Ok so I finally got my '94 960 to start, but it was running like crap. Today I started it & pulled the electrical wire off each coil one at a time to disable it to see if they where all firing.

Well, numbers 1, 2 & 6 are firing & the car will die if I pull off the wire from one of them. Numbers 2, 4, & 5 are not firing & nothing happens when I pull the wire off them.

I have GREAT compression in all 6 cylinders - 240PSI - & when I checked the wire going into & out of the coil, they both have power. I already checked the wiring scematic to be sure the coils are wired correctly, so I know they are correct.

Im wondering if maybe I have a bad ignition module. I know there are 2 modules, but I dont know which one fires which plugs, so I dont know if one of them fires 1, 4, & 5, & it is bad.

Any one expirience this problem before? Any ideas would be great!

Also, how hard is it to change the ignition modules?

 

It does sound like it is the power stages (ignition modules), but to be sure I would swap them and see if the even odd switch.

One power stage controls, 1, 3 and 5, the other controls 2, 4 and 6.

They cost about $100 per. So I would confirm first, maybe the connector is not completely in?

Swapping them is kind of a pain, because reaching the rear most one is tough.

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

 

Ok so where are they & how do I remove them or check the connectors?

 

The power stages are located front and back of the intake manifold, the part below the throttle body, where the intake manifold has a bulbous part. They are attached with a metric allen screw. The rear one is difficult to reach, having double jointed wrists is a great help. But if it is tough, going from underneath is the usual approach.

DanR

 

Ok, I checked some more on it today. I checked the connections at both modules & they seem to be OK. I then ran codes & got a 121 - "Faulty signal to/from Air Mass Meter". Thats the only code I got. I then erased the codes & got a 111 - no codes. I started it up & ran it for awhile - it was still running on 3 cylinders. The check engine light came on after about 10 minutes. I rechecked the codes & got a 121 again.

Can the AMM cause it to miss on 3 cylinders, or is it just adding to the problem? I still think it may be in the ignition modules. What do you think?

 

I think because OBi diagnostics is rather crude, because you have a miss on three cylinders you are getting the air meter code, one quick way to rule out the air meter is to disconnect it. If it is faulty many times the engine will run better with it unplugged. Do not make any connections with the ignition on, if your air meter is fine, making connections and disconnections with the ignition on, can fry it out.


If you are sure it is missing on three cylinders find out if they are even or odd cylinders. If they are all one or the other but not a mixture of both, then you do have a faulty power stage.

DanR

 

I have those power stages, ignition modules, whatever they're called. I'll sell em cheap. Have lots of parts from my 960's engine for sale Air flow meter too!

 

I found out today that my ignition modules are both new, so thats not the problem. However, I may be interested in an AMM & a neutral safety switch. How much for them?

 

Ok, so heres a mind blower for ya!

I was looking at my 960 the other day & was trying to figure out why it was running on 3 cylinders. I was letting it run, even though it ran like crap, & was trying to get it to idle. After it warmed up, it would finally idle, so I was able to check it while it was running. I found a vacuum hose off the manifold & plugged it in. That helped & it ran a little better, but still was missing. It also made a MAF code go away.

I then pulled the connectors off the coils on #s 2,4,& 5 to see if they were missing. (one at a time) They still were. Then I revved the motor up & pulled them while at high rpms. I could tell that when I plugged them back in, the engine would smooth out a little, so I figured they were firing, just not to full potential.

I then decided to switch coils between a cylinder that was firing good & one that wasnt. When I pulled the coils, I thought "why not change the spark plugs first & see what happens" So I swapped the plugs on #s 1 & 2. started it up & sure enough, 2 was firing, & one wasnt.

When I pulled all six plugs, I could see the ones that were firing & the ones that wern't. These plugs were all brand new plugs. They were Autolite 3924's. I called the parts store to find out what the OEM recommended plug was. They told me this car should have Bosch, or NGK platinum plugs in it. I ordered 6 NGK plugs & when they came, I installed them. I was hoping this would take care of the problem, but I had my doubts. Why would 3 brand new plugs out of 6 not fire?

Well, I turned the key & WOW! She started right up & purred like a kitten! I even took it out & drove around for awhile & it never missed a beat. Awesome!

I have heard that ceartain cars will not run without the correct spark plugs, but this is the first time I have seen it. So, Volvo guys - NEVER PUT COPPER PLUGS IN YOUR VOLVO - IT WONT RUN WITH THEM!

Whew, Im glad I figured that one out! No codes either! YA!

 

Copper plugs work perfectly fine. Just don't use wrong, or garbage plugs. I used NGK BKR6E for 25k miles and they were perfectly fine. Regardless, glad you got the issue fixed! Also - emailing you now!!

 

I also ran Denso copper plugs on mine with no issues. Sure, this whiteblock seems to like Volvo's 3-prong plugs the best, but like kendogg, I would not fault copper wires in general.

Actually, I had Autolites Coppers on my 850 a year ago with no issues.

 

Ill stick with platinum. It aint worth the hassle.