960 217K

The teen daughter's 960 runs great, especially when actually rolling. When it is in parked or in drive but not moving there is a minor shake from the motor. When the car is moving, or stationary but with the motor revved about 1K, the shake disappears.

The timing belt was changed by the previous owner (actually a reputable shop) about 10 months ago as well as some of the the front end (ball joints and some other stuff). Could those repair be causing the issue?

My daughter asks me regularly about the shake. Any ideas?

Thanks as always.

az

 

Could be one of number of things, some very simple as a bad coil, bad wire to a coil, the wire running on top of the head below the Volvo cover can abraid, causing shorts. Bad spark plug, bad intake gasket, a very common problem with the 960's. To worst case, a bad valve.

So start with the simplest, the wiring at the top of the head, idle the engine and gently move the wiring and see if the tempo changes.

Then try to isolate the missing cylinder by removing one coil at a time, again while the engine is idling, the offending cylinder should not change the miss much when removed. If you narrow it down to a cylinder, then swap that coil with another cylinder, if the miss follows that coil, then the coil is bad.

If the above fails, then you can swap the power stages and see if again it moves to another cylinder. They are located fore and aft of the bulbeous part of the intake manifold, below the throttle plate.

If none of that works, then you will need to test for a intake gasket leak and/or do a compression test.

You can use unlit propane from a torch, applying it around the intake gasket to see if that smoothes out the idle.

DanR '94 964 361,000 miles (127,000 on the new engine)

 

Do you have a CEL? If so, what is the code? What year is the car?

 

Sorry, 1997 960, 217K.

I do have a CEL, which I had read, but I no longer have the code numbers handy. One of the codes referred to cylinder 1 misfiring. The other indicated running rich, (O2, vaccuum leak, etc.). The misfife code makes sense based on previous comments in the thread.

I've yet to take the steps suggested as the last couple weekends were filled with holiday duties... and my wife insists the problem is a motor mount--she had a shake in a car 30 years ago that was solve by a motor mount replacement...since then ANY shake is the result of a cracked motor mount.

 

A recent thread here had similar symptoms.

Vacuum leaks can be detected and interpreted this way.

Stage 0 status?

 

In these well balanced cars/motors misfiring will cause the car to shake. The code for #1 misfire should have been P0301. Get that fixed and you should be good.

 

Okay guys...

I finally got the tinker today. Cylinder one is definitely not firing. Pulling the wires makes no difference in how the motor is running.

The wire connectors have seen better days. The grey plastic connector that holds the wire doesn't really hold the wore and was gunked up with brown goo. I cleaned the goo, pulled the wires out of the grey plastic and connected them directly to the coil pack. Connected or not, the motor ran the same way.

So I disconnected #2 while the motor was running and the motor changed behavior, still running amazingly smooth for being down two cylinders, but at least different enough to know that everything on #2 is good.

Then I swapped coil from #1 with the known working coil from #2. Number one still did not respond when connected and disconnected. Number #2 still did. So we know all the coils packs are good.

How can I determine if the problem is the wires? Is there a way to measure amperage or voltage to be sure the wires are delivering the power? I know how to test the spark plug (buy a new one and swap it) which I may do anyway.

What other tests should I run?

Thanks.

az

 

...and I located the power stages, (I think... flattish with a Bosch label and a wire harness that lead down?) How would I remove the aft one seems especially hard to get at.

Any ideas?

thanks

az

 

Thinking as I'm tinkering.

I hooked up #1's wires to #2. Started the motor, then disconnected the wires from #2. No change.

So the problem is either the wires or the power stage that controls it, right?

So...

How do I change the wires? They seem to disappear at the aft of the motor. I imagine they lead to the power stages, right? Which power stage controls #1?

Learning as I go.

az

 

Before you test the Power Stages, start with the simple things. I would try to be methodical, and first things first.

Spark Plug. I asked about Stage 0, and we got no answer from you. In this particular case means: visual inspection first -- NGK Spark Plugs USA

Second -- check the gap. Gap should be about 0.028-0.032 inch. I would also check if you in fact have the correct plug. Various plugs fire differently for different ignition systems. If previous owner used wrong plug, it may be kaput. Pull the owner's manual and check.

