jburcham04

I have searched and read different opinions on deleting emissions on this motor (4.9 efi). I cant get a clear answer really on what im looking for. I just purchased a 91 F-150 single cab short bed 4x4 manual. The truck has been sitting for a few years and i bought it off a guy for $1900. It has a new tranny, dist. cap, wires, plugs, and radiator. I have stripped it down to where i can take the valve cover off because it runs good except #1 isnt holding compression. I can look down the oil filler tube and see the 2 valves for #1 cylinder. Well the aft valve isn't moving with the truck running. i'm taking the valve cover off tonight and ill let you know what i see. I live in GA and have no emissions and the truck is gonna be used for running around in and hunting. Alot of the tubes, hoses, and plumbing broke and is dry rotted while removing the intake and I can move the air injection rail by hand which i hope is my exhaust leak sound while going down the highway. My main concern is while i have it tore this far down what can i safely and efficiently remove on this truck where it runs decent and wont be backfiring going through the hunting club? I've heard just plugging the injection rail, removing egr, and air pump but their from alot of old posts. Can you ol' timers share some knowledge with me? My goal is to have a good running truck without having hoses and tubes all over the place.

Just call me Sean

iTrader: (1)

Could be a pushrod popped out, happened to mine. Take off the lifter cover and look.

Keep the EGR, it helps with fuel mileage. You can get rid of all the AIR injection stuff except the control solenoids so the computer thinks it's still controlling it, but you have to hollow/delete the cat.

jburcham04

Yep, it was the intake push rod. Wedged between the rocker arm. It bent it a Lil bit so I'm getting some new ones. What do the control solenoids look like? And can I remove that pump and all the cans on the passenger side fender well?

jburcham04

Got it back together and runs excellent. I used a 2" brass pipe nipple with a cap 1/4npt. To block off the air rail injection holes and that fixed the exhaust leak sound. Replaced the Pushrod and put it all back together with new gaskets. I removed the hose that went from the Valve thing or whatever it's called that has a hose coming from the air pump then a hose from there to the air injection rail. Well I removed the hose for the rail and capped it off. I was supposed to run it to the cat? How?

Monty61377

I also have a 4.9 in my 91 f150 and at idle sounds fine but when driving has a noise like a serious exhaust leak. I was told exhaust manifold gasket but after reading a lot of posts here on the subject, I'm not so sure it isn't the air injection has a leak someplace. At any rate if I remove all of that and the EGR and cat and just plug it all off, will it run right and do I get the cel for any sensors?

Just call me Sean

iTrader: (1)

Dude, read before posting. That info is right up there ^^^^.

jburcham04

Well everything has been going good with the air rail deleted until last week it started spitting and sputtering and won't idle and very jerky down the road, I'm getting codes: 117 Low voltage Engine coolant temperature sensor (ECT) Normal operating temp not reached
126 MAP voltage above spec
122 Low voltage throttle position sensor (TPS)
112 Low voltage air change temperature sensor (ACT) Normal operating temp not reached
327 Electronic pressure transducer (EPT)/differential pressure feedback exhaust (DPFE) sensor/electronic vacuum regulator (EVR)
513 EEC IV module reference voltage V
552 Pulse air circuit failure
565 Canister purge solenoid (CANP)
556 Electrical circuit of fuel pump
558 Electrical circuit of (EVR) electronic vacuum regulator.

So I cleaned the grounds, new dist cap, plugs, wires, 02 sensor, iac, coolant temp sensor, map, fuel pressure regulator, fuel pump, new exhaust from 02 sensor back no cat just muffler, ecu relay, and got a ecu from a junkyard, still the same codes and running rough with all these changes. Wth?

Franklyn

bump
I'm in the same boat

jburcham04

I'm gonna replace the tank, another fuel pump and all the injectors next... This thing is killing me!

candyspaw

Gee, I suppose if you keep replacing stuff, you may eventually find the problem, however I have an idea. During my problems, I kept a log of what I'd done and the codes I got and when. Write down everything you've done and what codes popped up in the process and I'll bet you find that some of your alterations have caused some of the codes. Just a thought. Grounds, of course, should always be cleaned and checked as well as all connections.