Low side pressure drop - with less e content

MartinLe · 08-01-2022, 10:06 PM

I just logged a run with e41.2 and my low side pressure disappeared. Here are some numbers:

e50.1
6600 rpm
low 74psi
high 2873psi
IPW 4.9

e41.2
6600
47
2046
5.6

The e50 run topped out at 7K rpm, 70/2488 and 5.02 ipw with 14psi of boost. I had 15.3 @ 6700.
The e40 run started tanking at 6K rpm: 66/3016, 4.85 ipw. The low side kept dropping from there with their respective numbers dropping/rising respectively. If anyone would like to see the logs, let me know. I tried to attached them but I got the invalid attachment notice.

Any thoughts would be greatly appreciated.

Camaro1973 · 08-01-2022, 11:49 PM

Quote:

Originally Posted by MartinLe

I just logged a run with e41.2 and my low side pressure disappeared. Here are some numbers:

e50.1
6600 rpm
low 74psi
high 2873psi
IPW 4.9

e41.2
6600
47
2046
5.6

The e50 run topped out at 7K rpm, 70/2488 and 5.02 ipw with 14psi of boost. I had 15.3 @ 6700.
The e40 run started tanking at 6K rpm: 66/3016, 4.85 ipw. The low side kept dropping from there with their respective numbers dropping/rising respectively. If anyone would like to see the logs, let me know. I tried to attached them but I got the invalid attachment notice.

Any thoughts would be greatly appreciated.

What’s on your low side?

I’ll send you a pm.

swisstyphoon · 08-02-2022, 12:09 AM

Quote:

Originally Posted by MartinLe

I just logged a run with e41.2 and my low side pressure disappeared. Here are some numbers:

e50.1
6600 rpm
low 74psi
high 2873psi
IPW 4.9

e41.2
6600
47
2046
5.6

The e50 run topped out at 7K rpm, 70/2488 and 5.02 ipw with 14psi of boost. I had 15.3 @ 6700.
The e40 run started tanking at 6K rpm: 66/3016, 4.85 ipw. The low side kept dropping from there with their respective numbers dropping/rising respectively. If anyone would like to see the logs, let me know. I tried to attached them but I got the invalid attachment notice.

Any thoughts would be greatly appreciated.

Was is colder the day you logged E40, compare to the day you run E50? Did you log in the same gear, or put more load on it this time?
Another factor is COT. Did you log that channel to see if cat overtemp protection kicked in, and put too much strain on your fuel system?

MartinLe · 08-02-2022, 10:03 AM

Quote:

Originally Posted by swisstyphoon

Was is colder the day you logged E40, compare to the day you run E50? Did you log in the same gear, or put more load on it this time?
Another factor is COT. Did you log that channel to see if cat overtemp protection kicked in, and put too much strain on your fuel system?

Both pulls were in 90 degree weather and very close to identical in setup and execution. I have some fellas smarter than me looking at the logs. I should have this sorted out shortly. Stay tuned.

KingLT1 · 08-02-2022, 10:14 AM

I doubt it's anything to do with lower E as that would be backwards far as fuel demand. What do you have for a low side fuel system?

Joshinator99 · 08-02-2022, 11:49 AM

Quote:

Originally Posted by swisstyphoon

Was is colder the day you logged E40, compare to the day you run E50? Did you log in the same gear, or put more load on it this time?
Another factor is COT. Did you log that channel to see if cat overtemp protection kicked in, and put too much strain on your fuel system?

Good call on the COT. That can have a huge impact.

KingLT1 · 08-02-2022, 12:45 PM

So can variable voltage system. That is why generally JRE recommends the voltage booster to keep low side voltage the same. But yes COT can cause that issue, so can positive long term fuel trims.

MartinLe · 08-02-2022, 12:50 PM

Quote:

Originally Posted by KingLT1

I doubt it's anything to do with lower E as that would be backwards far as fuel demand. What do you have for a low side fuel system?

JMS. Otherwise stock. The bizarre fact is this happened after the final tune when I installed the 125 flex fuel package. I replaced the low side pump and immediately lost a couple cylinders. My local tuner looked at it and thought I got some debris in the fuel system with the pump r&r that clogged the injectors. I wanted to do the blower/cam thing anyway, so instead of messing with the current build, I bought the +30s and moved forward. I sent the injectors to FIC and they said they were fine. They could not tell if they were clogged, but when the ran them through the test, they performed without issue.

Fast forward to now, the three pulls (e50) needed for the tune went without issue. The first pull at e40 - deja vu all over again.

Quote:

Originally Posted by Joshinator99

Good call on the COT. That can have a huge impact.

Why would the COT kick in suddenly at very similar, (more that 90 and less that 100 degrees), atmospheric conditions?

Camaro1973 · 08-02-2022, 01:00 PM

Quote:

Originally Posted by Joshinator99

Good call on the COT. That can have a huge impact.

COT is off. His pressure is dropping into the 40’s like the JMS isn’t even volting properly, or working at all or there is indeed a problem with his low side.

The behavior though from the logs looks pretty identical to mine if I was to disable my aux pump. I’m Having him try a few pulls in a higher gear, monitor the voltage from the JMS and see how the pressure is on 93 with the JMS disconnected.

