O2 Sensors.

If you graph the output from an O2 sensor while the engine is running should it be a smooth output or will it swing rapidly.

Depends.

Really, it will likely swing rapidly. Remember that a very small change in the Oxygen level will cause a very large swing in the voltage at the sensor when you are at stoich.

rapid swing for sure on a narrowband. and widebands depends on the controller

most cars use a narrow band sensor.. it reads yes or no as far as O2 is concerned.. so it will swing widely and wildly.

A wide band sensor "sees" a bigger spectrum than too much oxygen or not enough oxygen, so it will tend to be more smooth

OK, here's the back story. 2002 E150, 4.2L V6. Still chasing a 1100-1600 rpm misfire. I'm going to assume Ford uses a narrow band sensor. That would make sense, the voltage was swinging from .1 to .9.

I'm starting to think I have a manifold leak somewhere. If I unplug the mas air sensor the misfire goes away. Probably making the ECU go into a safe or closed loop mode.

It didn't throw a code on the way home even though it was misfiring. I'll be putting about 600 miles on it tomorrow so I'll check it again when I get home.

What's driving me nuts is it doesn't misfire all the time. It will run great for a couple of days and then act up for the next week.

Another quick question. On the back of the engine on both banks, there is an actuator tied to an actuator above the bellhousing. What is that and what does it do.

Toyman01 wrote: What's driving me nuts is it doesn't misfire all the time. It will run great for a couple of days and then act up for the next week.

This happened to me on my race car... turned out my alternator output was all over the map. It was swinging from a nice 14v at idle to a not so wonderful 7v above 4500 rpms. Sensors need good reference voltage... worth a look if you haven't checked.

Toyman01 wrote: OK, here's the back story. 2002 E150, 4.2L V6. Still chasing a 1100-1600 rpm misfire. I'm going to assume Ford uses a narrow band sensor. That would make sense, the voltage was swinging from .1 to .9. I'm starting to think I have a manifold leak somewhere. If I unplug the mas air sensor the misfire goes away. Probably making the ECU go into a safe or closed loop mode. It didn't throw a code on the way home even though it was misfiring. I'll be putting about 600 miles on it tomorrow so I'll check it again when I get home. What's driving me nuts is it doesn't misfire all the time. It will run great for a couple of days and then act up for the next week. Another quick question. On the back of the engine on both banks, there is an actuator tied to an actuator above the bellhousing. What is that and what does it do.

that actuator is for the variable runner control. check your egr sounds stupid but trust me., also clean the maf. see what it does then.

Hmmm. In my experience, O2 sensors won't cause a misfire unless they croak, in that case the ECU thinks the thing's running lean and pours on the fuel to try to make up for it. So you get a rich misfire.

Do this: unplug and ohm the TPS, move it slowly through its travel and watch for big swings. Most of the throttle movement is in the lower 1/3 of its operation in normal street driving so that part of the TPS wears out first. If the MAF and the TPS don't agree, weird things can happen; the ECU sees Value A for the TPS and Value B for the MAF and sez 'OK I need to lean/richen it out so I keep the proper O2 ratio in the exhaust. All this is within parameters so no MIL (malfunction indicator lamp) illumination is necessary'. Trivia: the ONLY 'box' Cherokee transmission I ever saw replaced was actually a bad TPS causing strange shifts. No MIL. That took some tall explainin', glad it wasn't my customer.

I believe your actuators are for the short/long intake runners. They won't cause a misfire but they can kill the bottom or top end.

KATYB mentioned EGR, that's a possibility but that generally shows up as a surge at steady highway speed.

i just say the egr becuase when the e10 switch happened here in oklahoma we had all kinda of problems with 4.2 and 4.6's and 5.4 and misfires that were solved by replacing egr.

According the the code reader the TPS is reading smooth through out it's travel though it will only go to 97%. I'll get it through the trip tomorrow and pull the codes again and go from there.

So the TPS checks OK. Dammit.

KATYB: Wasn't aware of the E10/EGR problem. Maybe carbon accumulation?

97% is just fine......Curmedgeon: bingo carbon. e10 is such nasty stuff to use. loss of power and mpg and 50% on avg more carbon buildup oh what fun.

Toyman01 wrote: OK, here's the back story. 2002 E150, 4.2L V6. Still chasing a 1100-1600 rpm misfire. I'm going to assume Ford uses a narrow band sensor. That would make sense, the voltage was swinging from .1 to .9. I'm starting to think I have a manifold leak somewhere. If I unplug the mas air sensor the misfire goes away. Probably making the ECU go into a safe or closed loop mode. It didn't throw a code on the way home even though it was misfiring. I'll be putting about 600 miles on it tomorrow so I'll check it again when I get home. What's driving me nuts is it doesn't misfire all the time. It will run great for a couple of days and then act up for the next week. Another quick question. On the back of the engine on both banks, there is an actuator tied to an actuator above the bellhousing. What is that and what does it do.

