Engine runs better with MAP sensor unplugged? - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Laser145 · 07-30-2012, 07:02 PM

I've done the test where the voltage drops with my vac gauge. Came out perfect.

Timing I checked a month ago. Spot on...

Seriously though... Thanks for all this help I'm learning a lot!
Posted via Mobile Device

Laser145 · 08-05-2012, 08:14 PM

Found a crack in the MAP sensor VAC line at the back of the TBI... taped it up and my engine is much happier!

Not perfect though... It idles a little rougher. Before today it was idling so smooth you couldn't tell it was running...now it idles more like an old truck. Acceleration is much improved. Still a small hesitation at the first sign of throttle, but it overcomes very quickly and runs out.

My timing is slightly retarded... but we're having some trouble getting a wrench on the bolt to loosen the distributor... welded a bend in a 9/16th wrench then broke it. It's on really tight.

The smoking has been reduced greatly... I pulled the valve covers and the drivers side was pooling oil near the rear. Ran a rod through that valley and it drained down into the motor. I cleaned up with valves, and changed my oil again, adding Marvels this time.

I'll change again in a hundred miles or so.

We're getting there I suppose...

TheApocalyptican · 08-05-2012, 08:58 PM

For the timing wrench....I took one of the regular ratchet wrenches you can buy, and heated it up with a torch, and bent it with a vise and pliers. Made it so without the coil being attached, I can use the wrench by hand. Might not work with it being so tight on you, but just another idea to consider.

Laser145 · 08-05-2012, 09:37 PM

That's what we did... And broke it... I'm going to loosen that nut when I pull the TBI to replace a gasket next week.

I won't put it on so tight again.
Posted via Mobile Device

rfmaster · 08-05-2012, 11:09 PM

This is what you need for distributor nut
http://www.ebay.com/itm/Pro-Value-2p...3fa34b&vxp=mtr
Just replace MAP line with 1/4" hard vacuum line.

//RF

TheApocalyptican · 08-06-2012, 01:35 AM

Quote:

Originally Posted by rfmaster

This is what you need for distributor nut
http://www.ebay.com/itm/Pro-Value-2p...3fa34b&vxp=mtr
Just replace MAP line with 1/4" hard vacuum line.

//RF

See...I went and forgot to add distributor before "ratchet wrenches". The link above is what I was talking about. Worked, barely, then I heated and bent the correct size one, and it works great.

07-30-2012, 07:02 PM	#26
Laser145 Registered User Join Date: Oct 2011 Location: Brooklyn, New York Posts: 137	Re: Engine runs better with MAP sensor unplugged? I've done the test where the voltage drops with my vac gauge. Came out perfect. Timing I checked a month ago. Spot on... Seriously though... Thanks for all this help I'm learning a lot! Posted via Mobile Device __________________ 1987 R10 1976 K10

08-05-2012, 08:14 PM	#27
Laser145 Registered User Join Date: Oct 2011 Location: Brooklyn, New York Posts: 137	Re: Engine runs better with MAP sensor unplugged? Found a crack in the MAP sensor VAC line at the back of the TBI... taped it up and my engine is much happier! Not perfect though... It idles a little rougher. Before today it was idling so smooth you couldn't tell it was running...now it idles more like an old truck. Acceleration is much improved. Still a small hesitation at the first sign of throttle, but it overcomes very quickly and runs out. My timing is slightly retarded... but we're having some trouble getting a wrench on the bolt to loosen the distributor... welded a bend in a 9/16th wrench then broke it. It's on really tight. The smoking has been reduced greatly... I pulled the valve covers and the drivers side was pooling oil near the rear. Ran a rod through that valley and it drained down into the motor. I cleaned up with valves, and changed my oil again, adding Marvels this time. I'll change again in a hundred miles or so. We're getting there I suppose... __________________ 1987 R10 1976 K10

08-05-2012, 08:58 PM	#28
TheApocalyptican Registered User Join Date: Jun 2010 Location: Las Vegas, Nv Posts: 312	Re: Engine runs better with MAP sensor unplugged? For the timing wrench....I took one of the regular ratchet wrenches you can buy, and heated it up with a torch, and bent it with a vise and pliers. Made it so without the coil being attached, I can use the wrench by hand. Might not work with it being so tight on you, but just another idea to consider. __________________ 1995 Suburban K2500 454.....off road & towing 1999 Astro, work van 2006 Silverado 2wd 5.3 w/4.5" lift and 33s

08-05-2012, 09:37 PM	#29
Laser145 Registered User Join Date: Oct 2011 Location: Brooklyn, New York Posts: 137	Re: Engine runs better with MAP sensor unplugged? That's what we did... And broke it... I'm going to loosen that nut when I pull the TBI to replace a gasket next week. I won't put it on so tight again. Posted via Mobile Device __________________ 1987 R10 1976 K10

08-05-2012, 11:09 PM	#30
rfmaster Registered User Join Date: Oct 2003 Location: OC CA Posts: 1,374	Re: Engine runs better with MAP sensor unplugged? This is what you need for distributor nut http://www.ebay.com/itm/Pro-Value-2p...3fa34b&vxp=mtr Just replace MAP line with 1/4" hard vacuum line. //RF __________________ "The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17)



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