Egr fault clicking = low boost?? 150 d4d

[RealPrado Junior Member Find all posts View Profile Close RealPrado]

Hi Guys

Interesting and timely one today before xmas, leaving on a road trip to Melbourne from Adelaide on Boxing Day... anyway my problem..

While driving around town today, a short trip from my warehouse, vehicle was already warm from a 5km trip to the warehouse about 30 minutes prior, engine lost some power, boost was slow to react and never went above approx 7psi, measured on the intake manifold side. Usual boost is appox max 14psi.

Vehicle felt sluggish, no different turbo noise.

No fault codes, limp home lights etc.

Pulled over, shut the vehicle down figuring it may be a sensor fault, re-started and problem still exists.

Got home, looked for any obvious signs of boost leaks, eg hoses etc.

Disconnected battery with lights on, waited a while, reconnected and test drive. No difference.

Checked the Mass Air Flow Sensor, appear to be clean.

I did notice a fairly regular clicking sound from around the intake manifold approx 0.5 sec in rhythm. Shut the vehicle off and restarted, clicking seemed to disappear.

Went for another test drive, prob still persists.

Hooked up OBDC reader, no fault codes to read.

Assessed the Commanded EGR % whilst on idle, noticed it was up and down from 0.0% to approx 37% with the clicking evident. I filmed both this and the engine where I can distinguish an audible noise on the video.

Still no fault codes.

Cleared fault codes as a precaution.

Started the engine, no clicking. Test drove and boost and response back to normal. (Phew, thought I had done a turbo..)

Pulled back into the garage, popped bonnet and could hear the clicking noise still.

Other factors, it is approx

- 40 degrees here today
- trip was short, but vehicle was warm
- I have had turbo issues previously (2 turbos with dropped exhaust vanes) most likely due to a remap which has been since removed and replaced with a new toyota standard map
- I have noticed what I thought was the same issue on a couple of occassions, but it lasted less than 30 secs, disappeared when I shut down and restarted, and has not been apparent for over 12 months
- vehicle has 156k km's, is well maintained, GX Manual 2013 D4D
- Catch can fitted and breather isolated completely from manifold
- intake manifold has had full manifold off clean
- secondary fuel pre filter installed


So, questions to you lovely people:

- should the EGR Valve (or solenoid I'm guessing) make a clicking noise at about 0.5 second interval? (I'm guessing not)
- could a faulty EGR Valve (or solenoid) cause low boost?
- what else could I be checking?


I did log the Commanded EGR %, EGR Error %, Mass Air Flow, and Intake Manifold Absolute Pressure ( kPa abs) whilst taking for a drive, I also have a video of the clicking noise and the OBDC reader screen read whilst the EGR % was pulsing. I think these files may be too big to upload, but could email them if needed.

Any suggestions would be awesome!

[RealPrado Junior Member Find all posts View Profile Close RealPrado]

Hi guys,

quick update, the issue has disappeared overnight, I cannot replicate it today and the boost is back to normal.

I just went for a 1 hour drive whilst logging EGR and MAF data. All seems normal. EGR is approx 33% and steady whilst idling, MAF is approx 14% at idle.

The clicking noise is gone.

So the theory is, it may be a faulty (intermittent) issue with the EGR Control Solenoid. Apparently the solenoid controls the vacuum to the diaphragm which actuates the EGR, this solenoid can be faulty, apparently more so in hot conditions (40 degrees here currently). If the solenoids is pulsing in error then it cause the vacuum to be supplied and then off, supplied and then off etc, this would then actuate the EGR valve open and closed, open and closed etc which would then cause me to hear the clicking (of the actual EGR valve opening and closing).

With the EGR open when it shouldn't be, boost would be leaked straight back into the exhaust via the EGR meaning that the boost could not increase, ie it is leaking boost.

So thinking is, I will buy a EGR Control Solenoid to have on hand if the issue arises again. If the issue does pop up again and I can hear the clicking I will temporarily remove the vacuum hose from the solenoid to the EGR diaphragm to see if the clicking stops and also see if I can detect the vacuum pulsing. This would then confirm that this is the cause.

Apparently this is a common issue in Pajero's??

Any thoughts?

[RealPrado Junior Member Find all posts View Profile Close RealPrado]

Hi guys, another update after more thinking, research and investigation:

- on researching the commanded EGR %, this seems to be what it says, the command given to the solenoid(s) to control the actual EGR %
- therefore, as the Commanded EGR % was erratic at idle during the issue this suggests that the issue may not be with the solenoid but with the signal given by the computer, or the signals from other sensors that the computer determines the output "commanded EGR %"
- I do not have a readout of the "actual EGR %", which apparently comes from the sensor above the vacuum diaphragm, but I do have the error, which is a calculation between the "commanded" and "actual" EGR % (apparently: (Actual EGR Position − Commanded EGR) ÷ Commanded EGR = EGR Error)
- I tried back calculating the data I have for "Commanded" and "Error" but the figures are all over the shop, sometimes as much as +/- 3500% - so I think something is bogus here
- I have tested the diaphragm with a vacuum tester, at the same time I read the OBD readings. I got nothing for the "commanded EGR %" which re-enforces my thoughts that this is from the computer, but I did get the error % of 99.2%, as the valve would have been open (100%) but the command was 0.
- the diaphragm held vacuum. *Note here though that I had to block the second vacuum hose which goes to a second solenoid. So for this to work this solenoid would have to be closed to close the vacuum loop

What I do know:
- the boost is back to normal and my OBD figures seem to be back to normal, and I have not heard the clicking noise again
- when I operated the EGR valve manually by vacuum and then released the vacuum I heard the valve shut which sounded similar to the clicking noise I heard when the fault was evident
- the EGR valve itself along with the vacuum diaphragm is working fine I beleive
- the solenoids are working fine now, but I am not sure that they were not the causes of the issue previously
- the commanded EGR % reading was fluctuating when the clicking noise and the low boost was apparent
- therefore I would reason from this that the issue is more likely either the inputs into the computer (sensors inputs) that determine what the commanded EGR % should be, OR the computer itself had a little hiccup when determining the commanded EGR % (less likely I would have thought)

Does anyone have any idea what sensor inputs are used to determine the calculated EGR%?

Basically I think I have reached my limit with my tools at hand, unless anyone else can provide input? (help please??)

So next steps at this stage:
- booked into toyota tomorrow for their diagnosis (although I don't believe there are any fault codes, and the issues is not present at this stage)
- keep driving the vehicle to see if the issue replicates (this is fine locally, however we are heading off to Melbourne from Boxing day so this type of trip is a little more risky)



Some other interesting facts:
- if the solenoid is the cause of the fault you cannot buy the solenoid (from my research) individually, but it comes as part of the EGR assembly, which you can purchase for a lovely $678 from Toyota, or approx $350 online

Any feedback or discussion is very welcome..