Automotive Forums  Where Car Enthusiasts Go to Discuss Cars Online

So here is what I have. The scan I got wasn't nearly as comprehensive as the one I did on my 2006 Impala, but I don't know if it is because the Alero is older and doesn't support as many monitored parameters, or if it is limitations with the scan tool that I got.

I disconnected the battery (reset the ECU) before doing this. That was not by choice as I wanted to get readings from the ECU in its original state - but its a long story that involves me locking a set of keys in the car. I did give the car a short 5-10 minute drive though before taking readings, but some of them are still pending. I can take another set of readings in a day or two when the ECU completed its learning phase if you think it would be helpful.

The two images I attached contain what my tool pulled. It also showed that right after the ECU reset and while the car was idling the short trim was at 15% (long term at 0%) and after my short drive the short term was at -9% and the long term was at +9%. It definitely appears like the car is trying to compensate for something.

The data I pulled doesn't appear to be very helpful to me, but maybe your experienced eyes car see something that I don't.

By the way, thanks for taking the trouble to help me with this. My wallet and myself thank you, and I know my girlfriend does too.



 

print the tech 1 scan data image above.. see if you can find the live data stream to compare each line...

there are some really good articles online about mode $06 if you just google that term..


oh...  also .. disconnecting the battery usually erases some of the memory.. it does NOT always erase the actual codes..

on the voltage drop test...  i am taking that the last 3 voltages are actually written out 0.014MV

you will want to drive the car until the check engine light comes back on...

once it does.. then you can read the code.. and check the snapshot data that was saved by the ecm at the moment the trouble code set...

did your software and plug come with a link to a manual????

you can log in click my user name and send me a private message with that link.. or a good description of the software name and model.. so i can search for the link to the users guide..  

To clarify the voltage I posted earlier:

Engine to body: 28 mV = 0.028 V
Battery positive to negative post: 14.5 V
Negative post to body: 14 mV = 0.014 V
Negative post to engine: 12 mV = 0.012 V

I played around with the scan tool a little more yesterday and figured out how to get some live data readings. Apparently you have to construct a custom 'dashboard' with the parameters you want. I tried to put one together will everything on that tech 1 sheet, but not every parameter was available to be added to the dashboard. On top of that, I don't think the vehicle, or possibly the tool/vehicle communication supports all of the parameters. I was able to view a lot more information with my newer car, but there wasn't a whole lot available on her car. Below is a snapshot of the live data I was able to view. The parameters that weren't supported are just displayed as 0 it seems.

I'll look into the $06 mode a little more, although all of the on board diagnostics said they passed after she had driven it a little. The CEL is back on by the way so the ECU should be close to, if it already hasn't finished its learn phase.

 

the voltage drop test now look good to me... i just had to ask..

the tech 1 data is generic...

i usually advice.. to print the page.. start at your first reading..   write it down on the proper line...

then go to the next reading... find the line for that...

this way.. when done.. you can sit and compare what the readings are expected..

you might also want to see if the software is bidirectional....

where you can control various operations of the engine devices...

i am taking that the 105.8 coolant temp was taken on a COLD motor that had just been started...

as engine coolant temps after 2 to 3 minutes.. should be 190 to 215F..

what code came up?????  

Yes the car had just been started and allowed to briefly idle after it had been sitting a while. That why the coolant temp looks so low.

I checked the error codes again after the light has come back on. There is the same P0300 code, and now P0171. P0171 indicates that the 02 sensor (bank 1 sensor 1) is reading a lean mixture. I'll admit that that's not what I was expecting. Now I'm starting to wonder if there is a vacuum leak somewhere that I haven't found. The MAP sensor reading was within the range on the TECH 1 sheet. There is no PCV valve but I may give the brake booster line another look. Are there any other components you can think of that I may want to check?  

I will print off the TECH 1 page and see what exactly I can compare. I believe the tool was advertised as being bidirectional, but I haven't found any way to control the cars operations yet. I'll look through the help guide and see if there is anything on it.  

with my fuzzy fuzzy brain....    i should point out that a Po171.. is usually a vacuum leak...

check for it..   use some long nose and pinch off any vacuum hoses.. see if the idle changes for a split second..

could even be the power brake booster..

could be a collapsed hose that looks good.. but when the engine is running. the hose squeezes in..  

