What MAP sensor now that my EFI Source one stopped working? SOLVED!
06-25-2018, 06:28 AM
#1
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What MAP sensor now that my EFI Source one stopped working? SOLVED! Few months ago, I went with the common LS1 style, plug in MAP sensor from EFI Source.
It worked great for a while, but a few weeks ago, as soon as any boost was seen, the car would misfire, buck, break-up, etc...
Discovered low fuel pressure at idle (35-38 psi) and an immediate drop to zero psi with key turned off.
Found a split in the intank Racetronix dual pump setup, on the primary pump's hose. Fixed that and thought I had fixed the problem..
That DID fix the fuel delivery issue....Now 65psi, and 75 psi when 2nd pump is manually triggered.
Anyway....the fuel delivery was NOT the issue with the weird AFR's and timing drops under load...evidently, found that problem by accident.
Fast forward and viewing several recent datalogs, I see the MAP readings all over the place. Sometimes, 90 kPa, sometimes 40 or so...at idle. Car has a near stock acting cam...usually makes 16-17" of vacuum in gear @ 800 rpm.
Go to get another sensor, and the one I have, is Out Of Stock....so I order a Delphi "brick style", and change the pigtail.
I have my MAP sensor remotely mounted. IE, sensor is on top of intake, with a boost/vacuum hose connected to it, and verified to read both.
Now...the "brick style", advertised on Amazon, as a 3 BAR...WAS evidently, a 1 bar...This seemed to have "fixed" the misfire/breaking up problem, but the first time I made any boost, the MAP sensor failed to a full time 5 volt reading, which was 320 kPa, and showing 31# of boost, LOL. It reads 0 kPa Key On, Engine Off, but pegs to 320 kPa as soon as engine starts, or tries to...
Obviously, this made the car so rich, it barely ran...In fact, I had to reflash the MAP sensor scaling to read no higher than 90 kPa, so I could get the car fired up and back into the shop...
So, after the book I just wrote...
Cliff Notes:
What DEPENDABLE MAP SENSOR are you guys using?
I am thinking of the German made, Chevrolet Performance one for the ZL1/ZR1....
I will not be trying another one from EFI Source, even when it is available...and not concerned with yet another pigtail swap...Just want to drive my car again. It's been 2 weeks of dicking around with it.
I also don't really want to try another DELCO or DELPHI, since they're made either in China or Japan now, according to their boxes...
It worked great for a while, but a few weeks ago, as soon as any boost was seen, the car would misfire, buck, break-up, etc...
Discovered low fuel pressure at idle (35-38 psi) and an immediate drop to zero psi with key turned off.
Found a split in the intank Racetronix dual pump setup, on the primary pump's hose. Fixed that and thought I had fixed the problem..
That DID fix the fuel delivery issue....Now 65psi, and 75 psi when 2nd pump is manually triggered.
Anyway....the fuel delivery was NOT the issue with the weird AFR's and timing drops under load...evidently, found that problem by accident.
Fast forward and viewing several recent datalogs, I see the MAP readings all over the place. Sometimes, 90 kPa, sometimes 40 or so...at idle. Car has a near stock acting cam...usually makes 16-17" of vacuum in gear @ 800 rpm.
Go to get another sensor, and the one I have, is Out Of Stock....so I order a Delphi "brick style", and change the pigtail.
I have my MAP sensor remotely mounted. IE, sensor is on top of intake, with a boost/vacuum hose connected to it, and verified to read both.
Now...the "brick style", advertised on Amazon, as a 3 BAR...WAS evidently, a 1 bar...This seemed to have "fixed" the misfire/breaking up problem, but the first time I made any boost, the MAP sensor failed to a full time 5 volt reading, which was 320 kPa, and showing 31# of boost, LOL. It reads 0 kPa Key On, Engine Off, but pegs to 320 kPa as soon as engine starts, or tries to...
Obviously, this made the car so rich, it barely ran...In fact, I had to reflash the MAP sensor scaling to read no higher than 90 kPa, so I could get the car fired up and back into the shop...
So, after the book I just wrote...
Cliff Notes:
What DEPENDABLE MAP SENSOR are you guys using?
I am thinking of the German made, Chevrolet Performance one for the ZL1/ZR1....
I will not be trying another one from EFI Source, even when it is available...and not concerned with yet another pigtail swap...Just want to drive my car again. It's been 2 weeks of dicking around with it.
