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Old 07-02-2008, 10:54 PM   #1
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Default MAPdot accel affecting AFR at steady throttle

Stock 1.6, no AFM, I/H/E.

I'm getting spurious fat spots in 2000-7500rpm WOT pulls. When examined closely they correspond to quick fluctuations in MAP. My theory was that the 2 ms enrichment value was being activated so I made 50 kPa/s zero enrichment. That took the peaks off the fat spots in the logs but still some fluctuations that did not correspond to the VE table. So I made 100 kPa/s zero enrichment and picked up a tip in stumble, no surprise. For no the 100 kPa/s and faster settings are about 50% of the default MSQ and I'm putting up with the fat spots until I figure out a solution. I want keep it simple and not do the variable TPS mod if I can.

I see some mention of using a small inline fuel filter to damp the MAP signal. Any opinions on that or is there another fix?
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Old 07-02-2008, 11:23 PM   #2
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map line off the back of the manifold (fpr) and inline fuel filter should help. I had to increase the threshold so it didn't trigger....gone to TPSdot and it's much improved.
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Old 07-03-2008, 01:04 AM   #3
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I went to TPSdot too after I noticed this, and couldn't cure it. But that was NA.

I dont understand how TPSdot can work when you have boost though. Especially when the spool is really quick like in Braineack's case (saw the videos). How accurate can TPSdot be in those conditions? Or is it just that the fuel map is tuned rich enough as to negate the need for accel enrichment?
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Old 07-03-2008, 01:22 AM   #4
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I'm N/A
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Old 07-03-2008, 01:23 AM   #5
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TPS dot is very fast so I'm not sure what you mean. The AE is only active on tip in, not for the entire length of acceleration.

As for your issue emilio, use the port at the back of the manifold and make sure the threshold is pretty high to keep it from activating.
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Old 07-03-2008, 02:04 AM   #6
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Quote:
Originally Posted by cjernigan View Post
As for your issue emilio, use the port at the back of the manifold and make sure the threshold is pretty high to keep it from activating.
That's effectively what I did. The default threshold is 50 kPa/s and I'm still using that. The first step in the default rate scale is 80kPa/s and that's already set to zero so the effectve lower limit is now the second step in the default scale of 130 kPa/s @ 4 ms. I assume the default interpolating allows that setting to start effecting the VE table around 100 kPa/s.

Driveability is excellent there but the logs still show the accel indicator flickering a bit at WOT. Any higher rate threshold starts to effect driveability.

I'll try relocating the MAP line, tee'd into the FPR and see what happens.

Can I slow down or smooth the sampling rate of the MAP input?
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Old 07-03-2008, 02:09 AM   #7
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anyone have a link to an inline fuel filter small enough for vacuum lines?
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Old 07-03-2008, 09:51 AM   #8
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Could you post a copy of your MSQ and a data log of one of these runs where you're having spikes?

I suspect that relocating the MAP line to the one used for the FPR will fix a lot of this.
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Old 07-03-2008, 11:06 AM   #9
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Quote:
Originally Posted by Mach929 View Post
anyone have a link to an inline fuel filter small enough for vacuum lines?
Look through the lawn mower parts section at your local Sears, Home Despot, etc.
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Old 07-03-2008, 12:55 PM   #10
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Quote:
Originally Posted by ScottFW View Post
Look through the lawn mower parts section at your local Sears, Home Despot, etc.
cool didn't think of that, thanks
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Old 07-03-2008, 01:36 PM   #11
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Relocated the line and raised the threshold to 80 kPa/s. Got a few logs with no accel enrich triggered and nice flat AFR's. Problem fixed it seems. I'll try bringing the threshold back down to 50kPa/s as I had a slight tip in stumble when cold this morning that wasn't there before.

One odd side effect it that I've had to raise the values in the VE table above 70kPa after relocating the MAP line. I had dropped way down from the base map with the line at the TB but now I'm back closer to the original default values with the line at the FPR.

I have to say, I'm shocked at how hard a boneyard 1.6 can pull once freed of it's AFM and given a proper ECU. Everyone who drives it says it feels like a strong 1.8. Can't wait to get it to the dyno and let Church do his thing.
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Old 07-03-2008, 01:45 PM   #12
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Emilio, if you are not running an inline MAP filter, get one. A few bucks at your local FLAPS.

I concur that MAP source needs to be at the rear of the intake mani, and preferably through a filter.
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Old 07-03-2008, 01:59 PM   #13
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so the splice under the pcv in the MSPnP instructions is not ideal then?
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Old 07-03-2008, 02:00 PM   #14
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Advanced auto or autozone has a inline restrictor for the map line, it works perfect. Motorcycle filters are golden as well. I feed my MAP line from the back of the intake but splicing the FPR line works well too. The problem stems from people using the fitting at near the throttle body. The air there is apparently very turbulent and fluctuates alot. The rear ports are more stable.
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Old 07-03-2008, 02:49 PM   #15
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Chad it matters not what you post since I for one cannot seem to redirect my gaze from your avitar...
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Old 07-03-2008, 02:56 PM   #16
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What can I say, I love ******* and cats (in that order).
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Old 07-14-2008, 09:34 AM   #17
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I love ******* and pussies too but not in that order.
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Old 07-15-2008, 05:24 PM   #18
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50kpa/s is probably going to be a bit aggressive Emilio, unless you can filter the map signal signifcantly to smooth out the fluctuations. 70-80kpa/s seems to be the sweet spot. You are grabbing the map signal from the fuel regulator nipple right? That seems to have the least noise, but will still trigger 50kpa/s falsely.

You could also try lessening the PW at that low throttle opening so that it's barely adding any fuel, (but is at least adding something), that way, if you're setting the opening rate to the bleeding edge of a false trigger at least it's not drowning you in fuel when you don't want it. You could re-adjust the higher rate values setting one closer to this rate (maybe move the 130kpa/s to 100kpa/s) and adjust the fuel shot for it as well to smooth out the overall curve.

Just a thought that might help...
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