need help with accelorator hesitation

**dparson** · 07-29-2007, 03:22 PM

My 2000 Z28 has a hesitation when i accelerate medium to hard. At about 2000 rpm's acceleration flattens out, so i have to give it a little more pedal to get past the flat part. Seems like the motor is starving for air. I have an SLP lid with K&N air filter with free mod cut out air mod, and SLP Loudmouth II exhaust. I have stock cats on the exhaust could this be causing the flat spot in acceleration? When i pull my Z28 in the garage i smell a smell similar to sulfer, its not a typical exhaust smell. Also i installed a set of Granatelli racing spark plug wires(supposably 0 ohmz) but i installed 7 of them and am scheduled to take my car in to replace the last one that is almost impossible to get to. Could this be causing it? My Z28 has 61,000 miles on it. Any help would be appreciated. I figured i would ask this forum first before i take it in to a shop, since most of you on this forum probably know more about these vehicles than most mechanics. Thanks

**0rion** · 07-29-2007, 11:12 PM

From your description my best guess would be plugged cats. They'll cause a considerable drop in acceleration and produce the sulfur smell you're talking about. Just a guess but I've seen it happen.

**dparson** · 07-30-2007, 06:49 AM

Thanks for the info Orion, how can i test the cats to see if they are plugged without taking the exhaust apart or is that the only way to check them. If i were to put new cats on any suggestions on a good set that is California smog friendly. Thanks again

**SeVeReDiStOrTiOn** · 07-30-2007, 07:17 AM

Are you getting any codes thrown? Scan you car using a DTC scanner at autozone (you can rent/borrow them)...a code could be stored. If you have a p0420 or p0430 code the dealership will replace your cats for free under the federal emissions warranty (70,000 miles for cali cars)....also GM just extended the cats warranty to 100,000 miles so you shouldn't have a problem. If there's no code you should be able to talk the dealership into replaceing the cats because of the sulfur smell.

You can do the last #8 plug/wire yourself by moving the coil packs a few inches out of the way. A lot of people have had luck getting it from under the car also. A shop will probably charge you a lot...since that's the most time consuming part of a plug/wire change.

This site should help you along.. http://www.installuniversity.com/ins...sity/index.htm ...click on install documents and scroll down to plug/wire change.

**Blownone94** · 07-30-2007, 03:41 PM

you can always pull out the pre cat o2 sensors and try driving it again see if it gets better. One other thing i've also seen the MAF cause this problem which commonly can be misdiagnosed as a bad cat and its much easier to take off and inspect/clean first. Also should do a sweep test on the tps if you feel it always does it same part of pedal travel.