Should be able to tell if it’s the JMS or the pump itself. If he had an aux, I would also Suspect a restriction in the filter from Drilling the tank. (Not the case here)

KingLT1 · 08-02-2022, 04:05 PM

Sounds like a JMS issue. If the pump was bad I don't think it would hold 47psi. That sounds like what the pressure would be with standard 12volts and no booster.

Camaro1973 · 08-02-2022, 05:29 PM

Quote:

Originally Posted by KingLT1

Sounds like a JMS issue. If the pump was bad I don't think it would hold 47psi. That sounds like what the pressure would be with standard 12volts and no booster.

Exactly this. He’s probably making similar power to me and when I had issues with my aux pump my low side dropped into the 40’s.

Just seems like the JMS isn’t giving the voltage.

MartinLe · 08-02-2022, 05:52 PM

I am going to add those channels for the electrical signals to the fuel pump and make a couple pulls as you suggested. I have a little less than 1/3 a tank of gas. Afterwards, I will fill up the tank with 92 which should pretty much drown any appreciable e content and do another pull. We should know after that, wouldn't you say?

Camaro1973 · 08-02-2022, 06:28 PM

Quote:

Originally Posted by MartinLe

I am going to add those channels for the electrical signals to the fuel pump and make a couple pulls as you suggested. I have a little less than 1/3 a tank of gas. Afterwards, I will fill up the tank with 92 which should pretty much drown any appreciable e content and do another pull. We should know after that, wouldn't you say?

Yep, If it stays holding consistently on pump then I’m
Going to assume there’s an issue with the JMS.

Crusher Camaro · 08-02-2022, 08:30 PM

should be able to check the JMS fairly easy.

key on / engine off
check voltage on the JMS white wire, then have somebody cycle the throttle and watch the voltage. should start to increase at the 50% throttle mark if setup like Teds instructions.

I was having issue with my JMS right after install. found the T-harness at the pedal had a bad connect to the signal wire. took the harness apart and replaced the connector, new heat shrink and all is normal now.

08-01-2022, 10:06 PM	#1
MartinLe Drives: 2017 Chevrolet Camaro ZL1 M6 Join Date: Jul 2020 Location: OR Posts: 479	Low side pressure drop - with less e content I just logged a run with e41.2 and my low side pressure disappeared. Here are some numbers: e50.1 6600 rpm low 74psi high 2873psi IPW 4.9 e41.2 6600 47 2046 5.6 The e50 run topped out at 7K rpm, 70/2488 and 5.02 ipw with 14psi of boost. I had 15.3 @ 6700. The e40 run started tanking at 6K rpm: 66/3016, 4.85 ipw. The low side kept dropping from there with their respective numbers dropping/rising respectively. If anyone would like to see the logs, let me know. I tried to attached them but I got the invalid attachment notice. Any thoughts would be greatly appreciated. __________________ JRE Terminator Rough Idle Cam Magnuson 2650 - 15% lower, 90mm upper FIC+30% DSX Flex fuel/Low side NW 103mm TB/Roto-Fab CAI Monster S Series Elite E2-X 2" TSP LT's BMR:BK063, BK060,TCA061, UTCA060, UTCA063 Weld Beadlocks/17" NT5R2

08-02-2022, 10:14 AM	#5
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 6,797	I doubt it's anything to do with lower E as that would be backwards far as fuel demand. What do you have for a low side fuel system? __________________ 2016 NFG 1SS A8 Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA

08-02-2022, 12:45 PM	#7
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 6,797	So can variable voltage system. That is why generally JRE recommends the voltage booster to keep low side voltage the same. But yes COT can cause that issue, so can positive long term fuel trims. __________________ 2016 NFG 1SS A8 Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA

08-02-2022, 04:05 PM	#10
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 6,797	Sounds like a JMS issue. If the pump was bad I don't think it would hold 47psi. That sounds like what the pressure would be with standard 12volts and no booster. __________________ 2016 NFG 1SS A8 Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA

08-02-2022, 05:52 PM	#12
MartinLe Drives: 2017 Chevrolet Camaro ZL1 M6 Join Date: Jul 2020 Location: OR Posts: 479	I am going to add those channels for the electrical signals to the fuel pump and make a couple pulls as you suggested. I have a little less than 1/3 a tank of gas. Afterwards, I will fill up the tank with 92 which should pretty much drown any appreciable e content and do another pull. We should know after that, wouldn't you say? __________________ JRE Terminator Rough Idle Cam Magnuson 2650 - 15% lower, 90mm upper FIC+30% DSX Flex fuel/Low side NW 103mm TB/Roto-Fab CAI Monster S Series Elite E2-X 2" TSP LT's BMR:BK063, BK060,TCA061, UTCA060, UTCA063 Weld Beadlocks/17" NT5R2

08-02-2022, 08:30 PM	#14
Crusher Camaro Drives: 19 ZL1 Join Date: Jan 2019 Location: Tampa Fl Posts: 92	should be able to check the JMS fairly easy. key on / engine off check voltage on the JMS white wire, then have somebody cycle the throttle and watch the voltage. should start to increase at the 50% throttle mark if setup like Teds instructions. I was having issue with my JMS right after install. found the T-harness at the pedal had a bad connect to the signal wire. took the harness apart and replaced the connector, new heat shrink and all is normal now.

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