Loss of power after cleaning inlet manifold

[JamGrey]

Hi All

With the lock down, I am sure we will all become a lot more active on this forum. I thought I would put my recent experience on cleaning my inlet manifold.

The vehicle is a Land cruiser 79 V8. It has a degraaf exhaust and a unichip with a mild tune (Chip is important info to note for later.) With this combination, the stock clutch cant handle the torque, If i floor it, I slip the clutch. I did not want to put this in the Toyota thread as It could be valid for any brand.

So the vehicle has around 150 000km on the clock and I have been aware about carbon buildup and decided to open up the manifold. I went out and bought a Haynes manual for the vehicle from Autobooks. https://autobooks.co.za/

The whole job took me about 30 hours, there was a lot of learning curves: (I did not know there are two drain plugs for coolant and multiple coolant waterfalls and clean ups. I also re-assembled things in the wrong order and had to dissmantle. Lack of correct tools. Upon 90% re-assembly, my socket fell in to the V of the engine, this was followed by the most intense half an hour of "fishing" of my life. etc etc).

The day I started with the strip, I went out and bought a bluetooth OBDII reader so I could clear codes should any come up. I downloaded the Torque Pro App. I fitted it and tested everything worked. I am 80% certain I saw boost readings of 10 PSI.

Summary of manifold clean. It was horrendously full of K4K. I cleaned everything by scraping as much as possible, then wiping with toilet paper and finally using petrol to clean the last of it.



Side note here for some Dealer bashing. I ordered all the gaskets required for the job from Toyota Fourways. One of the gaskets arrived bent. I took one look at it and said I am not taking this. The guy behind the desk was confused, but I don't expect the desk guys who manage the sales to be too technical, so I asked to speak to parts manager. I gave the gasket to parts manager and said it was bent. I asked him if he would be happy to let that leave with a customer. His response was it looks like it was molded that way and he thinks its fine. I then asked him to open up the diagram on their system of what it looks like. He said its not easy to see if it is supposed to be flat or not. Realising there no point in continuing the conversation because he thought the part is fine, I just said I am not signing for it and they must order me a new one and left. It really gets to me that someone who is not technical can be the manager of parts. They would have let this leave their premises if I did not ask questions. When the new gasket was ready, I went to collect, the people I dealt with were "not available". Proper gasket for comparison.



Drama aside, I completed re-assembly. Very nervously, I turned the engine over. Started after about 30 seconds. No error codes. Very happy about that.

This is where this post really begins.

I took it for drive, and the car felt and sounds smoother. But underpowered. I cannot slip the clutch anymore if I floor it. I checked the boost and it would not go above 8 PSI. Looking at what the PSI should be at stock, it should be above 10 PSI. Immediately I thought I have a boost leak. I could not hear any whistle etc. The problem I encountered was that the car does not build boost if there is no load. So I could not rev the car in neutral with bonnet open. Following is what I did to try and find the problem.

1. Spray soapy water to try and see bubbles. No possible to see the gaskets that sit in the V under intercooler.
2. Bypass little gas filter that sits between MAP sensor and manifold to rule out clogged filter. No change.
3. Check all vaccum lines and connections. All Fine
4. Check operation of turbo vanes with syringe. Can hear them moving, no problem

At this point I was getting frustrated and willing to try some riskier things.

5. Made a connecter to attach to the intercooler where I could use compressor to pump air in. Pressurised to 1 bar and monitored. Pressure dropped slowly and cant hear any leaks (which is expected). Inlet is not the problem.
6. Made something to pressurise the exhaust. Same as inlet, no problem.


Getting more concerned at this point so I looked into how the Chip works. The chip sits between the MAP sensor and the ECU. It reads the MAP sensor and then lowers the reading and sends it on to ECU. Basically, the car will have a high limit on the boost where it will possibly go into limp mode. Lets assume this value is 1 Bar (dont know what it is). The chip wants to increase boost so there is more air for more fuel. But it cant go over the limit. So what it does is to "lie" to the ECU. So the chip will increase the boost to lets say 1.2 bar, but then tell the ECU it is 0.9 Bar. This way there is more boost without triggering an alarm with the ECU. The bluetooth adapter is reading the value from the ECU. So this is manipulated.

7. Remove the chip so that I am looking at proper data and then compare to stock boost. No Change

So now I have a head scratcher again. I speak to people and they just say take it to Toyota. Based off of previous experience with dealers, I believe they are incapable of diagnosing problems if there is no error code. Now I am thinking I damaged the Map sensor. I tried to find a way to test it with my multi meter but never came right. At this point I decided to get a standalone boost gauge to see what is really going on. I planned to get an EMS at some point, so this was the perfect time and I could justify the purchase. I opted for the 4x4Mon system and can say that I am very happy with it. I have removed the National Luna Solenoid and use the EMS to manage it. I would suggest looking at this EMS. https://sites.google.com/view/4x4mon/home

8. Fitted the system and went for a drive. The 4x4mon measures in bar and so the values going forward are in bar. 4x4mon 0.85 Bar, ECU 0.5 Bar. Bingo I thought, the MAP sensor is faulty.
9. Called up N14x4 and they had a sensor which I could trial and see if the problem is. Go there, fit the sensor and go for a test drive. The ECU still reads 0.5 Bar The sensor is not the problem.
10. Now I am lost and reached the end of my wits. I was advised to get hold of a turbo specialist. I did, they suggest I go to Toyota, I explained my reluctance to go to dealers. They agreed, but said that the guys at Strijdom Park are clued up. So I reluctantly contacted them and organised a time to go through where they could connect a laptop and go for a drive. We went for a drive. 4x4Mon 0.85 Bar, Toyota 0.85 Bar. They didnt even charge me for this.

