Hi, I have been all over this site trying to get this issue resolved. I have a 2006 HHR with a 2.2L Ecotec, When I start it cold it runs smooth for about a minute and then it starts pulsating eventually it will stall, Code P0300, it seems to run fine other than at idle.

So far I have checked all fuses, replaced the MAP sensor, cleaned the MAF, cleaned the throttle body, drained and replaced the fuel, replaced the ICM and spark plugs, changed the oil and filter, changed the air filter, checked all wiring connections.

I read something about a "camshaft position solenoid" that I can't seem to locate on the engine (2006 2.2L). does it even have one?

I also ran it with the o2 sensor unplugged with no change.
then I ran it with the MAF unplugged also no change.

Please Help!

 

to the forums, Jim. How many miles? You could check the fuel pressure, and another member reported that the timing tensioner was the culprit on his p0300.

 

Yes the tensioner could be weak, or TTR timing chain stretched, the 06 2.2 didn't have VVT so no camshaft solenoids.
Welcome to the site!

 

I guess checking the fuel pressure would be against some principle.

Just throw a fuel pump at it too.

With only a random misfire code why would you set about throwing all those parts at the car?

 

Thanks for the quick response!, the car has 174k miles, throwing all these parts at it trying to get it working again, in the beginning I got a weak MAP sensor code, that's why I changed it, I read several posts here about contaminated fuel, plugs, ICM, MAF, and so on.
the P0300 says "Random Misfire" but it results in the car bucking and stalling at stop lights, I have to manually keep the RPM above 1000 to keep it from doing that. the fuel pressure is strong. and the car runs great except when idling.

FYI, this problem started suddenly, also it idles fine when I start it cold, then it fades into the pulsating then eventually stalls.

Q: on a normal running 2.2L if I were to unplug the MAF what symptom would it create?
Q: is there a way to diagnose or check the timing tensioner without removing the timing cover?

 

A) you would get a CEL, and the engine would barely run.
B) no

You said the ONLY code was P0300. You did not say you had tested the fuel pressure.
What code is for "a weak MAP sensor"?
Does your coolant disappear?
A bad MAF would send a code.
Have you inspected all of the wires under the hood for fraying, laying on hot things etc.? Especially the part of the harness that runs under the EVAP purge valve
See post #8 in this thread:
https://www.chevyhhr.net/forums/prob...g-issue-57435/

If a code "says" something it usually "means" something other than what it sounds like. Much like my wife.

 

when I got a CEL I had a P0128 (thermostat),I cleared it and got a P0106 (manifold absolute pressure/barometric pressure sensor range performance.), and the P0300, that's why I changed the MAP sensor. that code never came back only the P0300 re-occurs.

coolant does not disappear.
just checked wiring under EVAP purge valve, they look good.

Yes I tested the fuel pressure, in fact I drained the fuel tank by connecting a piece of rubber tubing on the valve on the fuel block while it was running and filled 2 5 gallon gas cans in about 5 minutes.
Thanks for your help!

I also ran my VIN for recalls and I am up to date.

 

https://www.obd-codes.com/p0106
What is the fuel pressure?

All of the sensors have their own fault codes, so replacing them on suspicion is wasting your money.

Done a compression and leakdown yet?

Very important is that the ICM has a good ground.

Read the attached for the reason that the P0300 appeared when the other codes were cleared. Some DTC will not run if certain codes exist.
P0300 takes 40 drive cycles to clear itself from history.

What I'm getting at is that they are related. I suspect a bad ground connection. Lately there have been several instances of rodents munching on wires and living in air boxes.

 

about 38-40 PSI

I also reset the CEL and ran it for 5 minutes with the MAF unplugged and no code no change in the way it was running

 

Fuel pressure should be 50-60 PSI.

I don't know how a disconnected MAF would not cause a code.