Hey hoping someone might have some expert knowledge here for me as I've spent as much time as I can googling and youtubing with no results.

I've got a 05 Ion with the 2.2L ecotec

I'm getting P0300 random misfire and P0171 lean codes.

I've done the following seeing this car has over 315,000km

Compression test on all 4 cylinders all between 150-160psi

Replaced the coil pack and ignition control module, spark plugs, map sensor, maf sensor, checked for leaks on the minimal vacuum lines (as far as I am aware of) this motor has using carb cleaner with no change in RPM. Also sprayed some carb cleaner around the intake manifold gaskets with no change in RPM.


Every youtube video you watch points to the coil pack and/or the ignition control module. So I robbed another 2.2 (in case the new one was bad out of the box) to test and I get the same result.

Any help is greatly appreciated as I am so frustrated!

Thanks

 

Have you checked to see if the evap purge valve is stuck open? If it is, it will allow unmetered air into the engine, just like a vacuum leak. When the ECM opens the purge valve to clear the canister, it adjusts fuel delivery to account for that. But when it 'thinks' the purge valve is closed, it can't account for the extra air and triggers a P0171.
If you have a bad purge valve, it may also keep your evap system monitor from completing.

 

I have not checked this no. Is it as easy as removing and blowing some air through to see if its closed? I didn't get any evap codes so this never crossed my mind. Cheers!

I did a quick google and seems straight forward to test. I'll update when I get the chance. Thanks!

 

I have been working on the same two issues on my '06 Coupe 3 for over a year and I think I may have the answer: the ECU needs to be reprogrammed to the latest soft/firmware. Here's why I have come to this conclusion - I have done a complete timing job, including R&R the head with new int/exh valves and valve oil seals and fuel injectors; new MAP, MAF, crank position sensors; and new ignition control module and coil packs. I was also chasing an EVAP problem - replaced both the purge and vent solenoids. I did a smoke test and found no leak under the hood. It turned out to be a problem with the gas cap seat, the part that the gas cap locks into, had broken loose from the filler neck. A liberal amount of epoxy fixed that and the EVAP small/large leak detected errors never came back. So, after all that, the random misfires and P0171 came back.

First of all, it is HIGHLY suggested you get a good OBDII scan tool that can read live data to see the misfire counts and the Long Term Fuel Trim. There are a few good instructional videos on YT on what the LTFT does. I recommend checking them out. According to Saturn service documentation, the 2.2 throws a P0171 when it detects the LTFT has reach 19%. Common causes for this is a vacuum leak after the air filter box. Any air not seen by the MAF will be seen by the oxygen sensor 1 (forward of the catalytic converter) which will see too much oxygen in the exhaust which in turn will trigger the ECU to add more fuel.

As you can see, I have addressed many - if not all - the 'known' remedies to correct P0300 and P0171. My last stab at this is to have my ECU updated with the latest software / firmware. Many online resources point to misfires and fuel trim problems can be fixed with the updated ECU. I'll update this thread once I get the ECU installed and had run the car through many run cycles to get stable readings to see if this worked or not.

Hope this helps and Good Luck!

 

Do you know when the ECU software was last updated for the ecotec in your island? The newer versions close the ecotech most certainly cannot use the same ECU programming as the older ones.

If you do take the path you suggested, Chevy dealers seem to be most sympathetic to Saturn toners of all the GM divisions. Most dealers will claim they can't get the flash files for the older saturns. Truth is, they can request it from GM Central.

Did you replace the ignition module along with the coil packs or just the coil packs? Also, did you thoroughly spray down the intake manifold, including the undersides of the runners where they meet the engine, in search of leaks / unmetered air? Doesn't take much to upset the air fuel mix causing this fires and, as someone stated above, you are leaning out at least one of the cylinders so the ECU compensates by adding more fuel to the mix to obtain the front O2 reading it believes is associated with the correct air and fuel mix.

 

Hey Def.
So as not to get confused with the original poster, rock_solid, I'll answer your question as if it were addressed to me which is having the same two error codes (P0300 and P0171). He/She can answer separately....

Yes, I did the carb cleaner spray test all around the intake, throttle body, and checked all vacuum hoses - especially the one that goes from the power brake booster to the intake. No leak detected.

Replaced the ignition module, coil pack and plugs. Everything looks good. One thing I didn't check, through, is fuel pressure, but I doubt that is the problem 'cause the car is very responsive at the throttle. If it were starving for fuel at partial or WOT, I sure didn't notice it. The car does scoot much better after all the work I did.

I did get an ECU from a programming outfit. I need to return it though, because they didn't encode my vehicle's VIN, which screws up my ability to get the car inspected. My state uses a computer to attach to the OBDII port to read the VIN and perform safety/emission compliance checks.

 

Thank you for the info. I hate when people tag on to other people's unresolved posts. I don't mean you specifically. I usually keep track of it but I'm getting older

I'd still check the fuel pressure for yucks.
What are you using for plugs? Stock plugs?

 

I hear ya....I don't like jumping on someone else's post either unless there are similarities where we can get mutual help and understanding...

Anyway, yes, I installed the ACDelco Iridium plugs 41-105.

 

I have good luck with those plugs in my L61 Ecotecs.

 

checked the purge valve today it?s not stuck open.