355 What's wrong with this injector waveform ?

And set the timebase to 1 millisecond so we can get a proper reading of the width of the pulse on Cyl 5 and at least one cylinder on bank 1. This may mean that you won't see the pulses on the other injectors at the same (but we need an accurate reading).

 

That's the way it should work. But apparently that is not what is happening. There is unburnt fuel in the exhaust, a very "rich" condition, causing the cats to over heat. Under such conditions, if operating correctly, the O2 sensor "should" sense a lack of O2 in the exhaust and narrow the pulse width. But it's not doing that. It pushing the LTFT to 18 which means it's actually trying to correct for too much O2 in the exhaust. I.e. for some reason it thinks it's too lean. Why does it think it's too lean? Assuming the ECU is OK it must be getting a signal from the O2 sensor that there is too much O2 in the exhaust. The reason could be any of several: bad O2 sensor, Exhaust leak (Grant says no to that), bank 1 running on 3 cylinder, failure of the air injection system to shut down in closed loop mode.....

What could be done is to set LTFT to zero and see if it increases again, but I think an SD1 is required to reset it. I recall LTFT is not reset when power is cut to the ECU. Perhaps someone can confirm that one way or the other.

 

Grant, could you just confirm that you meant +18 LTFT.

Definitely not on the 5.2. No reset.

 

I believe we are all talking about the same thing but with different approaches

Ltft doesn’t reset after key off —- and ltft is a strategy to bring STFT to 0 —- the STFT has to rises or fall from what the feed back from O2 sensor is at that time the LTFT will rise or fall if the STFT stays above or below a predetermined value in the ecm so that the STFT is as close to 0 as possible

Add the 2 together and that your over all trim

A CAT in simple terms stores oxygen and the fuel mixture will create a high temperature catalyst reaction —- the O2 sensor monitors the fuel mixture to try to keep the system in the right “sweet spot “ not overheating the cat and have a reduction in lower emissions—— the air pump is supply oxygen to cat through exhaust valves to ensure there’s is enough oxygen for the emissions to be reduced and to help lite off the cat as fast as possible

The temperature sensor on the cat is to warn the drive the cat can not handle the the high temperature that is being created in the car and to allow the system to lower or add more Oxygen to bring the cat back in balance


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No it is switching fast on front and slower on rear

 

This was all due to a misfire on at least cylinder 4 due to fuel injector not firing so far

 

I can confirm as I have 2 ecu’s and my used ecu had LTFT at about 5 when I plugged it in and it slowly started to climb and car was still not working correct and STFT was at 10
When original was plugged in it was STFT 5 and LTFT was at 15
as LTFT went up STFT went down and even when unplugged for months it remembers it.
That being said I can supposedly 0 it out with my Leonardo.
Air injection shuts off about 3 min

 

Update. X 1 on Leeds from now on and voltage at 10 volts. DC coupling
So definitely bank 4 is not firing and when I move the main harness in towards engine it works and when I pull towards seats it cuts off and maybe even more than 1 cylinder.
Here is the trace from bank 4 when working followed by when not working.

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And now today not working

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this picture is zoomed
Of the above one
So would that mean grounding problem
Or supply voltage problem

voltages are set at 10 volts

when it was working those smaller vertical lines are exactly 28ms apart

 

The following pics are not from cylinder 4 but from1 when working
The first pic is zoomed out
Second pic is zoomed in a bit more
Final pic is zoomed right in
Probes are on X1 and voltage is at 10 volts


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Would it be the ground wire though or the voltage wire
Can we tell from the scope

 

Are you pulling on the harness in the cabin? The injector power wire for both the right bank and the left bank is probably only a single wire near the ECU (and doesn't go to the ECU).

Even on the bad waveform, the base voltage seems to be the same as on the good waveform (?). As Mitch says, it's more likely to be the individual ECU trigger wire/s.

 

Yes I am pulling on the main harness right at the bulkhead rubber
When I pull it miss fires when I push it back towards engine it runs good
I am not moving other connectors in the cabin and if I try to they do nothing
Only the main harness has an effect

 

So it sounds like there is a broken wire or two inside the harness. Perhaps the harness was stretched too much during an engine out.

Other than splicing in some temporary wiring, it sounds like an engine out job to repair the wiring.

Welcome to the club.... I still have a bypass harness for my alternator... until the next major.

 

If I understand the figures this is what I see. To the left is what you are seeing. The probe is sitting at the supply voltage before the switch closes. Then there is a spike down when the switch closes but it quickly rises back to nearly the supply voltage. This indicates a high resistance in the ground side of the injector, limiting the current flow. Classic response of and RL circuit to a step change in voltage. That resistance must be somewhere after the point where the probe is connected.

To the right is what the signal should look like.

I would check the harness to the ECU where the wire is crimped to the connector to see if the wire broke just before or at the crimp. I've had that happen. It's a high stress point.

Another option is to run a second wire parallel to the wire in the harness from the injector to the ECU and see if that solved the problem

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Here is a schematic ofwhat you appear to have on the left of the correct circuit on the right.

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Here is what I mean by a second wire. If doing this works it eliminated the ECU "switch" as the problem.

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Here is an example of what I mean by the wire breaking just before the crimp as I experienced.

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That's the hard part... running a wire through the firewall over the fuel tank into the cramped area behind the engine, then through the engine "V".

There is a concern that the old wire is shorted to something, so you may have to temporarily cut both ends of the old wire to take it completely out of the circuit.

 

Yes, but to test it you can just run it from the injector, out the rear deck, in through a window and to the ECU. If that works the problem is confirmed.

Shorted? To what? The wave form doesn't look like a short anywhere. The initial negating spike when the switch closes followed by a rise to nearly the supply voltage indicates a high resistance in series with the injector (not the injector resistance). The large positive spike when the switch opens is a result of the instantaneous drop in current to zero (open circuit).

Another reason why 2.7 cars are better. ECU right in the engine compartment.

 

Ferrari is still making up its mind about this
348 - out of engine compartment
F355 2.7 - in
F355 5.2 - out
456/550 - out
360 - in
F430 - out
F458 - in

 

I think that is correct but I was not smart enough to put that together
I am not sure John
All I know is that I did not get the correct trace when I pulled on the harness
This is without moving the main 88 wire connector
It is definitely within 6 inches of the bulkhead as you pull and push while isolating the wire from bulkhead to 88 wire plug
If I move just the 88 wire plug lots it does nothing

I did not look but do the time frames match up.
I assume they did and that. Was how you came up with that

 

I don’t blame ferrari for me likely pulling too hard on the harness
Mostly poor mechanics

 

Based on the scale though would it not be like 5 micro seconds between those
And on the good wave is it not 4 milli seconds based on scales
So would that actually be the same??

I think I read it wrong it does look close

So did anyone say weather this was power or ground
My understanding is it would be the switched ground is not switching good so would that mean the grounding wires are not grounding properly.

 

So from your diagram John the ground wire is broken, is that correct or mostly broken

 

If it was shorted would the injector not stay open?

 

I was thinking of it shorting to a power wire on the earth side, but I guess that would create a different base/starting voltage on your scope.

Does the scope position the baseline on the screen according to voltage or can it be moved around?