Jumpy RPM Signal

I seem to be having issues with a jumpy rpm. This messes up a virtual dyno graph pretty good. Also, I think this is why my real dyno looks jumpy even on 5 smoothing. The car pulls smooth, it certainly does not feel funny and the tach needle doesn't bounce. I'm using a DLI, hotwired coil pack(that is new), and BKR7E-11 ngk vpower resistored plugs.

Any ideas?

The red is my evoscan log unedited. I interpolated the rpm from the bottom to the top time and you can see how a jumpy rpm effs up the graph. Ideally I should have applied a curve to the lines but this was just a quick fix.

https://dl.dropboxusercontent.com/u/...umpy_rpm_1.png

https://dl.dropboxusercontent.com/u/...umpy_rpm_1.png

http://primaryboost.com/store/rt/dyn...ncorrected.png

If it makes you feel better, I've seen this on my car, too. I checked the feedback wire from the PTU to the ECU with no luck.

Attachment 6956

Quote:

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Originally Posted by Toni

I seem to be having issues with a jumpy rpm. This messes up a virtual dyno graph pretty good. Also, I think this is why my real dyno looks jumpy even on 5 smoothing. The car pulls smooth, it certainly does not feel funny and the tach needle doesn't bounce. I'm using a DLI, hotwired coil pack(that is new), and BKR7E-11 ngk vpower resistored plugs.

Any ideas?

The red is my evoscan log unedited. I interpolated the rpm from the bottom to the top time and you can see how a jumpy rpm effs up the graph. Ideally I should have applied a curve to the lines but this was just a quick fix.

https://dl.dropboxusercontent.com/u/...umpy_rpm_1.png

https://dl.dropboxusercontent.com/u/...umpy_rpm_1.png

http://primaryboost.com/store/rt/dyn...ncorrected.png

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What ecu are you running?

FlashECU.

When I first got my flash ecu the tech would not work at all. Ended up sending it back. might not be your issue, I would check you TPS

Hmm, whose flash were you using? I currently have Brett's clone. TPS? Did you mean PTU? (Either way, my TPS is brand new, came with my throttle and did not fix it)

Quote:

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Originally Posted by twinspoolin94

When I first got my flash ecu the tech would not work at all. Ended up sending it back. might not be your issue, I would check you TPS

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Probably had the ecu set up wrong.

Quote:

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Originally Posted by Toni

Hmm, whose flash were you using? I currently have Brett's clone. TPS? Did you mean PTU? (Either way, my TPS is brand new, came with my throttle and did not fix it)

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Mine is a Jester pnp. I cant remember what exactly the issue was but he sent it back to me and I had no further issues with the RPM gauge. PTU would be a good thing to look into, but if your tps is not set per the FSM it can wreck havoc on how your car drives

Other issues yes, mostly idle, certainly not jumpy RPM.

Quote:

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Originally Posted by twinspoolin94

Mine is a Jester pnp. I cant remember what exactly the issue was but he sent it back to me and I had no further issues with the RPM gauge. PTU would be a good thing to look into, but if your tps is not set per the FSM it can wreck havoc on how your car drives

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The jumpers were setup for the wrong year.
Chromed ECU | 94-97 US VR4 Plug and Play Flash Ecu Installation shows the jumper setup for second gen ecus.

Quote:

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Originally Posted by Toni

Other issues yes, mostly idle, certainly not jumpy RPM.

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RPM on the ECU comes from pulses out of the CAS. Both you and B-Man have the photo style CAS. While I don't have the solution, that's where I would start looking.

BTW RPM from the tach side comes from the PTU.

OHHH RIGHT, I always forget that one. That must be why my innovate logs are smooth because it's getting rpm from PTU. Hmm I'll have to try logging the CAS separately and see if I can log noise. Could the timing belt be stretching/tightening causing the minor fluctuation since it's run off one cam?

Nah I doubt that. More probable is the photo sensor itself is dying or the connector is crusty.

Mmmmm, crusty connector.

Time for a custom wiring harness, Ant!

We'll see. I'll figure this rookie biatch out. Hopefully it's just crustiness. These damn things are expensive. Forgot that I setup a frequency generator to simulate these things (Greg do you remember why I was doing this lol?). Anyway, comes back to the ECU as a 0-5v square wave. I'll just log a run on my scope and see what the ECU is seeing and go from there.

To test the frequency limit of the ECU.

Mines slightly choppy on the Emanage (ecu ignition trigger derived), the joy of the 1st gen cas (along with 2500rpm timing jitter..).

The dyno sheet won't be effected by the RPM crap you are seeing since it pulls it straight from a spark plug wire. Your curve is pretty smooth on my dyno. You should see the BRZ's that come in here LOL

Ahh, yup. Plotted the RPM in winpep and it's straight up. Also checked out the logs from the MAFT Gen II and they are jumpy. This uses the CAS for RPM so I don't see it being the ECU.

This is what the GEN II is seeing from the CAS

https://dl.dropboxusercontent.com/u/...umpy_rpm_2.png