I'll go ahead and say I'm new to tuning. I've been trying to read and learn all I can but this is kinda stumping me and I'd like to get the tune close at least so I can drive the car. I am running really lean and popping an SES code. I stuck the wideband on it and am seeing like 18 afr at idle. Idle sucks too. I tried bumping up the MAF table to throw some fuel at it, but it didn't really help much.
Trying to figure out how to attach my tune and log.
Got it attached. My specs are:
Car is a 98 Trans Am, T56 swapped, LQ9 6.0L, .02 over. Heads are stock with double valve springs and stock rockers, mild porting, bigger valves. Cam is a Futral F13 cam - 230"/232" .595"/.585" 112LSA. Longtube headers, no cats, FAST 92mm intake, Nick Williams 92mm throttle body, Whisper lid. Injectors are SVO red tops, 36# on GM system, and I'm running a single 255lph Walbro in tank. I have made the fuel system returnless.
Off hand do you know if those injectors are rated at 43.5psi or 58psi?
Fueling doesn't seem that far off per the trims, if you want to trust them. They aren't showing like it's way lean because the long term and short term aren't sky high like the wideband is. Maybe check for a leak at or before the wideband depending on where it's located or make sure the sensor isn't old or damaged.
If you've never reset the trims, wouldn't be a bad idea to do so to let them relearn. Also the way your tune is setup, it uses both the VE and MAF under 4,000rpm. So you can't just add the MAF, you have to tune both. The other thing is that your old computer runs a secondary VE table, which required a slightly different approach on the stock operating system. When you go to tune in speed density with your wideband to correct the VE, the computer uses the secondary VE table instead of the primary. So you make change to the secondary, copy over the rows to the primary and interpolate to make them nearly the same. That will be something to read into.
Also don't think your absurb IAT temps are helping anything, that is horrible heat soak for just idling.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
They are rated for 43.5psi.
I didn't notice the IAT temps being that high. That is crazy. I'll check and see what is up there. It was 90deg here but the car was sitting in the shade in my gravel driveway by my shop, so not like I was sitting in a blacktop parking lot.
I am tuning using the wideband in a probe on the exhaust. I can try and climb under the car today and weld a bung on there to see if I can get a more accurate measurement. I'm pretty sure there is no leak, I have the exhaust system sealed off pretty good. I was trying to use a probe so I can move it between cars.
Originally Posted by 5FDP
If you changed the factory fuel pressure down to 43.5 psi, then the flow rate is correct. These cars run right around 58psi from the factory, so the flow rate will need to be corrected if running 58psi.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
I'm running stock 58# pressure. I found a conversion table for the SVO injectors and updated my tune for it, so I'll try and see what it comes in at.
There is a proper data set for those injectors; you don't (or shouldn't) just jump in and push values around for a while.... They are called "30s" but move about 36lb/hr at our rail. Attached is an OE file (cal side; didn't check DTCs but that's not what this is for) for GenIII with all of the data for these SVO red-top units; IFR, offset, and short pulse tables. Generally speaking, these values should be set before ANYTHING IS DONE; well before ever getting to cranking, much less logging and refinement.
Yeah that ghetto trick isn't going to work. It adds error (and latency which you can't shift about) even at WOT where it "kind of" works. The only reason I even USE the tailpipe wideband on my dyno is that it's there... Cars get tuned with a sensor up front in a pipe and that guy is just a sanity check. At low engine speeds, you get nothing but fresh air around the sensor and it shows lean because you are exposing it (incorrectly) to outside oxygen.
One last note... those injectors haven't been made in over a decade and they are HUGELY KNOCKED OFF by Chinese suppliers. Fleabay is flooded with Chinese knockoff injectors. If the body looks black and shiny (painted), they are probably fakes. They are also commonly listed as "remanufactured" while still being "new" Chinese junk. These units hearken back to the 80s in OEM form.
Examples: legit (flat black body; looks annodized in hand) https://www.ebay.com/itm/Fuel-Inject...sAAOSwjYdbYpel
&
Knockoffs claiming to be "remans" that, the seller is so ignorant of that he's not even sure of what brand he's knocked off: https://www.ebay.com/itm/Reman-Genui...MAAOSwi7RZMiNN
And here you have a Web shop that is popular; FIVE-O Motorsport, selling outright Chinese fakes of these units. Again, a glance at that painted body should be enough, and also again, see how they are listed as "remanufactured units"... https://www.fiveomotorsport.com/30lb...zle-0280150945
Last edited by Frost; 08-20-2018 at 01:07 PM.
Thanks! I'll check all that stuff out.
These are real red tops. Believe it or not, I've had them for a really long time. Took me a while to finish this car. LOL
Great; the legit units work well. If they've had gas through them previously and been off the vehicle a while, consider sending them out for before/after flow & cleaning.
FYI, when tuning, youre gonna be in Open Loop so you can put your wideband where one or both stock sensors go and get everything dialed in. Once done, put the narrowbands back in. Most guys dont consider that unless you want to check to see your narrowbands are working right but that means they are just switching back and forth so not a ton of help anyways.
How well does tuning idle with a wideband work with a cam somewhat larger than his when a cam with more overlap could read a false lean?
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