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Reving up from idle, delayed responce
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Thu Jan 19, 2012 3:57 pm    Post subject: Reving up from idle, delayed responce Reply with quote

Right now I'm baffled and I'm not sure what I need to tune in correctly to get my rpms to jump up as soon as I hit the accelerator pedal.
In all my datalogs the cars engine doesn't seem to rev till after my map sensor hits it peak and starts coming down. I figured it should be reving up before that happens.

When I tried the maf the one time I was messing around with it I noticed it reved up much faster and sooner when I hit the accelerator from idle.

I can post up the tune\screenshots. Other then throwing in some timing to it from idle up the map, and adding extra gas, I'm baffled at what else I need to look at. I'm pretty sure properly tuned acceleration enrichments would help ( accel pump ).

Its a turbocharged 4 cylinder with a stock evo 8 intercooler and some piping, no bov.

I figured its all in the accel enrichments, is there type of knows for FI and accel ernichment that I can read up on, certain ammount of extra fuel vs time.
Maybe I'm wrong maybe there is something else somewhere that I"m overlooking. I just feel like there is too much of a delay from when I hit the pedal in to when the rpms actually go up.

Sorry for this noob post but I'm stumbed and trying to learn but don't like how this is reacting.
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Bugermass



Joined: 13 Aug 2007
Posts: 96

PostPosted: Thu Jan 19, 2012 6:12 pm    Post subject: Reply with quote

Which EMS are you working with? I can probably give you some ideas if I know what system your on.
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Thu Jan 19, 2012 8:45 pm    Post subject: Reply with quote

Megasquirt 2 CPU \ ms v3 pcb
MS2extra firmware 3.2.1
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Flr Power



Joined: 05 Jun 2007
Posts: 126

PostPosted: Fri Jan 20, 2012 11:48 am    Post subject: Reply with quote

Are you sure the main fuel map is tuned right?
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Fri Jan 20, 2012 2:53 pm    Post subject: Reply with quote

To tell the truth I'm not sure its tuned all the way properly. I will post up the fuel map in a minute. I had tuned my previous map before and still had the same issue. map sensor was in ecu with a long hose attached to it. Now I moved it to the engine bay and the areas I had tuned in while under cruise and in boost have gone lopsided so much so I'm retuning those areas. At the best I got it to rev up right once the map signal topped out, at worst it would rev after the map was failling. I'm thinking maybe I'm not giving it enough fuel compared to the amount of air is already around in the intake manifold.






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StantonWarrior



Joined: 10 Dec 2010
Posts: 188
Location: UK

PostPosted: Fri Jan 20, 2012 3:04 pm    Post subject: Reply with quote

If main map is fuelling as the engine requires, then sounds like a tip in fuelling issue.
Have a play, try richening it up a bit...
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StantonWarrior



Joined: 10 Dec 2010
Posts: 188
Location: UK

PostPosted: Fri Jan 20, 2012 3:07 pm    Post subject: Reply with quote

"looks" like fuel map is lean around mid revs/part throttle - to the right of the "lump". Usually goes a bit leaner around there, but yours looks a bit TOO lean in comparison.
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Fri Jan 20, 2012 4:09 pm    Post subject: Reply with quote

actually the area right of the first lump isn't really lean, between 1300-2000 is the lean area requiring me to keep throwing more fuel at it right now. Crazy how much changing sensor location and tubing can change how much fuel its getting. Likewise 4800-5500 in boost was another area that needed more fuel thrown at it because it was lean compared to before 13.5~ after sensors changed out, 12.5-1 before
between 2300-3200 its pretty close to stoich in there

I did change to a different CAS disc the same time I changed map sensor location from a 4+2 to a 24-1-1+1 set up as 12-1 crankspeed. Now I didn't think the cas would have much effect other then making know crank location and resolution better.
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Power-Tripp



Joined: 26 Nov 2008
Posts: 441
Location: Deep South, AL, USA

PostPosted: Sat Jan 21, 2012 7:21 am    Post subject: Reply with quote

Techsalvager wrote:
... Crazy how much changing sensor location and tubing can change how much fuel its getting.


It doesn't. It changes the reading of residual O2 - or more precisely combustion efficiency. For instance, if you are having afterburn in the exhaust (more common than many realize), and your sensor is located in the primary tubing, you get one reading. Now you move the sensor just after the turbo and get another reading. And finally, you move the sensor 12 inches further downstream, and you get another reading.

You have done nothing to alter mixture ratio, homogenization, ignition timing, etc., yet the readings all differ due to differences in residual O2 in the exhaust at different points.

Throw in issues with H1 and H2, and now a residual O2 sensor reading starts to make you really bang your head against the wall.

Do not get stuck on a target Lambda ratio. Give the engine what it wants for best output, and everything else will fall into place.

[A little understanding of combustion chemistry and multi-gas analysis goes a long way toward better accuracy.]

I hope this helps,

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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Sat Jan 21, 2012 8:59 am    Post subject: Reply with quote

Power-Tripp wrote:
Techsalvager wrote:
... Crazy how much changing sensor location and tubing can change how much fuel its getting.


It doesn't. It changes the reading of residual O2 - or more precisely combustion efficiency. For instance, if you are having afterburn in the exhaust (more common than many realize), and your sensor is located in the primary tubing, you get one reading. Now you move the sensor just after the turbo and get another reading. And finally, you move the sensor 12 inches further downstream, and you get another reading.

You have done nothing to alter mixture ratio, homogenization, ignition timing, etc., yet the readings all differ due to differences in residual O2 in the exhaust at different points.

Throw in issues with H1 and H2, and now a residual O2 sensor reading starts to make you really bang your head against the wall.

Do not get stuck on a target Lambda ratio. Give the engine what it wants for best output, and everything else will fall into place.

