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Discussion Starter #1 (Edited)
Running Rich *updated*

good morning fellas

this is my problem, stored the car mid Nov for the winter. got it running to get the etest done for next week, once I started drving it again this past Sunday check engine light came on. the a/f gauge showing rich mixture. so I took it into work (GM dealer) scanned it with the tech 1 and said code 13 LH o2 gone haywire. so replaced that drove the car a bit more and still the same, reading rich on the gauge again. watched the scanner for the values on the LH and RH fuel trims and O2 readings they are roughly around 128-132 down to 118-120. the o2 is reading between 900mv- 120mv on both sides. funny thing is the car doesn't stumble no misfire no running rough? I am out of ideas.

coolant temps are 210 on the scanner so the sensor is working
I changed the MAF to a new one and still running the same.
I have Tri- shorty headers with hi flow cats from CIA no leaks before the sensors.
the EGR seems to be working
new fuel from basically empty as well. 91oct
drove the piss out of it highway and around town.
fuel pressure is normal no leak down from the injectors, all injectors are correct miliamps.
car is tuned from a local tuner but car has passed with this tune in 2016 with flying colours
cats don't seem plugged, car has lots of power on accel.

the test numbers are
HC 1450
CO % 2.69
CO2 % 11.15
O2 % 4.40
like thats extremely rich right?

I need the test done by next week and I feel at a loss with the car, I have no idea where to look from now.

please anyone suggest where and what I should do to start throwing parts at it, it seems so weird it just started happening.
 

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Hi, i use Torque app on my android phone and watch the O2's bounce all the time.

your numbers after replacing seems normal. between .12v and .9v. .5v would be perfect mix.

So if the O2's are working and you still have the CEL on what is it for, the same code ? [13]

-ALF out....

EDIT:
Hi again, i would say you have 2 possible problems.
1. the O2 you got is bad out of the box, it's not a Bosch is it ?
2. the wiring from the PCM to the O2 sensor has an issue if the O2 itself is good.

Drive around and data log or just watch it in real time.
there is a ton of free stuff for OBD1 you can use to watch with laptop.
Throwing parts at it is not a good idea.
-ALF
 

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Discussion Starter #3 (Edited)
Once we reset the CEL it has not come back on, but the A/f gauge still reads rich.

Only delco O2 are in it, just like the MAF
 

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It is possible you have a exhaust leak on the DS (bank 1) which will cause the PCM to see more air and dump fuel which makes it run rich

also the CIA CATS being small may not be holding up to the motor
 

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Discussion Starter #5
No leaks at the header at all, tightened the bolts right up as well

Cats wouldn't cause the car to go rich, unless they are plugged then the car would have no power.
 

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The problem is most likely the fuel regulator . remove vac line see if it smells of gas.. plug vacuum line check the fuel trims ..

I find it so stupid for a GM tech to say replace the O2 sensors ...

could also be injectors dirty so again do the fuel pressure testing procedure ..

IMO throwing parts at the engine by codes is stupid .. testing not codes will narrow down what the failure is ..

fuel regulator is the most often cause ..you use stabilizer in gas ? LOL.................
 

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Cats wouldn't cause the car to go rich, unless they are plugged then the car would have no power.
the small CATS after the Tri-y's tube headers need to be A+ working condition...or they won't "lite off" enough to burn what fuel is getting into the exhaust which the smog test is reading

Always good to drive for about 30 min before test. Leave motor running when you pull up. Or sit there in parking lot and hold rpm at 2500 for 20 min to get those CATS good and hot before test
 

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the small CATS after the Tri-y's tube headers need to be A+ working condition...or they won't "lite off" enough to burn what fuel is getting into the exhaust which the smog test is reading

Always good to drive for about 30 min before test. Leave motor running when you pull up. Or sit there in parking lot and hold rpm at 2500 for 20 min to get those CATS good and hot before test
if his fuel trims are at the max the converters will glow ...

my HC last tested was 14PPM
 

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Op

test fuel pressure.

while 02 sensors can fail, usually that is high mileage "unless" the car has been running rich for a extended period of time and they can get fouled to the extent they just start to react slower. Basically its this the sensor feeding data which shows to much fuel=rich. So you need to find the "why". Your scan #'s saying the PCM is dumping fuel

Maybe a faulty injector(s)...(car was stored...did one or more gum up??)

