1999 Ford E150 4.6L Went from running like a champ to suddenly running very rough and lacking power.
My Matco scan tool gave me the following codes
p0305, p0306, p0308 Miss fire on cylinders 5,6 and 8
p0401 insufficient EGR flow
p0402 excessive EGR flow
p0174 Lean fuel on bank 2
p0430 Catalyst system bank 2 below threshold

Engine destroyed both upper and lower catalytic converters on drivers side. No power. I have gone through and pulled plug wires one at a time (all 8 cylinders) with no effect on the way engine runs and have repeated doing the same thing with injector wires. Simply can't tell the difference pulling any single plug or injector wire off a cylinder.

Have pulled all 8 spark plugs one at a time, 1,2,3,4,5,6,and 8 are all perfect ashy white color with no damage. Number 7 slightly blackened no build up and no damage.

Not understanding how plugs can look perfect and still be miss firing? Can not understand how pulling plug wires and injector wires doesn't cause noticeable additional running issues?
Van would take a full mile to get up to 35mph.
Extreme back fire occurring.

Put in "test" pipe on both sides to get past the two bad catalytic converters and dumped the muffler out... Then removed throttle body, EGR etc... found the two EGR ports inside throttle body spacer clogged probably 95% with carbon. Did a thorough cleaning and reinstalled with new gaskets.Cleared all codes.
Started it up and it seemed a bit smoother. Sprayed carb cleaner all along the upper and lower intake gaskets as best as I could get into the and did not find any intake leakage.Gave it a drink of Sea Foam through the vacuum line to do a little clean up below the throttle body...
Took it for a test drive and it had more power, though still back firing a bit. Drove it about 2 miles then it died. it would not start immediately, but after sitting 5 minutes it started easy, but would only run for about 1 minute then dies and has to rest for 5 minutes again. While running revving it kills it immediately, and fluttering the peddle also kills it. I got it home about 4 feet at a time as that is all the longer it would run (I guess my battery is pretty good if nothing else)...

Doing this took it down to 3 codes
0305, p0306 miss fire on 5 and 6
and I apparently didn't write down the exhaust O2 sensor code but had one code on it, but with no cats that makes good sense.

Found a crack in the hard plastic line of the pcv valve tube that runs from the throttle body to the pcv valve, (don't know if I did it while removing the throttle body or if it was already cracked). Replaced it with new rubber line and new pcv valve.

It is now running a bit better yet but will stall suddenly. Still occasional back fire. Now seems to throw a new set of codes. P0300 Miss fire not related to only one cylinder. P0401 bad or damaged dpfe sensor, P0102 Mass air flow sensor (have now cleaned it again and it seems to not be throwing that code now).

Really need help on what I need to focus on next.

 

Replaced the EGR pressure sensor tonight, no change in power and it is still missing... It is Giving me a P0300, after a major backfire it has again given me a P0305. I also got a HO2S21 Code now.

I was watching my scan tool and while I noticed for a while the fuel trims for bank one and two was running equal for both sides. Then suddenly bank one was running say 3 to 8% while bank two was up around 55%. Then the two began to run side by side again. Still didn't feel any difference in the running of the engine during this but definitely peaked my attention...

I feel like I am just throwing parts and cash at this thing already... any ideas are welcome...

 

Just some thoughts....with the erratic spike on the fuel trims...I would suspect maybe a cracked intake manifold or a vacuum line that is still letting in metered air in some where. Maybe the plumbing from the air filter to the throttle body isn't sealing well.

Have you cleaned your MAF sensor? Have checked the connection to, or the Crankshaft positions sensor?

 

Yes on cleaning the maf sensor. I've sprayed the intake upper and lowers as best as I can get into with carb and choke cleaner with no changes in rpm. Will go back through vacuum lines... had not even thought about crankshaft ps...

thanks for your replies.. any one else?

 

with things as they are, not working well...I would remove the throttle housing, (the L shaped unit that attaches to the intake manifold), throttle butterfly plate and all. This would also bring with it the IAC. There are 2 internal EGR ports that can get crusted over with carbon deposits and cause rough runnability. Then you can get to the back side of the throttle plate for better cleaning. It not a bad job takes a couple of hours.

spraying carb cleaner around the upper portion of the engine while running probably won't yield audible results.....the ECM reacts too fast. If your scanner can read "live data" spray, then watch the short term fuel trims for a spike.
where it spikes as you spray it pointing to the leak. Or is that what you were trying to say in a earlier post?

If the po305 is coming up again, repeating after clearing the codees, then you are getting a miss fire on cylinder 5

 

I thought I posted above but probably gets lost in that long thread, did the throttle body and L spacer clean up, gets was 95% blocked, now clean and clear
. Did not do the spray down while watching the fuel trim... Will have to get a helper and do that.

 

Ah yes you did mentioned it, Sorry I just missed it.

 

Tried spraying down the intake again while watching the data stream. Nothing noticeable...

however, last time the erratic fuel trims started after engine was warm. Today erratic until real warm. Still no power. Misfire continues codes today have included cylinder 5 and 6 mis fire along with the ever helpful p0300 misc mis fire. Also got p1151 lack of HO2S21 Switches indicate lean.

have noticed that the egr valve solenoid once engine has been running for a while once shut off. The valve makes a noise like a rubber hose squeezing air. Not loud but it is doing so. Would this be normal as vacuum drops from system? Hose connections seem good.

Help?

 

Forgot to mention crank sensor has no corrosion and tested good with a meter.

Numbers on data stream, these held fairly steady until engine up to temp then they leveled out
Numbers on data stream after leveled out
spraying carb cleaner around intake and throttle body had no effect on these numbers

 

Just noticed my b2 s1 o2 sensor reading a consistent 0.00V. Could this cause the erratic fuel trims?

 

You indicated over a week ago that you had a B2S21 DTC. You need to address it, otherwise, you'll just waste more time chasing ghosts.

 

That sensor ceased throwing codes, so I had dropped it from my list of woes...
however I have now replace it... no change...
no power, mis fire on 5,6&8 fuel trims jumping erratically then suddenly settles out then again goes erratic...

throwing money I don't have at this thing... so frustrating

 

Gone back to the camshaft sensor as it has arisen as suspect multiple times. Probing the two wires with my voltmeter shows me approx .8v fairly steady on one and fluctuating between .74 and .79 on the other... is this small fluctuation what I should be expecting or should it be a greater fluctuation? I'm reading. 5 to 1v is it's norm but not finding how great a fluctuation is correct...

 

Dumb question... how is your fuel?

Do you have water in your fuel? Is your filter plugged? Did someone accidentally fill it with diesel?

 

Finally got a day with temps slightly above freezing and have gone back to trying to figure this out.

Same exact problems today, no changes. after siphoned the fuel tank no water, fuel smelled fine but still put in fresh fuel.
Removed all pin connectors going to firewall, no corrosion and no loose pins, re applied dialectric grease and reinstalled.
Same miss fires, same erratic fuel trims...

I'm have no clue what next...