I think I'm going to get a can of starter fluid and spray it around a few places. If it is a vacuum leak I haven't found, it should rev the engine a little when I spray over the leak.

I'm also going to monitor the manifold absolute pressure, o2 sensor voltage, and the short term fuel trim for a while when the car is idling.

I suppose the same problem could be caused by weak fuel pump, clogged fuel line, or bad fuel injector. If the O2 sensor is reading lean like the error code says, its got to be either due to too much air or too little fuel.  

I don’t know if you will still be reading this Waynep, but here is an update on the situation. Things have been a little hectic lately and I haven’t had much time to work on the car. I’m starting to believe that this may be an internal issue with the engine though…

First thing I did was spray around all of the vacuum hoses I could find with some starter fluid. I didn’t see any sign of a vacuum leak.

I decided I would rent a fuel line pressure testing kit to evaluate the fuel pump and fuel pressure regulator. While I was looking for the testing port on the fuel rail, I pulled off what is called the “air cleaner intake.” It’s something of an odd part that I haven’t encountered on other vehicles. You can see it listed as part number 17 on the diagram below. I believe it serves as a resonator, and a manifold where some form of crank case exhaust draws its vacuum pressure from. (By the way, I don’t think there is a fuel line pressure test port on the 2000 Alero with the LD9 engine.)



When I pulled out the air cleaner intake, I noticed a vacuum hose (which I believe to be crank case ventilation) was internally coated with a yellowish gunk that I had not noticed before. I wiped a bit off on my finger and smelled it. It smelled of motor oil… As I understand, oil takes on this appearance when it becomes mixed with water/coolant. I immediately pulled the dip stick to check the oil in the sump and it fortunately appeared normal.





I then reinstalled the air cleaner intake CAREFULLY. I believed that after the last time I had it off, I may not have replaced it properly. Because of the location of that vacuum hose it is a bit difficult to install. This time I was sure everything was sealed up properly.

I cleared the error codes and fired up the car. No codes immediately popped up. The next day however, I found a new error code. The P0300 code and P0171 codes had been replaced by a P0302 code. I now think that I may have already resolved part of the problem, but masked my results by improperly replacing the air cleaner intake. The real heart of the problem though has now appeared as the cylinder 2 misfire (and possibly the yellowish gunk in the vacuum tube?).

My assumptions as to what the problem is are now:
1. Bad fuel injector
2. Burnt exhaust valve
3. Bad piston ring
4. Blown head gasket

Concerning the p0302 code:
I think I'll pull out the fuel injector on cylinder two and test/inspect it. Hopefully that's it because if not I'm starting to think big bucks to fix this.

Concerning the Yellow gunk:
Any ideas on this? Bad head gasket allowing coolant into Cyl 2? Could that also cause an external coolant leak (leaking slowly into both cyl 2 and the floor of my garage)?

I'm not sure what to do with the car if this is a major engine problem. I certainly don't have the tools, time, or experience to tear the engine down for repairs. getting it fixed at a shop would probably cost more than the car is worth. Maybe I should just tell her to crash it into a tree and collect the insurance    

i don't like the creamy yellow stuff.

i will reread the post.. only have a minute now..

are you loosing coolant????

will the cooling system hold pressure..

how does the engine oil look on the dip stick...

has this car been driven through deep puddles..  DEEP...

what does the inside of the oil filler cap look like..

some cars get water vapor trapped in the upper part of the engine... turns creamy...  perhaps removing and cleaning the valve covers inside..  if the engine is NOT loosing coolant.. and the system does not build pressure instantly upon start up..

how fast does the cooling system build pressure??? two minutes is kinda expected...

any bubbles in the radiator...

again.. this could just be trapped moisture... as the engine runs at or just below the boiling point... it cannot fully vaporize the moisture trapped in the upper valve covers ..

check the PCV system for proper flow if you can get to it..   hoses have gotten clogged...  pcv valves filled with sludge..  is the  PCV valve filled with the yellow mess also... if not.. its probably just moisture trapped on one side of the engine...

more later...  

