Chevy cobalt 2006 LT 2.2 l engine won’t start
Asked by Helixal Nov 21, 2019 at 09:24 PM about the 2006 Chevrolet Cobalt LT Sedan FWD
Question type: Maintenance & Repair
Several days ago the car started idling very roughly. It would stall when I
came to a stop when the rpm’s dropped under 1000. I took out the throttle
body and cleaned it thoroughly. That did not help. At this point the check
engine light came on. The codes were P0106 (map sensor) and P0300
(random misfire). I put in a new map sensor. It didn’t help. Put the original
back in. Checked the plugs and they looked ok. Tried a new ecm (engine
control module). Now the car would not start. I could hear the fuel pump turn
on and work for several seconds. I could also hear the starter motor turn the
engine. But the care would not fire up. Looks like I went from a rough
running engine to one that would not run at all..
Help would be appreciated.
Al
9 Answers
Find a shop that will do proper diagnostics to figure out the source of the problem. There are lots of reasons, usually electrical, that will cause the computer to think various components have failed. Simply replacing parts on older cars often does not solve the problem. Things like bad grounds and weak batteries can all send bad signals to the computer. Your car has a number of ground points on it. If you're a do it yourselfer you could start by finding them and making sure they are clean and tight. Load test your battery as well to be sure its in perfect condition. After that you likely need a pro to do the rest.
Since the car is not moving I’d like to at least get back to a rough idle. What happened is a result of my removing and reinstalling the ecm. As a correction to the above, the fuel pump does not start when I turn the key to on.
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. Al
When I put on the battery pack the voltages moved up as I said above. But after a while the voltages dropped and the battery pack might have been draining the car battery. The car did not start up at that time. I think I need to charge up the car battery. I'll let you know what happens. Thanks for the interest. Al
It does sound like it could be battery related. If the battery is 5 years or more old I'd just go ahead and change it. That's about the normal lifespan of a battery. If its newer than that have it load tested first to confirm if it needs replacing or not.
The b attery is just under 5 years old. The prior (original battery) lasted 9 years. The battery was at 38% charge level. I charged it up to 97%. Still no start. No fuel pump. But engine turns. I was hoping it was the battery - but no apparently Al.
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. Al
