Dry and MAF questions
01-20-2006, 08:49 AM
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Dry and MAF questions My car is set up with a wet and a dry, The dry kit has had a problem almost from day1 It was tunned to pull timming on the spray and it works well as long as its a small shot say a nos 55 pill but anything above that after about 5 secounds into the spray it puts the timming back in and goes lean. We have taken it back to the tunner but he was unable to fix this problem he says its like the maf doesnt see the n20 after a few secounds, The maf is a stock unported as he requested we asked if the maf could be freezing he said that thats just a myth, so thinking we had a bad maf we changed it still samething. Everyone we know running big shots of dry are doing it with a ported descreened maf So my question is is it possible to freeze the maf? is this somthing that happens when it freezes? If its not freezing what could be going on with it?
01-20-2006, 11:59 AM
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when the timing comes back on are you spraying the wet stage as well....or is this JUST when the dry is present.
edit...i just reread what you said. Your saying that on a 55 shot it pulls timing all the way down the track...but when you go to like a 100 it does not pull timing and you go lean? If thats the case it may be nozzle placement? Blowing past the MAF?
edit...i just reread what you said. Your saying that on a 55 shot it pulls timing all the way down the track...but when you go to like a 100 it does not pull timing and you go lean? If thats the case it may be nozzle placement? Blowing past the MAF?
01-20-2006, 05:19 PM
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Single nozzle? style nozzle ie: straight open, straight fan, 90* fan? location of nozzle? direction of spray? A lot of tuners really know little about dry set-ups and we see this often, as they sometimes are unable to come up with a fix when they should be able to. If your doing a small hit and have added no timing, then likely you need to pull no timing. But again, tuners often do this with out knowing?
Robert
Robert
01-20-2006, 05:47 PM
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The problem is with the dry its there even if the wet isnt being used, The fogger placement was in the middle of the air filter aiming at the maf but the tunner felt that that was the problem so now it is in the side of the air lid blowing straight to the other side of the air box but it didnt change anything.
As stated before if its a 100or less it will pull all the way through but 150 will go lean at 115 mph and a 175 will do it at 110mph Now the night it was tunned at rev extreme we tunned it at 188hp to the wheels dry only and it was fine but two days later at the track it wouldnt pull 550 feet.
When you log the run the air fuel is right around 12.1 and the timming goes from 24* to 21* at wot and with in 3 sec. af will go to 13.1 and then all at once timming goes back to 24* and af goes to 15.0.
As stated before if its a 100or less it will pull all the way through but 150 will go lean at 115 mph and a 175 will do it at 110mph Now the night it was tunned at rev extreme we tunned it at 188hp to the wheels dry only and it was fine but two days later at the track it wouldnt pull 550 feet.
When you log the run the air fuel is right around 12.1 and the timming goes from 24* to 21* at wot and with in 3 sec. af will go to 13.1 and then all at once timming goes back to 24* and af goes to 15.0.
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01-20-2006, 07:01 PM
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Ill ask the obvious first...what size injectors, have you checked fuel pressure, how much power do you make NA???.....What is the injector duty cycle doing when ya spray it?
Or have you already verified that the MAF signal does not change when you hit it with the spray?
Or have you already verified that the MAF signal does not change when you hit it with the spray?
01-20-2006, 07:06 PM
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Originally Posted by cantdrv65
Ill ask the obvious first...what size injectors, have you checked fuel pressure, how much power do you make NA???.....What is the injector duty cycle doing when ya spray it?
Or have you already verified that the MAF signal does not change when you hit it with the spray?
Or have you already verified that the MAF signal does not change when you hit it with the spray?
Fuel pressure is 58 psi during the spray, 42lb injectors, fuel system is a 255 walbro with a booster only runs motor and dry kit, at 188hp to the wheels duty cycle was 82%, motor makes 415na and when the dry worked the night it was tuned it went 602
01-20-2006, 07:09 PM
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Move the nozzle closer to the MAF and aim straight for the wires.
The MAF will signal a higher reading, the PCM calculates more load, you'll get more fueling and less timing... problem fixed.
The MAF will signal a higher reading, the PCM calculates more load, you'll get more fueling and less timing... problem fixed.
01-20-2006, 07:18 PM
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Originally Posted by white2001s10
Move the nozzle closer to the MAF and aim straight for the wires.
The MAF will signal a higher reading, the PCM calculates more load, you'll get more fueling and less timing... problem fixed.
The MAF will signal a higher reading, the PCM calculates more load, you'll get more fueling and less timing... problem fixed.
That is where it started at 6" from the maf aiming straight at it
01-20-2006, 07:35 PM
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Well..im sort of stumped. It certinly should not be freezing the MAF. I have sprayed 300+ all dry down the MAF and never had a problem with freezing. And if it froze i would suspect it would go rich.
