i got a 1992 960 wagon used as a project car, i got it started and found out it has a misfire on cyl #5, but it is not throwing the check engine light and has no codes stored. ive replaced all 6 spark plugs with bosch brand plugs and ive taken the ign coil for cyl 5 and tried it on cyl 1 and it does fire, so, coil and plug is good, but the coil will not fire when on cyl 5 wiring, found wiring into coil was loose, so i went to the junk yard and found a beautiful 92 960 (idk why it was there, it was in perfect shape) but anyways, i stole the wiring to the coils off of it and spliced into the wiring harness on my volvo and soldered a pigtail connector from the parts volvo onto mine, thinking loose connection was my issue, just completed that and still, cyl 5 coil will not fire at all, checked and found i have a battery positive signal all the time to the coil, so its getting positive, but im afraid to hook the test light up to the positive of the battery and touch the other wire, i dont want to fry the engine computer. what is my next step to getting the coil to fire so i can clear up this miss? and if it is possibly a bad engine computer, can i go to my lovely junk yard donor and take the one from that one and will it work in mine? im a bmw tech, not a volvo tech, i know you can swap engine computers around on older bmw's i was wondering if the same is true for volvo's. if anyone has any suggestions on my next step to figuring out my issue, it would be greatly appreciated

 

Are you getting fuel the #5 injector, is it clicking? A normal injector should read about 16 ohms resistance. If that all checks out, you should do a compression test. Could be a bad valve. Also another thing could be an intake leak around that cylinder.

Also you might check the wire to #5 and see if it has been swapped at the connector, or check continuity to the power stage.

Before all of that, you might swap the power stages on the intake manifold and see if it moves to another cylinder.

Let us know what you find out.

DanR '94 964 356,000 miles (122,000 on the new engine)

 

where are the power stages exactly on the intake manifold, i found a wiring diagram for a 94 model and im assuming its the same thing, i havent went out and got a repair manual yet, but im working on it lol. but the wiring diagram mentioned those power stages, i just didnt know what they were or what they do, i was also thinking maybe bad motronics? the coil works on any other cyl except for #5, as far as im aware the injector works, but ill do some further tests in a few and reply back

 

ok i just checked and you can hear the fuel injector for cyl 5 clicking away loud and clear, also i think i found the power stages that you were talking about, i just need to know which one comtrols what cyl's, i see theres one on the front and bolted to the back, which is which, the wiring diagram doesnt specify front or back, it just says intake manifold, thanks for the help btw

 

I am not sure which one controls which cylinders, but think it is 1, 3, 5 and 2, 4. 6.

Just swap them for now, if the miss goes to another cylinder then, you know you will need to buy a new power stage. If it stays at #5, then it will require further diagnostics, such as; bad valve, intake manifold leak, vacuum leak.

DanR

 

well i dont think i have a mechanical issue or vacuum leak because i tested the coil on that cylinder and it will not fire, but the coil will fire on another cylinder, so im pretty sure its wiring or that power stage, or possibly toe motronics, im going to the jumk yard this weekend anyway, im gonna pick up a spare motronics and ill swipe both power stages also, i dont have the $150 for a new one, but thanks for the help, ill swap them when i get a chance to tinker with it again and let you know what happens

 

One way to find out if it is a wire problem or a power stage problem is to swap them now, then you will know for sure if the trouble goes to another cylinder.

DanR

 

KC, If you have a burnt valve it will stop it from firing. You should do a compression test.

 

yea today during lunch i swapped them around and cyl 5 started firing again, i think it transfered to 2, i know it went to an even cyl, from the wiring diagram i have one power stage does the even coils the other does the odd coils, but now since i know the one power stage is bad, does anybody know what power stage controls what grouping of cylinders? theres one on the front of the intake and one on the rear (facing the firewall), if anybody knows which is which that would be greatly appreciated, since there both kinda a bitch to get off down in there

 

Your right about the pain of swapping those, I'll see if my volvo manual tells the tale. Will get back to you this weekend.

DanR

 

I don't know if this will help the wiring is for a 1997 965. The location for both is the same, just module 1 and 2:but here goes:

On my diagram all the pins labeled 2 are green/red so I will only list Coils and #1 pin.

MOTRONIC POWERSTAGE MODULE 1
***On my diagram there is a SERVICE SOCKET CLAMP. It comes of pin #1 of Coil #1. showing a red/white wire
Coil 1 Pin#1 is RED/WHITE
Coil 3 Pin#1 Is ORANGE
Coil 5 Pin#1 Is YELLOW/BROWN

MOTRONIC POWERSTAGE MODULE 2
Coil 2 Pin#1 Is WHITE\BLACK
Coil 4 Pin#1 Is GREEN/YELLOW
Coil 6 Pin#1 Is VIOLET

This maybe of no help at being different years, if I find anything to help I will post.

Good Luck

 

The forward facingpower stage controls 1, 3 and 5, the rear facing controls 2, 4 and 6.


Replacing that bad one should take care of this for you, good luck.

DanR

 

ok thanks, if you find out that would be a great help, and when i swapped them its not such a pain, i put it on a lift to get the back one off, getting it from underneath makes life sooooo much easier, but trying to get it from underneath the one at the junkyard, well, that was a little harder. i went to pull-a-part in ohio, and got both of them off my junked donor 960 for $15 for the pair, they dont know i just got $300+ worth of parts

 

ok awesome, thank you guys so much for the help like i said im a bmw tech, i know those things inside and out, i dont know volvo's very well and this is completely different than the 87 240gl wagon i had back in high school (yea it was my first car, still shoulda never sold it) but i will hook up my junk yard power stage to it and see how she runs and ill report back on monday

 

I only know my Volvo because of the years and mileage. BMW, I have an '06 550i, with 111,000 miles. Maybe the best car I have ever driven, had to do very minor things besides the 4 recalls. Hope it runs well for the next 3-4 years.

Good Luck,

DanR

 

Thanks You ! for this forum, I saved time and money repairing my 1992 Volvo 960 station wagon with a 160k miles. I had the same problem as mention. I drove 50 miles to my home on 103 degree day, when I pulled off the highway, I notice a rough idle. Drove the car that night when cooler it ran great, but next day it happen again. Checked for vaccum leaks found none, removed spark plugs, they all looked good except for #5 looked wet with gas, unpluged each coil one at a time, found a difference in idle except for the #5 cylinder. Installed 8 dollar junk yard front facing Power Stage module for the #1,#3,#5 spark plug coils. My wagon runs like new again.