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Discussion Starter · #1 · (Edited)
Hello. '13 LTZ 81k. Along with high long term fuel trims (recent problem) this car has always had an issue with oil in the PCV system, getting sucked back into the intake snorkel. I've noticed the oil in the clean PCV tube (runs from valve cover to intake snorkel. Yes I know there isn't supposed to be oil in there) is very milky, exactly what you would see with a head gasket issue. I have a head gasket tester that involves a tube with 2 chambers you fill with fluid and there's a bulb on the top. You place this in your coolant reservoir and if the fluid changes color it's bad. I've done this test a couple times exactly as the directions say to do it, and my head gaskets fine. So what would cause this oil to look so milky? I've found one reason for my high fuel trims and have fixed that, but now need to track down the others.

I've noticed my evap purge solenoid clicks very loudly, you can hear it over everything else. And the fuel trims don't start to get out of control until it starts venting, or what I think is venting. Watching on the scanner the trims are ok until the purge starts giving a % above 0 then they start going up. I've read mixed opinions that the solenoid is supposed to be that loud and others say it's not and that's a sign something's wrong.

I would've posted this in the thread I already started but I couldn't stay on it long enough before I was redirected to a "spin the wheel" site that I couldn't get off of.
 

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That's whole lotta stuff to take in.

The oil is understandable; I saw more than I wanted to at 16K just after I bought it.

The milkiness could just be condensation from the PVC system that isn't being drawn into the intake sufficiently and it mixes with the oil.

I'm a believer in oil catch cans on these motors. They can be pricey, but there are cheap ones that are junk, too, so I'd get the best one, with full functions, that you can find.

The fuel trims issue is why I shy away from tuning right now; I'd like to fix the annoyances I have with the drivability and shifting, but I don't want the hassle of it right now, I'm far too busy, and my luck, I'll be in the Dealer with warranty issues and it'd be another thing to have to hide evidence of. At 60K, for my '16, I'm able to do as I please, and with the miles I drive, that won't be long. You've got to 100K.

It seems as if the fuel and solenoid issues are tied; if it was me, I'd return to the defaults, see if the issue is solved, and start over with tuning when you can see you don't have parts failure issues.

Past that, everybody swears to use really good synthetic oil, really good filters, and change it when you should.

And buy only Top Tier gas. Costco and Citgo for me.
 

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Discussion Starter · #3 ·
Thanks. I'm sorry if my post was confusing but I don't have the car tuned at all, everything's stock. I'm really in the beginning stages of learning automotive mechanics so a lot of stuff is new to me. Ive learned if the fuel trims are high at idle but return to normal at higher rpm, it's usually a vacuum leak. If they're high at all rpm then it's usually a sensor.
My issue is strange because on a cold soak the numbers are fine and will be until you shut the car off and let it hot soak. After starting from a hot soak it will either behave exactly like a vacuum leak. Or they will be high at idle, but 500 rpm above idle and they will snap back to normal, then at 40mph at 1500 rpm just cruising along they will be back up super high again. Depending on the day higher rpm either makes them come down into normal range or sends them up into the 20's, there's no real pattern I can find for it. The only thing I noticed and it happened twice now, was after filling my gas tank all the trims both short and long were in the minus quite a bit, 14-18 right after I stated the engine after getting gas. I always use Exxon, or shell gas. Both top tier. The stations you mentioned we don't have in my area.
 

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Discussion Starter · #5 ·
Thanks, that's good to know..

Today I removed the evap purge solenoid and used my handheld vacuum pump to test to see if it would hold a vacuum. It did not. I got lucky and the dealer had one, I tested the new one to see if it held vacuum, and it did but it very, VERY slowly bled off. Is that normal or is it supposed to hold vacuum perfectly? I got it installed but it didn't fix the fuel trim issue at all. It did however make me think, the ECU (or something) runs tests on the evap purge solenoid specifically to see if it holds vacuum, and if it's not and the ECU's not tripping a code for it, could this fuel trim issue be a much more serious computer problem?

Something else I found interesting, if at idle the ltft numbers are high and I take my gas cap off they come down below 10. Bank 1 will stay below 10 while driving around (with the gas cap off) and bank 2 will stay below 13, which is not bad considering 22 is becoming normal to see. Does anyone know what's causing this?

I have an appointment Friday to have a smoke test done to see if there are anymore vacuum leaks. The one we found with the oil filler tube was sheer luck, and that mechanic doesn't have a smoke machine. It would be easier if it behavied like either a vacuum leak (high numbers at idle, but get better at higher rpm) or like a sensor (high numbers at all rpm), at least that's what I was taught. But I can be at idle 680rpm and ltft b1-17. ltft b2-19 I can just barely step on the gas and add 100-200rpm and both banks will snap down to normal 2 or 3. Then as I increase rpm they will start to come back up again, until I hit a certain rpm and then they will drop back down to 2 or 3 again. I know that's confusing so I'll make a chart to so it's easier to read. If anyone knows what this jumping around could be indicative of I'd really appreciate it.

RPM. LTFT B1. LTFT B2.

680idle. 17.2 19.4
850. 2.3. 3.6
1360. 8.6. 9.2
1570. 9.6. 14.8
1920. 10.2. 17.8
2230. 8.3. 14.4
2520. 2.6. 4.5
2810 3.7. 19.8

And tomorrow they could be completely different!!
 

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Discussion Starter · #6 ·
FYI - It's completely normal for the fuel trims to go "wacky" after right after you put gas in the car. That does not indicate a problem.

Sent from my HP SlateBook 10 x2 PC using Tapatalk

You don't happen to have logs of your fuel pump pressure as you were driving do you? I'm having the engine and exhaust smoke tested Friday but I'm pretty sure there's not any other vacuum leaks (I replaced the oil filler tube). But the fuel pump has dropped down to the low 30's (psi) at higher RPM. It's within +-4psi of spec at idle. I would think as RPM increases the pump pressure would increase? But even this is a long shot.

Why do your fuel trims go wacky when you get gas? I've found if I take my gas cap off the fuel trims will drop down to almost normal. Bank 1 will be fine and bank 2 will hit 10 at maximum. I also vacuum tested the evap purge solenoid and found it to be bad (would not hold a vacuum at all) so I replaced it but it didn't have any effect on the problem. So I'm wondering if there's something else in the emissions system going wrong.

with all of this I started watching the cat temperatures and even with the fuel trims behaving the cats peaked at 1600 degrees on the highway, they came down and settled around 1300ish but IF the data is correct that's pretty hot. Also the downstream 02 sensors switch around a little more than (I've read) they should. As I've said in previous posts I'm not sure how long I've had this problem so the cats may be on their last legs. If anyone knows a good home test please let me know

Something else unrelated to this, occasionally when my traction control kicks on I'll get a "service traction control" message and a u0100 code (lost communication with TCM/PCM). I've not really looked into it because it's random and doesn't happen often. But with this and the evap purge valve being bad and not having a code for it, plus the fuel trims that are really starting to look weird with their random good days and bad days, I'm starting to wonder if there's a possibility of a bad ECM?
 
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