So after all of this. The conclusion I came up with is that the bluetooth adaptor is reading a signal wrong. I did some research on the adaptor and the torque Pro App. From what I can gather, you have to manually set an adjustment to account for altitude. It is assuming that I am at sea level. So the drop in atmospheric pressure is not accounted for.

Glad that everything is working right, I put the chip back in. Boost is now at 1 Bar.

But I am still underpowered. Now to the crux of the title of the post. I lost power when I cleaned my inlet manifold. I have ruled out all possible leaks or alternative problems. I have a theory....
The vehicle was tuned with this "obstruction" in the inlet. By removing the obstruction, the air flows easier but different to when it was tuned. I have heard that anytime something changes on the exhaust or air intake, it should be retuned.

The vehicle was booked in on Tuesday the 31st March for a retune.... Sadly with the lockdown, I will have to wait....

This was a long post, but hopefully it would help someone else if they find themselves in the same position as I was in. I will update the post when I can confirm that retuning brings the power back.

[grips]

Have you checked the vacuum operated boost controller. You did not perhaps damaged the boost sensor on the intake?

[HobieDave]

Is your diesel temp sensor plugged in.

[Dungbeetle]

Many modern ECUs can monitor the EGR valve position. Now...if you dismantle stuff the ECU must be assisted to learn the position of the EGR valve from scrach. Meaning it is possible that your EGR valve is operating incorrectly. Or even not closing at all. Proper software is required to do this...

[grips]

Many modern ECUs can monitor the EGR valve position. Now...if you dismantle stuff the ECU must be assisted to learn the position of the EGR valve from scrach. Meaning it is possible that your EGR valve is operating incorrectly. Or even not closing at all. Proper software is required to do this...

Think you hit the nail on the head.

[Khakibush]

On my D4D 4X4 I cleaned the EGR as per google and then took it in to amteck to reset the computer. You will not believe the difference. Not only on sluggish performance but it certainly seems to run more smoothly coupled with better diesel consumption. I dare say Toyota make a lot of money out of people who are not aware of the EGR factor











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[Manana]

Fascinating post, please keep it updated with the what you find.

Have you eliminated the EGR feature? Not sure if it's possible on a Toyota, but on my Pajero there's a simple resistor that you place between two wires in the MAF sensor circuitry which tricks the sensor into believing the inlet air temperature is below 10 degrees C. The EGR won't operate at temperatures below 10 degrees.

[JamGrey]

Is your diesel temp sensor plugged in.

Took me a while to find it in the Haynes, but yes, temperature sensor is plugged in

[JamGrey]

Have you checked the vacuum operated boost controller. You did not perhaps damaged the boost sensor on the intake?

Havent tested it, but when the car was plugged in with Toyota, they could show the Boost requested by the ECU and the boost measured by the MAP sensor. The two lined up and they said there was no problems.
This was done with the chip off the car.

[JamGrey]

Many modern ECUs can monitor the EGR valve position. Now...if you dismantle stuff the ECU must be assisted to learn the position of the EGR valve from scrach. Meaning it is possible that your EGR valve is operating incorrectly. Or even not closing at all. Proper software is required to do this...

I have subsequently blocked the EGR port to see what difference it makes. Nothing really changed. But I have a check engine light now. Whether the valve is open or closed, it is physically blocked.

[Trevor_Mathews]

On these V8's you can turn the EGR off in the software...but if it is already faulty (faulty = stuck in open or closed positiin due to all the gunk) then you have a problem...so I am told...if switched off before it is problematic then no issue...my v8 76SW was remapped just after the 100k km mark and EGR was turned off at the same time...my cruiser now has 230k km on...

Also installed oil catch can to filter off all the oily sludge though from the positive sump pressure...this is also cloggs up the innerds you were cleaning even though EGR is switched off...

Not sure of this helps you in any way...

Trev

[JH84]

I have subsequently blocked the EGR port to see what difference it makes. Nothing really changed. But I have a check engine light now. Whether the valve is open or closed, it is physically blocked.

Really old thread, but very interesting!

@JamGrey if you are still around, did you ever resolve this issue?

[JamGrey]

Hi All

Apologies for not keeping my word and posting the outcome.
When things were open again, the vehicle went in for a retune and they did something to prevent the check engine light.

All the power is back. My conclusion: The vehicle was tuned with the restriction in the airflow. By removing the restriction, it changed the airflow and the previous tune was no longer applicable. Retune with no restriction and the car drives like a dream.

I requested a very light tune as I was not after power but better fuel economy.

I now get between 5.5 and 6.5 km/l on the open road with fully loaded rig and rooftop tent depending on wind and elevation. I try to keep it at 110 but everytime I look down, I am at 120. I guess I am actually 80% of the time at 120 (Tyres have been changed one size up so now the speedo is very close to true). Even hit a 7 km/l once.

I may even request a slightly lower tune as there is more power and torque than required and I do sometimes use it because it is there and not because I need it.