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Wiring Harness for 3.5 / 5 Bar Map sensors

2slowvw

Moderator
Location
VA
Car(s)
2016 GTI
I had a hard time getting my hands on a wiring harness to run the Aem 5 bar map sensor so I can push boost over 30 psi. So I decided to make my own and will make some for others.

Price is $37 and includes free Continental US shipping.

Why would you run the 5 bar instead of the 4 bar some people are running? I think Ed does a good job explaining the problem and symptoms.

Now on to the problem with the Bosch 4 bar... I think its the the pressure range rather than the resolution. The little data I've found on it, says it only reads down .5bar (-7.25psi relative vacuum at sea level). This is not enough for a gasoline engine as they tend to idle and operate at low throttle in the -9psi to -12psi range. So this sensor won't work properly when used on the manifold for load/fuel calculation. It'll work fine as a TIP sensor since it doesn't need to measure vacuum there. The AEM 5 bar, for example reads down to 0 bar (-14.7psi relative).

So this explains why some of you are having idle and low throttle drivability issues with the Bosch 4 bar in the intake manifold. There could be software tricks around this by calculating low load based on baro pressure, temperature, and throttle angle, but that's far from ideal. So until we can find a better a P&P 4 bar solution, it seems that the AEM sensor is the best bet.

..........


So I’ve been testing out the 4 bar sensor and there is definitely an issue at very low throttle angles right at the transition to decel. The sensor can’t read the high vacuum properly and results in -34% fuel trims and unstable a/f in that area. The result is a bit of a dead spot in the throttle in that transition as well as slightly jerky on/off throttle transition. This is most noticeable around 2000rpm in the 0-10% throttle range. I could see a lot of people not noticing or being bothered by the resulting drivability issue, but its not correct regardless. I’ve been able to smooth out the transition some with some tuning tricks, but at the end of the day, it’s just masking a real deficiency. For those talking about UM cars, I’ve only had one such car on my dyno, but that car also had a hard stutter at that spot, so I don’t think there’s anything too different going on.

FWIW, we’re at sea level and this issue would likely be much less prevalent or even cured at higher elevations. Maybe the folks reporting no issues are just at high enough elevations to get back into range of this sensor.

Thanks
— Ed

Includes:
All 3 connectors
Pinned and waterproofed
Length is 12inches long.

*A TUNE IS REQUIRED BY YOUR TUNER TO RUN A 5BAR MAP SENSOR*

Additional parts needed
4 Bar PUT sensor part #0281006059 (Bosch) #03K906051 (OEM)
AEM 5-Bar: https://www.summitracing.com/parts/avm-30-2130-75

20200401_171950.jpg

 
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8JVR6

New member
Location
Ottawa, Ontario
I make the harnesses @ 60$. If you’d look at the materials there is a huge difference.

Good for you for offering a more budget friendly option.




Sent from my iPhone using Tapatalk
 

2slowvw

Moderator
Location
VA
Car(s)
2016 GTI
While I do appreciate the constructive criticism, it appears the difference in "materials" he may be speaking of is the wire wrap. If you would like an upgraded wire wrap, spend 2 dollars at advanced auto and add a wrap of your choice.
 
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8JVR6

New member
Location
Ottawa, Ontario
It’s not criticism at all. I’m just trying to explain the higher cost / difference.

My harness features solder free crimped connections, tefzel wire and raychem heat shrink.

On my harness, the wiring is good for 400F / heat-cycling/ abrasion and vibration resistant

It’s more expensive because the material cost is high. I’m using left over harness material to help out my friends, and people who wanted them.
 

dwvw

Go Kart Newbie
I ordered the parts to make my own, but have no desire to make them for anyone else, lol.
 

nate704

Go Kart Champion
Location
Virginia
for DD and average drivers, $60 for a connector or two is still a lot (overkill in terms of material), so cheaper option will get my business. I'm sure even OEM wire harness uses cheaper material.
 
Last edited:

H22hatch

Ready to race!
Location
Vienna VA
I had a hard time getting my hands on a wiring harness to run the Aem 5 bar map sensor so I can push boost over 30 psi. So I decided to make my own.

If anyone else wants one let me know, I have heard people paying $60 shipped for this, I will make them for $35 and include free shipping.

Includes:
All 3 connectors
Pinned and waterproofed
Length is 12inches long.

2slowvw, I'll take one. I am on 4bar sensors right now and am considering switching to the 5 bar upper. Would i need to use the stock upper sensor? Or could i just leave the 4 bar sensors in and run the 5 bar sensor? It's probably really a question for UM.

Also, I'm in NoVA. Saw you are in VA as well.
 

2slowvw

Moderator
Location
VA
Car(s)
2016 GTI
2slowvw, I'll take one. I am on 4bar sensors right now and am considering switching to the 5 bar upper. Would i need to use the stock upper sensor? Or could i just leave the 4 bar sensors in and run the 5 bar sensor? It's probably really a question for UM.

Also, I'm in NoVA. Saw you are in VA as well.

You would leave the lower 4 bar in. Run the 3 bar up top in stock position and run the 5 bar off a boost tap off the manifold.
 

Calkulin

Ready to race!
Location
Central FL
It’s not criticism at all. I’m just trying to explain the higher cost / difference.

My harness features solder free crimped connections, tefzel wire and raychem heat shrink.

On my harness, the wiring is good for 400F / heat-cycling/ abrasion and vibration resistant

It’s more expensive because the material cost is high. I’m using left over harness material to help out my friends, and people who wanted them.


As an engineer that has worked with those materials, none of the stuff you mentioned equates to the $25 premium you mention for a 1 ft harness with that gauge size. Now if you want you say your time is more valuable, then that's on you
 

pieguy

Ready to race!
Location
Bay Area
You would leave the lower 4 bar in. Run the 3 bar up top in stock position and run the 5 bar off a boost tap off the manifold.

You get it tested with a tune already? Got this done pretty quick haha :D
 

613B6

Ready to race!
Location
Ottawa
As an engineer that has worked with those materials, none of the stuff you mentioned equates to the $25 premium you mention for a 1 ft harness with that gauge size. Now if you want you say your time is more valuable, then that's on you

As an engineer...how do you equate a value/dollar figure to heat cycling resistant?
 
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