Here is a question...how low do you run you fuel in the tank? Have you ever had any fuel feed issues. have you watched your fuel pressure during the run? When it goes lean during a run do you feel it in the seat of your pants?
Here is a question...how low do you run you fuel in the tank? Have you ever had any fuel feed issues. have you watched your fuel pressure during the run? When it goes lean during a run do you feel it in the seat of your pants?
Last edited by 383LQ4SS; 01-20-2006 at 07:46 PM.
01-20-2006, 08:00 PM
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Originally Posted by 383LQ4SS
Well..im sort of stumped. It certinly should not be freezing the MAF. I have sprayed 300+ all dry down the MAF and never had a problem with freezing. And if it froze i would suspect it would go rich.
Here is a question...how low do you run you fuel in the tank? Have you ever had any fuel feed issues. have you watched your fuel pressure during the run? When it goes lean during a run do you feel it in the seat of your pants?
Here is a question...how low do you run you fuel in the tank? Have you ever had any fuel feed issues. have you watched your fuel pressure during the run? When it goes lean during a run do you feel it in the seat of your pants?
Fuel pressure has been watched several of times and is always around 58psi even when it goes lean, The tank has never been below 1/4 tank and we have never had any problems running the tnt at 150hp wet with this system,
And yes you feel it in the seat of your pants, thursday night it was jeted with a 61 pill ( we thought the new maf was going to fix the prob) the first pass at about the 600ft mark it went flat so i got of it right then,
The plugs where pulled and three burnt the ground straps cylinders 2-6-3
We replaced the plugs and turn the dry off and the wet on jetted at 225hp af was 11.8
So do you think it is a tunning problem?
01-20-2006, 08:04 PM
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Let me ask this. If the motor is at 6500rpm witha heavy load and we block off half of the air at the maf what would happen? will the maf see that there is only half the air comming through it and reduse injector pulse?
01-20-2006, 08:08 PM
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really it shouldnt be a tuning problem because it works for short periods and goes lean over time.
I mean you are spraying dry and at the begining of the track it has the correct AF right?
Do you have a katech belt tensioner? Do you have black belt dust in your engine bay? I have seen the whole system freak out when the belt slips..but thats generally at the begining of the track where rpm rise is the fastest through first gear.
Check your TPS on those runs....make sure you are less than what the book calls out for at WOT. Sometimes when going down the track you tend to push harder on the pedal and if the TPS goes over 4.4 or 4.5 it will cuase weird things to happen. Is this a FAST TB?
Thats all I can think of right now. Ill think more and let you know if i come up with anything.
Robert? Any other guesses from anyone else?
I mean you are spraying dry and at the begining of the track it has the correct AF right?
Do you have a katech belt tensioner? Do you have black belt dust in your engine bay? I have seen the whole system freak out when the belt slips..but thats generally at the begining of the track where rpm rise is the fastest through first gear.
Check your TPS on those runs....make sure you are less than what the book calls out for at WOT. Sometimes when going down the track you tend to push harder on the pedal and if the TPS goes over 4.4 or 4.5 it will cuase weird things to happen. Is this a FAST TB?
Thats all I can think of right now. Ill think more and let you know if i come up with anything.
Robert? Any other guesses from anyone else?
01-20-2006, 08:12 PM
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Originally Posted by 383LQ4SS
really it shouldnt be a tuning problem because it works for short periods and goes lean over time.
I mean you are spraying dry and at the begining of the track it has the correct AF right?
Do you have a katech belt tensioner? Do you have black belt dust in your engine bay? I have seen the whole system freak out when the belt slips..but thats generally at the begining of the track where rpm rise is the fastest through first gear.
Check your TPS on those runs....make sure you are less than what the book calls out for at WOT. Sometimes when going down the track you tend to push harder on the pedal and if the TPS goes over 4.4 or 4.5 it will cuase weird things to happen. Is this a FAST TB?
Thats all I can think of right now. Ill think more and let you know if i come up with anything.
Robert? Any other guesses from anyone else?
I mean you are spraying dry and at the begining of the track it has the correct AF right?
Do you have a katech belt tensioner? Do you have black belt dust in your engine bay? I have seen the whole system freak out when the belt slips..but thats generally at the begining of the track where rpm rise is the fastest through first gear.
Check your TPS on those runs....make sure you are less than what the book calls out for at WOT. Sometimes when going down the track you tend to push harder on the pedal and if the TPS goes over 4.4 or 4.5 it will cuase weird things to happen. Is this a FAST TB?
Thats all I can think of right now. Ill think more and let you know if i come up with anything.
Robert? Any other guesses from anyone else?