When MAP sensors go bad.

[Throws]

I've recently been troubleshooting a issue where my Ty was stumbling at idle, and had on occasion died.

http://www.syty.net/forums/showthread.php?t=95022

Well... I think I might have found the issue: a broken/split MAP sensor

I found it when I was doing a bike tube (inner tube test), and after plugging two leak on the throttle body (loose vac cap on top, lower PCV hose sliding down), I kept hearing the noise coming from the MAP sensor. It was a MSD 3 bar MAP (# 2313), and I had no reason to think it had gone bad. I popped it loose to check the hose, and found that the top had separated from the bottom and the insides loose. I found it very hard to believe that the MSD was so cheaply made that it blew apart under boost and could easily pass for a Chinese made eBay $25 cheapo. So, I've got a new Delphi 3Bar on the way from RockAuto, which after seeing how the OEM one was put together, gives me greater confidence in lasting longer... much longer.

I had chased down testing Ostrich2 units, bad ECMs (on #3, 2nd remanned), plugs and wires (did find a cracked plug!), I'd even repinned the entire ECM side of the harness... this was an exercise in frustration and to a degree, patience.

If this next one fails, my next unit will be a VEMS(https://shop.vems.hu/catalog/sensor-p-89.html) or a Omni Power (http://omnipowerusa.com/product.asp?P_ID=158).... anything but an MSD.

MSD Internals (Notice cheap wires and RTV'd MAP sensor)

GM OEM (was unable to open MAP sensor itself)

Many thanks to those that helped and spent time with me diagnosing it: (Dave, Rob, Scott, Rod and Mark)

-P

 

[sytyguy]

Re: When MAP sensors go bad.

Great to hear it's (hopefully) fixed Paul! I too am surprised by the MSD failure. I've sold over 60 of them in the last 15 months and have had 8 DOA. All 8 were in white boxes instead of MSD labeled boxes. Not sure if MSD uses another supplier to fill orders sometimes or what but I too have occasionally seen this from MSD.

 

[bigmileage]

Re: When MAP sensors go bad.

Mine truck does what you're describing regularly, and I know the previous owner installed a 3bar; I'll have to look and see if it's a MSD or not.

I just figured it was the cheapo O2 sensor that I changed this weekend; the O2 readings were all erratic and all over the place according to the Tech1.

 

[sytyguy]

Re: When MAP sensors go bad.

FWIW, a lot of the cheap eBay 3 bars are built poorly as well. Many times they have no identifying numbers on them whatsoever.

 

[Throws]

Re: When MAP sensors go bad.

FWIW, a lot of the cheap eBay 3 bars are built poorly as well. Many times they have no identifying numbers on them whatsoever.

This MSD had no markings either, no stampings aside from "A,B, C" over the connector. I was surprised... usually MSD likes to brag on their stuff by making it red or labeling it somehow.

The only markings I found inside were on that circuit board, and they were hidden under a blob of RTV.

-P

 

[sytyguy]

Re: When MAP sensors go bad.

This MSD had no markings either, no stampings aside from "A,B, C" over the connector. I was surprised... usually MSD likes to brag on their stuff by making it red or labeling it somehow.

The only markings I found inside were on that circuit board, and they were hidden under a blob of RTV.

-P

Precisely what I saw with the aforementioned faulty ones from MSD. I suspect they use the "lowest bidder" from time to time. This is exactly why I quit selling them. If I cannot guarantee their quality then I may as well supply the cheap eBay ones for $25.

 

[Throws]

Re: When MAP sensors go bad.

Precisely what I saw with the aforementioned faulty ones from MSD. I suspect they use the "lowest bidder" from time to time. This is exactly why I quit selling them. If I cannot guarantee their quality then I may as well supply the cheap eBay ones for $25.

LOL...I think they clicked the "Buy it now!" button. :rotf:

-P

 

[the baPhoon]

Re: When MAP sensors go bad.

Hmmm... maybe adding a new map to my list of things to replace...