Testing coils on a coil over plug system?

[buzzinhalfdozen]

Art, yes hook up your meter and check the resistance, then switch meter to AC volts and crank the engine, you should see Approx. 1 volt AC give or take it depends on the cranking speed the faster it turns the higher the voltage. You said you moved some wires around... anything near the crank sensor or it's wiring? As I said these type sensors are quite sensitive to interference. By the way is this sensor shielded? Also as Ed stated there's no real replacement for proper diagnsis, I realize not everyone has a scope on hand... however by simply replacing a part you could be missing many things, poor connections broken wires ect. that's why that strategy sometimes back fires on people. We see alot of vehicles from other shops that have had large amounts of parts hung only to find simple wiring issues as the source of the problem. We have alot of customers balk at our charge to diag. their veh. however with a proper diagnosis a sucessful repair is almost guaranteed.

[art leong]

Originally Posted by buzzinhalfdozen

Art, yes hook up your meter and check the resistance, then switch meter to AC volts and crank the engine, you should see Approx. 1 volt AC give or take it depends on the cranking speed the faster it turns the higher the voltage. You said you moved some wires around... anything near the crank sensor or it's wiring? As I said these type sensors are quite sensitive to interference. By the way is this sensor shielded?

Nothing in the front of the motor was touched. But the cam sensor (hall effect) wires were moved a bit whe I put new trans in, then moved again when I changed intakes.
I called msd a while back, and asked how to check the cam sensor. They said if the light is on it's fine, that there is no other way to check it other than replace it.

[buzzinhalfdozen]

So you're running an MSD Ign. and a seperate controller for fuel? And yes they are partially right... if it has a cam sync LED that blinks it is seeing the signal however a hall sensor is easily checked, you could even use a DVOM if it has a fast enough sample rate, most switch from 0 to 5 volts. Adger had stated that you are seeing the engine go lean during the event is this the case and if so what reading are you getting?

[art leong]

Originally Posted by buzzinhalfdozen

So you're running an MSD Ign. and a seperate controller for fuel? And yes they are partially right... if it has a cam sync LED that blinks it is seeing the signal however a hall sensor is easily checked, you could even use a DVOM if it has a fast enough sample rate, most switch from 0 to 5 volts. Adger had stated that you are seeing the engine go lean during the event is this the case and if so what reading are you getting?

No mds ignition, only a hall effect sensor on my intake cam. The wires from it are in the back of the motor (drivers side in my case). And my battery and wires are also in close proximity. When changing the trans all these wires were moved a bit to get at the bolts etc. Again as always I got "excellent" customer service from msd. They said there was no way to check the sensor. I would have checked it way back on my list if I knew it could be done.
I was going lean during the 2 step operation. Which I believe is normal. During the stalls it doesn't seems to indicate anything but slowing to a stop.

[buzzinhalfdozen]

Art, as I stated before, and this is just my opinion from nearly 30 years of driveabilty diagnosis. A crank or cam sensor issue will 99% of the time result in an immediate stall, not slowly quit running. Basically if this engine runs normally in nuetral and you place it in gear you are really only doing 1 thing, increasing the load. The sensor responsible for measuring engine load is the MAP sensor. You said it seems to read normally, what BAR sensor are you using, after quickly scanning some of your systems operating capabilities I saw that you can use MAP or Throttle pos. as your load measurement. From my perspective the engine needs 2 things to happen when it's loaded 1 the fuel needs to increase and 2 the spark instant needs to increase. From what you're saying the engine just seems to slow down to the point of quitting which to me at least indicates it is lacking in proper amount of fuel or spark lead to maintain it's desired idle speed. If I understand correctly you have an indicator lite for Cam sync input? Perhaps on the ECU, if so does this lite quit blinking just prior to stall. Sorry for all the questions but I'm really baffled by this situation and trying to determine what's Not causing it.

[Pat Cook]

Art, is this a speed density or mass air system?