You say no exhaust leak. Check fuel pressure to confirm FPR isn't over fueling the motor to rule FPR in/out. Simple test if you have the screw on Schrader valve FP gauge. Those are sometimes available at auto part stores with a "loan a tool" program
 

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Discussion Starter #10 (Edited)
OK code 13 showed the LH bank o2 wasn't reading. it was also holding steady at 453mv for some odd reason hence why we have changed that sensor.

fuel pressure was reading normally after as well, its leaked down after an hour and at minimal maybe 20psi wasn't enough for concern. the FPR is fine no gas in the vacuum tube.

the car when reading on the gauge "rich" it was smelling like unburnt fuel was coming out of the exhaust, so it was pretty noticeable.

I used a full tank of fuel to fill before storing and used fuel stabli in it. done this for the past 6 years without any issue before, the injectors are fairly new like say 10k on them SVO 30# I highly doubt one would gum up that badly to cause this but could be wrong?

I tried resetting the ECM by touching the battery cables together so the fuel trims reset, I drove it again but I need more time running it (we had that snowstorm come through last night) the gauge was showing it back to normal but I can't tell until I get another scanner on it and drive it.

Is it possible for a 1.6RR to back off and cause this? I looked for a broken spring last night as well, didn't see any out of the ordinary but I did notice a slight tick more on the drivers then the pass side of the engine? it could be a small exhaust leak as well? I don't know I just starting to panic I guess. hearing gremlins that might not be there.

could resetting the ecm/fuel trims actually work?

Nels
 

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If you have an exhaust leak, even a tiny one, it will be enough to throw off the 02's. This will make the computer push more fuel into that bank because it thinks its running lean. I'd encourage you to give the entire exhaust system, from the cats to the heads, another look.
 

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Discussion Starter #13
water pump temp sensor / connector ..
scanner reads the sensor is normal, gets up to 210 before the fans turn on.
 

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water pump temp sensor / connector ..
If that was it don't ya think it would be running a hell of a lot crappier than he is saying ?
-ALF out...
 

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I would check ALL of your Vacuum hoses and connections. A vacuum leak can cause a rich condition and depending on their age, many hoses could be in bad shape.
 

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but I did notice a slight tick more on the drivers then the pass side of the engine? it could be a small exhaust leak as well?

could resetting the ecm/fuel trims actually work?

Nels
....you hear a tick on drivers side...you have that side reading rich.....classic exhaust leak scenario. You really need to confirm this as it is the MOST CLEAR evidence that a exhaust leak (gasket, pin hole in header, etc)

resetting pcm to clear LTFT will not resolve a exhaust or vacuum leak issue causing a rich condition. The LTFT will be re-learned based on the STFT....and if bank one STFT are still pegged....new LTFT will also be high for that bank
 

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Discussion Starter #17
....you hear a tick on drivers side...you have that side reading rich.....classic exhaust leak scenario. You really need to confirm this as it is the MOST CLEAR evidence that a exhaust leak (gasket, pin hole in header, etc)

resetting pcm to clear LTFT will not resolve a exhaust or vacuum leak issue causing a rich condition. The LTFT will be re-learned based on the STFT....and if bank one STFT are still pegged....new LTFT will also be high for that bank

10-4 what if no leak is found and a slight tick is emitting from the engine side itself? bad lifter/ spring rocker out of adjustment? it that possible to cause richness?
 

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10-4 what if no leak is found and a slight tick is emitting from the engine side itself? bad lifter/ spring rocker out of adjustment? it that possible to cause richness?
A loose RR can cause a lifter tick...not really cause a rich condition. A bent exhaust valve hanging open will cause a compression leak and likely spew unspent fuel into exhaust. Seriously doubt that is the case.

Storing vehicles can reveal surprises when you wake up the car...like exhaust or vacuum leaks

I chased a DS tick thinking it was RR adjustment. Did lash again, same noise....it turned out to be a header leak. I have a heat shield welded to header on DS (they came that way) and the weld came apart leaving a hole in header I could not see, or suspect. I was pulling/pushing on that heat shield in a attempt to see/hear wtf the noise (tick) was coming from...Bingo, as soon as I pushed the heat shield slightly the noise got louder and I could see the separated weld. Muffler shop welded it quick, now no tick

check you stuff....yeah you are going to have to get dirty and get under the car. A stethoscope helps or a length of vac hose held to ear and probe around...yeah headers get hot so be carefull
 

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Discussion Starter #19
Alright going to the doc bag for Sat/ Sun. should be a hell of a good time

thanks for all the info I think i'm going to have to narrow it down now.
 
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