Ok Folks, I've read through the posts on surging idle but did not see anyone who has KOEO code 41. Also it seems most posts on the subject do NOT include stuttering going down the road. The truck, not me .

Truck is a 93 F-150 4x4 with a 302 and AOD. Some recent performance background:

Truck has been running fine, maybe just a little low on power. Idle has always surged some, but clears when warm. Recent MPG on the low side of normal. Last few weeks I've noticed a sound that seems to come from the right side near the firewall, like a rubber diaphragm fluttering, kind of a hollow sound.

I've also recently noticed a very slight hesitation or vibration on the highway, just around the time you might expect the AOD to downshift out of OD to gain a little more power...but this has been so slight and in roughly the same place that I couldn't tell if the road had gotten a little ripple in it (can happen here).

3 days ago I was towing a boat (around 3k lbs) 30 miles including over a steep 4 mile grade, and I noticed the hesitation/vibration getting worse, and the surge after coming to a stop getting much worse too.

This morning KOEO code was 41c which is either "HEGO sensor circuit indicates system lean (right side)" or "HEGO sensor signal out of range always lean".

Just for the heck of it, I did a KOER too and got codes 42r and 52r; 42 being sensor voltage high running rich, and 52 being the power steering pressure switch open. No EGR codes at any time.

I figured I'd get the o2 sensor, but had to do a 120 mile round trip errand first, and barely made it back. Runs really rich too, and the MPG is shot to heck. Ran the codes again KOEO. Got 41 again.

I replaced the 02 sensor (LOTS of soot). A quick check with a multimeter showed 12 volts going to the o2 sensor, but I couldn't figure out how to measure the output.

I left the battery unhooked for 20 minutes, then fired it up. Ran smooooth for about a minute, then started going way up and down again. Took for a drive, and it was rougher at cruise than before, and smelling way rich. Upon getting out of the truck and taking a breath, it was gag city. KOEO 41...again.

I just checked it again with everything cooled off...truck started fine and ran smooth for 30 seconds, then it went to heck again, and started smelling awful rich.

If you've made it this far, thanks...so, any advice on which to check next? IAC, TPS, EGR, EGR sensor etc...or vacuum? Or could a bad 02 sensor have gummed up injectors and intakes so bad that I should try a dose of seafoam before embarking on the "fun" stuff? My gut says that the only reason I'm getting code 41 is because the sensor is getting sooted up fast, and something else is the real issue? Thoughts?

Thanks in advance...

 

Morning bump.

 

I'd go the seafoam route first and see what that does for you. It's cheap and has been known to fix most of the problems your describing.

Put a pint in the gas tank to clean the injectors. If you're inclined, I'd recommend pulling the injectors and giving them a good cleaning as Seafoam through the tank will take a few days of regular driving to really clean them. It's not that difficult to do. Link provided: http://www1.autozone.com/az/cds/en_u...rInfoPages.htm

Clean the intake real well by sucking Seafoam through a vacuum line into the intake. It's important to use a line that will feed all cylinders. Brake booster line is a good one. You'll need to keep the motor running while doing this as it'll want to stall. It also won't hurt to spray some intake cleaner up into the manifold and give them a good cleaning as well. Given the conditions your describing, this could do wonders to fix your problem.

While you're at it, put a pint in the crankcase to clean the motor. This won't do much (if anything) to solve your problems, but it does wonders to clean the motor.

You should also take this time to do the usual inspection of the firing system. Check the distributor cap and rotor for any wear. Inspect all plug wires for deterioration and a good seat on the plug. Pull and inspect the plugs. Replace any that are bad.

My 93 was duplicating the same slight hesitation at low RPMs - identical to what your describing. Put it under a load and it went to crap just like you describe. After doing all of the above, the best I can figure is this:

Build up on the distributor was causing a slight misfire in the #8 cylinder but only at lower RPMs. This was exaggerated by putting the truck under a load causing the plug to fail completely. This led to a rich condition which fouled the O2 senor and junked the EGR. Replaced the distributor cap, rotor and O2 sensor. Cleaned the injectors. Seafoamed the intake and she's was right as rain (which were finally getting here in the southeast).

