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adjacent cylinder no spark

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Noidanat

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Newbe here--having problems with our VolvoPenta 8.1 GI-G. Engine starts and idles fine--save for the fact that 2 adjacent cylinders are not firing,. Have used induction timing light to verify solid firing of six of eight cylinders--have swapped ignition coils from not firing to firing cylinders--no change so not coil. swapped spark plug lines from inactive to active plugs--no net effect so assume no spark plug wire defect. Nearest VP dealer 1.5hr away, and booked solid anyway. Kinda wondering if one can utilize a multimeter to verify delivered voltages to the ignition coil, although absence of timing light through a known functioning ignition coil kinda proves delivered electrical impulse is lacking. Control module?? any suggestions would be very appreciated. Thanks in advance SL
 
It would be best to scan the ECM to see what is going on....without the tool, there's not much you can do.

I would verify you have +12VDC to the coil with the key on - D terminal and a good ground on the A terminal.

If you have a frequency measuring capability on the meter, you can check the IC signal - C terminal.

other than that, you can reseat the J2 connector - the one over the mounting tab...
 
makomark said:
knowing which cylinders may help too....
Click to expand...

Thanks for giving some points to investigate--I will describe non-firing cylinders by location (as I don't know # id) Stern forward--rearmost cylinders on the right. Is there a schematic available that would show pin input into coil (as you described). As you can probably tell, I'm more familiar with points and timing issues, comes with my age :) Thank you, SL
 
as with all gm V motors facing the front of the engine (v belts,or serpentine)
on your right 1,3,5,7 on your left 2,4,6,8
 
If you look into the connector, with the locking tab up, the pins are A -D, left to right.

the only thing shared by 6 & 8 are the Reference and ground pins...they may have a bad connection between the connectors and their splices (all coils have these leads going to a common splice. Somebody may have damaged the harness...you can always try the wiggle test on the harness...another option would be to check for continuity between coil #8's B and and coil #4's B...and the repeat for the D pins. The drawback to the continuity test is that is is very low current so a marginal connection may show OK but won't let the coil fire...
 
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To be clear, when you are talking about grounding and delivered 12VDC, you mean the 4 pin connector attached to each of the 8 ignition coils---and when you say key on, you do not mean engine started, only key to first position clockwise? The reason I ask is I attached my neg lead to the battery, key on-not started, and surveyed the 4 female, incoming line posts on both non-functioning and functioning coils, and found no 12VDC on either. Perkaps with dual batteries, the battery I went to ground on might have been disengaged--I'll go to ground on the engine and try again. Thanks for the help--I will press on:)
 
One of our peterbilt trucks is automatic transmission--which failed (to move)--tech suggested we freeze ECM (with inverted aerosol air can) and see if it temporarily solved defect--which it did. So me thinks--why not give it a try on the Volvo Penta 8.1 , and, after freezing the module, I'll be damned if the igniters began firing--short term fix--Now to find a modem under 2K-that is properly programmed. Thanks for the advice. SL
 
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