Over boosting

[weeksa]

Hi mate
Mine does this, has never thrown the code tho it does regularly spike to around 20psi on the high way if I slowly feed the throttle on when I am cursing at around 100kms to overtake someone or go up an incline it will go from the normal 15psi very quickly to 20psi and instantly drop back to around 10psi, like it cuts it instantly.
Mine has the standard exhaust with no muffler.

Hi guys,

Will try and keep it short. First off thank you to all the contributors, there is a wealth of knowledge available on this site I and thank you all.

I have the exact same issues with the over boosting in my 2010 model (auto).
- 3" exhaust, no CAT but I do have a rear muffler
- EGR blank plate with 7mm hole
- K&N air filter

If i gradually build boost (in any gear at any speed) it will spike to around 20psi or even 25psi on occasion, however I have never received a fault code. Sometimes it happens some times not so I am of the opinion there is something wrong rather than this being typical behavior. While over boosting if i put my foot down harder it will instantly drop to 10psi and the slowly build to 16psi where it will hold. When the boost does drop from 20psi down to 10psi there is no change in power which is strange. If i accelerate more aggressively off the mark it will not over boost and just build to 16psi.

Whilst I do have a 3" exhaust without a restrict plate, K&N filter and EGR blanking plate, the problem has been happening for at least 12 months before I made any of these modifications. I have been in denial putting it down to the inaccuracy of the ScanGauge2 but after fitting a boost gauge over the weekend my fears were confirmed.

I have been reading through the articles in the forum (again thank you to all contributors). So far I have tried:
- Replacing k&N with factory filter - no change
- Reset ECU - no change
- Clean MAS sensor and MAP filter - no change
- Cleaned intake manifold (thought possible blockage) - was dirty but no change
- Checked all vacuum lines for leaks or tears - no issues

I have not tried replacing the MAP sensor yet as I think the fact it drops to the right boost if i accelerate hard indicates it is reading properly.

Thinking maybe dirty vanes / sticking vanes in the turbo and when I put my foot down it has enough pressure to free the sticky vanes? Any thoughts on this as a possible cause?

Does anyone else with a boost gauge experience similar behavior or does it only ever hit 16psi?


Thanks,
Andrew

[lindsay84]

Have you seen the condition exhaust side of the turbo.It could be possible that the Variable vanes could be sticking due to carbon deposits and causing them to stick throwing a MIL Code.Google search VGT problems and have a look.

[dano85]

I've gotten to the bottom of my boost issues
I think having my boost gauge tapped in between the map filter (grey-black thing on the passenger side) caused it at first so then I tapped a thread into the up pipe in between the turbo and cooler and found it was worse.
I began to think it was just normal, then I was driving to work the other morning and got an engine light with the code p0069 (map sensor/ atmosphere sensor error) so I popped the bonnet and found the hose I had replaced at the map filter had kinked. I replaced the hose and installed an elbow and no more over boost, so check that out and possibly clean out the filter and that may help.

[dano85]

[weeksa]

I've gotten to the bottom of my boost issues
I think having my boost gauge tapped in between the map filter (grey-black thing on the passenger side) caused it at first so then I tapped a thread into the up pipe in between the turbo and cooler and found it was worse.
I began to think it was just normal, then I was driving to work the other morning and got an engine light with the code p0069 (map sensor/ atmosphere sensor error) so I popped the bonnet and found the hose I had replaced at the map filter had kinked. I replaced the hose and installed an elbow and no more over boost, so check that out and possibly clean out the filter and that may help.

Lucky man, nice simple fix. Vacuum lines is the first thing i checked. Have also cleaned MAP filter and tried bypassing filter all together - no change.

Will keep searching.

Any other suggestions for fixes would be appreciated!

[babajangas]

Hey weeksa my problem has returned also checked all vac lines think it might be something to do with the vanes in turbo I can stop it over boosting by flooring it only happens mainly in second when when going through the revs with a steady slow right foot

[weeksa]

Hey weeksa my problem has returned also checked all vac lines think it might be something to do with the vanes in turbo I can stop it over boosting by flooring it only happens mainly in second when when going through the revs with a steady slow right foot

Exact same issue, I can also stop it by flooring it.

I am going to have a look at the turbo tonight. Last night I was turning the ignition on and off and holding the VVT actuator arm and it freely moved up when the ignition went on and freely moved down when I turned it off so not overly confident it is sticking but will have a look anyway.

[TheGreenThing]

Have you guys tried removing the EGR plate reverting to stock. Ive read somewhere that the EGR also serves as excess boost dump valve. Just my 0.02

[08highlux]

I have the same issue in my 2008 manual but get it in 5th gear when travelling. but yeah it goes back to 10psi when I floor it and it builds back up to 16psi. I have done everything mentioned here as well as replaced the stepper motor on the side of the turbo (ebay $500). still having the same issue. no idea where to go from here and the local Toyota dealer is not very helpful. I look forward to hearing more ideas.

[dano85]

I don't think that will work as once I found that kinked hose my over boost has stoped and I still have the blanking plate in.
I have seen in other un related threads that people had cracked map filter sensor things, that would cause the over boost,

[weeksa]

Didn't get a chance to remove the turbo. I am going to try an remove the EGR plate on the weekend. Maybe with the 3" exhaust, K&N and EGR plate it is all too free flowing and over boosting. Trying to arrange to swap MAP sensor with someone local to see if that helps. If it is still happening with the EGR removed I will start on the turbo.

This problem has been happening for me for several months but seems to be getting worse / over boosting more frequently. For the first time ever it threw a fault code tonight - P0046. Will still try and remove the EGR plate first before attacking the turbo.

[babajangas]

I noticed on mine today under suction control valve where all the Vacume lines go in it seems to be weeping oil out of a little breather could it be possible that a faulty scv could be causing over boost.when driving on the weekend it was the worst it has been engine sounded so rattley and had no power what so ever it's like when it over boosts there is no turbo working at all so lame

[weeksa]

Same same - over boost @ 20psi feels like there is no turbo at all.

[babajangas]

Alright I think I've got my parts mixed up I have oil weeping out the part where the little filter next to map goes into anyone know what that is
Cheers

[weeksa]

If I understand you right it is the MAP sensor filter. Is it grey and black?

If you follow the vacuum line from the MAP sensor it goes into the MAP sensor filter and then into the inlet manifold.

The filters get very dirty and clogged with oil. I cleaned it with MAS cleaner (other have used brake cleaner), make sure you only spray in the directing of air flow (so spray the cleaner in the black barb) and then blow out the excess liquid.

Hope this fixes your issue!

[babajangas]

No it's the other filter near the map looks just like it

[babajangas]

The vac lines go into the round thing on top of the throdel body that's what is leaking out oil

[weeksa]

This one?

https://drive.google.com/file/d/0B0K5F- ... sp=sharing

[babajangas]

Yep there is oil coming out the silver thing the lines go into been told it's from the egr car is going in on Monday to have the vanes in turbo checked out will post up and let you know the outcome
Cheers matt

[weeksa]

I have just removed my blanking plate (with 7mm hole). Took the car for a 20 min test drive and It did not over
boost once, problem fixed!!!!!!

babajangas, are you running an EGR blanking plate? If so remove that before doing anything else.

Thanks for the help guys!