Running on thr rich side
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Running on thr rich side O2 WS6 all stock, I bought it used with 40k on it. Car runs great BUT it runs a little on the rich side all the time. If I start it cold you can smell the exhaust is rich, once warmed up the exhaust has a constant sulfur smell to it. Sometimes strong sometimes just slight. The engine oil doesn't smell or look washed down BUT if you pull the oil cap off you can smell strong fuel smell in the cap.
Car has 47k on it and is all stock, what seems to happen is after a few 100 miles of normal driving the engine carbons up and starts to knock and ping at part throttle only.WOT its quiet and runs nice. If I add Lucas upper cylinder lube to the fuel and run its hard the knocking goes away and it quiet for a bit.
The car has fantastic power and doesn't miss a beat, no black smoke out the exhaust cold or hot start. I checked the fuel trims and everything was 0 except the driver side stft at idle was at 3%, as soon as you give it gas or drive it goes to 0.
I'm an experienced mechanic and usually know where to start but I just can't find anything wrong that's obvious. Intake is tight and no codes come up. PCV system is good and pulls good vacuum on the engine. No oil in the pcv system either, Its nice and clean. I've owned and driven quite a few LS1 cars over the years and this the quickest nastiest one I ever drove that was stock.
Someone shoot me some ideas, thanks
Car has 47k on it and is all stock, what seems to happen is after a few 100 miles of normal driving the engine carbons up and starts to knock and ping at part throttle only.WOT its quiet and runs nice. If I add Lucas upper cylinder lube to the fuel and run its hard the knocking goes away and it quiet for a bit.
The car has fantastic power and doesn't miss a beat, no black smoke out the exhaust cold or hot start. I checked the fuel trims and everything was 0 except the driver side stft at idle was at 3%, as soon as you give it gas or drive it goes to 0.
I'm an experienced mechanic and usually know where to start but I just can't find anything wrong that's obvious. Intake is tight and no codes come up. PCV system is good and pulls good vacuum on the engine. No oil in the pcv system either, Its nice and clean. I've owned and driven quite a few LS1 cars over the years and this the quickest nastiest one I ever drove that was stock.
Someone shoot me some ideas, thanks
Have you put it on a scanner? What are the STFT and LTFT? Are the O2's reacting and switching quickly? Hard to say what it could be without looking to see what the PCM is doing.
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I scanned it tonight, Both sides 02 working properly. LTFT1 at idle -1.6 LTFT2 at idle -4.7
LTFT1 high vacuum closed throttle -4.0 LTFT2 high vacuum closed throttle -8.0
LFTFT1 steady cruise 55mph 0.0 LTFT2 steady cruise 55mph 0.0
Seems its only rich at a idle and closed throttle high vacuum, I'm guessing leaky injectors.
LTFT1 high vacuum closed throttle -4.0 LTFT2 high vacuum closed throttle -8.0
LFTFT1 steady cruise 55mph 0.0 LTFT2 steady cruise 55mph 0.0
Seems its only rich at a idle and closed throttle high vacuum, I'm guessing leaky injectors.
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From: Scotland
Not that I know $hit but I `ve recently bought a 99 Z28 M6. The car has 17k miles and drives spot on. But, I`m thinking its running rich too but only during warm up and slow town driving.
Turns out the lazy ba$tard I bought it from didn`t service it in 7 years. The dirty fly and bee filled K&N filter was beyond washing so that was junked. I also think there was a gallon of oil on it. There was no MAF screen either which couldn`t have helped and the throttle body was really dirty. I cleaned that and the idle is now more steady as before it was slightly jumpy.
I reckon my MAF is causing my half my problem. I`ve ordered the correct MAF cleaning spray as I reckon my little platinum wires are coated in $hit.
Like i say your MAF sensor might be perfect but just on the off chance it isn`t.
Turns out the lazy ba$tard I bought it from didn`t service it in 7 years. The dirty fly and bee filled K&N filter was beyond washing so that was junked. I also think there was a gallon of oil on it. There was no MAF screen either which couldn`t have helped and the throttle body was really dirty. I cleaned that and the idle is now more steady as before it was slightly jumpy.
I reckon my MAF is causing my half my problem. I`ve ordered the correct MAF cleaning spray as I reckon my little platinum wires are coated in $hit.
Like i say your MAF sensor might be perfect but just on the off chance it isn`t.
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I cleaned the maf and the air cleaner element is new. I pulled a spark plug out and sure enough it looks on the rich side. I can tell by watching the scanner idle and closed throttle coasting its getting rich. Only thing it could be is injectors leaking at closed throttle.
