Missing at WOT with full power - ZR-1 Net Registry Forums

MrsMcNastys · 07-19-2012

Hi Guys,

Great forum. I have a customers 14,000 mile 1992 ZR1 in my shop. Has not been driven much last few years. He has 2, plus some other toys but decided he wanted to drive this one regularily for a while. He brought it in last week, missing, running rough, no full power. Pulled the codes and located a loose hose on the MAP sensor. Fixed. Car road tested good, full power no problem.

He brought it back this week with a miss. No codes. Tested the vacuum system. Pump good. Very very slow almost imperceptible bleed down on the plenum side. (Is this plumbed to maifold vacuum also? Plenum side of line pulls vacuum at idle) Road tested the car - great with full power initially. After a while at full temp, slight engine vibration at full power WOT. Flawless in full power off. Engine vibration and loss of power with key full power key on only. He reported those symptoms, then would go fine, then a miss again.

I am thinking secondary injectors? Is there a secondary fuel pump and/or fuel filter? One fuel filter was changed at our local useless GM dealer in 2010.

Any other possible culprits before we pull the plenum? Any help would be appreciated.

Ed

07-19-2012	#1
MrsMcNastys Join Date: Jul 2012 Location: Somerset KY Posts: 16	Missing at WOT with full power Hi Guys, Great forum. I have a customers 14,000 mile 1992 ZR1 in my shop. Has not been driven much last few years. He has 2, plus some other toys but decided he wanted to drive this one regularily for a while. He brought it in last week, missing, running rough, no full power. Pulled the codes and located a loose hose on the MAP sensor. Fixed. Car road tested good, full power no problem. He brought it back this week with a miss. No codes. Tested the vacuum system. Pump good. Very very slow almost imperceptible bleed down on the plenum side. (Is this plumbed to maifold vacuum also? Plenum side of line pulls vacuum at idle) Road tested the car - great with full power initially. After a while at full temp, slight engine vibration at full power WOT. Flawless in full power off. Engine vibration and loss of power with key full power key on only. He reported those symptoms, then would go fine, then a miss again. I am thinking secondary injectors? Is there a secondary fuel pump and/or fuel filter? One fuel filter was changed at our local useless GM dealer in 2010. Any other possible culprits before we pull the plenum? Any help would be appreciated. Ed