Pro-M mass-air problems

W

WickedLightning

Guest
My '93 has a Pro-M 77mm mass-air system on it that the previous owner installed. It is not running as good as it should be. One reason, I think, is because there is only one O2 sensor on the h-pipe. I heard there were supposed to be two, one on the passenger side hooked up to the original lead, and the other on the drivers side with the pro-m lead hooked to it. Also, whenever I start the truck, it idle surges for about 2 minutes. If I try to drive it with out letting it surge, it bogges real bad. Any thoughts from anyone would help.

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Jason O'Keefe
Black '93
#3844
 
The early Pro-M kits used only one O2 sensor. That's what mine had.

Two things to try on the surging - first is to disconnect the meter wiring and start the truck and let it run in "limp home" mode without the meter. See how it behaves. After doing that, disconnect the wiring at the Idle Air Bypass on the throttle body and set the idle manually. See how that behaves.

Let me know if either of those things calms down the erratic idle and then we can go from there.



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Later!
Jeff S.
President, NLOC
#74 in '95 - 11.92@115.2
#?? in '00 - 13.68@99.5
 
I did a computer test on my L and it came up with an O2 sensor that was stuck on the lean side, and never changes. Also, which lead did you hook to the O2 sensor, the stock lead or the pro-m lead? When I do run the test with the air meter not hooked up, what am I listening for?

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Jason O'Keefe
Black '93
#3844
 
Jason,

Does your Pro-M have a O2 sensor lead? If so, then you need to get a bung welded to the driver's side exhaust below the header and install a second O2 sensor there for the Pro-M lead. The stock lead will remain connected to the O2 sensor in the stock location.

All you're listening for is a lack of surging.



------------------
Later!
Jeff S.
President, NLOC
#74 in '95 - 11.92@115.2
#?? in '00 - 13.68@99.5
 
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