.... Have you tried a spare map sensor?

 

Just my .02 cents here.

Etching on the dist cap and rotor, along with the voltage fluctuations, and bad O2 readings, and bucking, would seem to point to a block to battery ground problem.

I just went through this with my truck (albeit I've got a 4.9) that's VERY block ground dependent at a single ground point.

I'd wire brush any and all block,frame,firewall,radiator support, grounds and check VERY thouroghly the main battery cable ground wire.

In my case there wasn't enough of a "good block to battery ground" for my MSD system (or the whole stock ignition system) to work correctly.
I fought a lean stumble for ages, even going as far as doing the EGR restrictor plate, vacuum delay valve, bandaid fix which I have since been able to remove.

Remember, a poor ground is resistive and will throw off any and all sensors values/readings (including the EEC) that rely on a good solid non-resistive ground connection.

Hope this helps.

Bob

 

Bought upper plenum set. Felpro came with plenum. Throttle body. Iac. Egr.
And some o ring for $7.00 Easier to remove smog pump crap with intake off.
Anyone know specs for torque on them? Or gutentight work? Lol
also picked up 11' of vac line. All told it was $18.
Figure even if this don't fix my issues... maybe i can see better what is wrong. And
With the age of the truck not like its a bad idea.

 

Thanks bob
Sounds similar to what i am getting. I was actually planning to run several new ground lines while doing this other work.
Was your truck running so rich u had fuel dripping out of tailpipes? I could damn near mount spark plugs in my exhaust and have flamethrowers. Lol

 

Sorry if this sounds dumb...
But i thought if i had mass airflow... i did not have map... :-/

 

Ok... i just looked at autozone.com... i'll be damned... it does have a map sensor... and what they say about it, is exactly what my truck is doing... where the heck is it on the engine?

 

Well it's not map but acts like it, right above your heater in the engine bay.

 

Ok Puddy, you win perfect fit idea of the year. Map sensor causes poor mpg. Bucking erratic idle. Pinging like timing is off. And several other issues i have.
Bought sensor. Had to look it up on their systems for a 5.8 but that is ok. I got home. There is no "map" sensor by the heater.and by god the idea seemed perfect... but it ain't there. And i can't see anywhere it could go unless it is under the intake. Or behind it.

 

Ok, I did some searching, like I thought.. Mass Air trucks don't have MAP. So, that even though it fit problem wise, cannot be it... now I am back to being totally stumped.

 

Try unplugging your MAF sensor and see how it runs.

Only the California/Mass F-150s got the MAF setup, which is why autozone lists a MAP sensor.

 

Unplug maf it idles up high then dies. Prior to fixing intake snorkle issue. Only way to keep it running was with maf unplugged.

 

It shouldn't die. I'm suspecting a possible computer or ground issue.

 

I have been thinking puter... going to re ground everything tomorrow afternoon.
But... i have heard it is a PAIN to get at puter in this truck. Not 100% how to get at it.

 

From inside the engine bay, need to remove the wheel skirt or at least half to slide it out. 10 mm socket on connector

 

here, its not a MAP sensor, its a BP sensor, (same thing pretty much when you convert from SD to MAF)
so Your MAF = BP
The Barometric Pressure (BP) sensor operates as a piezoelectric (pressure-sensing) disc. However, rather than generating a voltage, its output is a frequency change. The sensor changes frequency relative to intake manifold vacuum. The sensor frequency increases as vacuum increases. The BP sensor is used to sense the changes in barometric pressure, allowing the PCM to sense the altitude at which the vehicle is operating. Its signal affects, spark advance for altitude compensation.
The BP sensor was only used in early MAF systems. Starting in 1994 Ford learned that air pressure can be calculated once the MAF sensor tells the computer the amount of air ingested
Fuel Injection Technical Library » Barometric Pressure Sensor (BP)