Hi, and thanks in advance. I have a 1993 f-150 4x4 5.8L, i have been trying to fix something not sure what, if that makes since.

First off a few weeks back, i noticed it was missing and has bad gas mileage like 9mpg, it started erratic idle and running rough, and i was getting codes for thermactors and egr and occasional map, so i knew it was a vacuum problem. So i replaced all nylon lines with gates rubber hose and my vacuum canistor had a hole in the bottom so i replaced it with the plastic style that came on the 96' f150. Well thought i was doing good, but still missing and bad on gas but wasnt throwing codes(yet) i dont drive this truck much because of the gas mileage. but it started erratic idling like going down to 750 and up to 1100 or so, so that was aggrivating so i thought i would dig into my truck a little further. I had a egg smell so i thought my cats might be stopping up causing the erratic idle so........ here is what i have done so far.

-replaced all vaccum lines and canistor
-valve cover gaskets, ladder gasket, and tb gasket, and idle air gasket
-ECT sensor
-cleaned ACT
-cleaned IAC, it isnt very old but i figured i would clean it while in here
-cleaned throttle body
-deleted smog and plugged holes, turned smog pump into pulley, welded hole up on exhaust for thermactor piping.
-gutted converters
-left thermactors intact with electrical and vacuum, just plugged the ones going out
-left EGR and vaccum
-test o2 sensor, holds around 5 milivolts at idle and moves around with throttle changes, quick response on quick revs, truck was fully warmed up
-checked fuel pressure, think it was 32 with vacuum and 40 w/out
-checked spark plugs(#8 has oil on it) probably my miss
-set base idle
-checked map sensor tested with a different one just in case
-checked tps, adjusted to .99 volts
-unhooked canister for purge valve to see if that was doing anything

after all of that, i get a code 173(HEGO fault/rich), i have one o2 before cats and that is all, it has been replaced before, the truck doesnt have but 141,000 actual miles. i did not have this code until after all of the repairs. it seemed to run fine until i took it on about a 30 mile trip to lowes hardware, on the way there it was good, at lowes when i was leaving it started erratic idle went down to 500 and smelled of fuel bad until it idled up, then on the way back home it would be ok if no one was in my way just driving, but if someone turned or i had a stop light, when i would try to accelerate it was like it was struggling or something, it would be hesitant i guess until i got it on up on rpm's then it would be fine aside from a noticable miss. so when i got home i check KOEO codes got 173 and Continous code was 628, which i know is torque converter, KOER results in same code 173.

I am kind of lost at this point i barely have enough money to get through my week at time check so going out and buying a bunch of sensors is out question, does anyone know what could have triggered this code just by the things i have done so far, thanks

also was wanting to confirm something, i heard from a former ford tech, that code 173 was on a technical service bulletin, stating that if i dont replace the o2 that it would fry my computer if i keep driving it with this code. says its a bad o2, and that code has something to do with a circuit that shoots directly to the pcm with no fuses or anthing to protect the computer and it could mess it up.

 

Check the purge canister solenoid it is located beside the egr valve it will have a in and out vacum line. Unplug it and pull off the out vacum line going to the canister on the rail if it is pulling vacum with it unplugged it is bad. If its not pulling vacum its ok. As far as the 628 code ckeck the plug on the side of the tranny it will be on the passenger side behind a heat sheild make sure it is clean and not loose. Also check for bad grounds. If still no luck try pouring some seafoam trans tune in the tranny and run it for a bit and change fluid and filter along with draining the torque converter. If that dont work time for a rebuild or a new solenoid pack. Id try the solenoid pack first before the rebuild. Hope i could help

 

Ok ... just sort of stepping back away from all of the details and looking at the overall.

The motor was missing and getting bad gas milage.

You went to work on it and made some engine modifications.

The end result is worse than what you started with.

======================

The next logical step is to backtrack and figure out where things went wrong.

 

(I'm by no means any kind of expert so verify everything.)

Here's where i would start looking.

1: Double check your vacuum reserve canister to make sure that the new plastic one functions just the same as the old one. Two things to look for:
A: There's a check valve built into the old one
B: Verify that the inlet & outlet connections are the same.

2: I do know that the rotten egg smell is dilute sulphuric acid in the exhaust. It's due to high sulphur content in the fuel. I have no idea of what the implications of hollowing out the cat would be. I'm not an engineer.

3: The thermactor system dumps air into one of three places.

A: upstream of of the o2 sensor into the exhaust manifold.
B: downstream of the o2 sensor into the cat
C: straight into the environment

I don't know, but it seems reasonable to assume that the engine management computer(PCM) is basing it's decision on where to send the air on the readings it's getting from the o2 sensor.

If it's calling for air upstream and none is coming in ... what would be the effect on overall engine performance ?

I can't answer that question ... i'm not an engineer.

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What it all comes down to is that the self diagnostic was designed to work with all of the original equipment intact.

When you make changes, it throws a wildcard into the mix and that makes it difficult or impossible to correctly diagnose what's going on.

I wish i could have been more help but this is way over my head.

 

no, it didnt get worse it just didnt help it all.

 

well i saved everything that came off the truck just in case this failed, i used a smog pump i had laying and gutted it for a pulley, i have seen tons of people on this website do all of this and they said there vehicle ran better and got rid of a bunch of junk under the hood, its already difficult just change spark plugs without all that junk in the way, now its easier to check plugs. i checked my purge valve it doesnt pull any vacuum when unplugged from the canister.

 

What to pull off ... what not to pull off ? It's sort of an ongoing debate and everybody has their opinions. The thing is that it's your truck and your choice.

My viewpoint comes from hard earned experience. I bought my truck back in July from a small lot dealer about 90 miles away.

Part of the deal was that he would deliver it in a couple of days after his shop mechanic had a chance to change out the exhaust manifold gasket. ( It's a simple enough job )

He went to work and right off broke the manifold bolts off inside the head. The head had to be replaced and somehow in the process he messed that job up and destroyed the motor.

They fired him and brought in the next guy. He started the process of swapping out the motor and they fired him three days later after he threw a screwdriver at the boss.

It's going on three weeks later than the agreed upon delivery date.

Mechanic number three was finsihing the job but he was running into problems and more delays.

I flat out told them to bring the truck down because the longer those guys had their hands into it the worse it was going to be when it finally arrived.

I've been sorting the mess out ever since.

Now ... these guys weren't particularly incompetent. In fact ... when it came to nuts and bolts they were pretty good. The problems come from the fact that they had little or no understanding of the computerized Ford electronic fuel injection system.

That's actually pretty common.