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Old 10-20-2005, 06:45 PM   #1
kingtut12
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Default Rough idle and stalling directly related to MAF

Hey guys

As some of you know I 've been having weird issues with idle and low RPM driving, and stalling out at stoplights.

Well, this may not be news to some of you gurus, but I figured out today while I had my UTEC dashboard on, that the MAF % changed when my radiator fan kicked on, AND thats when my car starts acting funny. as soon as the fan turns off, idle goes back to normal. At 1st I though it was just a battery voltage fluctuation from the draw of the fan switching on. BUT... I blew into my intake filter (Perrin BIG MAF) and the car immediately ran rough until I stopped. If I blew hard, it died - everytime.

So, at this point should I shield the Intake filter from radiators fan airflow path or will I be able to adjust my 500-1000 - 0% fuel column?

As far as low RPM driving, I wonder if the fact that I do not have fog covers are allowing more air than necessary into my intake and thats why when i try to take off quickly or start to build speed my car stutters a bit? Any thoughts on this?
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Old 10-20-2005, 07:13 PM   #2
ride5000
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sounds like a big issue with turbulence.

is the bigmaf an intake/air filter? i thought it was just a maf pipe, but i could certainly be wrong.
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Old 10-20-2005, 08:03 PM   #3
kingtut12
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Quote:
Originally Posted by ride5000
sounds like a big issue with turbulence.

is the bigmaf an intake/air filter? i thought it was just a maf pipe, but i could certainly be wrong.
Well, I suppose the Big Maf part is just the pipe and the filter is a standard foam filter. But it is all sold together.

Explain more on the turbulence issue. BTW, I was fooling around with some sheet metal and made a quick shield to temporarily put between filter and radiator - it worked perfect, never idled rough or stalled out.

But on the other hand, by removing the shield and adding fuel in the 500-1000rpm - 0% load column, it didn't seem to really help much. I was figuring since the MAF was reading more air when the radiator fan kicked on, then it would fool the ECU , thus requiring more fuel. But that did not seem to be the solution...unless I didn't add enough fuel.
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Old 10-20-2005, 11:51 PM   #4
cdvma
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You adding fuel would just be eliminated by the fuel trims. This is very interesting...its probably mis-measuring the amount of air because its getting lots of flow over the sensor that is not consistent throughout the tube. However the chances of that are so low that I believe something else is going on. I'll have to think about this one for a bit.
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Old 10-21-2005, 01:25 AM   #5
kingtut12
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Quote:
Originally Posted by cdvma
You adding fuel would just be eliminated by the fuel trims. This is very interesting...its probably mis-measuring the amount of air because its getting lots of flow over the sensor that is not consistent throughout the tube. However the chances of that are so low that I believe something else is going on. I'll have to think about this one for a bit.

Yea, It's really odd. I just went out and started the car again and sure enough, if any air whatsover is blown toward or at the intake filter, it chokes it dead. Now, if I rev to 1000 and hold it while the radiator fan kicks on, then it does not die, but it does idle very roughly, and does die as soon as i let off gas. Can someone else humor me and try this? Let me know.
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Old 10-21-2005, 11:25 AM   #6
cdvma
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Can you record a log from the UTEC while you do this? I'm curious as to what happens to the MAF volts. IIRC one of the UTEC logs (1-6) captures MAF volts to two decimal places - use that.
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Old 10-21-2005, 06:39 PM   #7
kingtut12
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Quote:
Originally Posted by cdvma
Can you record a log from the UTEC while you do this? I'm curious as to what happens to the MAF volts. IIRC one of the UTEC logs (1-6) captures MAF volts to two decimal places - use that.
Ok - i will do that on Sunday. I will be outta town til then.
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