03-30-2018, 12:16 PM | #26 | |
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Join Date: Nov 2007
Location: Bay Area, Ca
Posts: 2,841
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Re: 6.0 runs and quits
GM never intended a MAF based vehicles fail safe SD system to be the main program to run from. It is intended to get you off the freeway and home safely, then to get it fixed.
I have done my fair share of disconnected MAF driving, I am not afraid of any near term issues. However contrary to popular belief, a severely retarded tune up couple with excess fuel causes damage. It might not be right away but over time things can get ugly. Washing cyls down Excessive fuel IE Rich condition can cause predetonation Add predetonation to fuel seeping between the rings and well so much for ringlands Fuel in the oil I am a big proponent of SD tuning, but not what is in the stock tune. May I ask how long you have been "tuning" GM ECU's? I am always learning and have been doing it since 2001. The truck I race is in HPT 1bar SD mode 95% of the 200 cars I have tuned are in SD mode or i started there. Quote:
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------Motor---------------Bottle 60'---1.53---------------1.41 1/8---6.58 @ 105.92----5.87 @ 118.41 1/4---10.38 @ 126.97----9.24 @ 142.49 |
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03-31-2018, 01:19 AM | #27 |
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Join Date: Mar 2018
Location: Ardmore
Posts: 100
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Re: 6.0 runs and quits
The only GM computers that don't default to low octane tables when the MAF is failed are the ones used in LS2 and LS7 applications. There's nothing wrong with running speed density if you need to because you are flowing too much airflow for your MAF sensor to handle or have a really monster cam, but just unplugging the MAF sensor is a terrible way to do it. Honestly going straight SD should be a last resort, the car will run better in most applications with the MAF. Especially E38/E67 Gen 4 stuff that rely even less on SD normally.
Not only are you running the low octane spark table, most of the LS engines including all of the gen 4 stuff has the IAT sensor included with the MAF sensor. The IAT sensor is a big part of airflow calcs when running speed density. While your engine may run smoothly with the MAF unplugged dave, that doesn't mean it's running at anywhere near its peak. GM's VE tables, especially the virtual VE tables used in the E38/E67 computers are known to be fairly rich. This is a safety issue since things like clogged airfilters heavily effect the accuracy of SD, and while the narrowband O2's can correct this at idle/part throttle they are no help during PE. And rich is at least safe, or least until you get so rich you start washing cylinders down. |
03-31-2018, 03:47 PM | #28 | |
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Location: ga
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Re: 6.0 runs and quits
Quote:
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4x4k30 if trouble was money i would have plenty |
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03-31-2018, 05:56 PM | #29 |
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Location: Manchester, CT
Posts: 433
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Re: 6.0 runs and quits
Open exhausts,eh? How close to the openings are the O2 sensors located? I'll bet they are seeing all that fresh air on reverse pulses, causing them to "see" a lean condition, then giving the PCM a rich command to the injectors, creating the over-rich gas smell and stumble. You need to look at live data and see what the O2's are doing
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04-01-2018, 04:41 AM | #30 |
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Location: Ardmore
Posts: 100
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Re: 6.0 runs and quits
yeah, you definitely need to get the exhaust buttoned up before you can really dig into this. open collectors will be hitting the O2's with tons of air making the computer think the engine is crazy lean.
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04-19-2018, 07:58 PM | #31 |
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Re: 6.0 runs and quits
I got the exhaust hooked up and I have been driving it all week and it still will not run with the maf hooked up . it runs ok with it not hooked up but it has low power . I keep getting a p0102 code maf low circuit I have checked all the wiring and found nothing . I checked the pvc its seems fine too and I cant find any vacuum leakes I don't know what else to do
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04-19-2018, 08:42 PM | #32 |
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Location: Ardmore
Posts: 100
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Re: 6.0 runs and quits
How did you check for vacuum leaks? The best way I have found is to lightly spritz carb cleaner around all the areas that can leak and listen for the engine rpm to spike. Gotta check all the vacuum hoses, the throttle body, the intake gaskets at the heads (known to leak on these motors), and all the air intake between the throttle body and Maf sensor.
If you are confident you don't ahve any vacuum leaks and the wiring is good you really need access to either a scan tool that can read real time data to check MAF hertz or a DMM that can read frequency. If you go the DMM route this is a good tutorial on how to do it. http://easyautodiagnostics.com/gm/3....sensor-tests-1 |
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