hey man i have the same problem i got a 95 tsi and i cant find shit really on how to remove or test the cam or crank angle sensors, my car has no spark and ive checked everything but those 2.

first you need a multimeter

CAS is the rectangular plug and crank is the triangular plug.

Disconnect CAS connector.
Measure the voltage on harness side pin 3, the red wire, with the key turned to on voltage should be 12 v or more.
Then make sure you have continuity, 0 ohms, on harness side pin 1, the black wire, to ground.
Then measure the voltage on harness side pin 2, the blue and red wire, with key on should be 4.8-5.2V.
Reconnect CAS.
Measure voltage on pin 2, blue and red, while starting the engine it should be 0.4-3.0V. With the engine idling it should be 0.5-2.0 V. If you have 0V your cas is dead since you should get some sort of volt reading.

its the same for the crank except the cranking voltage will be .4 to 4.0 v and the sensor wire, pin 2, will be blue and white. Idling is 1.5 to 2.5



props to luv2rallye he taught me how to do this test.

So I was on 93 (major highway up here in Mass) and my engine shut off. After getting across four lanes alive, I determined that nothing I could do was helping

Got the car home, went to test for spark and boom car is running again.

Then dies again. Noticed that CEL was on. Code was bad Crank Sensor.

Also at one point I could get one coil pack to fire but not the other. Now it is all apart.

I am hoping this dumb sensor fixes the issue...

Thoughts?

Since the CEL points to it it probably is but it could also be it's harness or connector not making good contact which would produce the same CEL so check those first.

I tried the old clean the connector trick. My guess (I am an electronics kinda guy) is that there is an intermittant open wire in the little harness between the connector and the sensor (Im trying to account for how one pack would fire. I wish I was sure that I understood the sensor.

Is it a magnetic trigger like MSD uses in their distributors? Or Hall Effect? I know a small block chevy is 720 degrees to fire all 8 cylinders, is this motor the same or does a piston fire every 90 degrees? (I assume that it does)

I love my car dearly but now that I am trying to restore my Chevelle, I have less and less desire to squish my hand between the engine compartment wall and the engine...

My one final question

do you have to pull the timing belt to replace the sensor? Some say yes and some say no. Anyone want to officially state the truth before I go and waste time


Thanks for the help.


Oh and here is a link to my webshots album of the Chevelle rebuild Chevelle Rebuild Pics



DSM is a 95 TSi (not sure why my car isnt showing in profile )

hpycoconut said:

I know a small block chevy is 720 degrees to fire all 8 cylinders, is this motor the same or does a piston fire every 90 degrees? (I assume that it does)

Click to expand...

It's a four cycle engine so it takes two full rotations (720*) before a cylinder is ready to fire again. With an inline 4 the pistons fire 180* apart.

Steve

The CPS is Hall Effect with a reluctor plate that travels through it. It is on the crankshaft sprocket sensing blade (reluctor plate). I will officially state you do not have to remove the timing belt but you will have to remove the crank pulley and lower timing belt cover (I've replaced the CPS myself). You can do all of this from underneath and it's not too bad. Attached is a picture (black thing with 2 bolts and white paint splotch on it). If it looks like the blade hit it, you need to check for crankwalk.

On DSM's 2 cylinders fire at the same time (one on compression stroke, one on exhaust) every half revolution since it is distributorless. The ECU fires the power transistors (which fire the coils) based on signals from both the CPS (crank position sensor) and CAS (cam angle sensor). Since your CEL says CPS that's probably it.

CPS: http://www.dsmtuners.com/forums/attachment.php?attachmentid=72783&d=1176363725

SO here is what I know

-both of the primary and secondary sides of the coil packs test good.

-The new Crank Position sensor is installed and appears to be working just fine firing 2 and 3. (The old one had a broken insulator on the blue wire).

-Completely disconnecting the Cam Sensor makes a SLIGHT difference in that the car runs rougher.

-With the exception of 1 and 4 never firing at all, the car runs great (aka 2 and 3 are dead on.

-There is no CEL and the injectors continue to feed 1 and 4 fuel.

