1992 ZR1 Seems Sluggish - ZR-1 Net Registry Forums

KJL · 07-04-2016

Car was running fine the last time I dove it. It has been about 6 weeks since then. I usually disconnect the battery as well. When I went to start it the battery was about dead, not enough juice to turn it over. I hooked up my remote charger and she fire right up with the usually guide chain rattle for a few seconds but this time she barked out a bit or smoke momentarily but that cleared up. When I drove it, it seemed to lack power, it idles fine but when I give it some gas, it is unresponsive. It feels like i am driving on 4 cylinders. The idle is smooth, there has always been a slight vacuum leak, the pump runs once every 2.5 seconds with engine off and when running maintains a steady 17" of vacuum. There is spark on all 8 cylinders. The car is drivable with no engine codes. The only thing left I can think of is bad or fowled fuel injector....or the fact I have been driving my 700 HP 434 cuin C3 around all week....

Any thoughts?

BigJohn · 07-04-2016

Is that a 454 C3 ?

KJL · 07-04-2016

Yes, it is a 434 small block.

RussMcB · 07-04-2016

A guess (I think I've heard other people mention this) - The small backfire pushed the vacuum tube off the back of the plenum, and the fix is to simply slip it back on.

BigJohn · 07-04-2016

Quote:

Originally Posted by KJL

Yes, it is a 434 small block.

That is what I was thinking!

KJL · 07-05-2016

Hello Russ, I checked all the tubes that can be seen.... my vacuum pump test with the car off runs at the same frequency it always has and my vacuum at idle is steady at 17". I am thinking the vacuum is likely not the culprit here. I guess I will just run the car some more maybe put in a can of injector cleaner and check the plugs before I pull the plenum and have a look around. Also going to pull the plastic intake and take a look at the throttle blades. I guess that is the best way to describe how it feels.... like I am pushing the pedal but the throttle blades are not opening up in a proportional manner.

efnfast · 07-05-2016

The vacuum line Russ is refering to is right at the back of the plenum. It tends to blow off with a backfire. Unrelated to the vacuum pump.

KJL · 07-05-2016

Understood, the line is definitely still connected.

KJL · 07-07-2016

Took it out for another drive yesterday. Ran better but still hesitates at times.

dredgeguy · 07-07-2016

Quote:

Originally Posted by KJL

Took it out for another drive yesterday. Ran better but still hesitates at times.

I have a 92 and same except that it starts to stumble badly around 3000 RPM. Think it is the common fuel pump issue. Just purchased a pair from RockAuto and hope to install them this weekend. Will let you know if this is the cure, I hope so.

07-04-2016	#1
KJL Join Date: Mar 2013 Location: Roswell, GA Posts: 232	1992 ZR1 Seems Sluggish Car was running fine the last time I dove it. It has been about 6 weeks since then. I usually disconnect the battery as well. When I went to start it the battery was about dead, not enough juice to turn it over. I hooked up my remote charger and she fire right up with the usually guide chain rattle for a few seconds but this time she barked out a bit or smoke momentarily but that cleared up. When I drove it, it seemed to lack power, it idles fine but when I give it some gas, it is unresponsive. It feels like i am driving on 4 cylinders. The idle is smooth, there has always been a slight vacuum leak, the pump runs once every 2.5 seconds with engine off and when running maintains a steady 17" of vacuum. There is spark on all 8 cylinders. The car is drivable with no engine codes. The only thing left I can think of is bad or fowled fuel injector....or the fact I have been driving my 700 HP 434 cuin C3 around all week.... Any thoughts? __________________ 1995 ZR1 #159 Ported,Corsa,4.10 Rear, Dual Disc RAM Clutch, Alum Flywheel, Haibeck Chip, ZFDoc Plates, Relocated Battery 400 rwhp 1992 ZR1 #280 Ported, Locked Secondary's, Flowmaster Exhaust, Haibeck Chip, 375rwhp 1996 Collectors LT4 (Stock) 1972 Convertible 434 Small Block 572 rwhp

07-04-2016	#2
BigJohn Join Date: Feb 2012 Location: Ledyard,CT Posts: 8,085	Re: 1992 ZR1 Seems Sluggish Is that a 454 C3 ?

