P0400 EGR....What causes the stutter/stumble?

[wtdash]

Edit: I fixed the P0400 code after following GD's advice to check the vacuum hoses. I had some non-stock connections and one-way valve going to the pass. side pressure MAP sensor (so the MAP wouldn't 'see' positive pressure under boost).

Fixed the stutter / stumble - Possible cause of stutter / stumble issues:
 

• Fuel injectors tested and cleaned. One was sticking a bit...but the shop thought it would have shown up during idle,too, not just during accel.
• The IAC / Idle air control valve has 3 bolts in the corners. Upper two are longer than the one on the bottom right corner. I noted that bottom was tight....but was too long and likely contributed to a vacuum leak????

 

'98 Forester with P0400 code: Exhaust Gas Recirculation Flow

-Running an EJ22E block with EJ25D heads. Turbocharged (7 PSI). Stock ECU/ECM. (I've done this 2 times previously with NO issues.)

- Engine stutter/stumbles until I get over 3K RPM. Cruises at 65 and idles just fine. What Causes the Stutter/STumble????

- Car seems to run rich? Black residue coming  out of tail pipe. 

- Checked injectors' resistance - OK; new fuel filter; tune-up is current. 

What I've done so far:

 - Replaced EGR valve, BPT (common cause), and EGR solenoid from a used working IM. 

- Cleaned out the hard lines/ pipes. 

- Checked vacuum lines. 

At this point I just want to figure out What Causes the Stutter/STumble????

 

Thanks

Edited October 12, 2021 by wtdash

[GeneralDisorder]

Make sure the vacuum lines for the MAP sensor and MAP sensor switching solenoid are EXACTLY as indicated on the under-hood sticker. 

If I were you I would run this with a standalone such as the LINK Monsoon. While it may run with an NA ECU it's definitely not ideal. The Forester ECU doesn't understand positive manifold pressure and in fact it's probably blind to it. The stock map sensor is probably a 1.15 bar, etc. 

GD

Edited August 8, 2021 by GeneralDisorder

[wtdash]

Thanks GD.

I had the Cruise and a one-way valve (so the MAP wouldn't code in boost) in-line. Removed them both and back to stock and runs better and no Code. 

EM: Wiring sux and unless there's a 'plugNpray' option, it's not worth it (to me @ least) to go stand-alone.  I had a Greddy EMU on this same Foz and had two tuners fail to tune it, so I gave up and removed it. If I keep the boost under about 8PSI and install my Vortech, it should be OK from what others have done. 

[GeneralDisorder]

We do have a plug and play harness adapter for the 25D harness..... it's $350 and runs the stock harness to a LINK Monsoon with no harness modifications. We also have base maps that will run the engine out of the box and be easily tuned by any shop with the skills and a dyno. 

GD