Another possibility is every time you decelerate the pcm goes to open loop and you run on the cold start parameters. I'm sure this is why If I come down my road into the driveway I can smell sulfur from the cats. Because I'm coming down a grade closed throttle into the dtiveway, the pcm is going open loop and using cold start settings to fire the injectors. I THINK LOL...............
Someone with some real knowledge please chime in here.
Another possibility is every time you decelerate the pcm goes to open loop and you run on the cold start parameters. I'm sure this is why If I come down my road into the driveway I can smell sulfur from the cats. Because I'm coming down a grade closed throttle into the dtiveway, the pcm is going open loop and using cold start settings to fire the injectors. I THINK LOL...............
Someone with some real knowledge please chime in here.
If it is a stock vehicle that is actually running rich, and nobody has screwed with the PCM, you need the vehicle repaired. O2 sensors, coolant temp sensor, air temp sensor, MAP sensor, MAF sensor, poor harness/PCM grounds, dirty or loose connections in the wiring, are the most likely culprits. Simply throwing parts at it is a dumb way to try to fix one, but I see that all the time.
A competent automotive technician, preferably one with the ASE L1 certification, is what you need to find. Nobody on any message board can just tell you how to fix it. Scan tool data is needed to start with, and somebody competent to interpret it.
Good luck.
A competent automotive technician, preferably one with the ASE L1 certification, is what you need to find. Nobody on any message board can just tell you how to fix it. Scan tool data is needed to start with, and somebody competent to interpret it.
Good luck.
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TY Well I hate to say it but three dealers looked at it and said it was fine........I know better that's why I posted. I'm not a working mechanic anymore but years ago I was and I know my way around a cars systems. I'm going to start by cleaning the injectors, everything else I seen on the scanner except the fuel trims looks ok. The 02s switch fast and are even BUT I will take your advice and try to find another experienced wrench take a look at it. Something is making it rich at low throttle high vacuum.
The car runs crazy good like this though. I bought the car used so who knows what someone could have loaded into the pcm. I guess I'm going to get it flashed to stock to be sure.
The car runs crazy good like this though. I bought the car used so who knows what someone could have loaded into the pcm. I guess I'm going to get it flashed to stock to be sure.
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Verdad Gallardo TY Well I hate to say it but three dealers looked at it and said it was fine........I know better that's why I posted. I'm not a working mechanic anymore but years ago I was and I know my way around a cars systems. I'm going to start by cleaning the injectors, everything else I seen on the scanner except the fuel trims looks ok. The 02s switch fast and are even BUT I will take your advice and try to find another experienced wrench take a look at it. Something is making it rich at low throttle high vacuum.
The car runs crazy good like this though. I bought the car used so who knows what someone could have loaded into the pcm. I guess I'm going to get it flashed to stock to be sure.
The car runs crazy good like this though. I bought the car used so who knows what someone could have loaded into the pcm. I guess I'm going to get it flashed to stock to be sure.
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The fuel trims are within 10% so in theory its ok. The car is all STOCK, but on a coast I can smell some sulfur from the cats and sure enough the fuel trims although not over -10% go negative when ever the throttle is closed LTFT1 -4.0 LTFT2 -8.0 on a high vacuum closed throttle situation.
Idle the LTFT1- 1.6 LTFT2 -4.7
Driving on the highway cruising the trims go to 0
The plugs look on the gray side, not black or sooty but gray.
Idle the LTFT1- 1.6 LTFT2 -4.7
Driving on the highway cruising the trims go to 0
The plugs look on the gray side, not black or sooty but gray.
Or, learn to love your new smell & gray plugs. :-)
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Car gets great fuel mileage 18-22 average but it has the worst piston noise I ever heard in a LS1. Cold it sounds like a diesel, warmed up it sounds like a CLATTER all the time. A light clattering noise, a clatter here... a clatter constantly.
If I add enough STP it gets quiet BUt then the oil is thick and performance suffers.
LUCAS upper Cylinder lubricant in the fuel COMPLETELY quiets the piston clatter. Funny thing is the engine doesn't use oil, every other LS1 I owned that slapped used oil. This engine also runs super crazy good, best running stock one I've ever driven.
If I add enough STP it gets quiet BUt then the oil is thick and performance suffers.
LUCAS upper Cylinder lubricant in the fuel COMPLETELY quiets the piston clatter. Funny thing is the engine doesn't use oil, every other LS1 I owned that slapped used oil. This engine also runs super crazy good, best running stock one I've ever driven.