IMHO....

You are actually on the right path in terms of cause.

The O2 sensor is capable of causing a misfire, but as was pointed out, it typically wont do that unless the info being passed to the computer is bad. And since you are getting a nice swing between .1 and .9, it seems like it's quite healthy.

By taking out the air meter, it changes how the air flow is measured- or in your case, estimated. It will be pretty close, and will use the O2 sensor to trim. Again, since it runs well, that's an indicator that the O2 sensor is good. The secong thing it tells you is that the air flow measurement is of question.

The resulting question of that it 1) is the meter bad or 2) is there a leak? Air flow meters are pretty reliable, and since it does run well a lot with it plugged in, that pretty much reduces the source to a leak.

On that- it's very possible to have a crack or something that seems small but will manifest itself in a large momentary error. Check all of the hoses downstream of the air meter for leaks.

One other possibility- there's an issue with the evaporative system. There are generally 3 big plugs in the main manifold- brakes (and other vacuum needs), purge, and PCV. Of those, purge and pcv seem more likely, since you don't mention braking as an issue. But check all of those hoses as well.

As for E10, that motor and fuel system is quite safe to E10- much of that is carried over to the Flex Fuel version of the E series.

Good luck with it!

(for the original question- very normal- actuall desireable for the O2 sensor to swing back and forth like that. Most WB set ups do something similar- not the same, but similar)

edit- this does NOT rule out an EGR issue. If you don't find a leak, and EGR caused misfire would be my next logical choice.

Alright boys and girls, I cleared the codes on it last night and dumped two cans of seafoam in a full tank of gas. Left at 5:30 this morning and made the 540 mile round trip to Macon and back. The CEL came on within a mile of home this morning.

I pulled the codes again when I got home a few minuets ago. There are four stored codes and one pending, as follows.

1. P0401 EGR Flow Insufficient.

2. P0171 System too lean Bank 1

3. P0316 Engine Misfire on Start (First 1000 Revolutions)

4. P0306 Cylinder 6 Misfire.

These are all repeats.

The pending code is P0174 System too Lean Bank 2.

By the time I got home it was running much smoother, but it still has the 1100-1600 rpm miss. I guess I'll go bak through the vacuum system again and then check/change the EGR valve. If it's an intake leak it'll be going to a shop. If y'all have any other suggestions let me know.

Thanks !

please clean the maf and replace the dpfe sensor and retest. and when was last time you replaces the plugs and wires? if they have over 80k on them replace them.

In reply to Toyman01:

Almost the same code sVRx is getting.

BTW, an easy way to find a leak- if you can get it to miss a little while working on it- a slow propane supply should smooth it out once it finds the leak.

As for the MAF, unless you are using an oil soaked air filter, MAF's generally don't get so bad that you'll get a partial misfire like that. It's a pretty small leak- one that starts at 1100rpm (as the engine starts to move), and becomes pretty insignificant at 1600rpm. Or at least small enough that closed loop fuel and adpative fuel will be able to comensate for it. Which is actually a lot. Not sure what the lean threshold for a light is.

Plugs and wires have less than 15k on them. I'll do the DPFE Friday or Saturday. I cleared the codes again, we'll see what comes up tomorrow. I'll be putting another 300 miles it.

ford has issues with dirty dpfe`-s including tsbs for system to lean problems on all cars. 15% is the lean threshold.

KATYB wrote: ford has issues with dirty dpfe`-s including tsbs for system to lean problems on all cars. 15% is the lean threshold.

That's the adaptive limit. If he's getting a misfire, it's that plus another 15-25% (depending on who calibrated it)- since the system is capable of correcting at least a 25% error and not lead to a misfire. I'd guess that the hot lean limit would be an actual 10%- which is quite a bit after adaptive fuel and basic closed loop fuel.

BTW, do you see the dpfe crack? Or the hoses to leak?

EGR flow insufficient? Check for a clogged EGR tube (our old friend carbon again).

Misfire on initial startup? In many cases that's a RVP (Reid Vapor Pressurization) problem. That's a measure of fuel volatility. We used to see that a lot with premium fuel during the season change, going from winter to summer fuel formulation. The engine would run like crap on initial start and stall, then restart and run fine like nothing was wrong. I don't think you are running premium so I doubt that's your problem, cheapskate.

It can also come from sticking valves. I haven't seen it in years, but there used to be a sticky yellow crap that would build up on the intake valve stems. it would harden as the engine cooled off and cause them to stick open a little on initial startup.