-There is NO spark in the 1 and 4 pack secondary at all. I have disconnected cleaned, and reconnected the CPS, Cam Sensor, Coil Primarys, all plug wires and the power transistor.

What do you think?

My gut feeling is that if the ECU wasnt firing 1 and 4 that it would also shut off the injectors and throw a CEL. Since neither of these things are happening, I have to believe that the power transistor took a hit during the loss of the CPS and simply roasted. at least one side of itself.

I am about to pull it out and check it according to the manual. Anyone else have any thoughts or maybe an internal scematic of the power transistor? I hate to buy one for 100 bucks to find out I was dead wrong.

EDIT -Using the manual test the transistor passes the test... sigh.


Thanks guys

JT

hpycoconut said:

My gut feeling is that if the ECU wasnt firing 1 and 4 that it would also shut off the injectors and throw a CEL. Since neither of these things are happening, I have to believe that the power transistor took a hit during the loss of the CPS and simply roasted. at least one side of itself.

Click to expand...

Not necessarily. Firing the plugs and firing the injectors are 2 different circuits in the ECU. So you might have a bad ECU (pull it apart and check for leaking caps and/or swap with a known good one).

Know also that if a CPS or CAS signal is missing but the other one is there, the ECU can calculate approximately when to fire the plugs and injectors based on the other signal if it thinks it should, although you should get a CEL in that case (which is why it runs rough when you disconnected the CAS).

Or as you say the PT may be bad. Test it this way: http://www.dsmtuners.com/forums/showthread.php?t=229419.

Or a wire may be broken somewhere on the 1 & 4 circuitry (CAS/CPS to ECU to PT to coil).

Or the 1 & 4 coil may even still be bad (good resistance does not guarantee it's good). Try swapping coils or reversing the primary wires to see where spark goes. You can also momentarily touch a ground wire to the PT side of the coils (blue/black and blue/red wires) with the PT disconnected and key on but engine not running. This just does what the PT does and should fire the coil (to see spark at plugs).

Thanks as always for the advice!

You mentioned a couple of things that I had on the list for today.

Could the ECU be stuck in a situation where it thinks that it should not fire that pack? Would resetting it even be useful at all (since I have no spare)

JT

If the ECU is bad anything is possible and resetting it is unlikely to help. You can swap ECU's with any 2g turbo one for engine testing.

Some more data. I tested both coil packs and they tested good. (swapped the trigger leads and the plug wires. So whatever should be telling 1 and 4 to fire is not. I am starting to suspect ECU but I have no swap out parts. (this was my daily driver my toy is an old Chevelle).

Thanks


JT

Test for a signal going to the coil pack by plugging a test light into the coil harness plug connections. It's simple and another way to eliminate possibilites(like the coil pack). It can be found in the hanes manual under the ignition section.
The way they explain it is to plug 1 wire(from the test light) to the center pin and the other wire to one of the two outer pins(test both outer pins). crank the engine. You should see the light blink. If it doesn't, then you'll know the problem is before this point like the PT or ecu.

Or in the wiring. This is a great test. If the light blinks and there was no spark at the plugs, you have a bad coil or plug wires.

Will keep at it. I have a PT on the way and hope that is all I am dealing with.

I cant imagine how it could be the CPS or CAS at this point.

The no CEL scares me because I think the ECU would be able to tell if a sensor or coil were blown or if the PT wasnt firing the coil.

Ill be getting out the continuity tester again and checking every wire.

I did in the meantime buy another daily driver. (06 Ford Fusion SEL V6)

I love my Talon but it simply has passed into "not reliable enough for new england winter" territory.

I wish I had a two car garage so it could be project car number two. But the Chevelle lives in there and has been my baby since I was 18.

I think the car senses my need to sell it and wants to torture me first....


It has only had like 10k$ and 2 pints of my blood fed to it.

Fixed:

Was the Power Transistor that was bad.

So odd....

Oh well

which one is the power transistor?

I'm a newb but i did a head gasket and timing belt on my 4g63 and it started for a brief second and spit fire out of the then disconected exhaust and now i dont have spark. Did my ecm shut down everything. Any ideas on what i should do

When the engine turns over with the starter, do you see the tachometer in the car move at all?

ill look next time i turn it over