My 2006 cobalt LT 2.2L started running rough a couple of weeks ago. So I cleaned the throttle body - didn’t help. At this point I got 2 engine codes - P0106 map sensorand P0300 random misfire. I put in a new MAP sensor (standard parts brand) - didn’t help and I put the original back in.





At this point I took off the ecm - it plugs into the coil bank. I cleaned the terminals and plugged it back in. Now the car would not start. When I turn the key to on I do not hear the fuel pumprun. When I try to start the car I hear the starter motor turn the engine but it does not fire up.



I put in a new ecm (standard parts) - didn’t do anything. Put the original ecm back in. Checked the plugs and they look good. Checked the ecm contacts and they look good. The fuses look good.



I’d like to first get back to where the car was running rough. The no start problem was the result of my removing and reinstalling the ecm.



Would appreciate any suggestions.

Al

 

Connector voltage





As a follow up, I tested the voltages at the input to the ignition control module with the ignition key in the on position. Looking at the connector with the release mechanism at the top, there are 5 positions along the top row and 4 along the bottom. Numbering from left to right 1) to 5) and 1) to 4)



Top row: 1) black wire 0 volts, 4)white wire 4.7 v, 5)red wire 11.3 v.



Bottom row: 1) brown with white stripe wire .08 v, 2) orange wire 4.7v.



When I clipped on a battery pack the voltages rose from 4.7 to 5v and from 11.3 to 12v respectively. The car battery is no doubt run down.

 

Fully charged the battery from 38% to 100% still no start. I don’t hear the fuel pump but the engine turns over. Probably no spark since I had someone spray starter fluid into the throttle body when I turned the key.

 

Double-check your power connections to your fuse box, including grounds. You can see if you're getting spark, but it sounds very doubtful. After you check for main power just check going down circuits to see what is and isn't getting power.

 

I wonder what the heck happened when you unplugged with ignition module the first time. Is there any chance you shorted something out when you cleaned the terminals?

 

Thanks for your helpful replies

Ninja: How would I go about checking the power. Can I do this from the top of the fuse box in the engine compartment? I assume that the ignition key should be in the on position.

JDbaugh1: I checked all of the fuses and did not see anything blown. The only thing I can think of about a short is that when I removed the three T15 head screws holding the ICM ( ignition control module), the T15 bit came loose from the driver and fell down into the engine. I still can't find it. It may have struck the leads of the female connector but the ignition was not on at that point.

A further question: Does anyone know what the significance of that .08v reading I mentioned above. What is the brown with white stripe wire? I've been looking but haven't found the definitions of the 5 leads in the connector to the ICM.

Al

 

The best way would be to get the wiring diagram from somewhere. The best place I can think of is autozone.com. From there, I'd go through everything that's needed to start. Most basic is make sure the red post has power. That should be good since the starter is cranking. Then, if you know there's no spark you can trace that circuit as far back as possible to see if it's open somewhere. Just go with things you know are or aren't working to see if you can trace back to the problem.

However, what do you mean by "into the engine"? I'd find that torx bit before it causes more problems!

I can't comment on the wiring and voltage since I am totally unfamiliar with the 2.2 system.

 

The “into the engine” is a misstatement. It should be into the engine compartment. It didn’t reach the floor. It’s lodged somewhere that I can’t see.

Al

 

Based on the number of wires I am guessing you should have:

1. Power supply wire (+12V) - Red wire?
2. Power ground - Black wire?
3. Coil 1 signal wire - White wire?
4. Coil 2 signal wire - Orange wire?
5. Signal wire ground - Brown with white strip wire

To test voltage of signal wires you need to use the signal wire ground as your negative. I know when I set up my standalone system they had warnings about grounding any of the 5V systems to standard 12V ground. Here I can't really say if that will cause issues or not but just be aware that the 5V systems, in my very limited experience, utilize a separate ground from the standard 12V system. This is probably why you are picking up .08V when you connect the 5V ground to the 12V ground.

The L61 uses wasted spark ignition system so two cylinders share a coil. This is why there are only two trigger wires. Because you tested them both at near 5V with the ignition on I am guessing that the signal to fire is when that voltage drops to 0. However, the ignition sequence is going to be very fast and I don't know if you would be able to observe that to test with someone cranking over unless you have an oscilloscope.

Keep in mind these conclusions are based solely on my very limited experience and I could have very easily gotten something wrong. But they always say that the easiest way to get the correct answer on the internet is to post the wrong answer and wait for someone to correct you.

 

Here is the ignition coil schematics

 

And connector view of said "ign control module" (coil pack connector, there isn't a end view of the actual module)
Edit: Found the end view in description and operation.

 

What is the CMP sensor?

 

The brown and white wire is the camshaft position "signal", not really a traditional sense though. The l61 with the coil pack uses a "compression sense" system that detects the last fired cylinder number based on crankshaft position and sends a signal back to the ecm that lets it know which injector to fire next. Kinda a hard to understand weird setup but it works.

Edit:Sorry that was wrong, it detects the compression stroke on a cyl and relays that signal as a cmp position to the ecm.

 

 

Question: could a faulty coil module prevent the fuel pump from kicking on in a 2.2 L engine?

 

No

 

Partial progress?



I replaced the ignition coil module with a Delphi brand unit even though it was sold as an ac delco. But then the one I took out was a Delphi (probably original).



So now I can hear the fuel pump rev up and get a strong spray at the schrader valve. Still turns over but doesn’t start.



Just to test things I disconnected the external connector to the ignition control module, I then turned the key to the on position and I could hear the fuel pump rev up. So here the fuel pump was working even though the new coil module and icm were out of the system.



The only thing that I can deduce from this is that the the new coil module reset something somewhere to allow the fuel pump to engage.



Now I only need a spark.



Any insight would be appreciated.



Alq

 

Did you check your pinout to see if you are getting the proper signals from the engine harness to the ignition module when cranking?

 

I did check the pin out with the ignition in the on position but not cranking (see above). Do you know what I should see when the engine is cranking?

 

Kolt may know a good way to test but according to the diagram he uploaded, pins B and G should alternate pulses when the ECU is commanding the Ignition module to fire if I understand the way it works correctly. I'm not sure what the voltage is and the pulse would be very brief so a voltmeter may not have the resolution to display this. I'm sure someone who has actually tested this may know a better method.

I just don't think it sounds like your ignition coil is either getting power/ground (which you checked) or it isn't getting signal to fire from the ECU for some reason. I'd also wager that whatever is wrong is a result of something that happened while you were working on it. Have to retrace your steps and see if it was possible you broke or shorted a connection somewhere. Idk what would happen if you shorted or accidentally energized one of the ignition control or sensor pin but you may have accidentally caused damage to the ECU. Kolt would know better than me if that is possible.

 

I’ve just been told that my problem is the timing chain. Does that make sense given the history of what I’ve described? Also that some other damage might have been done to the valves, lifters, head.

Car has 163k miles. Trying to figure out how to proceed.