Did Somebody Put a MAF engine in My SD Truck?

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BessietheBronco90

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Hey all,

I'm a brand new member, but have gotten lots of great info from this site. I would first like to thank you for bearing with me, as this might be a long post. I'll try to stay on topic but let me preface with a little about me, and my Bronco "Bessie"

I purchased my 1990 Bronco XLT 302 from a third party friend of the previous owner for $285. At the time, it was not drivable due to a leaking fuel rail at the crossover pipe. I patched it up with a piece of hose since it was just a pinhole dead center, and it hasnt leaked yet. But more on that later... The engine would run so-so with a hesitation on acceleration, a shake at idle, and a bad engine vibration at 1500-1900rpm while cruising. After a few mins of running, the MIL would illuminate and truck would essentially be in limp mode. Upon trying to recieve codes, the pcm was determined to be faulty. I replaced the PCM myself and matched the numbers on the old one to the new one, which also happened to match the stock specs on the truck. 1990 302 non-** with 4AOD trans. This fixed the "limp mode" problem completely, but the engine still ran rough.

I replaced all spark plugs with NGK R platinums gapped to .42, Motorcraft wires, Napa select cap and rotor. Ran a compression test. No less than 148psi no more than 151psi on all 8 cylinders. However, when I went to hook the wires up according to the stamped firing order. No start. After some fiddling and head scratching, I tried the **/351w firing order to my surprised success. SWEET!

Except it still ran like crap. No MIL illuminates, but it smells like it is over fueling. Plugs were soaking wet after a long drive this weekend. Lacks a lot of power, the engine vibration at 45mph shakes the whole truck.

I was able to locate a casting number on the block above the starter that read F1SE. My question is this: Does this stamp specifically mean my engine is from a 1991 Thunderbird? Or is it just an initial cast date? Does this mean I have aroller cam in my truck? If so, is it a possibility that my PCM isnt designed to run either the firing order or the cam since the PCM is for SD and uses non-** firing order?

I plan on tearing the intake off tomorrow to replace the fuel rail and some valve cover gaskets, and find the partial VIN stamp on the back of the block to help further identify this motor. I was considering pulling the cam out anyway to help identify it (Previous owner could very well have changed it) and possibly upgrade it. I also have a friend who is selling me a good fuel rail and has the wiring harness, maf, and pcm. This has been kind of a headache for me and I've been using this site in a lot of my searches. Thank you for reading this, and if anyone who's ever gone through something similar can chime in, I would be forever grateful.

-Randall

 

miesk5

96 Bronco 5.0
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Yo Randall,

Welcome!

I just typed a long reply, but lost it when my tablet hung up on a pop up ad at Supermotors.

Here is a recap. But I am tired now, so will hive you some of

Info for now.

plug wire routing in 90 Bronco by Tank92 @

http://www.supermotors.net/clubs/superford/registry/5180/32495

Speed Density EFI Overview; "...In 1986, Ford switched to EFI on 5.0 Bronco engines. 1987 brought the first EFI 5.8. The EFI Ford used for almost all Broncos is what is called speed density. Speed density EFI uses a manifold absolute pressure sensor (MAP), a throttle position sensor (TPS), an air intake temperature sender (ACT) , and the knowledge of the factory intake/exhaust tract which gives your engine certain volumetric efficiencies over it's RPM range. This allows the EEC-IV (Electronic Engine Control IV) to determine the mass (different than volume) of air coming into your engine, and hence the amount of fuel needed to go with this air. Speed density EFI also uses what is called bank fire injection. 4 injector are fired at one time on each side of the engine (only 2 wires for firing injectors from EEC-IV)...."

Mass Air EFI (Sequential Firing) Overview; "...A mass air sensor directly reads the mass of air (or number of molecules of air). By doing this, it can detect the changes in the volume of air, in addition to it's pressure and temperature. Mass air EFI is usually what is called SEFI (Sequential Electronic Fuel Injection), which has one separate wire for each injector and fires them twice for every power stroke of the engine. This makes the injector timing more accurate and will help emissions along with power..."

MAF Upgrade in a 90 5.8 by SEATTLEFSB @ http://www.fullsizebronco.com/forum/7-1980-96-bronco-tech/164963-maf-upgrade-lessons-learned-thread.html

See his PCM SWAP info, etc.

Did previous owner or shop install a MAF Sensor on throttle body side of the air filter box?

Also, is MAP Sensor still wired and have vacuum hose on passenger side of firewall?

Manifold Absolute Pressure (MAP); used only in Speed Density Systems; Location pic in an 88 by Jem270 @

http://www.supermotors.net/registry/media/667259

Wiring Diagrams, partial @ http://www.revbase.com/BBBMotor/Wd

And in SEATTLEFSB SITE @ http://www.supermotors.net/registry/20487/76450

Supermotors is VERY SLOW. IT GAVE ME A HEADACHE.

WILL THINK MORE ABOUT YOUR PLIGHT.

 

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