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p0105 and p1251 diagnostics.. help?


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Hey guys, 2005 Rav4 d4d here. I've had the awful p0105 and p1251 codes now for a while. The 0105 comes up at anything over 2250 RPM or so, but only when I'm flooring it. The 1251 will only come up in third or fourth gear when its in relatively high load, 2750+ RPM up a small grade or something.

So far, I've replaced:

  • Turbo pressure sensor (89421-20210)
  • VSV (25860-28040)
  • Suction control valves
  • Turbo boost valve (25819-27040)

Doing all of this has made the problem far better, but still an issue. It used to throw a 1251 as soon as I hit 2200 RPM, now it only throws the 0105 and bucks a bit.

Here are some diagnostic charts I took with a USB OBDII sensor:


The one above here was taken in second gear. You can see at about t-8 I start accelerating with my foot on the floor. The boost reaches 22ish and cuts it looks like, causing that peak. Same happens in the intake manifold pressure, so I'm assuming its not either of those sensors being bad.



Same idea in this one. This was a second gear pull to almost 3500, then shift to third, then let off. Same thing here, at t-8, boost peaks in the low 20s and flatlines, I shift, boost returns to peak then I left off cause the cars bucking a bunch. Manifold pressure tells the same story. MAF shows higher airflow in the second gear part of the pull, as the boost/air/fuel/something cut has probably taken effect by time I'm in third.


Any ideas? I've replaced everything I can think would affect this. This feels like the turbo vanes may not be fully closing, but when I run bypassing the turbo boost controller (leaving the vanes at what would be closed), the boost pressure is slightly negative, so there's no boost flowing to the sensor at all. Thus, I don't think the vanes are the issue here either.

I can get more diagnostic data if need be, so let me know if you want to see something in particular.

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  • 2 weeks later...

I would suggest you have a vane control issue.

When you remove the controller, do the vanes open and close fully with no sticky sections?

Make sure the vacuum pipes are all in good order too.

I would suggest your issue is, the vanes are not tightening up to spool quickly enough, but them when the boost is made it cannot gently modify the vane possition to control the maximum target boost amount - this is the spiking on the datalog graphs.


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