Turbo Recon.

[codswallop]

Hi Saffron,

I'm going through exactly the same issues as you, getting intermittent limp mode. I've tried most things already (and replaced a number of components), and like you it is possibly looking like the turbo, however turbo's are fairly simple things, the only difference on ours is the variable vane feature operated by vacuum. Have you tested the linkage on your operates smoothly ?

I'm going to try running without the variable vane, by disconnecting the vacuum tube to it (and blocking off where disconnected), this will reduce the effectiveness of the turbo, but may give some clue as to whether the turbo is ultimately at fault or not.

Good Luck,

Regards,

Tim.

[saffron]

Hi Saffron,

I'm going through exactly the same issues as you, getting intermittent limp mode. I've tried most things already (and replaced a number of components), and like you it is possibly looking like the turbo, however turbo's are fairly simple things, the only difference on ours is the variable vane feature operated by vacuum. Have you tested the linkage on your operates smoothly ?

I'm going to try running without the variable vane, by disconnecting the vacuum tube to it (and blocking off where disconnected), this will reduce the effectiveness of the turbo, but may give some clue as to whether the turbo is ultimately at fault or not.

Good Luck,

Regards,

Tim.

Hi Tim,

Thanks for your note. I’ve been following the same thought process.

I tested the EGR electrically and the resistances are as per spec. Cant take it off for inspection as I won’t be able to get a new gasket until the weekend.

So I thought to drive with the electrical connector to the turbo sensor disconnected. Car runs ok but has no get up and go so turbo not kicking in. Then, when idling, if you take the pipe from the VSV off the vac unit above the turbo, there is no vacuum detectable. Reconnect the turbo sensor and the VSV switches over and vacuum is back at the end of the pipe.

Pushing the pipe back on to the vac unit I can hear and feel the actuator rod pull up and hear boost being applied to the intercooler. So, I conclude that the turbo sensor, VRV and turbo vanes, basically work. Repeating this process by slipping the pipe on and off several times confirms this. Then, when reconnected,having someone rev the engine shows that the vacuum stops and the actuator goes back down thus opening the vanes to reduce boost at higher engine speeds. So, all seems to be working as it should.

My initial conclusion is that the turbo vanes are not closing sufficiently at higher engine speeds causing over boost even when the actuator rod is in the down position. (It does stick at the bottom of its travel but the vacuum is more than sufficient to pull it up when idling to provide boost but perhaps the vanes don’t totally open when it returns to rest at the bottom of its travel).

Then, like you, I decided to disconnect the pipe from the turbo vac unit, fold it back and seal it off with a tie wrap. When driving, despite a barely noticeable sluggishness when moving off, the car performs well with plenty of get up and go all the way up the rev range in all the gears although it does hesitate a bit above 4500 revs. Theoretically, there should be no boost at all, but compared with performance with the turbo sensor disconnected, there is, and no eml light and limp mode present!! I could happily drive with this modification in place.

Any thoughts as to what's going on anybody?

Cheers

Alan

[saffron]

Hi Saffron,

I'm going through exactly the same issues as you, getting intermittent limp mode. I've tried most things already (and replaced a number of components), and like you it is possibly looking like the turbo, however turbo's are fairly simple things, the only difference on ours is the variable vane feature operated by vacuum. Have you tested the linkage on your operates smoothly ?

I'm going to try running without the variable vane, by disconnecting the vacuum tube to it (and blocking off where disconnected), this will reduce the effectiveness of the turbo, but may give some clue as to whether the turbo is ultimately at fault or not.

Good Luck,

Regards,

Tim.

Hi Tim,

Thanks for your note. I’ve been following the same thought process.

I tested the EGR electrically and the resistances are as per spec. Cant take it off for inspection as I won’t be able to get a new gasket until the weekend.

So I thought to drive with the electrical connector to the turbo sensor disconnected. Car runs ok but has no get up and go so turbo not kicking in. Then, when idling, if you take the pipe from the VSV off the vac unit above the turbo, there is no vacuum detectable. Reconnect the turbo sensor and the VSV switches over and vacuum is back at the end of the pipe.

