yes, and now some new codes popped up.

KOEO: all good again.

CM:
21-ECT out of self test range 0.3 to 3.7 volts.(probably from unplugging it earlier)
54-ACT sensor signal is greater than the Self-Test maximum of 4.6 volts.
33-again

KOER:
13-again
31-PFE or EVP circuit below minimum voltage of 0.24 volts.
44-again

I'm gonna unplug the bat for a lil while to clear out the codes that popped up from me messing with it earlier.

 

Not a good idea, you should clear the way Ford says to do it.
You can generate more codes by unhooking the battery.

 

Thanks for the correction, found in my chilton the right way.

Reset the codes, took her out for a drive and got the same codes back as before.

CM:
33-again-EGR valve opening not detected.

KOER:
13-again-Cannot control RPM during ER Self-Test low RPM check.
44-smog pump is removed.

The check engine light tends to come on when the engine has more load on it. When I try to accelerate quickly it comes on. When I'm going up a hill in 4th and need to give her some more gas to keep a constant speed it comes on.

 

When you give her some more gas the EGR valve is supposed to close and only opens on an warm engine at ~mid throttle. It is also closed at idle.

If IAC is OK and its wiring/plugs is OK from the Computer to the IAC and you say the RPM goes up and down with taking the plug off the ECT sensor then you got me on this CM #13.

 

Well i gave it some more thought. I didn't really check for vacuum leaks in vacuum hoses that well. On the manifold i get a solid 20hgs of vacuum at it's highish idles, between 800-1000 rpms. So I think that the manifold doesn't have any vacuum leaks with gaskets. Also if i give her a little throttle the vacuum drops about 4-5 at first then jumps up past 20. I take it this is because the initial opening of the butterflys drop vacuum on top of the manifold for a second.

I'm still getting the check engine light when putting a load on the engine, and the only thing popping up in CM is the 33 code. How much does the egr effect throttle. the EVP voltages checked out, as did the vacuum line at the EVP. I think i'll check out the EVR a lil bit.

However, the check engine light doesn't come on at idle, and it tends to go off if i push the pedel to the floor. So it does seem that the EGR is just always staying closed. This should not keep the idle high should it?

Also even though my TPS is in the correct specified range @ .8vdc at closed throttle, i'm going to go ahead and adjust it to .95 or .99 since many people seem to think that's the perfect range.

Results and codes to follow.

 

Checked out the EVR, it's passed all tests. EVP is still getting the correct voltages. Adjusted my TPS to .96-.97vdc. Lil better throttle response, but no change in idle. I could not find any vacuum leaks. All my sensors are good.

I'm thinking that there probably is a vacuum leak somewhere though. I took out my old IAC, which is still good btw. And hooked it up so i could see what the ecu was telling it to do. It looked to be at closed throttle, then when i unplugged the ACT(mistake on ECT earlier) it opened up. So it acted the same as the IAC on the throttle body did.

So if the map sensor is telling the ecu that the engine is getting enough air then the ecu will not need to open the IAC, correct? Which could easily be the fault of a vacuum leak right?

Also when your driving and you get off the throttle to decelerate the IAC opens up to keep the engine from dying right? When i let off the gas the engine slows till it hits around 1500rpms, then jerks forward like it just hit idle. This could be because the IAC is open and the vacuum leak is supplying the engine with enough AIR/fuel to keep decent power at 1500rpms i think.

Recently when i had to change my oil pan, anyone who has done it know you have to take the upper intake off to get the clearance. The original gasket was metallic, the one i replaced it with was cheap paper-type felpro and i did not use gasket sealer. I'm betting this could easily be a vacuum leak between the upper and lower intake manifolds. Would you agree, should i buy a nice gasket, use sealer, R&R, and then go from there if i'm still having problems.

Still getting 13 on KOER btw. and 33 on cm

 

Chilton, Haynes etc. manuals are for lazy cheap CPA's that have never gotten dirt under their fingernails, but want to tell somebody they DIYed their vehicle.
When the books provide no specifics, they can't be wrong.

 

THAT sounds like an O2 sensor.

 

the O2 sensor only has about 4k miles on it. also this problem didn't appear until i replaced my oil pan about 3 weeks ago. i'm not running rich or lean, I'm doubting it's the O2 sensor.

the manuals can be very vauge in many areas, but are also very helpful in many. Everyone that starts working on their vehicles has to have some sort of reference to start with. Not all references or instruction manuals are complete. there is no way in hell you can tell me that chiltons or haynes are only for newbie mechanics. Many people on this forum use these manuals for reference, whether they are newbies or 50 year wrench turners, you just have to make sure you use them as a reference, and not an complete instruction manual. No manual or person is completely full of knowledge in any areas, thats why we look in many places to find our answers.

 

Actually i think i may have just found my leak. The top of the intake manifold gets a good 20inhg of vacuum like i said before. But i just remembered that when i checked the vacuum of the 2 spouts on the throttle body behind the IAC, that go to the purge canister; before it was quite low. I just checked them again, and i have practically zero vacuum.

The little coolant hose on the bottom of the bottle of the throttle body has been rubbing up against another metal hose below it and has caused slight clearance issues when reinstalling my throttle body. Maybe this is throwing my seal off, i just didn't think about it too much before because i had no change in idle when spraying carb cleaner around the TB.

 

I have been a wrench turner for right at 50 years and I have never bough a chiltons or haynes manual in my life.

I did buy a lot of Motor's auto repair manuals (starting with the 1948 edition) & The Motor's Auto Engines and Electrical systems series in the early years. Still have stacks of them and also stacks of OEM shop manuals and other books.

Also GM sent out a lot of free tech manuals in the early 60's just for the asking and I still have all of them. Back then I had to work on what ever came in.

 

Chilton's and Haynes manuals are not gospel, but they are far more useful than you describe.

And those codes do not point to an O2 sensor. You sound like a CPA.

 

With no smog pump, and the cel coming and going, no matter WHAT the codes, the O2 sensor will make the light come on intermittently. And - no CPA - I'll match my time @ the Ford plants test line next door to the Henry Ford Museum on the diesel Excursion and OR A.C.Carron in Inkster against most anyone.
I maintain that the Haynes and Chiltons manuals are a waste of paper.

 

Well we could debate about this for days i'm sure, but to get back to the purpose of this thread, what do you old pros think about my truck not having vacuum on the TB.

 

The '91 throttle body has 2 vac ports iirc, and they tee into 1 line for the cannister solenoid line? @ an idle there may not be vac. there. Hook up your vac. gauge @ the tee, raise the rpm and see what you get. Even then, I don't expect it will be much. The cannister is part of the emissions system, not the fuel system.