legacycentral bbs

I've heard from a few sources that our stock valvetrain is good up to 7000rpm. Can anyone confirm this? Has anyone run the stock valvetrain that high? And if so, how did you get around the ecu's reve limiter?

I just noticed this weekend that my car isn't running out of steam in the higher rpms . . . just the opposite. The engine seems to want to pull some more, well past the 6500rpm redline. I'd just like people's opinions on raising it a little more . . .

I thin kan AFC will kill your rev-limiter if you want it to? certainly any of the piggyback chips will do it. Maybe a trip to the dyno after you've gotten rid of the rev-limiter would shed some light on this subject. I mean, if it keep sproducing usable power past 6500, that means you're not getting valve float or whatever. that would reduce power dramatically.

I don't know if the autos have rev-limiters. mine just upshifts automatically at 6250-ish . I hate it. Ican't even touch the redline. I wish there was a way to disable the auto-upshift. then I could help you with this. unfortunately, my slush puppy has a mind of her own.

Maybe an email to Cobb would shed some light. I think they've worked with EJ22t engines before. might be worth a shot.

Dave was saying before that after installing his MSD he could make the engine hit the rev limiter before the transmission could react and upshift.

Your auto upshifts at 6250ish even in "power" mode? My old '93 auto turbo and my old '91 non-turbo were both happy to go all the way up to redline.

One way to get up to redline is to put the shifter in 1st and leave it there. The TCU should override and upshift after you get to redline to protect the engine. That might be bad for your car in the long run though.

If it does it in power mode but not in normal mode, it is possible to trick the TCU into always staying in power mode, I believe. You tie the TPS line going to the TCU (not to the ECU!) to ground (or maybe to 5v, I don't remember). It ends up thinking you've instantly floored it and never let go.

How would a piggyback chip disable the rev limiter? As far as I understand it, the ECU will always know the engine speed because it's reading the cam and crank position sensors and has to meter fuel appropriately. I'd think the only way to raise the rev limit would be to modify the ECU.

I've had my MT up to 7000 once in 2nd gear before, I didn't feel any shaking or hear any complaining from the engine, neither did it feel like it was hitting a rev limiter, hmmm...

Josh has the TorqueChip that claims to override the ECU rev limiter, regardless of crank/cam angle sensors, I guess... But he took it out, maybe he'll put it back in and give us some feedback, hint, hint

I wasn't aware that the torque chip disables the rev limiter . . . hmmmmm . . .

The torque chip disables the speed limiter by modifying the VSS signal. I don't think it can do anything about the rev limiter.

Al, help us out! :)

the msd ignition has a programable rev limiter. but the stock ecu might still cut in. I don't know for sure. I never set my rev limiter when the msd was installed. it seems to be set at 6500. I could set it to 7000. the engine will take it.

It's been awhile since I was looking at the TorqueChip, I just checked Al's site. I think vrg3's right, it's the 112mph speed limiter that the ECU disables, not the rev limiter...

Sorry guys

Al, get on here and tell your customers about your products j/k

kelley wrote:the msd ignition has a programable rev limiter. but the stock ecu might still cut in. I don't know for sure. I never set my rev limiter when the msd was installed. it seems to be set at 6500. I could set it to 7000. the engine will take it.

Don't you have a standalone anyways?

The MSD doesnt override the stock limiter. The reason for the MSD to have one is when the vehicle doesnt have one of its own.

An AFC also will not remove the rev limiter.

In reality I dont know of anyone who has removed the rev limiter on the forums....

It is the speed limiter that the Torque Chip removes but I am just finishing the assembly of a plug and play ECU that has the original ECU in a case with an additional board that removes the rev limiter, adds fuel in relation to boost, controls timing, torque chip, probably will end up controlling boost in the WRX and possibly the Turbo Legacy and has the capability to do more. The first ten units are being assembled now and four are already sold. The first will be going into a turbo 2002 Outback the next in a turbo 2000 Impreza RS with a built motor. I made several runs with a n/a motor at Bandimere Speedway at 8500 rpm. My Turbo Legacy motor has a audible shift signal in that the boost starts holding the valves open at about 7400 rpm but it pulls very well until this point. Please don't tell the Impreza people about this yet I am working 7 days a week now trying to catch up.
AL(CO)
al@iwtu.net

3 simple words:

I Want One.

Dave

There is actually two rev limiters in the first gen auto subies.

There is one in the TCU, and there is one in the ECU. The one in the TCU shifts the transmission at redline to protect the engine. The one in the ECU cuts spark from the engine. I've had mine do it once.......for being an automatic and bouncing off the ECU rev limiter......it's a little freaky because you're really not used to it happening because the TCU rev limiter shifts the car for you.

There is an engine tach output that goes to the TCU from the ECU. I would believe this controls or at least tells the TCU what the rpm is so it can shift. However I don't know if there are other things that act as a redundant setup.....because I think with my booboo wiring it was disconnected and it still shifted automatically.

The MSD units I believe come standard set at 6250. I had to bump mine to 6500.

I don't know why the turbo legacy auto's shift at 6250. Mine goes all the way to 6500 no problem. I'm not sure if Dave's shifted at 6500 with the MSD and the auto still in.

Al......also I'm still definitely interested in that thing we talked about before......when you get time of course

We'll be good and keep the impreza crowd away from your new toy you have

There are a few ECU's with different rev limits for some strange reason. I found one in a pile of ECU's that I was looking through to possibly buy. It is for a '98 EJ25 with a rev limit of 6700, just the thing to sell the Impreza crowd. This all started out trying to protect the EJ25 from blowing up when turbo'd and we just happened to be data logging when one did and then we bought the customer a new shortblock(no profit in that turbo job) but I found what caused it and that it could be done without a lot of dials, buttons, and knobs.
AL(CO)
al@iwtu.net

Keep us informed of the progress with this super-secret-mod of yours!!

Will do but it will take a while I first have to get the EJ25 aftermarket turbo
cars that will want this done that we have out. The first one is a car that has lost three engines in as many years. Seems that nobody can resist turning up the boost on them with the usuall bad results. Also with a little time I will be able to make this a little smaller so it will fit into the early cars. Somebody gave me a '91 sedan for fixing his car and mine is running a EJ22t so I have something to work on in my spare time.
AL(CO)
al@iwtu.net

I left my MSD rev limiter at 6250. With my stock configuration, the engine starts to run out of breath up there anyway, but the primary purpose is that the MSD has a soft limiter as opposed to the hard limiter of the ECU, which is much easier on me and the car.

this is just a thought, but wouldn’t it be possible theoretically to "clamp" the cam and crank signals in order to raise the rev limit? Not allow the signals to go above a certain level. The ECU would think that the engine RPM is at the clamped value while it is actually higher then that.

I guess that idea is a little far fetched for something as important as RPM

Yeah, you can't do that.

The ECU uses the cam and crank position sensors to control injection and ignition timing.

I thought for a second about maybe overclocking the ECU by changing out the crystal or modifying the PLL (I haven't examined the circuit closely enough to know how exactly to do it yet); that might make it think the engine was going slower than it really is. You'd of course have to increase fuel pressure or injector size, because the injector pulses would be shorter too. A bonus would be that it would read the VSS wrong and think the car was moving slower, so you would bypass any speed limiter you might have had.

That sounds pretty far-fetched too, though. In the end you'd have to do so much custom work to make it run right you might as well use an aftermarket ECU.