My problem has been going on for some time. It is getting progressively worse.

I have changed/replaced.
AMM (new)
Temp sensor
Plugs/cap and router and wires
fuel pump relay
Fuel regulator
Transfer pump
throttle switch
Knock sensor
Coil
Ignition control modual...behind battery
harmonic balancer ( just because to was cracking and looked bad)
wires at Gray connector look good.


While checking my timing I noticed the light would skip a beat every once and a while. I checked incoming voltage at the coil and it cuts out momentarily at random times.

In the Bently they talk about taking the ICU plug backshell apart and checking voltage. I can't see how it comes apart.



My question is, go after the ignition control unit under the dash or something else?

Pulling my dang hair out....

Anybody else have/had this issue?

Thanks
Trevin
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89 244

In your list I do not see any mention of the CPS -- Crank Position Sensor.

I have one on Order now.

The one thats in the car is only 1 year old.
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89 244

We could help you if you will provide some details please.

Please describe (with nothing left to assumption) how you saw voltage at the coil cutting out randomly. Don't pull any more hair. The ICU is probably not the issue. What are the symptoms in drivability terms and what have you learned using OBD? Are you an experienced automotive technician?


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Art Benstein near Baltimore

Do you realize that in about 40 years, we'll have thousands of old ladies running around with tattoos?

The car started stammering and studdering while driving. At first I thought it was a fuel problem hence all the fuel related items.

I was checking my timing just as a trouble shooting step. I noticed that the strobe would skip a beat every once in a while. I hooked my fluke meter to the + and - on the coil and watched. If I raise the RPM it will usually do it more frequently. The voltage will drop completly off and then come back causing the engine to stammer. the meter reads OL.....

I wouldn't say I'm an experienced Auto mechanic. I am a helicopter mechanic by trade. I have worked on this car for 14 years....anything from head gasket to TAB replace.
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89 244

Good description. Using a digital multimeter across the ignition coil in that manner would probably fool you based on the high collapse voltage compared to the small drop across the coil when the ignition power stage is not dropping. The autorange couldn't keep up with it and if you lock the range you'll see overload.

What you saw makes sense if the meter "cut out" in concert with the sound of the motor skipping or the timing light skipping. If you suspect "power to the coil" measure between ground and coil positive. That's sometimes a problem due to corrosion in the harness connector just below, but that really doesn't sound like your situation.

Did you check the OBD?

I found a bad CPS this way also, and it was one I had just replaced. Painful, because one tends to trust a new part that seems to work when freshly replaced. I think this will be your fix too, based on having two OE (Bougicord Electricfil) develop intermittent open. On the way to being open it actually would be partially open, as in an internal high resistance in series of between 50 ohms and several hundred K-ohms.

So far I'm rid of my CPS problems. See this post AIP CPS

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Art Benstein near Baltimore

A good wife always forgives her husband when she's wrong.-Rodney Dangerfield

Thanks Art.

I talked to a guy at IPD he said, the CPS or possibly the ignition switch.

What is your take on that idea?

I will wait patiently for the CPS to arrive and go trough the pain of loosing that stupid bolt all over again.
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89 244

Hi Trevin,

"What is your take on that idea?"

Gets me to chuckling.

You want someone to tell you what part to replace. I want you to diagnose it. Asked you twice about the OBD. Told you how to rule out the ignition switch by connecting the meter between ground and coil positive instead of between coil negative and coil positive. Suggested you can't rule out the CPS just because you replaced it before.

If you trust your timing light (and you had it on the coil wire) I think you've already pinned this on the CPS. Sure it could be some weird thing (has happened) due to a damaged or rusty tone ring, but my bet is that CPS you've got on its way will change the story.

Ideas are cheap. Only you can think it through and test your theory. You wouldn't guess and use the parts cannon on a heligoflopter would you? Are you missing documentation? Check out volvowiringdiagrams.com :-) Pursue this like you do your day job.

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Art Benstein near Baltimore

Did you hear about the guy whose whole left side was cut off? He's all right now.

Sorry meant to put this in my earlier post.

I checked for codes in the OBD. Nothing. When I say noting it didn't do anything no 1-1-1 code or anything which makes me think. Looking at the schematic, it is in the system, but wouldn't think it would send a return signal to the control unit. Not sure. I should get something.

Tomorrow I plan to get off early and have more daylight to further check the coil voltage.

Trevin
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89 244

"I checked for codes in the OBD. Nothing."

Trevin, this is a serious clue not to be ignored. Yes it could be the OBD box got water in it, but pursue this one first, as it may be related. You should get light from both sockets when you push the button. The voltage does come from the key switch, so your friend at IPD may have had more clues than we did.


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Art Benstein near Baltimore

The butcher backed up into the meat grinder and got a little behind in his work.
Then a lady at the airport backed into the spinning propeller of a plane—disaster!

Well,

The problem seems to be fixed. the only thing is, it seems to have all come together at the same time and I'm not sure what really fixed the problem. Possibly the coil.

Changed the CPS----------- still no start
Changed ignition switch---no start
Ran through the Ignition control trouble shooting at the connector everything checked out except throttle position sensor. It wasn't opening properly fix that-----no start
checked voltage at ignition modual = good volts
Checked voltage at +lead of coil to ground = good volts
put timing light on #1 = nothing
install 'another' new coil= fired right up!

I took it for a short drive but with the weather coming I didn't want to get to far from home. Once the streets clear up give it the test flight.

Thanks to everyone for there help and ideas. If nothing else I have learned a lot and have a new ignition system.

Trevin
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89 244

Hey Trevin,

I'm with you; I wouldn't drive it very far either, but I might get a stick and use it to shake the secondary wires (esp. the coil wire) and the CPS cable while the car is idling in the driveway, hoping to see it cut out again. Most of us would prefer having a solidly defined problem to solve than one that comes and goes.
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Art Benstein near Baltimore

The man who fell into an upholstery machine is fully recovered.

Art,
That seriously makes me smile....you are absolutely correct....unfortunately I can tell you when the rotor head is out of track on the helicopter but when it comes to my car I cave......Thanks.

Tonight I went out and now it isn't starting at all, which I'm happy about. Now I have a headstone.

Thanks
Trevin
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89 244

wiggle the CPS wire . down by the Sensor, and see if it starts
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