[art leong]

Originally Posted by Pat Cook

Art, is this a speed density or mass air system?

Pat I believe it is Alpha N


I think (HOPE) I found the problem. I took off the cam sensor to check an see if the magnetic was still there and didn't move. When I put it back and tried the test the coils.
I had no spark at all from the coils. through the tester. I noticed the light was off I rechecked the connection and it was tight. I put 12 volts to the sensor and the light remained off. It is normally on when the ignition is on, when the motor spins it flashes.
I just ordered a new one I should have it Wednesday. I hope I still have circulation in my body by then. Because I'm crossing my legs, arms, and fingers that, that is the problem.

[art leong]

Originally Posted by buzzinhalfdozen

Art, yes hook up your meter and check the resistance, then switch meter to AC volts and crank the engine, you should see Approx. 1 volt AC give or take it depends on the cranking speed the faster it turns the higher the voltage. You said you moved some wires around... anything near the crank sensor or it's wiring? As I said these type sensors are quite sensitive to interference. By the way is this sensor shielded? Also as Ed stated there's no real replacement for proper diagnsis, I realize not everyone has a scope on hand... however by simply replacing a part you could be missing many things, poor connections broken wires ect. that's why that strategy sometimes back fires on people. We see alot of vehicles from other shops that have had large amounts of parts hung only to find simple wiring issues as the source of the problem. We have alot of customers balk at our charge to diag. their veh. however with a proper diagnosis a sucessful repair is almost guaranteed.

Back to square one.
I checked the coils they are all able to jump the gap at 40K the spark doesn't look very healthy to me but I don't have anything to compare it with.
I checked the voltage across the crank pickup and on my volt meter set on ac I get .4 volts with the starter turning the motor. I have a 20 tooth wheel on the crank. I triple checked the timing, Put a new cam position sensor on.
And I still have the problem

[buzzinhalfdozen]

Art, I'll assume the cam sync lite blinks now? Do you mean it still doesn't start, or it starts and stalls when put into gear? I'd say if the coil is capable of jumping at 40,000 volts it's sufficient. So we're back to the basics, Air, Fuel, Spark. Perhaps we could try this test, hook your meter to the wires crank sensor wires @ the ECU, assuming the engine starts, set to AC voltage and start engine if possible raise RPM, the voltage should increase with rpm. The .4 volts AC seems pretty low to me however I'm sure different sensors can produce varying amounts of voltage. IF in fact the engine does start now you must have at least some trigger input to the ECU.By the way what supply voltage did you decide on for the cam sync? Also how much timing do you have ?

[art leong]

Originally Posted by buzzinhalfdozen

Art, I'll assume the cam sync lite blinks now? Do you mean it still doesn't start, or it starts and stalls when put into gear? I'd say if the coil is capable of jumping at 40,000 volts it's sufficient. So we're back to the basics, Air, Fuel, Spark. Perhaps we could try this test, hook your meter to the wires crank sensor wires @ the ECU, assuming the engine starts, set to AC voltage and start engine if possible raise RPM, the voltage should increase with rpm. The .4 volts AC seems pretty low to me however I'm sure different sensors can produce varying amounts of voltage. IF in fact the engine does start now you must have at least some trigger input to the ECU.By the way what supply voltage did you decide on for the cam sync? Also how much timing do you have ?

It starts but still has no power.
At idle I run 26 degrees timing. I put a couple of sewing needles in the connector for the crank sensor. And started it up. I get 9.5 volts AC when running.
One thing I did notice was the timing was jumping a bit on cylinders 1 and 2 It was sort of missing. It would miss and the timing would jump.(only on those 2 cylinders though) I'm going to get my wife to hold the timing light and try to tell me what goes on when I put it in gear. I didn't change the supply voltage. Because it ran fine before and I don't want to get 10 miles from where I started. When I make a change I always try to bring it back to the start point, to see if the change worked.