Symptoms of bad 3 bar MAP sensor?

[NYTurbo]

You shouldn’t be seeing boost numbers like that key on engine off.

 

[1nc 2000]

You shouldn’t be seeing boost numbers like that key on engine off.

Those numbers are from a 3 bar tune with a 2 bar map sensor installed. Was helping a guy out because TD told him he had a bad 2 bar map sensor for the 2 bar tune he purchased from them. They had installed a 3 bar tune instead and the customer ordered a 2 bar tune and did not sell him a 3 bar map sensor.
Anyway all was good with a 3 bar map sensor installed.
Just sharing some numbers that the different tuners use as a base setting with the same base voltage and pressure.
Not the same from one tuner to the next.....

 

[earthling]

I don’t think the stock. Map sensors are a full 2 bar .

Usually if u put a 2 bar in a sled where the flash is built around a 3 bar you get a boost calibration error and vice versa.

The stock sensor may be calibrated differently. It may have a built in offset for atmospheric.. dunno..

 

[NYTurbo]

The stock sensor may be calibrated differently. It may have a built in offset for atmospheric.. dunno..

Possibly , I think it Max’s out around 17 psi (memory serves me correct)

 

[74Nitro]

I'm having issues with a 19 Winder. TD stock muffler bundle with 3 bar sensor. Sled usually starts off the day good until around 50 kms are on it, then wants to backfire mostly on decel, and run quality continues to get worse the more its driven. But it's not always consistent.
I'm leaning towards Map sensor.
Looks like we may be getting a little melt down this week, so not sure I'll be able to simulate this running condition.

 

[74Nitro]

I'm having issues with a 19 Winder. TD stock muffler bundle with 3 bar sensor. Sled usually starts off the day good until around 50 kms are on it, then wants to backfire mostly on decel, and run quality continues to get worse the more its driven. But it's not always consistent.
I'm leaning towards Map sensor.
Looks like we may be getting a little melt down this week, so not sure I'll be able to simulate this running condition.

It also outright stalls sometimes but will start right back up.

 

[Fleecer]

It also outright stalls sometimes but will start right back up.

Sounds like a bad fuel pump and/or possibly plugged/dirty fuel pickup socks/filters in the tank. For the 50-60 bucks, I'd change the pump and clean the socks in the process, then rule it out.

May as well buy the big pump while at it, then your ready for more power.

 

[74Nitro]

Sounds like a bad fuel pump and/or possibly plugged/dirty fuel pickup socks/filters in the tank. For the 50-60 bucks, I'd change the pump and clean the socks in the process, then rule it out.

May as well buy the big pump while at it, then your ready for more power.

I first suspected fuel pump also, but I put mine in it with the filters a few weeks ago.
I'm leaning towards the MAP sensor at this point.

 

[jonlafon1]

Fuel Regulator? Guessing you checked pressure.

 

[74Nitro]

Fuel Regulator? Guessing you checked pressure.

Maybe I'll have to put datalogging on this sled.
He tells me it only does this while decelerating.
When I get the sled back here I'll check fuel pressure again.
He also noted when the fuel tank is completely full it is OK until the tank gets to 3/4 and lower.

 

[sideshowBob]

Sounds like the sled doesn't have data logging or you would have found the issue already.
A couple things come to mind:
-map sensor
-plugged fuel tank vent
-vacuum source leak
-fuel pressure regulator issues or regulator vacuum or fuel return line
-weak blow off valve spring or valve sticking/leaking...once it opens it then remains partially open
-wastegate or blow off valve solenoid issues
Some are pretty obvious and I am sure you have checked/elliminated them already

A weak blow off valve spring on a turbo car will definitely give the symptoms you have described.

 

[sideshowBob]

Maybe I'll have to put datalogging on this sled.
He tells me it only does this while decelerating.
When I get the sled back here I'll check fuel pressure again.
He also noted when the fuel tank is completely full it is OK until the tank gets to 3/4 and lower.

That sounds like a fuel pick up issue.

 

[Fords4life]

Same thing i chased, i have fuel pressure gauge so i could see in real time what is going on, under braking hard fuel pressure would drop into teens then recover but throttle would be slugish as tank emptied it would get worse to the point of light throttle to keep it moving, at this point its strugling to maintain 32 psi, changed pumps 3 in total would wrk for a ride and back to same crap, turned out was fuel filters, first pump filter then the 2 on the y, changed all 3 and my origanel pump wrks great no more issues.

 

[jonlafon1]

Same thing i chased, i have fuel pressure gauge so i could see in real time what is going on, under braking hard fuel pressure would drop into teens then recover but throttle would be slugish as tank emptied it would get worse to the point of light throttle to keep it moving, at this point its strugling to maintain 32 psi, changed pumps 3 in total would wrk for a ride and back to same crap, turned out was fuel filters, first pump filter then the 2 on the y, changed all 3 and my origanel pump wrks great no more issues.

Where did you find the filters on the ends of the "Y" ?? I have a lead on the filter sock that connects to fuel pump, but those on the end of the Y ?

 

[sideshowBob]

Where did you find the filters on the ends of the "Y" ?? I have a lead on the filter sock that connects to fuel pump, but those on the end of the Y ?View attachment 171384

I have a couple of these in my SW spares supply....not sure where I got mine but they are the same part number. SPI SM-07367

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