Couple codes I haven't figured out 94 ranger 4.0

[Buds94XLT]

Been working through getting a 94 xlt 4.0 ohv back on the road and have been quite successful other than the following

I'm getting these codes all the time.

Koeo
185 and 186
Maf has been replaced albeit with a aftermarket version, output voltage was within spec when hooked up to see live data.

Koer
172
This dreaded thing. O2 sensors were replaced when I got the truck with Bosch, same as what was in there with the Ford name. Same issue. Ran a smoke test and found a single vac leak coming from the throttle body butterfly shaft. But this shouldn't center this to just one bank.

The only oddity here when hooked up to a scanner is the output voltage on the passenger side was pegged at 0v for a while before it finally started to show voltage. The drivers side was outputting voltage the entire time.

Now sometimes when I start the truck I get what sounds like a horrible exhaust leak on the passenger side and she runs rough with low rpm, hitting the gas a few times or waiting a couple minutes that goes away and it runs fine.

Idle sits around 800 to 850 so nothing out of the ordinary considering the small vac leak.

The main issue the truck had when I bought it was the bad capacitors in the PCM. Replacing those brought the entire truck to life.

Next thought is lower intake manifold gasket or exhaust gasket where manifold and downpipe connect before the o2 sensor. But before going that far, do any of you nice people have any other ideas?

 

[Poppa_R]

From your description with exhaust noise on start up and the oxygen sensor not showing until engine gets warm i would suspect there is a broken exhaust manifold bolt.

 

[Buds94XLT]

From your description with exhaust noise on start up and the oxygen sensor not showing until engine gets warm i would suspect there is a broken exhaust manifold bolt.

It's not all the time. Just sometimes and when it does have the noise it's the only time it runs rough. Most of the time it runs just fine with barely any idle surge at all from the minke vac leak I have to fix. If this is common occurrence for these engine I will take a gander tonight and see what's up.

 

[SenorNoob]

That makes sense. Exhaust doesn't leak all the time. When it does you hear it and have rough running. You might get lucky and find a bolt loose on the passenger side. Don't forget to check both the manifold to head bolts and manifold to y-pipe bolts. (I know mine leaks there.)

Edit: It could even be a slightly loose or cracked O2 sensor on that side.

 

[Buds94XLT]

That makes sense. Exhaust doesn't leak all the time. When it does you hear it and have rough running. You might get lucky and find a bolt loose on the passenger side. Don't forget to check both the manifold to head bolts and manifold to y-pipe bolts. (I know mine leaks there.)

Edit: It could even be a slightly loose or cracked O2 sensor on that side.

Yeah I read about the intake bolts. I'll check the downpipe flange before the o2 sensor and the actual manifold bolts when I get home. Replacing the throttle body and reinstalling a Ford maf to see if I get any changes. Appreciate all the helpful feedback.

 

[Buds94XLT]

Update. New/old maf from a company who had it in the shelf for 20 years fixed my maf issues. New to me but another 22 year old throttle valve fixed my vac leak at least a bit more.

Now the only issue I have is when she starts, she idles up for a few seconds then drops down and runs rough till I gas her a bit. Then she smoothes out and is good until I restart her later. More bugs but I expect it with a 30 year old truck with possibly 330k on it...

 

[SenorNoob]

Amazing how old parts work better than the new ones sometimes isn't it?