Ignition wires: they do crumble and you need to fix them too. You can also buy them from Dave Barton Dave's Volvo Engine Wire Harness Page - 960 and S90. Another option is to buy the connectors from Tasca and wire crimp. For more read 960 '95 960: disintegrating spark plug coil plugs... WTF? - Turbobricks Forums

After you do the above, and problem is still there -- then swap the 2 power stages. If the misfire moves to another cylinder, then you know which one of the 2 Power Stages is bad.

If you are interested how this particular Bosch Ignition system works, pull a chair:

Ignition is controlled by ECU with the help of 2 power stages (located on front and rear of intake manifold). Each power stage fires 3 cylinders (135, and 246).

Ignition is done by individual coil-on-plugs. ECU controls ignition by grounding coils at appropriate timing, via 2 Power Stages.

Ignition Relay supplies 12V to each coil when KOER (Key-On Engine-Running). This is the Green/Red wire to each coil.

It is the Ground wire that has timed activation, which occurs in milliseconds interval. You will need special equipment to read this. That's why swapping is the easiest thing.

 

Front Power stage fires the odd-number coils, Rear fires the even-number coils.

 

Sorry. I tend to jump ahead when i think i know the answer. It used to annoy my teachers when i was in school.

I'll pull the plug and give you a report.

I also just checked the red/green wire with the engine running...got a steady 16.5V. Hmmm.

 

That wire should have battery voltage. Either the voltmeter is wrong or you have a short somewhere. Go to that link that I gave you, either order the connector and wire-crimp yourself and heat-shrink, or order from Dave. Regardless of plug that seems necessary.

 

Could very well be a misread by the meter, it's a cheapie.

Still, the input on the coil says +15V. 16.5V is right in line with +15V.

Not disputing, just observing.

I'll check what the meter says at the battery. Do I still need to pull the spark plug?

Dave's harness is $150(!)...and out of stock. I'm hoping for a better answer.

 

I just checked the voltage across the battery with my cheapie meter and it also reads 16.5V(!?!) So, to test the meter, I checked the voltage on a new AA battery, which should be about 1.8V and the meter read 1.78V. Seems like the meter is accurate, at least on low voltage. Both the AA and car battery were tested using the same range. I'm hoping the issue is with my $20 volt meter rather than the car's electrical system.

And meanwhile, the #1 cylinder is still out.

Should I continue and switch the power stages? The rear one is a real bear to get to.

Thanks for your indulgence. I really appreciate everyone's expertise here, even if ask a whole bunch of questions.

az

 

Change the spark plug first. Order also the connector from Tasca (or the other place TrickMick says to) and do the crimping yourself and heatshrink. AA batteries should be 1.5V. Are you sure you are selecting the right setting on the meter?

Rear Power stage is a bitch to get to. Another reason why you should do the easy things first.

 

Trickmick? Who's that?

I looked on the Tascaparts website but didn't see ignition wires. Am I missing something?

AA batteries are rated at 1.5V and begin to fail if they drop below that voltage. All new AAA, A, C and D batteries come shipped from the factory at 1.75-1.8V. Otherwise they would die shortly into the first usage. Test for your self on a new battery at your house. (My background is consumer electronics on which I can speak authoritatively. Car repair, not so much.)

I had my meter set to the 20 scale in DC Voltage. Still, I can't promise the meter is working as it should. Car batteries should not run at 16V from what I've learned.

I'll pull the spark plug and replace it tomorrow. Small investment.

Again, thanks for your help. I truly appreciate it.

az

 

I pulled spark plug #1 and it exhibits normal use per the NGK site. Model is NGK BKR6EGP. BKR6E is the recommended plug for 960's according to several parts sites, and "GP" is NGK's code for "Superior Performance," presumable an upgrade from the standard BKR6E.

There are signs that the cylinder has been firing. Maybe it only fires when revved? Perhaps that's why the vibration smooths out when the RPMs are higher?

I agree that the wires need attention, and I will go ahead and get that wiring kit, but for this issue, I'm focusing on that power stage.

Ebay has a guaranteed unit for $20.00. I'm going to grab it and swap it for the front power stage. Worst case, I can resell it on ebay. Best case, it solves to problem.

Comments?

az

 

Is that a used Power Stage for $ 20? I would not even spend 20 cents to just throw parts at a problem. But hey, that's just me. Maybe it will work for you.

 

I got the "new" power stage from ebay. Installed it and still have the same issue...it didn't make any difference. (Yes, Henry, you were right...again).

What now?