Why are the values in my VE table so high?
Thread Starter
Joined: Aug 2004
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From: Pace, FL
Why are the values in my VE table so high? So I was out datalogging today to try and get more data points into my VE table. What I don't understand is why my VE table values are so high. I'm seeing 140s in there. That doesn't seem right. I had played with my injector data some after noticing the IFR was off, which caused me to multiply my VE table by 1.15, but I can't believe I'd still need to be adding to those numbers. I thought 110 would be about as high as I would see?
Any thoughts? Tune and the datalog that produced it attached.
Any thoughts? Tune and the datalog that produced it attached.
Thread Starter
Joined: Aug 2004
Posts: 11,258
Likes: 146
From: Pace, FL
Ah nevermind. The IFR table directly corresponds to the VE table. If I had LS3 injectors (which are 42lbs @ 58psi) in there, my numbers would be .767 of what they are now... so I'd be at 105 max.
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Joined: Jun 2012
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From: SV, AZ
You should be able to swap in injectors, change your data and the only thing that should change is your duty cycle. As long as the data is correct.
Remember the VE and MAF tables are dealing with airflow not fuel. If your injector data is incorrect and you use it and wideband feedback it will tell you you are processing more air than reality.
Example:
14.12 g air need 1 g fuel.
141.2 g air need 10 g fuel.
Injector flows 10g/s fuel.
Injector will stay open 1 sec to supply fuel for 141.2g air.
If injector flows 8g/s fuel, but thinks it flows 10g/s it will still try and stay open only 1 sec. This will show lean on the wideband. So we tell it there is more air and it flows more fuel.
In order for the 8g/s injector to flow 10g fuel it most flow 1.25sec.
Our 8g/s injector thinks it's 10g/s still.
If a 10g/s injector stays open for 1.25sec it will flow 12.5g of fuel. This is enough fuel for 176.5g of air.
176.5g of air will show a larger number on your ve table.
Last edited by eaglegoat; Apr 21, 2015 at 04:15 PM. Reason: Posting from my phone
Thread Starter
Joined: Aug 2004
Posts: 11,258
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From: Pace, FL
Well that's what I thought. I didn't think the VE table changed. A change in injectors should be accounted for by the injector data itself if all the data is right. But I saw something on HPT where it looked like that the IFR had a relationship to the VE table.
So, now I don't know.
I didn't think the VE table looked right at all. But I know you can tune around it if you have sketchy data as eagle pointed out.
The question then is... why are my numbers so off? Is the injector data that bad? Got this directly from FIC... offset, IFR, etc. I don't think they'd be off 30%?
Vacuum leak? That'd require me to dump a ton of fuel to get my wideband readings in line...
So, now I don't know.
I didn't think the VE table looked right at all. But I know you can tune around it if you have sketchy data as eagle pointed out.
The question then is... why are my numbers so off? Is the injector data that bad? Got this directly from FIC... offset, IFR, etc. I don't think they'd be off 30%?
Vacuum leak? That'd require me to dump a ton of fuel to get my wideband readings in line...
Last edited by JakeFusion; Apr 21, 2015 at 04:37 PM.
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From: SV, AZ
Well that's what I thought. I didn't think the VE table changed. A change in injectors should be accounted for by the injector data itself if all the data is right. But I saw something on HPT where it looked like that the IFR had a relationship to the VE table.
So, now I don't know.
I didn't think the VE table looked right at all. But I know you can tune around it if you have sketchy data as eagle pointed out.
The question then is... why are my numbers so off? Is the injector data that bad? Got this directly from FIC... offset, IFR, etc. I don't think they'd be off 30%?
Vacuum leak? That'd require me to dump a ton of fuel to get my wideband readings in line...
So, now I don't know.
I didn't think the VE table looked right at all. But I know you can tune around it if you have sketchy data as eagle pointed out.
The question then is... why are my numbers so off? Is the injector data that bad? Got this directly from FIC... offset, IFR, etc. I don't think they'd be off 30%?
