uprated cam gears and full stainless. Just worried if there is a possibility that the ecu will make it run lean, had no experience with them before at all. Thanks in advance

I thought the Mines were an "Upgrade" for the stock Toyota ECU but that would be for the standard injectors also. Pretty sure you cannot "Tune" these ECU's it just has some piggyback electronics inside which basically does the same as my external boxes.

My understanding is that there is nothing special about these ECU's its basically nothing you cannot do with a few external boxes like FCD and SLD because ultimately if you crank up the boost the stock injectors become the limiting factor not the stock ECU.

If your CT26 is totally stock then its pretty hopeless anyway changing ECU, the stock CT26 simply cannot maintain full boost over 4200rpm. I see yours is a "Hybrid" but what has been done to it ? Typically it gets a compressor wheel way to big and all you get is massive lag and a big drop in midrange power.

I still run the stock ECU with some external electronics, sure it looks a bit messy but it works. The CT26 has been modified and has a modified CT20b compressor so it still makes 17 psi at the redline like the stock CT20b. At 17psi you have reached peak boost in terms of the fuel the stock injectors can handle, beyond this the car starts to run to lean for safety under full boost.

It sounds to me that you have already made more changes than the stock or Mines can handle and you should be onto something more modern in terms of an ECU that can be fully tuned on a Dyno.

What size are the injectors ?

Nothing new under the (rising) sun.

OP, check out the links in this thread - -https://mr2oc.co.uk/forum/41/163549.html

Mines dropped the MR2 ECU from their range long ago.
Plus with a s/h unit you have no idea what's 'under the hood'.*

Particularly what specific changes have been made to the ignition and fuelling.
https://www.supraforums.com/threads/jdm ... cs.589071/
(I know the latter is about a different car but the principles are the same).

* Not something I'd be happy about, especially with a freshly rebuilt engine. YMMV.

Bigger injectors and basically stock ECU its just going to run way rich. Will probably run okay at motorway cruising speed if the O2 sensor is good and the ECU goes into closed loop control but under boost its on the stock map and open loop and its going to be pouring fuel in as the ECU assumes its controlling the smaller stock 430cc injectors.

You can start trying to offset the rich condition by cranking up the boost but thats really crude and likely to cause damage, especially if you have no AFR gauge and therefore have no idea whats going on.

The beauty of the stock ECU is it has just a little bit of idiot proofing allowing you to get another 10-15% power by just increasing the boost because the stock map is very rich under full boost with like 10:1 AFR. As you increase the boost just a few psi, this quickly turns from rich to lean under certain boost/engine load/throttle position conditions.

At any point beyond this minor boost increase and then trying for more power with bigger injectors etc its aftermarket ECU time.

Stop guessing at what conditions your engine is running and at very least install a wideband O2 and check yourself. Better yet, chuck the ECU in the bin and install a proper aftermarket EMS and get Tuner to program. This will gain the most power under safe AFR’s .

Just my 0.02 worth.

Jim

Cheers for the advice guys. Much appreciated

MR2DI4 wrote: ↑18/08/20 0:17 I thought the Mines were an "Upgrade" for the stock Toyota ECU but that would be for the standard injectors also. Pretty sure you cannot "Tune" these ECU's it just has some piggyback electronics inside which basically does the same as my external boxes.

They use a TECHTOM daughterboard, and they can be mapped for larger injectors, but I don't think anyone in the UK is equipped to do it anymore. ATS in the US do ROM tunes on thier own TECHTOM based ECU's. They've done a lot of work on it and as a budget option it works well with bolt on modifications, but even ATS will tell you that a standalone like a Link G4X is a much better option and worth the extra money.

Most Mines, Blitz or any other "branded" OE type ECU (they all use the same hardware internally pretty much) are as you say - removed / raised RPM limit, fuel cut, speed limit, boost cut etc, more agressive ignition timings and refined fuelling, and for Gen3 (not applicable for OP) they're likely to be targetting a higher boost level as well.