MAP sensor discrepancies
Thread Starter
Joined: Dec 2018
Posts: 446
Likes: 81
From: Midwestern Illinois
MAP sensor discrepancies Started making some pulls and datalogging the runs. On the datalog it shows the MAP sensor saw a peak of only 5.1psi around 4,000rpm and held steady all the way to 6,500rpm. My fuel pressure base is 43psi and saw a peak of 59psi. So a total of 16psi increase.
I bench tested the map sensor with regulated shop air. With the sensor plugged in to the holley harness the boost gauge on my dash was spot on with whatever pressure I set the regulator at. The sensor screws directly into the intake. I trying to figure out where or why there is an 11psi difference. I tend to trust the fuel pressure sensor because it needs mechanical force on the diagram before the sensor can read an increase in pressure.
L33 5.3
S488
BOSCH 210's on E85
Holley mid ram intake
Holley terminator x
A2W intercooler
Currently only using spring pressure on twin 38mm gates
1.80 glide, custom PTC converter
I bench tested the map sensor with regulated shop air. With the sensor plugged in to the holley harness the boost gauge on my dash was spot on with whatever pressure I set the regulator at. The sensor screws directly into the intake. I trying to figure out where or why there is an 11psi difference. I tend to trust the fuel pressure sensor because it needs mechanical force on the diagram before the sensor can read an increase in pressure.
L33 5.3
S488
BOSCH 210's on E85
Holley mid ram intake
Holley terminator x
A2W intercooler
Currently only using spring pressure on twin 38mm gates
1.80 glide, custom PTC converter
10 Second Club
Joined: May 2018
Posts: 168
Likes: 21
I would hook up a mechanical pressure gauge to the the intake and put the gauge where you can see it while making a pull.
It sounds redundant, but it would be a good double check. Eliminating all electrical problems.
It sounds redundant, but it would be a good double check. Eliminating all electrical problems.
Started making some pulls and datalogging the runs. On the datalog it shows the MAP sensor saw a peak of only 5.1psi around 4,000rpm and held steady all the way to 6,500rpm. My fuel pressure base is 43psi and saw a peak of 59psi. So a total of 16psi increase.
I bench tested the map sensor with regulated shop air. With the sensor plugged in to the holley harness the boost gauge on my dash was spot on with whatever pressure I set the regulator at. The sensor screws directly into the intake. I trying to figure out where or why there is an 11psi difference. I tend to trust the fuel pressure sensor because it needs mechanical force on the diagram before the sensor can read an increase in pressure.
L33 5.3
S488
BOSCH 210's on E85
Holley mid ram intake
Holley terminator x
A2W intercooler
Currently only using spring pressure on twin 38mm gates
1.80 glide, custom PTC converter
I bench tested the map sensor with regulated shop air. With the sensor plugged in to the holley harness the boost gauge on my dash was spot on with whatever pressure I set the regulator at. The sensor screws directly into the intake. I trying to figure out where or why there is an 11psi difference. I tend to trust the fuel pressure sensor because it needs mechanical force on the diagram before the sensor can read an increase in pressure.
L33 5.3
S488
BOSCH 210's on E85
Holley mid ram intake
Holley terminator x
A2W intercooler
Currently only using spring pressure on twin 38mm gates
1.80 glide, custom PTC converter
Andrew
Thread Starter
Joined: Dec 2018
Posts: 446
Likes: 81
From: Midwestern Illinois
Andrew, thanks for the reply. Can you elaborate a little bit on MAP sensor matching the Baro channel, and sensor ICF, and sensor calibration. I'm still very new with the Holley system but do enjoy learning in baby steps.
Andrew
Thread Starter
Joined: Dec 2018
Posts: 446
Likes: 81
From: Midwestern Illinois
I do everything with a laptop, in fact I have probably only used the 3.5 screen two times and hated it. I will check those things and report back. The car will somewhat be on the back burner for a bit with fall coming, and as of today trying to close on a house.