Hope it helps.

 

Cross your fingers. My game plan was similar to what you've described, but before I Seafoam everything I think I'll pull the plugs to see if they tell me a cylinder by cylinder story. Hopefully I can find the time this morning. I'll post back after it's done. Thanks.

 

I didn't have much time this morning so I ran the seafoam but didn't pull the plugs. I did pull and clean off the O2 sensor. It helped the surging going down the road, but the engine is still surging and dying coming to a stop, and surging badly at idle. Threw another code 41 at me (HEGO lean), while smelling like it's running rich. I also sprayed cleaner into the intakes and noticed black gunk on the inside of the butterflys.

No time left today, but I'm going to pull the plugs tomorrow, and seafoam it again. But what bothers me is the 41 lean code while it's obvious that there is excess/unburned fuel. Could a plugged injector(s) make a lean reading that would cause the computer to dump excess fuel in all over? Or could it be a bad plenum/manifold gasket causing lean code reading plus incomplete burn (like what member "Old Paint" has described)?

 

lookin forward to see what ur problem is, did u ck the vaccum at ur intake w/ a vaccum gage???

 

Yes, a lean reading will cause the computer to dump more fuel in all cylinders. That combined with an incomplete burn would create an exhaust that smells rich. The KOEO 41 is not necessarily telling the truth. Clear your codes and retest and see what comes up. Also, always test KOEO and KOER. As it threw KOER 42, it is burning rich with the engine running. The KOEO 41 could be a stored code from an earlier/existing problem. The reset should give you a clear slate. See here to clear the memory: http://www1.autozone.com/az/cds/en_us/0900823d/80/0a/2d/f5/0900823d800a2df5/repairInfoPages.htm

I'd still recommend checking your spark on all eight cylinders and running Seafoam through the intakes and the fuel system. Again, the injectors will take a while to clean if only using something through the tank. It may be worth your while to pull each and clean thoroughly.

I should have said this before, but check your vacuum lines for leaks and good seal.

Clean the intake. Black gunk around the butterfly is bad.

Finally the gasket for the upper plenum (manifold) is known to fail from time to time. As 'Old Paint' mentions, this will cause a lean condition.

 

hey i have the same code.. but my truck is running gr8 and smells rich also so dunno maybe we have a bad O2 sensor?

 

I'd look at the air bypass valve, and the engine coolant temp sensor first. actually, reverse that, ECT first, and THEN IAB. (aka throttle bypass air, idle air controller, etc..)

 

Ok, so with limited time and the parts houses stocking a limited supply of expensive sensors...

I've replaced the cap, rotor and plugs. Old plugs were all pretty much the same, no one cylinder seemed bad off. All showed heavy black from running rich. I've checked and cleaned the IAC solenoid and valve...it tested fine sitting next to a new one for comparison. I've seafoamed the engine twice, and sprayed/scrubbed the inside of the throttle body. Plug wires are MOtorcraft and less than a year old. Firing order is correct.

Cleared the codes, reset the computer.

Same thing happens. Starts fine, runs well for a minute or so, then the idle wavers, drops way low, and you can see the unburned fuel coming from the tailpipe. It revs fine from idle as long as you're not driving (i.e. working the throttle body by hand). If you try to drive it, it trys to die and surges. I did not drive it more than 200 yards 'cause I didn't want to scrape up a tow on Sunday.

KOEO showed no codes, although I didn't drive it long enough to get much. KOER still shows 42R, "HEGO sensor voltage high/system rich". Does this mean that the voltage is high BECAUSE the O2 sensor is working or that it's out of range/not functioning properly?

What does the O2 sensor report to?

I guess my next move is to replace the TPS and/or coolant sensor, and look for vacuum leaks, though I'm a rookie at that.

 

Speaking of the TPS, mine appears to be on the bottom of the throttle body. Is there any big deal/trap to removing the TB, or is just the 5 or 6 bolts, the linkage, and a cooling pipe or two as it looks at a glance?

