430 engine misfiring

Welcome aboard. Sorry you’re facing this misfire problem. You should definitely post and search in the 360/430 forum (in the Model-Specific area). I’m pretty sure I’ve seen threads on this issue.

 

Where did u get the coils and have you checked the Maf sensors

 

What are the fuel trims ..O2 sensor readings

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Maybe an air leak in the intake manifold gasket?

 

It was a bit pointless changing plugs and coils if the misfires are random, if you had a bad plug or coil it would show on the same unit all the time. The 2 fuel pumps each have a low and high speed relay. Odd things happen if relay PSR7 goes wrong, try fitting a new one to see if it helps.
Also what volts are you getting whilst driving ? Very voltage sensitive car if alternator not working right or aux belt slipping

 

PSR7, Mike? Isn't that one of the starter relays? PSR7 = "SURP" relay

Did you mean PSR9 ("speed 2") for the LH bank and PDR9 ("speed 2") for the RH bank?

 

Thanks, Mike. Still doesn't make a lot of sense. PSR7 is only active when you push the starter switch.

As far as I can see, PSR7:
Provides voltage to the starter relay (earth provided by F1 TCU).
Deactivates some heavy current devices during start (to help with start)
Sends some kind of signal to the Instrument Panel
Sends a voltage to the F1 TCU, presumably to initiate the cranking sequence.

I think you would have to ask Scud-Ing Swiss about it.

 

Check your upper intake manifold bolts. I believe with colder weather it can possibly be contracting and vibration can wiggle the bolts too.

 

According to an instrument panel pinout, this signal is not used.

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The OEM relay graphics are not helpful. I think I needs some better diagrams.

 

What would you check to see if you had a constant volt supply to the coils, i would think a variable voltage would cause misfiring as it would alter the ignition timing ??

 

Unfortunately, I don’t have any ignition diagrams for the standard F430.
Do the ECUs drive the coils directly or is there a supply rail.

 

i have e mailed you some i have, see if they help. It looks to me the coils get their signals from the ECUs behind the seats

 

The trigger signals are provided by the ECUs, but do the coils use fuse power? e.g. PSF16 (left bank) and PDF16 (right bank) as they do on the Scud?

 

Quick search show According to this it does
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Did you happen to change/add oil before you started to get the mis-fire? If so, remember these are dry sump engines and many people overfill by accident.

 

... and the injectors.

If it's random cyclinders on both banks, the problem must be further upstream... but the only thing in common with the left and right banks is the battery/alternator.

Battery bus bar (behind driver) >>> maxi fuse PSF28 >>> fuse PSF23 >>> LH Motronic Relay PSR10 >>> fuse PSF16 (for the left bank).

Battery bus bar (behind driver) >>> maxi fuse PSF29 >>> fuse PDF23 >>> RH Motronic Relay PDR10 >>> fuse PDF16 (for the right bank).

 

My 430 had this problem exactly. It was, as has been stated before, the intake manifold gaskets were leaking. A smoke test confirmed that issue and they were replaced. That completely solved the problem and made a lot of difference in the performance and no misfires thereafter.

 

A little brake cleaner fluid and you should see if that is the issue ..spray in cold running engine near gasket and see if engine changes tune/rpm ..easy

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Neat idea