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Tony4

1UZFE VVTi Cam position offset

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Hi all,

I have a 1uzfe vvti having mapping issue where it stops making power after 3krpm. The engine did not like running with vvti plugged in (0deg) and feels like mis-firing on one bank. There is no consistency amongst the dyno run with 260ftlb and 80hp at 3krpm.

However, with vvti control unplugged, it behaves better with some consistency of 260ftlb and 150hp at 3krpm and then tail off not making any power after.

One thing I notice is the cam offset is different to the base setting on RH cam (139deg), but cam angle test is showing 205deg. Which one should I use?

Edited by Tony4

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Hi Tony,

Things to check would include having the correct sensor wired to the correct ECU input and making sure the reluctor polarity is correct.

How do you have things currently wired? Can you attach your base-map?

Scott.

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It is running with ITB and I did all the wiring myself, checked all the sensors polarity are correct.

Attached is the base map with default 1uz vvti cam offset, I then changed it from 53.5deg to 56deg LH cam; 139deg to 144deg RH cam.

I think there is also a bug in the script that the vvti cam angle will not show less than 0 deg.

After the cam angle offset corrected, it is running consistently at DC5% at 0deg VVT, whereas before it was sometime at DC0% and DC20%; and there were a difference of up to DC10% left to right bank even the angle cam is showing 0deg.

Efi tuned V8.pcl

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The intake cams will not go below 0.0 as this is the most retarded position, and they advance when activated.

You could double check that you have the correct VVT solenoid wired to the correct aux output.

Scott

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Hi Scott, I've double checked all the wiring, aux output, polarity... checked the all sensor's resistance which is in spec.

The engine doesn't like it when the map is in the "VVT zone", it's like hitting a rpm cut or misfiring. I have attached the latest pci and log. Is there anything else I should look at?

 

 

Log 11-09-16 12;08;08 pm.llg

Efi tuned V8-2.pcl

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Hi Tony,

Thanks for the files. Looking through the log file I can see the VVT is working without any errors being generated, this is a good starting point. I did notice that when VVT is active the wideband reading goes very lean. Comparing your fuel table to one from our dyno engine it looks like your fuel table values are a fair bit lower in the same area. If you increase your fuel table values to be similar to ours, does this help? the difference in fuel tables could also be due to something like injector size differences.

Here is a screenshot from the log file showing where it goes lean:

Timeplot.thumb.PNG.8c70844100c809adde29b

Here is your fuel table:

Fuel_table.thumb.PNG.d52a6b663c5679b8fcb

Here is the fuel table from our base-map:

Fuel_Table_link.thumb.PNG.850979f80a89fd

One other thing I noticed is that the cam position is not tracking the target as well as it could. If you are willing to give it a go it may be worth adjusting the VVT PID values in an effort to get the system more responsive. However I don't think this is the cause of the problem you are seeing.

Scott

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Thank you Scott for spending time on analysing the log.

I have been to another round of dyno test today, we have increased the fuelling but it seems that no matter how much fuel is added in the VVT activation zone, it is just showing lean AFR >21. We have no idea where all the fuel went?

It is running standard injectors and the ARF looks ok on idle and under load, but just not when VVT is engaged. Also, after 4.5k rpm without VVT.

Just to double check the VVT operation, is it normal for VVT to output 25%DC to the solenoid hold the cam at 0deg some of the time?

 

 

 

Capture.PNG

Edited by Tony4

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Looking at those logs you definatly have a fuelling issue.

If your adding more fuel in the table and the AFR is staying constant on the WB then you need to check base line pressure under load. If it drops off theres either a restriction or the pump isnt up to the job.

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 and feels like mis-firing on one bank.  

 

I have been to another round of dyno test today, we have increased the fuelling but it seems that no matter how much fuel is added in the VVT activation zone, it is just showing lean AFR >21. We have no idea where all the fuel went?

 

Looking at those logs you definatly have a fuelling issue.

If your adding more fuel in the table and the AFR is staying constant on the WB then you need to check base line pressure under load. If it drops off theres either a restriction or the pump isnt up to the job.

 

From Tony4's comments I don't think I would be jumping to the conclusion that it is a fuel issue yet.  If there is a misfire or even "poor combustion", a wideband will usually read full lean due to excess oxygen which appears to be what's happening in these logs.  Injector pulse widths appear to be sensible in the problem area.  I don't have much experience with VVT so cant be much more help but just wanted to say that the lean AFR is a symptom rather than the cause.

 

Edited by Adamw
formatting

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From Tony4's comments I don't think I would be jumping to the conclusion that it is a fuel issue yet.  If there is a misfire or even "poor combustion", a wideband will usually read full lean due to excess oxygen which appears to be what's happening in these logs.  Injector pulse widths appear to be sensible in the problem area.  I don't have much experience with VVT so cant be much more help but just wanted to say that the lean AFR is a symptom rather than the cause.

Certainly worth looking into.

The VVT and trigger settings are the same as what we run on our 1UZ dyno engine.

Scott 

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I remember I had to set the ecu system voltage limit to 25v as it was exceeding the standard setting when I first got it.

How is it possible for the ecu to see more than 20v when my actual vehicle system voltage is less than 14v (measured). Could it be something wrong with the ecu unit?

This may also explain why the engine is misfiring at high rpm even without vvt pluged in.

 

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There are two options that I can think of:

1. The ECU is mis-reading the system voltage, and adjusting settings like injector deadtimes and dwell times incorrectly, there-by creating a problem.

or 

2. The system voltage actually is spiking up to what the ECU is measuring and system components are malfunctioning because of this.

A volt meter averages the signal, so may not pick up on voltage spikes. Ideally you would want to check the supply voltage to the ECU at the ECU's wiring connector using an oscilloscope. You could also try taking the belt off the alternator and seeing if the problem continues. A failing alternator regulator could cause a problem like this.

Scott.

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The over voltage limit was triggered when the engine wasn't running, so it's unlikely is the cause of a problem alternator.

It could be battery but I will double check again. I'm using Odyssey Extreme 40.

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It seems that the over voltage only happen when VVT is engaged, see the attached logs. This is very strange, before someone ask, I have checked all 4 ECU ground to chassis are 0.4ohm.

Zero VVT (voltage spike at 4K rpm+):

VVTi zero.PNG

VVT engaged: It seems that the battery voltage is tracing RH solenoid profile.

VVTi on.PNG

Edited by Tony4

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Good news.  That's a pretty odd problem you had there, I still cant quite work out how that relay would have had such an effect.  I know a relay coil collapse would give a short sharp voltage spike but yours seems too long for that.  Maybe it was effecting alternator control somehow too.

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