A quick Google showed a lot of folks having spark plug problems setting that code, too. It appears that the deal is this: 316 is a generic misfire code, 306 is the actual cylinder misfiring.

The lean running codes point toward a vacuum leak. But, the bad thing about generic type O2 codes is that there are several possible causes. Does your engine have a plastic intake? If it does, like alfa says check for cracks. A MAF can do this as well. Welcome to the hall of mirrors.

hoses either rot or dpfe goes bad. never have tested what has gone bad. just learned it from another techs advice. 99% of ford insufficient flow codes are a bad dpfe according to him and ive come to find that true. 15% is the light threshold. most ford i have seen will comp up to 25% on eec-v systems.

a lil digging also found this Engine - MIL ON/DTC's P1131/P1151 Set

TSB 05-22-6

11/14/05

MIL ON WITH DTC P1131 AND/OR P1151 - 4.2L ENGINE

FORD: 2001-2003 E-150, E-250 2001-2004 F-150 This article supersedes TSB 05-17-3 to update the vehicle model years and issue.

ISSUE Some 2001-2003 F-150, 2004 F-150 Heritage and 2001-2003 E-150/250 vehicles equipped with a 4.2L engine may exhibit the malfunction indicator lamp (MIL) on with diagnostic trouble codes (DTCs) P1131 and/or P1151 (system too lean bank 1 or 2). This condition may be due to leaking isolator bolts/port gaskets in the upper-to-lower intake manifold mounting area. This condition is sometimes intermittent and may not be apparent on a warmed-up engine. ACTION Refer to the following Service Procedure. SERVICE PROCEDURE

NOTE THIS CONDITION COULD ALSO BE DUE TO WARM AMBIENT TEMPERATURES AND THE USE OF WINTER GRADE FUELS WHICH HAVE VERY HIGH VOLATILITY AND MAY BOIL IN THE FUEL LINES (VAPOR LOCK) DURING A SHORT HOT SOAK. OXYGENATED FUELS WILL AGGRAVATE THIS CONDITION. IF NON-OXYGENATED FUEL IS NOT AVAILABLE, USE MID/HIGH OCTANE FUELS WHICH HAVE LOWER VOLATILITY AND MAY HELP ALLEVIATE THE CONDITION. 1. Perform a self test. If DTC P1131 and/or P1151 are the only codes stored in the powertrain control module (PCM) proceed to Step 2. If any additional DTCs are present, follow normal diagnostic procedures found in the PC/ED Manual. 2. Remove the upper intake and replace only the port gaskets (9H486) and isolator bolt assemblies (9S479). The new isolator bolt assemblies use a rubber material that is green in color, do not install the old isolator bolt assemblies with the black rubber material. Do not replace any other intake parts or gaskets. Refer to Workshop Manual, Section 303-01 (In-Vehicle Repair; Upper Intake Manifold) for removal and installation procedure. 3. While the upper intake manifold is removed, check the exhaust gas recirculation (EGR) orifices that are pressed into each primary port of the lower intake manifold. If any of the orifices are plugged with soot, clean and unplug them with a pick and solvent. CAUTION DO NOT USE SMOKE DETECTION, PROPANE GAS, CARBURETOR OR BRAKE CLEANER TO TEST FOR VACUUM LEAKS. CARBURETOR OR BRAKE CLEANER MAY CAUSE INTAKE MANIFOLD RUNNER CONTROL (IMRC) BEARING FAILURE. SOME LEAKAGE FROM THE IDLE AIR CONTROL (IAC) OR EGR VALVE AND IMRC SEALS IS NORMAL, DO NOT REPLACE THESE PARTS. DO NOT REPLACE THE LOWER ALUMINUM INTAKE MANIFOLD.

Parts Block

WARRANTY STATUS: Eligible Under Provisions Of New Vehicle Limited Warranty Coverage And Emissions Warranty Coverage

OPERATION DESCRIPTION TIME

052206A 2001-2004 F-150 4.2L: 1.8 Hrs. Check For Diagnostic Trouble Codes, Replace Gasket Between Upper And Lower Intake, And Clean EGR (Do Not Use With 6007A1, 6007A2, 6007A5, 6007A14, 6149A, 6584A, 6584AT, 6020A, 12650D, 12650D35, 8005A, 10346A, 9438A, 9424A1)

052206B 2001-2003 Econoline 4.2L: 2.0 Hrs. Check For Diagnostic Trouble Codes, Replace Gasket Between Upper And Lower Intake, And Clean EGR (Do Not Use With 6007A1, 6007A2, 6007A5, 6007A14, 6149A, 6584A, 6584AT, 6020A, 12650D, 12650D35, 8005A, 10346A, 9438A, 9424A1) DEALER CODING CONDITION BASIC PART NO. CODE 9424 D8 OASIS CODES: 490000, 499000

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