Pushing the pipe back on to the vac unit I can hear and feel the actuator rod pull up and hear boost being applied to the intercooler. So, I conclude that the turbo sensor, VRV and turbo vanes, basically work. Repeating this process by slipping the pipe on and off several times confirms this. Then, when reconnected,having someone rev the engine shows that the vacuum stops and the actuator goes back down thus opening the vanes to reduce boost at higher engine speeds. So, all seems to be working as it should.

My initial conclusion is that the turbo vanes are not closing sufficiently at higher engine speeds causing over boost even when the actuator rod is in the down position. (It does stick at the bottom of its travel but the vacuum is more than sufficient to pull it up when idling to provide boost but perhaps the vanes don’t totally open when it returns to rest at the bottom of its travel).

Then, like you, I decided to disconnect the pipe from the turbo vac unit, fold it back and seal it off with a tie wrap. When driving, despite a barely noticeable sluggishness when moving off, the car performs well with plenty of get up and go all the way up the rev range in all the gears although it does hesitate a bit above 4500 revs. Theoretically, there should be no boost at all, but compared with performance with the turbo sensor disconnected, there is, and no eml light and limp mode present!! I could happily drive with this modification in place.

Any thoughts as to what's going on anybody?

Cheers

Alan

Sorry, where I said VSV I menat VRV

[codswallop]

Well I've done some further testing over the weekend and finally had some success!

I started by disconnecting the pipe from the vacuum pump to the VRV and blocking it. This meant the variable vanes on the turbo were non-functioning as no vacuum was present to operate it. The car drove sluggishly, but did not cut out - although I could still feel a slight glitch at about 2500rpm.

Next I put the vacuum back to the VRV, and connected the Turbo pressure sensor directly to the manifold vacuum pipe - bypassing the VSV completely. On the test drive the car had smooth quick acceleration, with no glitches (and no fault lights). I can honestly say it had never felt so good.

What I have now done is to just disconnect the electrical connector to the VSV, which achieves the same result, without having to swap pipes around.

So the question is why is the turbo pressure sensor connected via the VSV (which can obviously switch the vacuum on and off) - is this part of the EGR function ?

Is there anything I can do to correct this back to normal operation (although as it is the car drives perfectly with no fault light present)?

[Bodgit-fixit-run]

As said in Independence Day "Hi guys I'm back!!!"

I'm determined to crack this yet. So:- rebuilt the turbo, Replaced the the fuel pump pressure valves, Cleaned the EGR (again), Lost my job got a new one Moved house, No mortgage Broke my foot whilst hoovering . Replaced the clutch (again), this time with a solid fly wheel £126.00 plus fitting BARGIN! . replaced some vacuum pipes, ran fine for a week, still getting code. Recovering from depression. Gonna try some of the above ideas. Watch this space.

[three5]

As said in Independence Day "Hi guys I'm back!!!"

I'm determined to crack this yet. So:- rebuilt the turbo, Replaced the the fuel pump pressure valves, Cleaned the EGR (again), Lost my job got a new one Moved house, No mortgage Broke my foot whilst hoovering . Replaced the clutch (again), this time with a solid fly wheel £126.00 plus fitting BARGIN! . replaced some vacuum pipes, ran fine for a week, still getting code. Recovering from depression. Gonna try some of the above ideas. Watch this space.

Nice to see you back! You managed to get a hell of a lot of "life" into such a short message. I reckon you could write a book with that much material! "Broke my foot whilst hoovering" that has to be worth a complete chapter.

[Davrav]

As said in Independence Day "Hi guys I'm back!!!"

I'm determined to crack this yet. So:- rebuilt the turbo, Replaced the the fuel pump pressure valves, Cleaned the EGR (again), Lost my job got a new one Moved house, No mortgage Broke my foot whilst hoovering . Replaced the clutch (again), this time with a solid fly wheel £126.00 plus fitting BARGIN! . replaced some vacuum pipes, ran fine for a week, still getting code. Recovering from depression. Gonna try some of the above ideas. Watch this space.

Nice to see you back! You managed to get a hell of a lot of "life" into such a short message. I reckon you could write a book with that much material! "Broke my foot whilst hoovering" that has to be worth a complete chapter.

Just keep away from the Dyson ball cleaner!

