Here is all I could manage. it intermittently records the correct pressure, seems to work best right after starting the car but as you can see from the log i get spikes of lows and highs. ill install the new feed line connector which is from a zl1 actually so its supposed to not have the check valve. I'll do that next week.low side drop4.hpl
Originally Posted by kenand1988
I'll check this log shortly.
Of course the sensor is buried deep beneath the vehicle... That's so annoying. I'll have to set up a channel and a graph for that sensor so it may take a bit, but I'll get back to you on that shortly as well.
Have a quick read of this. Whatever THIS is IS what is going on with the pid.
https://www.corvetteforum.com/forums...-pressure.html
Check post #36 on that thread. It may have the answer that you need.
https://www.corvetteforum.com/forums...post1605817385
It appears it is a common recurring phenomenon on the Vettes for some reason. Give what post 36 suggests a shot and see how it goes is my advice for the moment.
The poll rate is set to fastest. Interesting it's a problem for all c7s which makes me think it's hptuners related. I can get it to read sometimes by disconnecting and reconnecting the scanner but usually the pid will drop out soon after that. It's so random when it works and doesn't.
I wouldn't put it past being an HPTuners issue. For a long time I had an issue with my wideband reading then freezing and everything was hooked up. Every once in a while I still get weird wonky issues and glitches when datalogging as a whole, and it's not cable related so the program itself is just being stupid.
Yes on multiple different platforms I've had pids go dead or the whole log go dead but still recording. I've even had freezing while logging and the program will restart and not save any of the data. Not a perfect system I mean I do love hpt but I've never had a severe problem like this with a pid. The only fix I can see is installing a sensor where the feed line meet the under manifold feed line right by the brake booster and having it connected to the mpvi
Hook up a regular scanner to it and see what your fuel pressure on the low side is while you are driving it. If it is an HPT issue you'll see it right away.
Tried that there is still some flatlining but it's way way less. I don't know why it's like this. Why 399 kpa is what it is defaulting to. I believe I can actually use my handheld scanner to record some pids during a pull and play it back. There is not as much resolution with my handheld scanner but it will at least show me if I am dropping low side pressure
low side drop5.hpl
I had a chance to do another pull after replacing the feed line with one that does not have a check valve. I do not believe the 80 lb min # on the log I think its just super rich. I did some work dialing in idle and partial throttle using the maf vs freq table but of course have not touched anything while in PE but I can say the whole tune is probably 15-20% rich in a lot of places. I do think it may have made a little more power given that we hit 1lb more of boost thanks to the weather. I just hope that once I have a wideband it'll show that up top is super rich so I can pull alot of fuel out which will give me more room to add power.
Finally got the wideband installed and i think working right but im not sure. Its way richer than I thought. Its a pretty consistent .7 lambda when wot. Do you have any old logs of your car when you first started logging with a wideband I could compare it to?
No I do not because by the time I got my wideband I was already in the tuning process and running pretty efficiently at 0 knock and .80 AFR if I remember correctly. So all we had to do was scale the MAF a little more to get to the target AFR we wanted of .83-.86 for E85 and 100/91 mix. .7 lambda is MAD pig rich for these cars.
Last edited by ZLRob; 11-05-2022 at 01:59 AM.
Yes, it is very rich but here are some other things to consider. My MAF reading topped out at 83.8 lb min in 50F air tonight. So a stock z06 is making 800 hp? I don't think so. My car also can't really maintain the low side, why? well 20% rich is a good reason. I will try one more free air calibration tomorrow and see if I get the same results. The math works out to 10.3-10.5 to 1 AFR. When you reduce my most recent max maf of 83.8 you get 67 which is a lot more believable on a stock setup.
You should be topping off somewhere around 530's through high 500's grams/ sec. Do you have an intake on this thing? I don't know your mods so if you are topping out the MAF then you got some things to worry about there. If you are feeding that much fuel to the engine that would explain why your low side isn't keeping up.
Theres no modifications to it. Everything is stock. Here is a list of the maintenance I have done.
1. Oil change
2. Cleaned air filter
3. Resealed all fuel injectors, top and bottom seals.
4. Cylinder compression check, all within 5psi of each other 177-182 psi
5. New sparkplugs
6. New wiresets
The MAF is right by the air filter so all its doing is taking a frequency and referencing it to the maf table which I haven't changed. A vacuum leak would show up in driving, idling, fuel trims. Theres no boost leak, it hits 10-10.5 psi consistently every pull. I'm far beyond 530 g/s more like 630 g/s. but again thats just what the stock system says its doing at X frequency. I've never even removed the MAF, could it be bad? I doubt that unless it only shows up when at a high frequency but there isnt anything wonky going on when looking at the logs, they are smooth. So, the only explanations are the maf table is off, on the rich side or a stock z06 makes what a highly modified z06 does lol OR i guess the MAF could be bad.That would also explain a much higher reading than is normal but would MAF fail consistently making the fuel system 20% rich at WOT, I doubt it. The wideband is totally separate from the ECU so they dont have anything to do with one another. To me this looks like the MAF is 20% rich, I would think this is because it has no widebands so it has to be that way so it will never be lean no matter the DA. DA tonight was like mid 300s btw. Setting up on the dyno would be the only real way to tell the health overall of the car and the stock tune.
Now that I remember correctly, the Z's from the factory were tuned pig rich by GM. Once the ZL's came out they learned from those mistakes and they tuned the DI motor to be leaner and to something that should be much cleaner. From the factory the Z's ran around 10.8 at full gun if I remember right. Scale the MAF and then go from there.
Did another free air calibration. Cleaned the maf sensor. Exact same result. Extremely rich WOT. Ill begin changing the maf curve now.
I think the wideband may be faulty. I consistently read 10.2:1 during wide open pulls after doing a few free air calibrations so I moved forward with MAF adjustments. After doing all that to get in line with a 12:1 afr I checked the plugs and they looked lean, really lean. Like a very light tan, and I was also seeing a good bit of knock. I had hoped the tune was just rich, originally, which would leave me more room for fueling later but now I'm not so sure. I believe I have the correct transform function entered for the innovate psb1 to EQ which is (input/1024) + 0.5 = output for EQ Ratio. Idle EQ is 1, good. Decel fuel spikes to 1.5, good. All seems correct but I just don't trust it after seeing those plugs. I had to pull a substantial amount of fuel out to make the maf give the correct EQ, at least according to the WB. I'm torn between buying something like an AEM 03-334 or just buying a new 4.9 wb sensor. The wb is in the midpipe after the X which I was hoping would give a good reading of both banks. If anything I would think it could be skewed lean given the cats. Kind of at a stand still at the moment.
Hold on. You are using an Innovate gauge? Historically speaking Innovate gauges are junk. If you are using one, are you using one of those useless good for nothing, piece of shit Bosch LSU 4.9 sensors?
Also, that wideband is in a bad spot. It should have been before the cats either on bank 1 or 2 (it doesn't matter which side) now the cats are going to skew your readings.
Its an innovate psb1, its not cheap at least price wise. Yep its a bosch lsu 4.9 sensor. It was what my friend uses as well so I felt it was a good enough purchase. There is no room for another bung pre cat. like thats just not gonna happen on the stock manifold. That's why it was put in the rear after the X. Tuners put sensors in tailpipes so its not like they dont work but they can be skewed lean is what I'd read. Mine is the opposite of that. Just for science I'm installing the WB in the sensor 1 location bank 2 and i'll see if i have better results.
Reply With Quote