Another DOHC EJ25 Head install on EJ22T block-Misfire-FIXED!

[skid542]

When you say no load you mean no boost? I.e. if you're driving down the road and keep the manifold pressure just below 0psi it'll redline?

Dumb question but I just wanted to make sure I understand what you mean by no-load.

[wtdash]

Not dumb if I wasn't clear.

Correct, if I keep the boost gauge @ 0 or below, I can rev it 'til it'll rev no more....not much fun, BTW.

Here's my list of things to do (not all @ once):

1. Move rear 02 to CC (get rid of P0420 code)
2. Re-plumb breather hoses to intake (reduce crankcase pressure and blue smoke on deceleration)
3. Check Starter and Battery Ground (slow/weak starting)
4. Differenct MAF
5. Newer front 02 (help w/idle issues)
6. Coil pack (slow/weak starting)
7. Check/upgrade vac lines to FPR (again)
8. Run WG pressure (TD05's actuator is 10psi, I think)

[Legacy777]

Todd,

Check out this thread
http://www.rs25.com/forums/f7/t67173-co ... ensor.html

I don't think it is exactly the same issue that you are having, but it may be part of it.

Have you reset the ECU recently? If not, pull the power from the ECU for an hour or so, and then start it up and see how things run.

[wtdash]

Todd,

Check out this thread
http://www.rs25.com/forums/f7/t67173-co ... ensor.html

I don't think it is exactly the same issue that you are having, but it may be part of it.

Have you reset the ECU recently? If not, pull the power from the ECU for an hour or so, and then start it up and see how things run.

Josh, believe it or not I just read that same post earlier today! It came up while searching on the 'positive manifold pressure' issue you mentioned earlier.

Main difference is it refers to MAP-based cars, while mine is like our Legacy's - MAF-based - and uses the same JECS/AUTECS as the NA cars.

Haven't reset the ECU....I'll add it to the 'to do list'.

Thanks,
Todd

[wtdash]

NO LUCK on the below:
- Re-plumb breather hoses to intake (reduce crankcase pressure and blue smoke on deceleration >>>I think this is fixed, if not it's much better - Minor victory.)
- Check Starter and Battery Ground (slow/weak starting>>about the same)
- Different MAF>>no difference - EDIT: WRX MAF fixed it!
- Newer front 02 (help w/idle issues>>not much, if any)
- Coil pack
- Check/upgrade vac lines to FPR
- Run WG pressure (TD05's is about 6 psi per my gauge)

I found THISpost about the VSS causing fuel cut @ about 4500 RPM.

Also, found THISpost about valve clearances causing misfires. I have the EJ20K turbo cams in my EJ25 heads.....when I took them to the shop, I gave them the parts to put together, and told them what I had, but when the clearances are set would the cams matter?
REmember - I didnt have issues running the stock fuel injectors/ECU/VF11...would upgrading those components cause the valve issue to show up?

EDIT:
Found the problem - MAF Sensor.

I'm not clear on Why, since I can't log my MAF voltage, but I swapped in a WRX MAF, which can flow more air before maxing out, and the Misfire is gone!

I played w/both my modded MAF and the stock one, and they both acted the same. So, I wired in the WRX MAF and Presto! It's running much better. The idle is still wonky, but I'll reset the ECU on Josh's recommendation and see if it settles down.

The modded MAF not working is confusing as the tuner told me a couple of times that it wasn't above 4 volts, IIRC, which is well below the 4.7 I've read is where issues start to occur....5 volts is the max.

Regardless, it pulls hard all the way to the 6200 redline now.

I put the MBC back to 13-14 PSI (until I get my wideband installed), which is where it was on the dyno. As an example of the power difference compared to my 17psi TD04 Legacy, I have an on-ramp I use to log data on my Legacy w/the Revtronix chip. I can just get to 90 mph where I merge onto the freeway; Today I got to 100!

Thanks to all for your help!

[Legacy777]

Good you figured it out.