[Bodgit-fixit-run]

Actually DavRav it was a Kirby, and to think they just started out making hairgrips. I tripped over the cable and landed awkwardly. 8 weeks off work for that one. Just started driving again. Considered a ball cleaner but thought better of it too much of a risk with the hose.

However really impressed with the new clutch.

[PazRav4]

On ‎23‎/‎05‎/‎2010 at 1:12 AM, ohphoto said:

Hi Anchorman.

First post on this forum. I have a 2003 Rav4 D4D. I Have been trying to fix the same problem as descibed by many on this forum. Intermittent erratic acceleration, occasional EML. Toyota diagnosed generic 34(2) turbo problem.

With the help of a mechanic friend I've checked the turbo, actuator, and all the pipes for faults and cleanliness. All seems good. So now I'm looking to replace the VSV. I stubbled upon this picture you've posted which seems to show two VSV's. The one circled in red and also the orangy/brown one which sits beneath the turbo pressure sensor.

According to the 'vsv layout.pdf' downloaded from the above link this is known as the 'VSV for Turbocharging Pressure Control'. I've checked on my own vehicle and this seems to be linked to the EGR system.

My friend also feels that the VSV you've circled in red is the more likely culprit of the two, but I'm trying to work out which part I need to order. I cannot get the part number and have already incorrectly purchased a turbo pressure sensor from Pentagon Toyota after requesting a 'Vacuum Sensor Valve'.

Whether changing this part will fix the problem is obviously unknown, but getting hold of one would be a start. This seems pretty tricky however, without the full name or part number for it.

Any help would be greatly appreciated.

Hi, I've had this problem of the engine light coming on when going up hill or accelerating hard and the going into crawl mode for 8 months now... I did come up with a temporary solution which was to change the green and white (one way valve!) thingy, situated between the VSV shown above and the actuator its a plastic cylinder shaped object. I replaced it with a smaller one way valve from an aquarium! and that stopped the light coming on and engine going into limp BUT it lost power and the turbo was only cutting in at 2700rpm and then wouldn't pull much after 3500rpm although it was better than before I still needed to find out what was going on with my car.

I have used the advice of here and Anchorman has been a great help.. I HAVE FIXED IT YAAAAAAY BUT! it wasn't the VSV sensor it was the VRV the one in brown next to the VSV.

I now have no lag, no hesitation and no engine light! yippeeee

 

DEAD EASY to as well so try this.. (take about 20 minutes) THE BROWN ONE IS THE PART TO CLEAN

1. Locate the VRV sensor, its the brown one located above the EGR and next to the VSV as pictured

2. (remove the air box for easier access, but not totally necessary) You will need to remove the mounting bracket from the side of the engine that holds the VRV and VSV sensors, so first remove the VSV (2 bolts either side) then disconnect the air feed tube to the VRV sensor (the long one which runs to the front of the VRV), then undo the bolts and remove the mounting bracket. Also at this point clean the contacts on the turbo pressure sensor (black with purple label as pictured)

3. Turn the bracket which should now only have the VRV left on it upside down and unscrew the black screw holding the VRV sensor onto the bracket.

4. Disconnect the breather cap and spray WD40 or similar into the holes and give it a damn good shake and tap it on a hard surface a few times to loosen up the innards.

5. Drain the WD40 and put back together..

Oh PICTURES ARE UPSIDE DOWN dunno how to spin em around

HOPEFULLY yours will now be working as it should.

[kenben]

Hello everyone,  

I also get the p1251 code come up when the diagnostic is plugged in, my engine management light came on last week, and it went into limp mode, luckily I was on a back road so managed to pull in, I switched off engine then restarted, but the light stayed on, the engine actually runs much better with the warning light on, and doesn't go back into limp mode, I cancelled out the fault code again and took for a test drive, I decided to boot it up the road again but the warning light came on and same old story slowed down switched off and restarted, light stayed on but she is driving perfectly, I am seriously thinking about just ignoring the light now and driving with it on until the next MOT test when I will turn it off again, unless anyone has any Ideas how to cure this glitch.            

[dawsieboy84]

I know this is an old thread but I have been having the same issues. Investigation has let me to the VSV (turbo boost pressure vacuum sensor valve) the one at the back nearest the turbo....

my question is... should this buzz when the ignition is on but engine not running??