[A little understanding of combustion chemistry and multi-gas analysis goes a long way toward better accuracy.]

I hope this helps,

When you talk about moving the sensor I take it you mean o2 sensor?
The o2 sensor has stayed in the same location before and after moving the map sensor.
Or you mean changing map sensor location can effect o2 readings?
I know for sure that where I used to be fine before changing map location (high 14.x:1s mid 15.x:1s ) I was way to lean 18.x:1+ after changing map location.

I"ve tried to locate someone locally with a multi-gas analyzer but no one seems to have one, doesn't suprise me consider there is no inspection or emissions here locally. Tried to find one on ebay, but high prices are bit prohibited right now so I am trying to learn with what I can.

I appericate the responce and will keep it my mind, it does make sense.
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Sun Jan 22, 2012 7:17 am    Post subject: Reply with quote

So I went out and did soem tuning of the idle 800-1200 to 100kpa region for fueling as shown in my fuelmap pic posted below. I got it to where I gotten before. Reving up after about map has hit the top most and its on its way down as shown in the datalog below.


Yellow = tps
purple = map
green = afr
light blue\green = rpm
You can see in the first one the rpms drop but come back up quickly. My guess is I'm getting a lean enough spot right there and then right after I get enough fuel for it to rev up. Adding the extra fuel on the map helped but now I"m guessing its all tip in tuning.
AFR goes from 14.1 to 18.3 then down to 12.x before going into overrun \ decal fuel cut.



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Bugermass



Joined: 13 Aug 2007
Posts: 96

PostPosted: Sun Jan 22, 2012 9:39 am    Post subject: Reply with quote

If your pretty certain that your main fuel table is spot on then I would concentrate on the tip in enrichment. when I do tip in tuning i usually focus more on how it feels and responds rather that trying to chase an O2 value. If it feels crisp and responsive then your probably pretty close.

Also can you post a log of what your ignition is doing during your tip in event?
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stevieturbo



Joined: 29 Aug 2006
Posts: 1235
Location: Norn Iron

PostPosted: Sun Jan 22, 2012 12:35 pm    Post subject: Reply with quote

Tuning accel enrichment to AFR's is pointless and futile.

Turn off all transients and tune your main map.

Then turn on transients, and start from nothing and increase fuel until response is sharp.

Some people get carried away and always think they need more and more fuel, when it is this richness causing the sluggish response, regardless of what a wideband might say.

Of course the above also assumes basic things like your ecu is wired and set up correctly, and all sensors ( ie TPS and MAP etc are all working and configured correctly )
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Sun Jan 22, 2012 1:31 pm    Post subject: Reply with quote

Here is the log with what the spark does and a view of the spark table.
I'm looking at it and notice its only around 20s advance while till it starts moving over in rpm and goes to higher 20s finally hitting at 32.4 advance at 2169rpm but map is already freefall.

The middle is part is PW\PW2, setup batch fire

For the tuning of this I've been trying to get it better by feel, thats why I notice it so easily when you hit the gas pedal the delay in rpms. Of course its better higher rpms and load.



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stevieturbo



Joined: 29 Aug 2006
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Location: Norn Iron

PostPosted: Sun Jan 22, 2012 3:30 pm    Post subject: Re: Reving up from idle, delayed responce Reply with quote

Techsalvager wrote:
Right now I'm baffled and I'm not sure what I need to tune in correctly to get my rpms to jump up as soon as I hit the accelerator pedal.
In all my datalogs the cars engine doesn't seem to rev till after my map sensor hits it peak and starts coming down. I figured it should be reving up before that happens..


Everything you're saying is very confusing.

So are you saying there is lag on the datalogs, or is the engine actually very slow to respond to your foot ? Are the sensors slow to respond ? Or are they responding quickly ?

And why jump to the ignition timing table ? That will have virtually no impact on accel response/accel enrichment unless it was horrifically bad ( which it doesnt seem )
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MrDomino



Joined: 01 Oct 2009
Posts: 190
Location: Indianapolis, IN

PostPosted: Sun Jan 22, 2012 5:36 pm    Post subject: Reply with quote

A legend with that data log would be nice.
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Sun Jan 22, 2012 5:42 pm    Post subject: Reply with quote

Say you hit the accelerator with you foot from idle, I can watch my boost gauge go up to near atmo before I even see my rpm go up. To me it feels wrong, delayed, non responsive to my input. Basically I hit the throttle and wait till I'm off the throttle to get going from a dead stop.

so basically engine is slow to respond.

Bugermass asked me to post the ignition table so I did.
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Techsalvager



Joined: 21 Jun 2011
Posts: 304
Location: Leesburg, GA

PostPosted: Sun Jan 22, 2012 5:47 pm    Post subject: Reply with quote

MrDomino wrote:
A legend with that data log would be nice.

Light blue = rpm
blue = MAP in KPA
green = AFR
orange = tps % 0-100
purple = pw
red = pw2
green = spark

I will note this to author of the datalog viewing program that a legend would be nice to insert.
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MrDomino



Joined: 01 Oct 2009
Posts: 190
Location: Indianapolis, IN

PostPosted: Sun Jan 22, 2012 7:59 pm    Post subject: Reply with quote

AFR should change pretty quickly when you stomp on it. I think that's contributing to your problem somewhat although it looks like the PW increases pretty quickly. I'm not sure what's going on.
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stevieturbo



Joined: 29 Aug 2006
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Location: Norn Iron

PostPosted: Mon Jan 23, 2012 6:02 am    Post subject: Reply with quote

Those logs make no sense. The various items look totally out of sync.

By those, you're touching the throttle briefly and closing again before the engine even response. Which is impossible, unless you had some ridiculously huge plenum or something
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http://www.youtube.com/watch?v=XgWRCDtiTQ0
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