Specific EGR Questions - P0400

[mitchmac]

Hey guys,

Yes, I know the EGR system and associated fault codes have been well discussed and trust me I've spent hours online searching and watching videos but I have some specific questions that I have not been able to find answers for.

Background: I have a 2011 Hilux 3L D4D KUN26R with the 1KD engine. About 12 months ago I did an intake manifold clean and reassembled, all went well. A few days after the clean a check engine light appeared and has not gone away. No symptoms, no limp mode, the car runs perfectly. Code is P0400 - Exhaust gas recirculation flow malfunction. My mechanic suggests as this is the only code present the EGR valve itself is faulty and not allowing flow past it. I've taken the intake system apart and cleaned it multiple times and the valve moves freely. I've visually checked all of the vacuum lines and have strong vacuum at the brake booster. If I disconnect the battery overnight the code clears but always comes back after about 20min of driving.

Specific Questions:
- The EGR valve moves freely but took more force than I was expecting, how much force is typically required to move the valve? E.g. light pressure with one hand, fair force with 2 hands, full body weight leaning on it?

- I've tested the vacuum on the EGR valve lines and it is lower than I expected, how much vacuum should be present at the EGR at idle? Should it be the same as the brake booster?

- Would the cooler bypass valve have any effect on this? I recently pulled the whole thing apart AGAIN and found that the cooler bypass valve was seized, I thought this must be the issue so cleaned, got it moving freely and reassembled only for the code to come back after 30min of driving.

- I have disconnected one of the vacuum lines on the EGR at idle and if I block the line I can hear a slight whistle somewhere nearby, is this a vacuum leak or just the system under load?

- I've removed the vacuum actuator on the side of the EGR and connected it to a battery with a wire and multimeter and has 12V across it, is this a solenoid and should it click when connected to power?

Any answers or advice is greatly appreciated.

Thanks, Mitch

[hiluxxury]

This is a real shit of a code.

I note that you have done a bit of searching - have you looked at this https://www.youtube.com/watch?v=UpMGQdOUBiA and his series on P0400? He seems to think it is the cooler is sometimes the issue.

If you have techstream, you can run the EGR test viewtopic.php?t=26434 but I dont know a way to test the vacuum of the pressure you should expect. I do know that several people here have experience problems following cleaning the manifold.

[Gipsy]

If the vacuum is lower than expected and there's a whistle this could point to the problem. Vacuum lines should not whistle! Check the vacuum lines. If there's insufficient vacuum the egr valve will be sluggish to move. Do you have the egr blocking plate? This also can cause p0400 if there's too small a hole in the plate... Insufficient flow. It seems 7mm hole is the ideal size.

[mitchmac]

Thanks hiluxxury, I have watched a few of his videos and thought when I found the seized bypass valve I was onto the solution but unfortunately it hasn't worked. I'm not sure the cooler bypass would throw a code as the gases will still flow past this area whether it's open or closed, which points me back toward the EGR valve operation.

No, I don't have techstream, if I can't solve it soon with what I've got I'll just book it in with Toyota and let them have a look.

Thanks Gipsy, I'm suspicious of the vacuum lines to the EGR but can find no signs of a leak, I've tried spraying aerosol around the area and no change in revs at all and I've filled the area with smoke but can't see any getting sucked in.

No, I don't have blanking plate, just a catch can.