I think: change IMT flaps from one bank to another to rule that out.

What about engine oil consumption? Valve stem seals? (Exhaust side seals are more hot so they give up more early than intake ones.)
I suppose engine oil in 1.000°C hot exaust gas can burn the rest of O2.
Perhaps bank 2 is more hot than bank1, too.

By the way: defective crank case ventilation can affect this, too.

catfondler

 

Norcat, resetting the fuel trims was definitely the way to go. Big negative trims on Bank 2 definitely explains the misfires with trying to go so lean. High load at lower RPMs (3000) is definitely hard to fire if lean. Since you have thoroughly checked the coils and the fuel trims jump negative so quickly, it is likely either the fuel or the O2 sensor on Bank 2. Since you previously started to see the misfire reduce to cylinder 2, I would probably swap that one to the other bank, and maybe even swap the upstream O2, bank 1 to bank 2 as a second step. Something is definitely causing it to lean the fuel on bank 2 aggressively.

FWIW, I chased a misfire on bank 2. My first step was swapping coils, then replacing one and it made no difference. I ended up replacing a fuel injector to solve it, but it was pretty obvious that the injector was bad at idle occasionally and at other conditions as well, and pretty unique to a cylinder.

 

I can't see how it can be the O2 sensor without codes for it.

 

Both the O2 sensors on bank 2 were original new ones about 100 miles ago. Since the fuel trim reset its gone back to its old routine of random misfires on all cylinders on bank 2. I can try and swap the IMT s over as thats easily done. It definitely shoots up to negative trims on sensor 1 even if I just blip the throttle in park, but if I drive like a pensioner it will go for miles without the CEL coming on, its only when the trims go over -25 then it stays on. I can’t find any new injectors so am thinking of buying a complete used fuel rail for about $100.
The engine hardly uses oil so I don’t think valve stem seals are a problem. Thanjs guys for persevering its great to have some extra heads on this frustrating problem.

 

If you are taking your IMTs out to do a swap over, you might as well do a quick and dirty bench test of them to make sure they are operating as expected.
In all likelihood they will be OK but you are dealing with a really strange problem.

If you don't have access to a regulated DC bench power supply that will allow you to progressively ramp up the drive voltage to test your IMTs, you should be able to just use some 1.5v batteries instead.
Apply one (1.5V) to each IMT to see if you get a reaction, then 2 in series (3V), then 3 in series (4.5V and finally 4 in series (6V).
You should see the IMT rotating further and faster with the increase in voltage and also the speed of rotation will be more responsive when you apply the higher voltage.
You probably don't need to go much over 6 volts to drive the IMTs fully open.

Just a sideline question....have you noticed any ignition noise coming through your audio system?
Remember the bad old days of alternator whine or ignition interference in your car stereo?
Just want to make sure you don't have a suppressor cap issue on your coil supply, which would be more pronounced at higher RPM.
There is a suppressor cap mounted near the radiator which stabilizes the coil supply line it the engine harness.....no idea what value it is and I have not removed and measured before.
But that would likely create misfires at higher RPMs and unburnt fuel being detected by the exhaust sensors, not a leaning out of your exhaust emissions.

 

Norcat, did you check the tank ventilation valve (purge valve)?

Manifold injectors are easy to check and clean (ultrasonic) with a relatively cheap injector tester.
Many workshops should own such devices.
But are random cylinder 2 - 4- 6 lean misfires likely (with one to three [of 6] defective injectors)?

catfondler

 

Did you check fuel temperature?
Did you check fuel pressure?
Your engine don't have a fuel pulsation damper, have it?

What about compression?

Do your engine have an exhaust gas temperature sensor?

But first: IMT valves and tank ventilation purge valve.

catfondler

 

Idling fine with good trims and then shooting to -25 with just a throttle blip only on Bank2 is pretty bad and unusual. It doesn't seem like fuel injectors or even the rail for that matter, with one side fine and the other bad. Most Ford ECM strategies will limit correction around 25% or 30%, so that is why the CEL triggers ON while it is over the threshold. You should disconnect the upstream Bank 2 O2 sensor, to see if it is causing the -25 trims, assuming they are short term trims (no long term). You should also log the O2 sensor even with it disconnected to see what the computer is reading, which may indicate some faulty wiring.
Assuming that fuel, air and spark or functioning well on Bank 1, the computer going 25% lean on bank 2, should definitely cause misfires under load. I don't think the reverse is very likely, that bad fuel/air/spark somehow only on Bank 2 would read as very rich since the unburned oxygen usually reads as lean (with positive trims as the result). The only thing I think that controls the short term fuel trims is the O2 sensor for that bank. The engine should run with the O2 sensor disconnected on Bank2, and if the computer stops trimming negative, the engine will likely not misfire under load.