 

You will need an upper gasket set for $10

Yes just disconnect the linkage. *careful not to adjust the T.V. cable positioning to the Transmission* The TV is not like a kickdown , it works during the full stroke of the linkage , not just 3/4 like a kickdown dose. AOD's will burn themselves out quickly with this TV out of adjustment.
And the only proper way to set them is with a pressure guage hooked to the transmission.

You can set the TPI with a meter and the positioning screws. the Book will have your referances (0.34 minimum volts - 4.84 Maxium : Chiltons)
( 1*-13* Throttle valve opening rotation = 0.66-1.22 volts)

Also with the surging , all to ofen this is an intake leak somwhere.
The idle surges , can be a combonation of a leak and the IAV pumping to keep the engine running.


There is 2 vacuum lines to the right sided of the throttle body (looking at the windshied) one on top of another. they can be well hidden lines to leak.

And pull the hose off of the PCV valve, plug it with a bolt temporaraly.
Crank the engine and see if it smooths out.......It should smooth out a lot .

If it fixes the surging then replace the PCV with an expensive PCV not the cheap $3 ones.

Just cause the PCV rattles dose not mean its Not bad, there is a spring inside that helps keep the weighted plug from opening without enough vacuum pressure.

I don't use a PCV system at all and have Plugged it off at the back of the intake a number of years ago. (short brass, double male fitting, cap and teflon tape - Home Depot Plumbing section)
I left the PCV in the cover and run a 3' hose down the inner fender to the side of the frame and secured it with zip-ties. The crank case still narurally "burps" it self , but the vacuum leak problem is compleatly gone there.

The PCV is for emmisions not engine preformace.

 

A KOER 42 code just means the system is running rich as measured at the HEGO. Since you know the engine is getting plenty of spark (runs fine for the first minute), it's got to be the result of the fuel system dumping too much fuel into the cylinders.

Several possibilities...start with one, eliminate it and move on to the next:

Idle Air Control - you've checked and it seems to be fine

Engine Coolant Temperature Sensor - This modifies air/fuel ratio depending on the temperature of your motor. Given the truck doesn't fail until warmed up, this could be a possibility. The ECT is supposed to create a rich mixture when cold to allow the engine to run better...as it warms it will decrease the mixture. Check this first. Likely culprit.

Intake Air Temp Sensor - Much like the coolant temp sensor. Measures the incoming air and adjust the air/fuel ratio accordingly. Check for it to be working properly. Possible problem. The fact that it runs fine for a short period would make this unlikely, but you never know.

Throttle Position Sensor - Unlikely but check it anyway. The symptoms don't signal a bad TP sensor. Still, you never know. The engine should fail more quickly if the TP were bad. But I've been wrong before.

Finally, check for vacuum leaks. Pull the vacuum diagram and go over everything.

If that won't do it, I may be out of suggestions.

 

Ok, so with today's 45 minutes I replaced the water temp sensor, no change. started it, ran it down the road and the CL came on...KOEO came up with code 31 now. I checked the fuel tank caps, and one was not tight.

Pulled the EGR, no gunk, just a little soot and the diaphragm holds vacuum. Thought I heard some cross-sparking (plug wires are less than a year old) so tonight I'll go looking.

Question about vacuum leaks. When I pull assorted lines the idle goes up, but when I pull the little vacuum line on the EGR nothing happens. Does this mean that my leak may be along that line? I'm unclear of when how the EGR does it's thing.

Thanks.

 

Well the EGR's vacuum line..... if I remeber right....... ran to an emissions silinoid (VSV) before going to the diaphram.

But the EGR dose not operate at idle or full throttle, It works at crusing speeds (highway)

It allows Inert Exhaust Gas (non flameable) to be reintroduced back in to the chamber.

So it takes up space (chemically shrinks the chamber) in the chamber, and thus requires less air and fuel to make a combustion .

Like a super mini version of Nitros kinda....Lol

This is how the cars get most of there fuel economy