I also don't really want to try another DELCO or DELPHI, since they're made either in China or Japan now, according to their boxes...
Last edited by rel3rd; 06-26-2018 at 09:00 AM.
06-25-2018, 08:19 AM
#3
I had the exact same issue with that particular sensor. I run the Holley system so I ended up going with their 5 bar. It looks like a pressure transducer and threads right into my vacuum block. Works like a charm. Not sure if you can make it work with your system, but if so it’s worth it. I believe they make a 3 bar too in the same style. My Holley guy just had the 5 bar on hand when my EFI Source took a dump. Here’s a shot of it.
06-25-2018, 09:23 AM
#4
TECH Regular
I have the Holley 3 BAR 554-107 as MAP and the 5 BAR 554-108 as dome pressure and have had no issues with either. They're kinda pricey though.
I've used these cheap transducers from ebay for other items but not for MAP https://www.ebay.com/str/industrials...cat=2911276017
I've used these cheap transducers from ebay for other items but not for MAP https://www.ebay.com/str/industrials...cat=2911276017
06-25-2018, 09:35 AM
#5
In for info on this as well. I have had the 3 bar ls1 style from EFI Source on my car for 3 years and no issues. Went to buy the same for the 4.8/turbo Rambler Im working on and went with the other "GM Style" they have in stock. Have not fired the car yet but hope to in 2 weeks. Anyone have feedback on the brick style with pigtail EFI Source sells?
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06-26-2018, 06:12 AM
#8
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Thread Starter
iTrader: (43)
After one POS sensor from EFI Source, and one POS sensor from Amazon...
Decided to go to my local dealership.
Here's what I went with...
GM part # 12592525 (list price: $45.53, for the ZR1/ZL1 3 bar MAP sensor itself)
GM part # 13585850 (list price: $38.67, for the required pigtail)
Paid $71.41 with tax, for both...$36.42 sensor, $30.94 pigtail, $4.05 tax
ZR1 MAP SENSOR WIRING: (FWIW, Pins on this sensor are NUMBERED, NOT lettered)
Pin #1 = TAN 5 volt reference wire (might be GREY, hard to tell w/ my old eyes, lol)
Pin #2 = BLACK Ground wire
Pin # 3 = GREEN sensor to pcm signal wire
Can't remember who, but I saw a plug & play adapter, so that your LS1 MAP harness plugged into the adapter, then plugged right into the new sensor.
I chose to simply cut off the pigtail I just put on the other day (for the GM "Brick" style sensor), and spliced in the new pigtail/harness. It's roughly a foot long, so since my MAP is connected remotely, I have it over close to it's vacuum source...near the brake booster. The pigtail actually comes with decent weatherproof butt connectors, made to be heat shrunk after crimping.
HPTuners SETTINGS:
LINEAR: 312.50
OFFSET: -11.25
Decided to go to my local dealership.
Here's what I went with...
GM part # 12592525 (list price: $45.53, for the ZR1/ZL1 3 bar MAP sensor itself)
GM part # 13585850 (list price: $38.67, for the required pigtail)
Paid $71.41 with tax, for both...$36.42 sensor, $30.94 pigtail, $4.05 tax
ZR1 MAP SENSOR WIRING: (FWIW, Pins on this sensor are NUMBERED, NOT lettered)
Pin #1 = TAN 5 volt reference wire (might be GREY, hard to tell w/ my old eyes, lol)
Pin #2 = BLACK Ground wire
Pin # 3 = GREEN sensor to pcm signal wire
Can't remember who, but I saw a plug & play adapter, so that your LS1 MAP harness plugged into the adapter, then plugged right into the new sensor.
I chose to simply cut off the pigtail I just put on the other day (for the GM "Brick" style sensor), and spliced in the new pigtail/harness. It's roughly a foot long, so since my MAP is connected remotely, I have it over close to it's vacuum source...near the brake booster. The pigtail actually comes with decent weatherproof butt connectors, made to be heat shrunk after crimping.
HPTuners SETTINGS:
LINEAR: 312.50
OFFSET: -11.25
06-26-2018, 09:29 AM
#9
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A Genuine GM ZR1 map sensor can be had on ebay for around 35/40 bucks, or the same as a china efi source one. A $10 direct wiring connector can be bought there also so no wire spicing or re-pinning needed. Here is one pictured here