I was going to try to clean the PCV valve to troubleshoot some of the earlier problems. As I eventually found out after some research, the 2.4 Alero does not have a pcv valve nor does it have an EGR valve.

Yes there is an intermittent coolant leak. Every once and a while after the car has been parked, a small puddle will show up under the car. I've only been able to catch it leaking once. I couldn't pinpoint the location of the leak... It was coming from somewhere near where the heater hose connects to the engine.

Not driven through any DEEP puddles that I am aware of...

Engine oil on dip stick appeared to be at correct level, and of normal used oil appearance. With look at the underside of the filler cap later.

I'll have to check with the local auto parts store to see if I can rent a cooling system pressure test kit. I'll see if I notice any bubbles when I pull the radiator cap off.  

I was at the auto parts store getting ready to check out a coolant pressure test kit when I suddenly remembered that the car doesn't have a radiator cap. I was looking at the adapters in the kit for the pressure gauge wondering if there was one that would fit when it hit me.

I'm not sure how to test coolant pressure if there is no radiator cap. There might be an obscure specialty tool somewhere but I have no idea where to look.

I'm not sure what GM was thinking when they designed a coolant system without a radiator cap.

Tonight I'm going to pull the fuel injector on cylinder 2 and take a look at it and test it's resistance. I'll compare it against one of the other fuel injectors. Is there any way I can run voltage across it to see if it responds without worrying about sending too much current through it?  

great.... no regular radiator cap...

http://www.stant.com/repository/documents/12270.pdf

the top left item of page 4 of the six pages...

12032  

12032 threaded system adapter and 12033 radiator cap adapters are required
to test threaded radiator caps on later models GM cars and trucks, also
Freightliner and IHC trucks. (Vehicles using the Stant® 10248 radiator cap).



this is what i use for a LOT of shapes of caps..



Mityvac 04505 Universal Adapter  

phew what a long night. I pulled off the fuel rail and injectors. I measured the resistance across each injector. I have the values written down but I don't have them with me. They were all around 12 ohms though - nothing too suspicious for a high impedance fuel injector. I switched the two middle injectors (2 and 3 if the numbering of cylinders goes from 1 to 4 in order). If a bad fuel injector was causing the cylinder 2 misfire then the code should switch from p0302 to p0303. When I started the car up the CEL was off, so I'll read the codes this evening after it has been driven a little. Hopefully that's a good sign that it is a fuel injector.

The worst part of the night was when I lost the o-ring that sealed the fuel pressure regulator to the fuel rail. I didn't know it was missing until gas started pouring out of the seal. All of the auto parts stores were closed so I had to run out and get a pack of o-rings this morning. My garage now wreaks of gasoline.   The cap for the coolant overflow also magically disappeared and I had to pick up a replacement.

coolant was a little low due to the leak so I topped it off. Oil was also a little low. Hopefully that's due to the misfire and not something else...

Pics below are of the coolant port and fuels injectors. The threads for the cap on the coolant port are on the inner diameter. Will that adapter you posted work for it?


Coolant port





Notice how 3 of the 4 injectors have discolored tips... Is that an indication of anything or is it natural for them to discolor like that?  

a few things...  is this a FREON port.. for the a/c system...  it looks like it might be a bleeder for the cooling system.. as i can see coolant in it.. but it really looks like a freon port for the AC




~~~~~~~~~~~~~~~~~~~~~~~~~~~

i never pull fuel injectors and replace them without putting new seals on at least the fuel side...

its just an invitation to less gasoline smell around the garage... and the smell of burned car... and burned garage...

i am hoping that you cleaned up the gasoline smell...   gasoline vapor will stay low to the ground..  will build up to concentrations where it will ignite off a pilot light or open flame in a water heater or forced air furnace.. even into the kitchen stove..  causing a trail of fire until it sets off the main puddle..

please ventilate your garage properly..