ecu rev limiter

[demigtod]

I have chipped p72 in my 91 ex. The motor is a f22a6 with a 5 speed. I have the tune set up for 30 psi fuel pressure, and basically a stock tune but with the o2 disabled, launch control set for, supposed to be 4000, but it shows at about 3500, and the rev limiter is supposed to be at 6500 with shift light at 6200. The problem I am having is that the rev limiter and shift light is coming on at different times. Sometimes the tach will go to 6900 and sometimes to 7300 but the shift light is always about 300 below the rev limiter.

Before someone says to look it up, I have.
What should I look at to fix?

[cb9love]

the tach is not correct, you would have to remove it to calibrate it. there is a write up on it in jdm accorn's members ride thread.

[demigtod]

I tried looking them up but I can't find them

[sonikaccord]

...

http://www.cb7tuner.com/vbb/showthre...=95154&page=74

[deevergote]

Honestly, installing a PT6 would solve all your issues.

[F22Chris]

Deev beat me to it. P72's are usually for B's right?

[demigtod]

Sonikaccord thank you.

Deevergote the motor was originally an a4 I ended up having to swap another motor in. I have the a6 im on it but with double iab plates but both are gutted, so a pt6 wouldn't help.

[deevergote]

An ECU that is tuned correctly for the engine wouldn't help? I doubt that. Doubled gutted IAB plates aren't such a drastic modification that a PT6 wouldn't work properly. You'd be doing yourself a favor by replacing the IAB valves in one of those plates, and hooking it up correctly.

A P72 is a good ECU if you have a genuine need for it. It even has IAB control already. However, if you don't need a tunable ECU (which no F22A with minor bolt-on mods short of a wild camshaft or turbo does...) or if it isn't tuned correctly (which sounds like it may be the case with yours), it will do more harm than good.


Get a PT6. Hook it up properly. Fix any evident issues. Then look to having the P72 tuned by a competent tuner when you have enough mods to actually make use of it. Anything else is just asking for problems.

[F22Chris]

Sorry for the off topic, but aren't p72's out of Acuras? If you have a map for a GSR it will cause issues, right?

[deevergote]

I'm assuming it's chipped and tuned (or at least running an F22A basemap... I'm giving him the benefit of the doubt here.) But yes, P72 is the GSR ECU. It's one of the less common options. Usually reserved for VTEC engines, as a better alternative to a P28 (as it has IAB circuitry already.) For an F22A, it's overkill. P72s usually sell for quite a bit, whereas a P06 (with no IAB control or VTEC circuitry) is a good deal cheaper.
Regardless, the P72 is the most capable of the Civic/Integra ECUs for tuning purposes.

[F22Chris]

Thanks Deev. And could gearing have an effect on this? Or do you think it's still ECU/calibration related? Sorry if the question seems dumb, my knowledge of ecu's isn't the best

[demigtod]

Well to give some insight on it the p72 I got from a friend and if you read the first sentence it states that it is chipped and it is for a f22a but it's not a basemap. My original ecu pt3 started running the motor horribly, so I got the p72. I'm looking at putting a turbo on my accord once I can get the rest of the fittings in, which unfortunately keeps getting pushed back.

[djcaz_aom]

I see quite a few problems with this setup.

How much time did YOUR car spend on the dyno?

Why is it tuned at 30 psi fuel pressure when it should be between 40-47 psi stock?

Why no O2 sensor on a stock motor?

If your car has not spent anytime on the dyno with this setup, the map on the P72 IS a BASEMAP, unless you got the motor from the same friend that gave you the ecu and it was the one used for the tune.

The second question gets me. Been doing this along time and have never seen anyone knowingly want to starve an engine of fuel. Hopefully you didn't adjust the pressure at the rail as well.

Stock motors work really well on a good O2 sensor. Why you aren't running it beats me.

Also, as stated above, Honda tachs need calibration. If you want to see where your motor is reving to, get a dedicated gauge with shift light.

[deevergote]

If you have an F22A6, of course a PT3 isn't going to run it properly. It's not the right ECU for the engine. However, it's not going to make it run horribly. That's not the ECU's fault. There are other problems with your engine, most likely. A failing o2 sensor, for example, would make the engine run "horribly"... and installing that chipped ECU with the o2 sensor disabled (a majorly ghetto fix, truthfully) would make it seem to run properly again.

I'm assuming you haven't installed forged pistons for use with turbo... If I am correct, don't expect that engine to last very long. You'll likely experience a broken ring land in a month or two.

djcaz_aom said pretty much everything else I was going to say, so no need to repeat that.

[demigtod]

djcaz_aom my car has not been on a dyno simply because it is not gonna be a drag car. It has been street tuned multiple times. The p72 was put in before the f22a6 was put in the car. The reason it is tuned for 30 psi and not more is because that is all that there coming out of the filter. I did replace the o2 sensor multiple times, all were densos.