whiplash-smile Posted November 11, 2003 Share Posted November 11, 2003 On the maf sensor of a 1988 turbo, does anyone know what the little screw(has a black plastic cap over it) that is next to the sensor plug-in does? I was hoping it could enrichen my air/fuel ratio... if so what way to turn it? Thanks! Quote Link to comment Share on other sites More sharing options...
calebz Posted November 11, 2003 Share Posted November 11, 2003 Been wondering the same thing,, I asked a couple of months ago, but no one responded..I have an 88 factory service manual, but it doesn't say anything about that screw Quote Link to comment Share on other sites More sharing options...
GLCraig Posted November 11, 2003 Share Posted November 11, 2003 I'm going to guess that the screw is for a variable resistor, used to calibrate the base line voltage for the MAF. Quote Link to comment Share on other sites More sharing options...
whiplash-smile Posted November 11, 2003 Author Share Posted November 11, 2003 Hmmm, I was wondering how many people have dealt with this... Did you experiment at all with it? Quote Link to comment Share on other sites More sharing options...
GLCraig Posted November 11, 2003 Share Posted November 11, 2003 No I have never played with one. Quote Link to comment Share on other sites More sharing options...
whiplash-smile Posted November 11, 2003 Author Share Posted November 11, 2003 Caleb, did you do experiment with this? Sam Quote Link to comment Share on other sites More sharing options...
XSNRG Posted November 11, 2003 Share Posted November 11, 2003 I haven't looked at mine. Quote Link to comment Share on other sites More sharing options...
calebz Posted November 11, 2003 Share Posted November 11, 2003 Nope, Haven't messed with it.. wasn't sure waht it was, so I didn't want to mess anything up. Quote Link to comment Share on other sites More sharing options...
electryc_monk Posted November 11, 2003 Share Posted November 11, 2003 well I have a V-O-A meter and we will be able to find out in a few days... I'll look at my FSM and think about it and see what happens later this week, okay? Quote Link to comment Share on other sites More sharing options...
whiplash-smile Posted November 12, 2003 Author Share Posted November 12, 2003 Caleb, yeah I know what you mean, I wasn't real excited about dinking with it on a Sunday afternoon... when I was using it to get to and from work, but my other car is back, so Electryc_monk, you tell me which way you turn it and how much and I'll go the other way! Rich is GOOD! Quote Link to comment Share on other sites More sharing options...
78TurboBrat Posted November 12, 2003 Share Posted November 12, 2003 The little screw on the MAF is for enrichment of fuel, but only a small ammount, it is set at the factory, to regulate the fuel supplied to the motor acording to how much air the MAF sees going through it. kind of like a multiplier, say you have 100 cfms of air coming in, EXAMPLE ONLY dont take my words for truth on this part about the numbers... the maf has a potintiometer in it that tells the computer that where the vane is, and the vane says im at 100cfms of air, so you are allowed to multiply x 2 to make up the fuel mixture for it, so if you turn it one way you will notice a slight difference, but nothing really noticable. so you could say you could move the multiplier by one or two points, maybe more. but not enough to really make a difference even for the turbo motors. cause the O2 sensor will correct you when it see's u running richer, and the computer will adjust to lean it back out. LOL gotta love those computers. the only purpose for the screw is to basiclly set a point for the computer, and the computer has its margines to ride in, so the screw makes that happen. and not give you a check engine light. but you would really see a fuel inchrichment if you took out the O2 sensor or unpluged it. although you would have a check engine light on, and black smoke coming out the rear, now who wants that. so the best way to richen your fuel with a turbo and high boost levels is to run a second set of fuel injectors set up through a boost controller and when you reach a certain ammount of boost it will open the other fuel injectors and give you more gas for the higher boost, but usually only needed for running 16 PSI and up with boost levels. Sorry didnt mean to be so lengthly about it. but i have seen people do it to get what they needed. never did it myself. Oh yeah that black cap is there so people dont mess with it !!! but that is why we are always wanting to find out what they dont want us to know about... :banana: Quote Link to comment Share on other sites More sharing options...
mitch184 Posted November 12, 2003 Share Posted November 12, 2003 i'v heard the limp mode caused by disconnecting the 02 sensor makes the engine run richer than normal. Has anyone with a turbo tried to just disconnected the o2 sensor permanantely? just a thought. Quote Link to comment Share on other sites More sharing options...
Skip Posted November 12, 2003 Share Posted November 12, 2003 I'm sorry 78TurboBrat, your excellent description is for the wrong style mass air flow sensor, we were discussing the hot wire not the vane style. But your comment on the the no need for fuel enrichment untill you get to 16 PSI is on the mark as far as my empirical observations go. Subaru, as they often do, over engineered the fuel delivery system, mine runs super rich - up to 15 PSI (where I have my boost level set) Quote Link to comment Share on other sites More sharing options...
78TurboBrat Posted November 12, 2003 Share Posted November 12, 2003 Thanks Skip, didnt know which one thye had, i only know of the Toyota MR2's i play with, i can adjust the actual vanes spring load under the cap, and turn the screw counterclockwise, and gain alot more fuel. on the note of them having the hot wire. will have to play with the one in the 87 wagon and see what happens. i have a gas analyzer, and i can see if something changes, and of course performance. although it is a 1987 wagon, automatic, turbo. probably wont be able to tell much of a difference. but i will play with it this weekend and get back you all about it . Quote Link to comment Share on other sites More sharing options...
