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- #1,921
Build Stretched 1-Ton FJ40
- Thread starter Mike Shull
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- Thread starter
- #1,922
I need some help tuning my engine. I've gone off of the deep end after spending the past 5-6 weeks at the tuner and I am now deep into various HP Tuner tables with my tuner's help.
The Cruiser is running pretty well and it is way better to drive than before, but I am getting a knock from the engine off idle and sometimes when putting a load on the engine, like pulling a hill at lower rpms. This is new and everything has seemed fine up until we started adjusting the tune. I can't load the original tune back into the PCM because we changed the intake and MAF sensors so I may get my old parts from the tuner and see what happens.
When the engine is under medium load at 5-700 rpms, and the engine knock is present, the PCM is advancing the timing to around 12 degrees and the st fuel trim is around -8%. My knock retard is it 8 degrees. Any ideas what settings that I might check?
The Cruiser is running pretty well and it is way better to drive than before, but I am getting a knock from the engine off idle and sometimes when putting a load on the engine, like pulling a hill at lower rpms. This is new and everything has seemed fine up until we started adjusting the tune. I can't load the original tune back into the PCM because we changed the intake and MAF sensors so I may get my old parts from the tuner and see what happens.
When the engine is under medium load at 5-700 rpms, and the engine knock is present, the PCM is advancing the timing to around 12 degrees and the st fuel trim is around -8%. My knock retard is it 8 degrees. Any ideas what settings that I might check?
Intake sensor & MAF, isn't the MAF the intake sensor ? What year is your comp for ? is it looking for the right MAF signal, they switched to card style MAF in early 2000's IIRC. Have you looked at the plugs ? have a look at fuel pressure for consistency, put 30WT synthetic oil in it. Lastly, what are your O2 readings looking like during the knock ?
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- #1,924
The PCM is from 2008 and I am a running 2009 card style MAF, which the tuner adjusted the tables for. I don’t have a baseline table for a corvette or Camaro so I don’t know whether this is right, and I suspect that the intake/MAF could be part of the problem. Yes, my IAT is in the MAF.
The plugs are new and I am using 10-30 full synthetic oil. I was also wondering about my O2 readings and I’ll have to pull up the scanner I see if I logged those.
where is your card, like the layout of pipe, right before a 90*, 4" straight both sides, ???? how far off TB is it ? where are your o2's ?
I know lots of ?'s, sorry, just curious as I went thru all this back when my motor was put in. Mine is 01' with the screen style MAF, yes I carry a spare BION.
I know lots of ?'s, sorry, just curious as I went thru all this back when my motor was put in. Mine is 01' with the screen style MAF, yes I carry a spare BION.
- Thread starter
- #1,926
Your 5.3l was knocking?
My card is in the straight part of the intake about halfway from the air filter to the throttle body. My o2 sensors are maybe 4-5 inches from the exhaust manifold flange.
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- #1,928
What is your compression ratio and what octane are you running? My engine has a 10.5:1 compression ratio and I was told that I need to be running high octane. I’ve been running mid-grade.
Mine is whatever stock is for a 2001 Denali. Altitude may be a factor as well. I am not sure about the octane causing the knock. Its more a function of dialing in the fuel and timing but that takes a minute as you have to drive, record data, try to match the data with the event so you are after the right adjustments and it may never quite knocking under certain conditions. 30wt.
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- #1,930
Hi. I’ll get it out on the road this weekend and get more comprehensive events logged. I am curious about my O2 readings though I think that having wideband sensors installed would make me more comfortable with changing fuel mixtures.
The engine only knocked one time before and it was after driving for 10 hours in 100 degree heat. The knock happened at the exact same event, at low rpm under medium load when I was pulling away from a stop. I let it rest that night and I’ve never heard the knock again until a few weeks ago. I’m hopeful that the engine is okay and that I can tune out the knock.
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- #1,932
Interesting. Mine lives at 5-10k depending on the time of year, which makes me curious about my MAP, MAT AND IAT calculations, though I don’t know enough to be confident with changing those perimeters.
Is it pinging or Knocking 2 very different things . To me it sounds like its pinging
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- #1,934
I had both problems, or the pre-detonation is so bad that it sounds like knocking. I don’t hear any pinging anymore. The problem that I am trying to solve for is being picked up by the knock sensors.
Do you have a wideband?
- Thread starter
- #1,936
No, do you?
Only way I would tune. I have a CAN based one that can log through HP tuners, I'll try and find the model. Highly recommend.
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- #1,939
I agree. Thanks for the recommendation. The tuner used a wideband to dial it in. I wasn't planning to mess with the air/fuel without his help.
- Thread starter
- #1,940
Here are my 02 sensor readings on the start/stop log file. I don't know what to do with this so I don't plan to touch it, but I am concerned about the airflow configuration at low rpms. I will get more data tomorrow. I'm going to dial back the timing a bit under the knock/ping conditions to see if that helps.
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