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Discussion Starter · #1 ·
I have a 1987 mustang gt. Its running real rich and is getting between 5 and 6 mpg. Id like to get better gas milage, but I also need to pass state emissions for an inspection sticker. I've brought it to a few mechanics and everyone has said it has a cam in it, and I also had an idea that it might by the way it idles. One guy was telling me how the 87 mustangs had m.a.p. sensors, and those can't compensate for a bigger camshaft or any other mods you do to the engine. An option that he thought might help would be to get a mass airflow conversion. I've checked those out online and have seen them from about $500-600. Does anyone have an information on either my problem or and info about the mass airflow conversion kits? If I bought one would it make up for the cam and not run so rix? And what would it do to my gas milage?
Tom
 

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The sensor used in an 87 Speed DEnsity car is called a MAP - manifold absolute pressure sensor. BAP - barometric atmospheric pressure sensor is used in MAF cars. If you have a MAP and it's connected to read manifold vacuum, then yes the cam is to much cam and your idle vacuum is too low and the EEC is getting the wrong info that the car wants more gas than it needs. SD cars need good vacuum to work correctly - 13+ " of vacuum at idle. Check it.

Converting to MAF will correct the problem but you may have to buy two new O2 sensors to get everything to work right again. Running rich for so long may have damaged your O2 sensors.
 

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a9l- $100-125
splice in harness- $35
stock maf meter- $30 or spend the extra 120 on an aftermarket
few hours of work- priceless

and much cheaper than the conversion kits
 

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Discussion Starter · #4 ·
I've checked the vacuum pressure is way to low. Would converting to mass airflow help out my gas milage?

and to madmax- what do you mean by a9l?

Thanks
 

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I just converted my a couple weeks ago, getting another 50kms/tank, with the gas prices, I'll take whatever I can get :D...lol

the a9l is the computer you have to get.
 

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Before you go get an A9L , which transmission are you using? Manual or auto? If it's manual, go with the A9L.

I was running Speed density for a long time with heads, intake manifold, throttle body, 21lb injectors, headers, offroad H pipe upgraded and the smog / egr removed, and IMO ran better than stock. Once I bought this 89 GT (mass air flow) , the idle was so much more precise and I did notice better MPG.

After I upgraded the MAF to a larger unit, I felt a huge performance gain. After I went to ported trickflow heads and their cam.... that was the biggest night and day difference I have ever felt.

Rule of thumb, speed density doesnt like cam changes like Tmoss stated, because the vacuum drops from 114 Lobe seperation to usually 112 or even 110 depending on the cam. There Iskarian (Isky , spelling?) cams are out there that are supposed to be speed density friendly but they are pretty mild and don't justify the work required to change out a camshaft IMO.
 

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Discussion Starter · #8 ·
ghostdog - its a manual transmission

aleborjas- Im not sure what cam is it in, because the kid who sold it to me had no idea and wasnt even sure if it had a cam. Ive tried to reach the people who owned it before him but havent been able to. Does anyone know if theres anyway to somehow look up who has owned the car previous to you?
 

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After reading this,I'm going to start collecting the Mass Air pieces.E-Bay,here I come.....................
 

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madmax,
I'm doing the conversion this winter. I'd like to get the parts vs the $500+ kit. Do you know of any posts detailing the splicing into the harness or do you have to replace the whole harness? Also, what MAF sensor do you recommend for a 70mm TB and cold air intake? (running the Typhoon upper/lower and doing heads and cam AFTER the conversion)
 
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