Vanislru Posted November 13, 2003 Share Posted November 13, 2003 I haven't ran without the o2 sensor but i am running without my engine coolant sensor. After days of poking around I found the reason for my hesitation probs. engine coolant sensor. removed replaced. noticed car ran cooler/rich without ecs. connected. hesitation problem came back 2 weeks after new ecs was installed so I disconnected ecs. connector and voila! no hesitation rich/cooler engine. No pinging @10 psi with no ic and timing @ 25 btdc. I'd like to find the source of the ecs b.s. but thats another thread, for now I'll run rich. still 500km to 50$ tank of 94, Hard drivin. Quote Link to comment Share on other sites More sharing options...
Adam N.D.J. Posted November 13, 2003 Share Posted November 13, 2003 Yes, if you disconnect the O2 or have a faulty one for tha matter, the computer will run in a default mode (won't go into closed loop), and you will run really rich. I'm having this problem with my Brat right now cause I haven't put a place in the exhaust to even put an O2 so I don't have one in there. When I accelerate, huge clouds of thick black smoke are produced, and I have crap for gas mileage (less than 10 mpg) Quote Link to comment Share on other sites More sharing options...
mitch184 Posted November 14, 2003 Share Posted November 14, 2003 i've got an 87 turbowagon and was wondering if disconnecting the sensor would work with the hot air wire MAF. What thermostat are you running, im going to run a 160 if that makes any difference. Quote Link to comment Share on other sites More sharing options...
WJM Posted January 21, 2005 Share Posted January 21, 2005 Does anyone know what the screw is for?????? Ive got 3 MAF's and im about to play with one if them...so some help would be useful. Quote Link to comment Share on other sites More sharing options...
JWX Posted January 21, 2005 Share Posted January 21, 2005 get yourself a wideband or something Quote Link to comment Share on other sites More sharing options...
WJM Posted January 21, 2005 Share Posted January 21, 2005 damnit, what is the screw for? Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted January 21, 2005 Share Posted January 21, 2005 This is kinda funny because I was planning on posting something today about the same thing. I guess great minds think alike, eh?!! LOL Anyway, I messed with that screw last night for the short while that my MAF was working(need to replace it *ECU courtesy of Calebz Horsepower Industries:grin: * J/K LOL). After the check engine light decided to turn itself off(for approx. 15 mins), I took the car around the block and kinda got on it a little. It felt like it had a little more power than it used to, well before my old ecu crapped out. But right before I pulled into my parking space, the CEL came back on and the car started to run like crap and throw the code 23 again. So, in conclusion of my little scientific experiment, I have absolutly no idea if it does something or what have you. All I can say is make sure you know where the thing is adjusted, and try giving it a slight turn(forward or backward). It might help, or it might suck, but at least you know how to adjust it back to the right setting. Patrick Quote Link to comment Share on other sites More sharing options...
calebz Posted January 21, 2005 Share Posted January 21, 2005 Patrick. I probably have a MAF here for you too.. Of the four I have, one is bad and I can't remember which it is though:-\ Quote Link to comment Share on other sites More sharing options...
rallyruss Posted January 21, 2005 Share Posted January 21, 2005 the screw is a fine adjustment for IDLE air control at the MAF same as the flaper style. I dont think making the car run richer at idle has any performance benifits. this is the wrong way to modify fuel delivery in my opinion. either keep your fuel system stock and working properly or go all out and set up a Mega Squirt or some other programable fuel system. engines that run too rich OR too lean dont last. O2 and coolant temp are inportant to keep your car running well if you have to disconnect/remove either to make you car run better there may be another problem. Quote Link to comment Share on other sites More sharing options...
All_talk Posted January 21, 2005 Share Posted January 21, 2005 I’m with Russ on this one, the stock system already runs quite rich in the boost region of its fuel map (sensed by flow not pressure), this supplemental fuel is to provide some charge cooling and a good safety factor. With an IC the stock system should handle some additional boost without going lean (it’s the added flow that will bite you in the top end… fuel cut). The stock system is VERY well engineered to do what the maker intended it to do, they just didn’t build in the adjustability for extensive mods. If you are serious about big power mods an aftermarket fuel system is the only way to do it right. Just my thoughts Gary Quote Link to comment Share on other sites More sharing options...
Myxalplyx Posted January 21, 2005 Share Posted January 21, 2005 I’m with Russ on this one, the stock system already runs quite rich in the boost region of its fuel map (sensed by flow not pressure), this supplemental fuel is to provide some charge cooling and a good safety factor. With an IC the stock system should handle some additional boost without going lean (it’s the added flow that will bite you in the top end… fuel cut). The stock system is VERY well engineered to do what the maker intended it to do, they just didn’t build in the adjustability for extensive mods. If you are serious about big power mods an aftermarket fuel system is the only way to do it right. Just my thoughts Gary Nice point Gary! If our fuel system is optimum though, why did my air/fuel ratio change from an optimum 12.0:1 air/fuel ratio to a 13.0:1 between dyno runs? It even went up to 14.0:1 and all I had done was a pulley install. Perhaps playing with the maf sensor screw could've 'Garnered' better results. Quote Link to comment Share on other sites More sharing options...
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