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Engine hesitation after retuning

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Hello,

We have engine hesitation esp. at boost area after retuning.

We checked the mechanical possibilities but could not find anything. The tuner says runtime values are ok at that stage.

Here is the base map.

Do you have any clue if there is any signal that this is about tuning?

Thanks for your help.

 

basemap.pclr

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I see a couple of things from the log that might be worth a look (pic attached)

image.thumb.png.d02982327f93ee4a9ed07707352b9020.png

1.  It looks quite rich (0.68) at the start of boost, before stabilising later.

2.  Boost Mode is set to 'closed loop'  but the Target Boost Table only has a row for TP = 0%.

It should include rows up to TP = 100%.

Boost Status is shown as OFF all the time, due to the above I expect.

Hope that helps?

 

 

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2 hours ago, TimmyD said:

I see a couple of things from the log that might be worth a look (pic attached)

image.thumb.png.d02982327f93ee4a9ed07707352b9020.png

1.  It looks quite rich (0.68) at the start of boost, before stabilising later.

2.  Boost Mode is set to 'closed loop'  but the Target Boost Table only has a row for TP = 0%.

It should include rows up to TP = 100%.

Boost Status is shown as OFF all the time, due to the above I expect.

Hope that helps?

 

 

Thanks for the reply.

I am confused at boost target table in the way that if conflicts with EVC.

would it stabilize the boost further than wastegate?

finally I appreciate if you share a sample target table since I couldnot find it in the base maps?

 

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I'm not sure what you mean by "EVC" ? 

I believe that you're basically running open loop, i.e. from the wastegate table.  However, the Boost Mode is set to 'closed loop'. I don't think this is what's causing your "engine hesitation" problem, but it would be a good refinement to carry out at some point.  

From Impreza STI, 2.5 (2007), here's Target boost table:

image.png.8cfb88888c14afcf8410aa923377de4e.png

 

I think the first thing to tackle is the fuelling IMHO....

 

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5 hours ago, TimmyD said:

I'm not sure what you mean by "EVC" ? 

I believe that you're basically running open loop, i.e. from the wastegate table.  However, the Boost Mode is set to 'closed loop'. I don't think this is what's causing your "engine hesitation" problem, but it would be a good refinement to carry out at some point.  

From Impreza STI, 2.5 (2007), here's Target boost table:

image.png.8cfb88888c14afcf8410aa923377de4e.png

 

I think the first thing to tackle is the fuelling IMHO....

 

Many thanks.

I will check the fueling first.

By EVC I meant that I have electronic valve controller (HKS) installed. So I have several boost modes. I am not sure according to which mode should I fill this table. Will it deteriorate the other modes for example? That's what I'm confused.

Is it better to change it basically to open loop if that's already the case in practice?

 

 

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Do you have any hint on whats happening in lower rpms? It happens when trying to stabilize the rpm but not on acceleration. Could it be also fuel related? This time AFR seems to be within the limits.

screen.JPG

lowboost.llg

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An "electronic valve controller", sorry I never realised that.  In that case, I guess you wouldn't want the Link ECU doing closed loop aswell. My mistake.  

Looking at your latest log, despite the oscillations they look pretty small in amplitude (it's zoomed in quite a lot).

Bit stuck on this I'm afraid, apart from the fuelling on acceleration looking too rich.   I could have helped with setting up Link boost control, but I don't think that's your problem now.

 

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13 hours ago, TimmyD said:

An "electronic valve controller", sorry I never realised that.  In that case, I guess you wouldn't want the Link ECU doing closed loop aswell. My mistake.  

Looking at your latest log, despite the oscillations they look pretty small in amplitude (it's zoomed in quite a lot).

Bit stuck on this I'm afraid, apart from the fuelling on acceleration looking too rich.   I could have helped with setting up Link boost control, but I don't think that's your problem now.

 

I'm really confused. Ok my fuel pressure was a bit lower. I have corrected that one and problem at acceleration was decreased.

I realized that hesitation at the low TP was not happening when the engine is cold/warm (say before flooring). But it starts appearing after flooring couple of times.

So there is no hesitation at 100% TP, but there is hesitation after travelling (not before).

If it was ignition it should appear at flooring as well in my opinion. We have checked the plugs/gap they were ok.

Only remaining candidate might be fuel pump but then why its not happening at all circumstances then?

That's why I tried to check tuning as well since this wasnt the picture before retuning.

Totally stucked here.

 

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I will try it as soon as I have time. But as far as I recall there was no bucking at least was not noticeable this much.

I tried to eliminate mechanics -changed the fuel pump and plugs but no luck.

Would TPS calibration help?

 

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Is it a bad idea to adjust fuel or ignition table according to this specific spot in order to eliminate problem from most probably my cams (being stage 3)? i know this will hurt my afr.

general question is that should the fuel and ignition tables have sequentially increasing or decreasing values all of the time?

is it possible to have some unsequential jumps where for example afr is off target?

thanks.

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Does the bucking sound like a lean misfire? Popping?

Your target Lambda at 65kpa is .95. It is oscilating between 1.04 and .98 over about 5kpa range in a very steady throttle position
(out of your low  boost log.)

 

 

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update: my lambda values on the ecu was crap since calibration was wrong. could not find the correct values but we have retuned fuel according to gauge this time. most of the bucking went away and it's better now. so there were wrong afr values in ecu readings. now only in 2nd gear if you force to drive constantly at 2500 rpm there is a little bucking and i guess this is normal?

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Hi- An old saying is - An engine wants what it wants - . Perhaps make it richer in the areas where you feel this noticeable bucking. To me this is a sign of running lean . With your cams you can get intake reversion and all sorts of weird pressure waves happening that can effect smooth running . Especially at that point of light throttle and low/medium engine speed . Dont be stuck on A/F targets at this particular problem area - Try it at 0.9 and see how it runs . 

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5 minutes ago, Ken Dunkley said:

Hi- An old saying is - An engine wants what it wants - . Perhaps make it richer in the areas where you feel this noticeable bucking. To me this is a sign of running lean . With your cams you can get intake reversion and all sorts of weird pressure waves happening that can effect smooth running . Especially at that point of light throttle and low/medium engine speed . Dont be stuck on A/F targets at this particular problem area - Try it at 0.9 and see how it runs . 

Well said Ken. I mentioned in another forum that the wideband only measures "burnt fuel" and the cams skew the readings.

Mine Ej engine runs best at cruise .9-.95 with cams rather than the more traditional 1.0+

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