OK, i have a range of MAF sampling tubes I need to test on my car. The different tubes are calibrated for different sized injectors but I do not know which one is for which. Theory at the moment suggests i have the wrong sampling tube for my *insert Raynier Wolfcastle voice* puny 19 pound injectors.
Can anyone enlighten me as to the theory of the sampling tubes? I understand how the MAF/hotwire/sampling tube works but would like people's thoughts on:
If a larger sampling tube will cause the engine to run richer? or vice versa?
I'm thinking - larger sampling tube, seeing more air for any given mass of air flowing into the engine and therefore supplying more fuel. Smaller tube - seeing less air for any given mass of air flowing into the engine and therefore supplying less fuel.
Cheers
Martin H
__________________ 1995 EF Futura: 4.9L V8 w/ Powerdyne Supercharger @ 7-8psi. Water Injection @ 3psi and above. Vortech Rising Rate FMU. 73mm C&L MAF. Shift Kit, VSS override, TCC override. Blue dash. Custom blue courtesy lights. Switched A/F meter, boost/vac and oil psi gauges. 6.5" TV, CarPC w/1500+ MP3, DVD and porn, precious porn
I'm thinking - larger sampling tube, seeing more air for any given mass of air flowing into the engine and therefore supplying more fuel. Smaller tube - seeing less air for any given mass of air flowing into the engine and therefore supplying less fuel.
Correct, larger tube = more fuel. Just check the colour of the sample tube, you should have a clear tube with the part number 101 (if you can read it). If it is blue (PN 102) then you have the wrong tube suited to 24lb injectors. Problem is that if you do have the clear 19lb tube, there is no smaller not that I think that would help you anyway. Because you are running rich under full throttle it is not a MAF problem because the MAF is not used under full throttle. The way to solve this would be using an adjustable fuel pressure regualtor to turn the fp down a bit, or reprogram the EEC to supply less fuel.
Ahhhh, my forced induction con******ts to the rescue!!!!
ebxr - lol, i'd have to agree with ya, this does not sound like an ideal solution. And im not sure how much assistance CAPA would be willing to provide if they cottoned onto me doing this They've been real good so far, would hate to get them off side.
Grant - cheers for confirming my thoughts. The sampling tube I have in the MAF now has the red mark which I believe is for the 30lp injectors. One of the tubes sitting here has no mark on it and is visibly smaller than the 'red' one. Fair to assume this is the correct one for my injectors.
Im interested to hear more about the MAF at WOT.... I was under the impression the opposite was true. i.e. under WOT, EEC looks at the MAF and TPS values and calculates fuel requirements and engine load based on MAF/TPS voltage. Under open loop (i.e. cruising) I thought fuel requirements were based on HEGO and several others (coolant temp etc.). Having said this, all the advice you've provided over the last month or so has been GOLD so im inclined to take your 'side' lol.
Appreciate the comments fellas. I guess truth will only be told on the dyno.
__________________ 1995 EF Futura: 4.9L V8 w/ Powerdyne Supercharger @ 7-8psi. Water Injection @ 3psi and above. Vortech Rising Rate FMU. 73mm C&L MAF. Shift Kit, VSS override, TCC override. Blue dash. Custom blue courtesy lights. Switched A/F meter, boost/vac and oil psi gauges. 6.5" TV, CarPC w/1500+ MP3, DVD and porn, precious porn
Assuming the 4DED EEC is similar to the A9L stang EEC then the tables tell me exactly what i wanted to hear (these windsors are likened to the 86-93 5.0L HO from the states arent they?)
__________________ 1995 EF Futura: 4.9L V8 w/ Powerdyne Supercharger @ 7-8psi. Water Injection @ 3psi and above. Vortech Rising Rate FMU. 73mm C&L MAF. Shift Kit, VSS override, TCC override. Blue dash. Custom blue courtesy lights. Switched A/F meter, boost/vac and oil psi gauges. 6.5" TV, CarPC w/1500+ MP3, DVD and porn, precious porn
Is that where the maf always sits on a blown windsor?
No there is 2 ways of running the MAF on blown motors. 1st is the way 4.9 EF Futura and CAPA do it which is a blow through design. The other way is how I have done it which is to mount it before the blower in a draw through setup.
Quote:
Originally Posted by 4.9 EF Futura
Assuming the 4DED EEC is similar to the A9L stang EEC then the tables tell me exactly what i wanted to hear (these windsors are likened to the 86-93 5.0L HO from the states arent they?)
Correct, same type of EEC. Having the red 30lb tube would explain your problems , now just have to get it back up on the dyno.
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They've been real good so far, would hate to get them off side.
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