Vacuum leak? That'd require me to dump a ton of fuel to get my wideband readings in line...
Last edited by eaglegoat; Apr 21, 2015 at 05:15 PM.
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From: SV, AZ
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Thread Starter
Joined: Aug 2004
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From: Pace, FL
I had originally put them in for 3-bar. I noticed the disclaimer said you need to multiply by 1.1547 for 4-Bar. So I had tuned my VE with the 3-bar IFR data. I multiplied the VE table by that much after putting the correct IFR data (because the injectors were that much bigger than what the PCM thought and my VE table was off that much). Then I did the log I posted to see if there were any changes. Most of the changes were fairly minor, but the higher kPas changed and made those numbers grow even bigger.
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Verdad Gallardo Thread Starter
Joined: Aug 2004
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From: Pace, FL
One other thing. High IATs will make for leaner conditions correct? If I've logged and tuned over time am I just adding to them? The TSP 100mm MAF makes for some higher IATs using the LS3 IAT integrated into the MAF. Today they were in the 90s-110 and ambient was about 80.
I'm thinking it might be time to reset the VE table to stock with 15% more fuel, clear the LTFTs, and make sure my IATs are low and log against that and see how far off it is. Get my cell counts near 30 and make adjustments.
I'm hopeful my wideband is still accurate... As the connector hit against the exhaust pipe and melted. Wiring looks okay but it could be reading whatever. Might be time to order a new harness and wideband.
I'm thinking it might be time to reset the VE table to stock with 15% more fuel, clear the LTFTs, and make sure my IATs are low and log against that and see how far off it is. Get my cell counts near 30 and make adjustments.
I'm hopeful my wideband is still accurate... As the connector hit against the exhaust pipe and melted. Wiring looks okay but it could be reading whatever. Might be time to order a new harness and wideband.
Thread Starter
Joined: Aug 2004
Posts: 11,258
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From: Pace, FL
One other thing... Stoich is set to 14.14 for E10 and my wideband (NGK) is set for this as well. I'm wondering if my formula is off for the NGK in the scanner? Maybe reset to the factory stock NGK settings in HPT and reset my fuel to 14.67. Verify that's not an issue.
Just trying to think how to troubleshoot and redo the VE table to verify accuracy before buying new injectors.
Just trying to think how to troubleshoot and redo the VE table to verify accuracy before buying new injectors.
Thread Starter
Joined: Aug 2004
Posts: 11,258
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From: Pace, FL
Well I went and rented a fuel pressure test kit...
I did this while the car was "cold" so maybe I need to run it and then test the pressure. But the point is. I only got 10PSI when I turned the ignition to ON. 10. It built pressure as I turned it on and off. But it bled off fast. Really fast.
I didn't even bother to crank it. I know where my issue is - could be an install error since it is a Racetronix pump/hotwire kit.
But that would definitely mean the injectors are smaller than the PCM thinks, would account for my hard start issues, and my VE table problems.
Car seems to run fine but I haven't really pushed to upper RPMs because of the issues. One thing that is weird - I had to realllly lean it out for it to have lean idle. Seems like that's counter to having smaller injectors than what the PCM sees? So could it be a leaky injector? Although at the rail, the pressure never built. Tomorrow, I'll start it and monitor it as fuel is delivered.
I did this while the car was "cold" so maybe I need to run it and then test the pressure. But the point is. I only got 10PSI when I turned the ignition to ON. 10. It built pressure as I turned it on and off. But it bled off fast. Really fast.
I didn't even bother to crank it. I know where my issue is - could be an install error since it is a Racetronix pump/hotwire kit.
But that would definitely mean the injectors are smaller than the PCM thinks, would account for my hard start issues, and my VE table problems.
Car seems to run fine but I haven't really pushed to upper RPMs because of the issues. One thing that is weird - I had to realllly lean it out for it to have lean idle. Seems like that's counter to having smaller injectors than what the PCM sees? So could it be a leaky injector? Although at the rail, the pressure never built. Tomorrow, I'll start it and monitor it as fuel is delivered.
