Volvo Penta 8.1 PFI missing on 3,5,7 and 8

[Magic Man]

Port fuel injected with throttle iac body. Clearly missing at idle and all speeds. New ecm, new cam sensor.. oem, new crank sensor oem. no vacuum leaks, timing chain inspection is tight, intake manifold was removed and no issues found. Had 7 codes, new ecm and cam sensor corrected those and now no codes but still missing bad on those cylinders. Compression is all at 145-155 no valve train noise, cam looks great. Fuel injectors swapped and problem stays on those cylinders. The intake runners are connected on those cylinders. Inspected intake as thorough as possible and looks new honestly. Spark plugs have been swapped and problems stays on those. Rhinda scanner is what we use. seems like an easy find this issue but has eluded us thus far. Any help from you good people is appreciated. Im sure we are overthinking it all at this point.

 

[alldodge]

Do you know if the misfire is caused by fuel injectors or spark plugs?

NOID light can be used on injectors to see if they are turning ON/OFF

 

[Magic Man]

Do you know if the misfire is caused by fuel injectors or spark plugs?

NOID light can be used on injectors to see if they are turning ON/OFF

Swapped injectors and spark plugs did test with noid light. All good. still has issue

 

[alldodge]

So using noid light on injectors there were no misses?
If correct then this is a coil firing issue.
I don't have a PFI manual but do have GI and GXI, or was the PFI a slip?

Should ring out the wiring back thru connectors to the ECM.

 

[Magic Man]

So using noid light on injectors there were no misses?
If correct then this is a coil firing issue.
I don't have a PFI manual but do have GI and GXI, or was the PFI a slip?

Should ring out the wiring back thru connectors to the ECM.

I understand, wiring looks great. swapped out coils. pain in the rear. no change though.

 

[Magic Man]

So using noid light on injectors there were no misses?
If correct then this is a coil firing issue.
I don't have a PFI manual but do have GI and GXI, or was the PFI a slip?

Should ring out the wiring back thru connectors to the ECM.

NO issues with missing on noid testing. Craziest stuff I've seen on these so far.

 

[alldodge]

Looks are deceiving, might look good but there is a connection in the harness or connector which is not making contact.

Swapping is not the issue, need to find out why the coils are not firing. This is why wires need to be ohmed out (ring out). The coils just like the injectors and feeds which power some many of the coils, but not all. This is called batch wiring. There is probably a splice inside the harness or a connector which is the problem

 

[Magic Man]

Looks are deceiving, might look good but there is a connection in the harness or connector which is not making contact.

Swapping is not the issue, need to find out why the coils are not firing. This is why wires need to be ohmed out (ring out). The coils just like the injectors and feeds which power some many of the coils, but not all. This is called batch wiring. There is probably a splice inside the harness or a connector which is the problem

Good info, I will remove the harness and open and inspect with an ohm meter soon.

 

[Magic Man]

Looks are deceiving, might look good but there is a connection in the harness or connector which is not making contact.

Swapping is not the issue, need to find out why the coils are not firing. This is why wires need to be ohmed out (ring out). The coils just like the injectors and feeds which power some many of the coils, but not all. This is called batch wiring. There is probably a splice inside the harness or a connector which is the problem

Coils are firing but no way to see if on time. You know what I mean?

 

[alldodge]

This is the GXI-C/D and may help. The injectors have full time 12V via the Pink/white coming from the main power relay (MPR) then goes to a connector which its split into Pink and Pink/White wires. They are batched fired by applying a ground by the ECM

The coils are all powered by the Pink/White coming from the MPR and individually fired by the ECM. Coils have a common ground

 

[Magic Man]

This is the GXI-C/D and may help. The injectors have full time 12V via the Pink/white coming from the main power relay (MPR) then goes to a connector which its split into Pink and Pink/White wires. They are batched fired by applying a ground by the ECM

The coils are all powered by the Pink/White coming from the MPR and individually fired by the ECM. Coils have a common ground

View attachment 346364

Great info. I'm pretty familiar with most EFI setups but this will certainly help me to diagnose this one for sure. Thank you very much I'll reply after I've had a chance to go through the wiring thoroughly. May be a few days or so.

 

[Magic Man]

Update: problem solved. $3,000.00+ ECM was bad with 7 codes including cam sensor code, and 3 bad injectors. Injectors on bench test showed fine, swapped them into different cylinders and problem moved. Thought my man had done this prior. Oddly, Found some tiny particle of metal inside the bad injectors after a really close inspection. Runs perfect now. Thanks for all you guys help!

 

[tricia222]

Update: problem solved. $3,000.00+ ECM was bad with 7 codes including cam sensor code, and 3 bad injectors. Injectors on bench test showed fine, swapped them into different cylinders and problem moved. Thought my man had done this prior. Oddly, Found some tiny particle of metal inside the bad injectors after a really close inspection. Runs perfect now. Thanks for all you guys help!

Where did you find ECM, been looking for one for my GIL-H and no luck.

 

[Magic Man]

Dealer source. Had it flown in from Sweden. Are you a dealer? If so I can share the info privately. MOD EDIT - Use your head and do not post your phone number in a forum.