 

Another useless comment from you with the intention of defaming !? You can't stop...
Are you about to post funny pictures to pollute the thread?
I've reported your post!

Where are your technically helpful analyzings!?

Just because you have not read the thread in full and, above all, have not understood it, my considerations are not bad!
You are very arrogant!

By the way: I don't throw anything at the wall. I give tips in which direction one could look. Read correctly!

catfondler

 

Hi MichaelDavis!
Without connected upstream O2 sensor(s) there would be no control loop and no controlled trim. It would trim according to the map.

However, it may also be possible to notice the effects of defects this way...

@Norcat
Unlikely: But have you ever exchanged the two upstream sensors (the new original Denso from bank 2 against the used one from bank 1)?

catfondler

 

Hi Catfondler, yes disconnected upstream O2 will not allowed closed loop. I am assuming that -25 is possibly caused by the ECM trimming incorrectly, and theoretically will not trim as much in open loop. If the throttle blip in park is enough to produce the negative trim surge, I expect that it would be a useful test, and it should also be ok to run in open loop, if the trims are small, for testing. Your suggestion to swap the upstream sensors is a better test, but definitely more work to do. I'm just lazy.

 

I will first test the IMT’s and swap,over at the weekend. The fuel pressure is in spec and the fuel temp reads correctly. There is no exhaust gas remp on this engine, I will also test the tank purge valve system.
There is some interesting logic being posted here, I too thought about testing the new upper O2 sensor by simply plugging in the old one I took out which appears to have been working correctly to see what happens when the ECU sees atmospheric oxygen levels which should provoke it to go positve on the fuel trims, with a sensor not actually in the exhaust stream. It should prove whether the ECU is using the info from the O2 feedback and making it run lean. Will report back, thanks again everyone.

 

"The EVAP canister purge valve is located on the engine compartment bulkhead."
I cannot see the point of injection exactly.

Please read the text, it's very interesting. In normal operation it affects the fuel trim / adjustment!

(The EVAP canister is located at the fuel tank.)

catfondler

 

I didn't go through all posts so sorry if this is already been mentioned, but have you changed the fuel filter. Ive seen a clogged fuel filter cause very similar issues multiple times. Car will drive normally but lean out when a load is applied at cruising speed. I've also seen this with cam timing but fuel filter is obviously easier

 

Oxygen sensor is actually kind of a misnomer. It actually reacts with the byproducts from the un-burnt fuel not the oxygen in the exhaust, so I don't think your going to get any reliable data from this

 

Unfortunately, you are wrong. O2 sensors can only measure the oxygen difference to the reference oxygen level (outside).
Based on the flow of oxygen ions.

Cheers, catfondler

 

You know what. I don't like being wrong, but can admit when I am. I never realized that an O2 sensor was vented to outside atmosphere. I always considered it a sealed sensor. So now that makes more sense. Sorry for the confusion as normally I'm right. Just not this time. I'll try harder in the future

 

@Norcat Any progress? Especially with the EVAP canister purge valve (and hose)?

Did you see my post #33 about that?

(Please take a photo with the position of the purge valve.)

Cheers, catfondler

 

I checked the IMT valves and they work correctly when voltage is applied to them. The evap hoses look ok, I would think any leak here would affect both banks as the evap hose connects to the manifold before it branches to the two cylinder heads, and there have never been any codes for evap system. I have ordered a complete used fuel rail as it cost less than one new injector so I can rule out injector problems before I try to find a front cat which don’t seem to exist! Work in progress...

 

No exchange against each other?
By the way: is it possible to accidentally mix up the cables / plugs?

Ok, although it would be very easy to pull off the hose and close the hose connector.

Testing (and cleaning) with a injector test device was not an alternative?


I could imagine that a single injector would cause too much gasoline in the exhaust manifold, and afterburning would lead to a lack of oxygen.
But I have no real practical experience there.

I am curious whether your new injectors will bring anything!

Perhaps you will test it if they are not yet installed. They could stuck.

I once got stucked ones in a motorcycle, where 2 out of 4 had injected only about half the amount or less. Because of month of no driving. But that was so much too little fuel that one, sometimes two, cylinders did not work.
(The machine had no lambda control. Otherwise it might have been noticed earlier.)

catfondler


P.S. Without a tester, injectors hanging at the rail on the motorcycle you could see that the 4 did not spray super evenly with the naked eye, the difference (and it was already big) I could only see when spraying into 4 glasses for measuring.

Then I wanted to have a test device, so it could be rated very well, and ultrasonic cleaning with constant opening / closing was possible.