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Discussion Starter #1
Been rebuild/swaping the engine on my 1995 E320 convertible. I have gotten everything connected and the engine cranks but I am not getting any spark out of the coils. Things I have tried so far to fix this.

1. Test the CPK(CPS) crank position sensor. Reads 0.1 ohms however I am not confident in this reading. Hard to see what I was doing under the car.
2. Unplug the CPK(CPS) and see if the RPM reading stayed at zero which it did. Plugging the sensor back in restored the rpm reading when cranking the engine. This makes me think the sensor is ok.
3. Tested/swapped the coil packs off the scrap engine.
4. Checked for engine codes with the built in LED. Did not see any.
5. Tried cranking the engine in neutral.
6. New spark plugs.
7. Measure voltage on the low voltage side of the coils. Reads 9-10v DC
8. Checked all the fuses I could see. . none were bad.
9. Check the OVP (over-voltage protection circuit). No corrosion on terminals. Audibly clicks when turning the key. Possibly Good...anyone know how to test this?
10. Checked the resistance on the plug wires. Read 2k ohms. Not surprising this was a new set from MB.
11. Getting pressure on the fuel rail. 50-60 psi when cranking.

Observations thus far:
-I can definitely smell gas in the exhaust and in the cylinders when I pull a spark plug. Injectors working...
-The starter smells like it is cooking. (probably from to much cranking??)
-Very rarely I can see a spark on plug 1. This was after ~10 cranking session of 30 second duration. (this only happened once)

Car info:
-Wiring harness has been replaced. (hooray for ecojunk)
 

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Check the carbon brush in the centre of your distributor .Sometimes they get damaged after the distributor cap is removed and as its lined back up it damages the earth brush in the centre of the distributor .Another thing if engine was rebuilt , do a check on all the earth points, as they may have been removed , and not re fitted back in place. Earth leads are a return path back to the battery .Even battery poles can be a problem if dirty or loose .Remove earth leads grease them up and refit after cleaning the body . Check all fuses in the fuse bax . If you see a spark the alarm and imobiliser is ok . You could look in the engine in the dark .You will be looking for electrical shorts you will see them better in the dark if it is going on. Good luck .
 

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No distributor on the OP's car and he's stated that he can smell gas. I would replace the OVP. Without it being 100% solid, your car will not run.

Jayare

Sent from my XT1710-02 using Tapatalk
 

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Discussion Starter #6
Got the new OVP in from mercedes and the car still will not start. Testeded for spark again on the plugs with a timing light and nothing. Not sure what to try next...crank sensor?
 

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A healthy crank sensor should measure in the neighborhood of 800 ohms.

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check your ignition module/CDI. or you can check the voltage on the cable towards the coil pack, maybe around 12 volts. if it's not there, maybe your ECU or CDI [ignition module] has a problem. try to find ECU or CDI that you can borrow, so you don't buy the wrong item.
 

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I would suspect that you have a bad ECU. If the injectors are firing and the tach is responding while cranking, then the CPS is putting out a sufficient signal. Since you have ruled out the other components of the ignition system, that leaves the ECU. Was the non-start condition sudden? Perhaps the ECU was damaged by the ecco junk wiring while it was still in the car and now it has failed.
 

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Discussion Starter #11
Ordered a crank sensor to test first. The no start condition started when I put the rebuilt/swapped engine in the car. The car ran well after the new wiring harness was installed and even ran when I first changed the head gasket on the old engine. Head gasket failure and to much machining is what eventually killed the old engine. The voltage on the coils is 11.8 V DC when the key is in accessory mode. When the starter turns the engine over this voltage drops to about 9-10 volts. What is interesting is that the car will almost start with a freshly charged battery and a 200 amp car starter. Also checked the ground connection on the bell housing and it seems clean and solid.
 

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How is the condition of the voltage regulator? Its pretty quick to inspect and see the contacts on it
 

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. . The no start condition started when I put the rebuilt/swapped engine in the car. . . .
When you changed motors did you install the (known working) coil packs from your original engine into the new one?
 

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Discussion Starter #15
Yep made sure I used the known good coil packs from the first engine. Ordered a crank shaft sensor. Should be here tomorrow so I'll see if that fixes things.
 

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The plot thickens...Installed the new crank sensor and the car would still crank but not start. After installing the new sensor and cranking a few times I checked for diagnostic codes and counted 20 and 22 pluses. My car has the California built in button. When leaving the car key in accessory mode I can hear the throttle body whining a bit (not sure if it is stuck). I held the diagnostic button down for 45 seconds and cleared the codes but the car still would not start. Poking around online I found a manual that indicates codes 20 is "Speed signal not present" and 22 is "Camshaft position sensor signal defective". Not sure if a bad camshaft sensor would cause a no start condition. Out of curiosity I pulled out the batter and ECU to find that it has been reprogrammed by quickchips. At this point I have found an inexpensive ECU to test on the car. Maybe the reprogrammed version is messed up? I have not seen the codes 20/22 after clearing them however the check engine light does come on and off randomly.
 

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How is the condition of the voltage regulator? Its pretty quick to inspect and see the contacts on it


Always check the simple, cheap stuff first.

On the back of the alternator, perhaps behind a plastic screen, you will find two screws that fasten the voltage regulator to the alternator.
Remove the 2 screws and gently twist off the VR.
Examine the two brushes. If they are shorter than 1/2" in length, replace with a new VR- about $30.

There should be a part number on the side of the VR, which you want to match.

This is one of the most common causes of electrical/ignition failure.
And so easy & cheap to fix.
 

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Discussion Starter #18
I checked the voltage regulator yesterday. The brushes were longer than 0.5" and made solid contact with the rotor. The alternator is fairly new. My brother had replaced this about 2 years ago.
 

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Always check the simple, cheap stuff first.

On the back of the alternator, perhaps behind a plastic screen, you will find two screws that fasten the voltage regulator to the alternator.
Remove the 2 screws and gently twist off the VR.
Examine the two brushes. If they are shorter than 1/2" in length, replace with a new VR- about $30.

There should be a part number on the side of the VR, which you want to match.

This is one of the most common causes of electrical/ignition failure.
And so easy & cheap to fix.
This has nothing to do with the car being in a no start mode. For that matter, you could cut the serpentine belt and start the car.

Jayare

Sent from my XT1710-02 using Tapatalk
 

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Discussion Starter #20
Got the new(used) ECU in today. Installed it plugged up the battery. Turned the key on to accessory mode and waited 4 minutes for the ECU to initialize. Turned the key off then tried to crank the car. Unfortunately the car would still crank over but not start. At a loss as to the problem now. Anyone have some ideas?
 
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