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Joined: Aug 2005
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From: Monroe,NY
What is your pressure while it is running? I have a 5.3 swap in a 1992 chevy pickup and I had my hose come loose on my fuel pump. Truck still ran fine(idle and part throttle) but I only had 20 psi while running.
Thread Starter
Joined: Aug 2004
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From: Pace, FL
I used the VCM bi-directional controls to turn the pump on (got home late and didn't want to fire it up). It builds to 58 PSI. But as soon as I turned the pump off, it dropped to 0 very quickly and didn't hold any reserve in the line. I'm taking less than 5 secs it was back to 0. None in the rail so that when I hit the pressure release on the fuel pressure tester, no fuel came out.
I need to crank it and see if it holds steady - this would explain my cold start issue, VE table issue, and my warm up issue. If the fuel pressure fluctuates it's hard to tune with that variable.
I'm betting there is a small leak somewhere. I don't think the injectors are the culprit, but maybe they are. I'll check them. I'm inclined to think I have a hole in the line in the tank or my FPR is going south. Or the check valve is gone in the Walbro pump. I'll see tomorrow how it holds pressure.
I need to crank it and see if it holds steady - this would explain my cold start issue, VE table issue, and my warm up issue. If the fuel pressure fluctuates it's hard to tune with that variable.
I'm betting there is a small leak somewhere. I don't think the injectors are the culprit, but maybe they are. I'll check them. I'm inclined to think I have a hole in the line in the tank or my FPR is going south. Or the check valve is gone in the Walbro pump. I'll see tomorrow how it holds pressure.
Last edited by JakeFusion; Apr 22, 2015 at 11:16 PM.
Thread Starter
Joined: Aug 2004
Posts: 11,258
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From: Pace, FL
Well, the racetronix pump is supposed to have a check valve. But that may be a different problem. At idle it holds 60 psi and when i rev it doesn't move off 60.
So I guess I'm back to the injectors.
So I guess I'm back to the injectors.
Thread Starter
Joined: Aug 2004
Posts: 11,258
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From: Pace, FL
The issue is the fuel pump. Stopped raining today and I was able to go do some blasts down the highway with a mechanical fuel pressure gauge taped to the windshield. Moderate throttle and I'm seeing it drop 10+ PSI. That's why my table is so far off. It's losing even more the more throttle I give it.
It's a Racetronix Pump with a hotwire kit. I don't think the pump is bad. I think the line from the pump to the tank has a hole in it. Will drop the pump today after the exhaust cools and see.
It's a Racetronix Pump with a hotwire kit. I don't think the pump is bad. I think the line from the pump to the tank has a hole in it. Will drop the pump today after the exhaust cools and see.
Thread Starter
Joined: Aug 2004
Posts: 11,258
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From: Pace, FL
I cut a trap door, pulled the in-tank assembly out. The line wasn't leaking, but it was a little loose. So, I tightened everything down and it fired off with the stock prime and afterstart enrichment tables first time. I've gone through three crappy rent-a-gauges from Advance and AutoZone and all of them fail after a few minutes. So I haven't gotten a good number on the FP going down the road after I played with the pump.
My VE table has leaned out about 10-12%, but it's still too high. So I purchased a real FP gauge to monitor what's happening. If it's holding 60psi and still wants huge numbers in the VE table, I may just live with it as the injector data is off, or swap over to some LS3s and retune.
My VE table has leaned out about 10-12%, but it's still too high. So I purchased a real FP gauge to monitor what's happening. If it's holding 60psi and still wants huge numbers in the VE table, I may just live with it as the injector data is off, or swap over to some LS3s and retune.
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From: So.Cal.
Do you use the in-tank FPR (which is not manifold referenced) or do you use an adjustable FPR (which is manifold referenced) at one of the rails...?
Last edited by joecar; May 9, 2015 at 08:00 PM. Reason: typo