Thread Starter
Joined: Dec 2018
Posts: 446
Likes: 81
From: Midwestern Illinois
If the sensor is not configured correctly would it be displaying incorrectly on my dash? Sensor plugged into harness, then regulated shop air on the map sensor at different pressures, the holley dash was alway within .5psi of the mechanical gauge on the shop air regulator.
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What map sensor are you using? There is a built in map, so you not only need to make sure your not using that, but need to make sure that you have it configured for the correct sensor you are using, as well as previously said, make sure with key on engine off, it should be right about whatever your normal atmospheric pressure is (not sure where you live)
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Verdad Gallardo Thread Starter
Joined: Dec 2018
Posts: 446
Likes: 81
From: Midwestern Illinois
What map sensor are you using? There is a built in map, so you not only need to make sure your not using that, but need to make sure that you have it configured for the correct sensor you are using, as well as previously said, make sure with key on engine off, it should be right about whatever your normal atmospheric pressure is (not sure where you live)
Why are you doing MAP in psig instead of absolute pressure?
You set your base fuel pressure at engine idle which was pulling manifold vacuum at the time. +5 psig manifold pressure is a lot more than 5 psi rise from whatever were the vacuum readings at idle.
Also, you're losing sensor resolution by having a MAP sensor with such a large range in excess of your needs. I don't know if it matters though. It does matter that you have the right transfer function from voltage to pressure programmed for the sensor.
You set your base fuel pressure at engine idle which was pulling manifold vacuum at the time. +5 psig manifold pressure is a lot more than 5 psi rise from whatever were the vacuum readings at idle.
Also, you're losing sensor resolution by having a MAP sensor with such a large range in excess of your needs. I don't know if it matters though. It does matter that you have the right transfer function from voltage to pressure programmed for the sensor.
Last edited by QwkTrip; Sep 17, 2022 at 03:31 AM.
Sorry if this comes off the wrong way, but I know your username, but can't come up with more. IDK if I've met you or anything else. It's just odd you mentioned Alton, that's where I live. Not a town most people mention is all.
My memory kinda sucks.
Thread Starter
Joined: Dec 2018
Posts: 446
Likes: 81
From: Midwestern Illinois
The map sensor was a freebie when I purchased the terminator x. If there is too much resolution using it, I will switch to a different one, but I don't think resolution is the issue. I think you were interested in a turbo from me at one point, or you had parts for sale that I was interested in, I'd have to look at my old PMs. I just remember your username and is saying A-town.
The map sensor was a freebie when I purchased the terminator x. If there is too much resolution using it, I will switch to a different one, but I don't think resolution is the issue. I think you were interested in a turbo from me at one point, or you had parts for sale that I was interested in, I'd have to look at my old PMs. I just remember your username and is saying A-town.
Thread Starter
Joined: Dec 2018
Posts: 446
Likes: 81
From: Midwestern Illinois
Why are you doing MAP in psig instead of absolute pressure?
You set your base fuel pressure at engine idle which was pulling manifold vacuum at the time. +5 psig manifold pressure is a lot more than 5 psi rise from whatever were the vacuum readings at idle.
Also, you're losing sensor resolution by having a MAP sensor with such a large range in excess of your needs. I don't know if it matters though. It does matter that you have the right transfer function from voltage to pressure programmed for the sensor.
You set your base fuel pressure at engine idle which was pulling manifold vacuum at the time. +5 psig manifold pressure is a lot more than 5 psi rise from whatever were the vacuum readings at idle.
Also, you're losing sensor resolution by having a MAP sensor with such a large range in excess of your needs. I don't know if it matters though. It does matter that you have the right transfer function from voltage to pressure programmed for the sensor.
Base fuel was set with engine off, pump running. 43psi.
TECH Fanatic
Joined: Nov 2014
Posts: 1,308
Likes: 660
I relocated the map remotely from the manifold because I felt I was getting readings affected by the pressure pulses in the manifold. That also allows me to run the same boost feed the the map and the fuel regulator. So while the engine is not running and ignition is on, I can manually pump the feed line with a bicycle pump and check the fuel pressure and map reading with a manual gauge as well as digital. Takes out the guesswork.