Hello everyone!
I just bought an 88 5.0 C6 F150 Custom. I got a rediculously good deal because the guy said that the engine had thrown a rod and was frozen. I had every intention of swapping in a carbed 351W, untill I discovered that the nosecone had broken off the starter, and the engine wasn't really done for. Especially nice since it was supposedly remanufactured with only 15000 or so miles. I'm keeping the 5.0 for the forseeable future, but I'm new to intensive work on EFI.

That isn't to say nothing was wrong with it. The muffler looked like it had been blown up and the tailpipe had rust holes. Both of them got replaced. The engine idles and runs rough. I changed plugs, ignition wires, distributer cap, and rotor to good effect and plugged a few minor vacuum leaks.

Today, I bought a code reader and did the KOEO test, turning up codes 31 and 66 - EGR and IAC trouble. The EGR was completely clogged with crud, and the truck ran much better after I got the worst of it off and freed the valve. Next, I took off the IAC and discovered an uncapped vacuum port on the intake below it. The IAC didn't look jammed up, but I'm cleaning it tomorrow and plugging the vac port. If anyone has any suggestions on where to go from here, I'm all ears.

My questions involve emissions. Testing isn't a problem where I live, and a previous owner has replaced the replaced the catalytic converters with a straight pipe. Also, the thermactor has had it's vacuum lines cut out and the tube coming off it appears to terminate somewhere around the transmission. I assume this could be the source of the exhaust noise I'm hearing. Removing emissions is not a choice I would have made, and I have no plans to do away with EGR or anything else.

That being said, I think the non-functional smog pump has to go, and I have no intention of violating what I see as a perfectly good exhaust. What kind of problems can I expect from the EEC-IV without the smog pump and cats? How can I get around these problems? What size serpentine belt will I need? How hard is it to run bolts into the holes in the head where the the thermactor plumbing attaches to the heads?

Thanks for your patience in reading this long post and for all of your help.
Joe

 

My vote is to put a new smog pump back in. Depending on where it dumps the air into the system of course. If it feeds it before the 02 sensor, leave it, if not, dump it. Cant help you on the air pump delete belt, try a search of the database here, or a google search. Use keywords 5.0 air pump delete belt or something like that. (for google) on the board, 5.0 wont work, its not long enough of a word

 

Normally the air pump output goes to the cylinder head (and thence the exhaust ports) during cold start and warm-up, and is then re-routed to the catalytic converter once the engine is fully warmed up. Without the catalytic converter, the air pump does realtively little to reduce emissions. The line on your truck that "terminates" near the transmission is the one that used to go into the converter.

Lots of guys report that they can remove the air pump without freaking out the EEC-IV too badly. Unless you plan to put the catalyst back in, I'd say the path of least resistance is to finish removing the air pump. Research some of the other posts on the subject of "remove air pump" or "remove thermactor".

 

masterbeavis: Without cats, I've got no interest in a new thermactor. Right now, it's just pumping air out under the truck.

fefarms: Thanks for easing my mind. I've done the required reading and I'm ready to pull the pump. I think I'll even do it "right" and install the proper resister so the computer doesn't balk.

After leaving the battery unplugged and giving the EGR and IAC valves a thorough cleaning, the truck still runs rough. I redid the KOEO, and I took care of the IAC code, and the KOER turned up a thermactor code (not surprising), a power steering code (I've got a slow leak), and no.77 (user error). The EGR code is still there, saying that it's stuck open or closed. The thing is, it's not. Could it be a faulty sensor? Would this affect the running condition?

I drove the truck today, about 30 miles round trip to get some new front tires mounted, as the old ones were shot. She'll do 65 mph on a flat stretch with a tailwind (groan). No power whatsoever. I guess I'm back to basics: compression check, vacuum meter, and timing check. I'm sort of paranoid about some white smoke I saw today, once first thing in the morning, and once this afternoon. Needing a head gasket (or worse) would certainly prod me into the 351W swap.

There's a continuous pulsing that I can feel hard through the steering column. It's most prominent between 25 and 35 mph, and I hoped the new tires would fix it. No luck, and it's not the U-Joints. By the time I was getting home, the tranny was slipping. Pulling into the driveway, I noticed smoke from under the hood. A shoddy patch on the lines going to the radiator led to a major leak, and transmission fluid went everywhere. It took nearly 3 quarts to fill it back up.

As always, help is appreciated. I'll post more tomorrow.

 

Code 31: EVP circuit below minimum voltage of 0.24 volts.

You need to troubleshoot the EGR Position Sensor for this problem.
Your truck seems to have been hacked enough that I would start by checking the wiring to it.

Best wixhes,
Popa Tim

 

Heres a tip. Dont drive er too far from home lol. I think it'll be worth it in the end and if the old 302 pukes, you have a 351 ready to throw in er.