07-04-2016	#3
KJL Join Date: Mar 2013 Location: Roswell, GA Posts: 232	Re: 1992 ZR1 Seems Sluggish Yes, it is a 434 small block. __________________ 1995 ZR1 #159 Ported,Corsa,4.10 Rear, Dual Disc RAM Clutch, Alum Flywheel, Haibeck Chip, ZFDoc Plates, Relocated Battery 400 rwhp 1992 ZR1 #280 Ported, Locked Secondary's, Flowmaster Exhaust, Haibeck Chip, 375rwhp 1996 Collectors LT4 (Stock) 1972 Convertible 434 Small Block 572 rwhp

07-04-2016	#4
RussMcB Join Date: Jan 2015 Location: Marietta, GA USA Posts: 1,160	Re: 1992 ZR1 Seems Sluggish A guess (I think I've heard other people mention this) - The small backfire pushed the vacuum tube off the back of the plenum, and the fix is to simply slip it back on.

07-05-2016	#6
KJL Join Date: Mar 2013 Location: Roswell, GA Posts: 232	Re: 1992 ZR1 Seems Sluggish Hello Russ, I checked all the tubes that can be seen.... my vacuum pump test with the car off runs at the same frequency it always has and my vacuum at idle is steady at 17". I am thinking the vacuum is likely not the culprit here. I guess I will just run the car some more maybe put in a can of injector cleaner and check the plugs before I pull the plenum and have a look around. Also going to pull the plastic intake and take a look at the throttle blades. I guess that is the best way to describe how it feels.... like I am pushing the pedal but the throttle blades are not opening up in a proportional manner. __________________ 1995 ZR1 #159 Ported,Corsa,4.10 Rear, Dual Disc RAM Clutch, Alum Flywheel, Haibeck Chip, ZFDoc Plates, Relocated Battery 400 rwhp 1992 ZR1 #280 Ported, Locked Secondary's, Flowmaster Exhaust, Haibeck Chip, 375rwhp 1996 Collectors LT4 (Stock) 1972 Convertible 434 Small Block 572 rwhp

07-05-2016	#7
efnfast Join Date: Nov 2011 Location: Dunbarton NH Posts: 7,335	Re: 1992 ZR1 Seems Sluggish The vacuum line Russ is refering to is right at the back of the plenum. It tends to blow off with a backfire. Unrelated to the vacuum pump.

07-05-2016	#8
KJL Join Date: Mar 2013 Location: Roswell, GA Posts: 232	Re: 1992 ZR1 Seems Sluggish Understood, the line is definitely still connected. __________________ 1995 ZR1 #159 Ported,Corsa,4.10 Rear, Dual Disc RAM Clutch, Alum Flywheel, Haibeck Chip, ZFDoc Plates, Relocated Battery 400 rwhp 1992 ZR1 #280 Ported, Locked Secondary's, Flowmaster Exhaust, Haibeck Chip, 375rwhp 1996 Collectors LT4 (Stock) 1972 Convertible 434 Small Block 572 rwhp

07-07-2016	#9
KJL Join Date: Mar 2013 Location: Roswell, GA Posts: 232	Re: 1992 ZR1 Seems Sluggish Took it out for another drive yesterday. Ran better but still hesitates at times. __________________ 1995 ZR1 #159 Ported,Corsa,4.10 Rear, Dual Disc RAM Clutch, Alum Flywheel, Haibeck Chip, ZFDoc Plates, Relocated Battery 400 rwhp 1992 ZR1 #280 Ported, Locked Secondary's, Flowmaster Exhaust, Haibeck Chip, 375rwhp 1996 Collectors LT4 (Stock) 1972 Convertible 434 Small Block 572 rwhp