Can injection timing or some other variable cause a random misfire? I recently changed my cam and make good power at WOT when I hit from 3000 rpm up and don't get a misfire code. If I smash WOT from a dig it causes a misfire. Compression appears to be good and pushrods are correct length. I guess that there is a possibility that one of the new ls7 lifters went bad. Mechanical or in the tune? Thanks in advance.
07 Silverado 5.3 full exhaust, CAI, BTR Stage 2 turbo cam and springs 226/231 .605"/.598" 113+4
Here are a couple of logs and the tune file. Silveradov1Log.hplSilveradovLog2.hplSilveradoIntakeExhaustStage2CamLiftersSpringsDODelete91V1.hpt
07 Silverado 5.3 full exhaust, CAI, BTR Stage 2 turbo cam and springs 226/231 .605"/.598" 113+4
Could the misfire be a result of one oxygen sensor being removed but still plugged in? TIA
07 Silverado 5.3 full exhaust, CAI, BTR Stage 2 turbo cam and springs 226/231 .605"/.598" 113+4
I cant help you much as far as the theory goes and why the Misfire shows up, but my 06 Z06 has had the misfire DTC since installing an RPM B3 Cam. I have read elsewhere that the cam causes the Random misfire code so I just disabled it after looking at the light for a few months. I will say that my CEL came on at idle as soon as i started the car after clearing the code without driving anywhere.
Last edited by Kfred 513; 09-02-2018 at 03:07 PM.
2006 Z06, AHP stage 4 Heads milled .020", Superbee 103 Intake, RPM B3 Cam, Billy Boat Catless Headers, X-pipe, Alky Control Meth Injection
Totally sounds similar to my problem. Whats weird is that the code never shows up when running the truck in SD. I am having trouble figuring out how to get this cam to make power in lower RPM as it feels as though it is falling on its face during throttle application but clears out quickly as the RPM's rise. I am not sure where to set the PE ramp in and delay as those could be contributing to the lack of response in lower rpm. Thanks for the response.Originally Posted by Kfred 513
07 Silverado 5.3 full exhaust, CAI, BTR Stage 2 turbo cam and springs 226/231 .605"/.598" 113+4
So this isn't related to the misfire anymore, but my car also has a slight stumble if i try to accelerate aggressively from a stoplight. it is only immediately after clutch release, and lasts about a second or less, once it catches itself it rips like normal. I came across a thread where someone suggested adding timing down low with bigger cams. Take a look here https://forum.hptuners.com/showthrea...esponse-on-E38
2006 Z06, AHP stage 4 Heads milled .020", Superbee 103 Intake, RPM B3 Cam, Billy Boat Catless Headers, X-pipe, Alky Control Meth Injection
I will play with the timing as suggested in your link and see what she does. Thank you
07 Silverado 5.3 full exhaust, CAI, BTR Stage 2 turbo cam and springs 226/231 .605"/.598" 113+4
your B1 02 sensor is reading almost no voltage.
the hit on the gas timing drops to 0. that could be the misfire. your bad 02 data could tell the PCM it has a misfire. I believe its the spark retard on the hit causing the misfire. disable burst knock and disable tip in torque management for the engine.
your problem seems to be under 4000rpm as you describe it, the PCM is referencing the VVE and MAF at this time. your VVE table looks very backwards to me and could also be making it lean causing the misfire.
Will do. Could you elaborate as to the "backwards" VVE? I have been working at dialing in the VVE according to the methods I have researched within this forum. Thanks
07 Silverado 5.3 full exhaust, CAI, BTR Stage 2 turbo cam and springs 226/231 .605"/.598" 113+4
I have one of the o2's removed for wideband installation maybe causing the low sensor voltage? Should I be using narrowband for everything but WOT tuning? I wasnt aware that the removed sensor would cause issues while tuning.
07 Silverado 5.3 full exhaust, CAI, BTR Stage 2 turbo cam and springs 226/231 .605"/.598" 113+4
that's why its reporting 3mV then. if you remove one I would suggest disabling closed loop and disabling LTFT and also STFT during open loop.
otherwise add another bung for the wideband and leave both narrow bands in if you wish to tune in closed loop with STFT active.
the engine needs less fuel at low rpm and low MAP pressure. as RPM and MAP increase the engine requires more fuel. so to be very crude the value in the 400rpm 10KPA cell should be the smallest and the values increase with MAP and RPM. the VE table should slope upwards and values get bigger as you move up in RPM and MAP. within reason of course. your VVE has bigger numbers in the low RPM and MAP area and as an average they get smaller with RPM and MAP increase commanding less fuel.
a big cam VE table will have much more variation with smaller values for idle/cruise and larger values for WOT and high load. a standard cam will have a similar pattern but not as much variance in values.
Why would my vve be backwards? Afr looks good according to the wideband. Vve was corrected based off of vve afr error histogram.
07 Silverado 5.3 full exhaust, CAI, BTR Stage 2 turbo cam and springs 226/231 .605"/.598" 113+4
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