Rough Idle/Hesitation/Backfire - ZR-1 Net Registry Forums

Gary Yarbrough · 07-21-2009

I'm hoping for some help with my 90 ZR-1. It idles just a little rough (not too bad), but it really hesitates if I floor it from idle. It will also sometimes backfire. If I smoothly and slowly give it the gas or start from about 2500 RPM, it is fine.

Things I've checked:
MAP hose is fine.
No vacuum leak (well...I've got the usual very slow leak).
Plugs & Wires are ~1 year old with ~5,000 miles.
Injectors are Accel with about 3,000 miles.
I have a chip from Jim VanDorn, otherwise the car is stock.

About two weeks ago, I checked codes because I got a brief SES light while cruising on the free way and had a left oxygen sensor code. I replaced the sensor and that problem seems resolved. I've had this idle issue for a while now and would really like to get it resolved. Any suggestions would be greatly appreciated!

07-21-2009	#1
Gary Yarbrough Join Date: Nov 2008 Location: Wilson, AR Posts: 63	Rough Idle/Hesitation/Backfire I'm hoping for some help with my 90 ZR-1. It idles just a little rough (not too bad), but it really hesitates if I floor it from idle. It will also sometimes backfire. If I smoothly and slowly give it the gas or start from about 2500 RPM, it is fine. Things I've checked: MAP hose is fine. No vacuum leak (well...I've got the usual very slow leak). Plugs & Wires are ~1 year old with ~5,000 miles. Injectors are Accel with about 3,000 miles. I have a chip from Jim VanDorn, otherwise the car is stock. About two weeks ago, I checked codes because I got a brief SES light while cruising on the free way and had a left oxygen sensor code. I replaced the sensor and that problem seems resolved. I've had this idle issue for a while now and would really like to get it resolved. Any suggestions would be greatly appreciated!