Z28ant

Heres my problem, I just put a catted y on my H/C Z28 and took it out for test drive. Car ran fine all the way to 7k for a couple pulls, then on the way back to the house it started stumbling and my gauges went nuts. (not just a normal test) and every light on the dash came on. It wouldn't idle anymore so i ran stops signs till i got home and reset the computer. The car ran fine on the way to my friends house the next day (I only hit 5k on the way there) then on the way home I hit 5700 and it did the same thing. This time i figured out if I shut the car of after it died and took the key out, then started it, it would idle and drive "normaly". Now whenever it its 3k it does this same thing. I've checked the ground wires on the back of the driver side head and they are tight. It's a brand new optima battery (i had a battery die and me and cause the car to have a similar issue but the guages would just sweep and return to normal and did that at random rpms) Am I looking at a PCM or are they other things to check first. Any input is much appreciated

Doc

iTrader: (9)

Was everything ok before putting the cat'd Y on?

Z28ant

yeah everything was fine

DrkPhx

iTrader: (15)

Try replacing the battery with a battery from another vehicle that is known to be good. Also make sure the battery is properly secured and does not move rearward toward the strut tower. If not, it will tilt back and arc against the a/c condensor or strut tower. But if this is the problem, it will usually happen under hard acceleration like from a standing start. Check the battery ground strap on the passenger side block for a loose connection as well.

Z28ant

thanks I'll try that out as soon as my car cools down I just got home, so I dont' want to fry myself.

DaddySS

I think it's more than coincidence that you do the y and it starts acting up. Describe what you did when you installed the y.

Z28ant

Normal procedure just pulled the cat back off to get some clearance and slid the new one on. I've removed it several times the only difference is, this one will drag pretty bad when i pull in my garage due to ground clearence (my driveway really sucks) Are there any ground wires near the exhaust system I might have hit? And if so why would it let me get 3 or 4 good pulls in before it acted up?

Z28ant

::Update:: Today me and a buddy started going over things. Checked all the grounds in the engine bay, all are tight and have no signs of corrosion. The positive battery cable had some corrosion where it meets the battery, I cleaned that with a wire brush and took it for a drive. Drove pretty smooth didn't mess up at 3k but still had some slight stumbling and and 6k would still go hay wire. I put his optima in my car and drove around and it did the same thing except after it threw its fit i couldn't get it to idle. Got back home put my battery back in and it still wouldn't idle. I unplugged my MAF to run sd and it started idling. Oh yeah on the way home when i hit a bad bump the gauges would reset and it would act up. Something is loose but I dont' know where is to look.

DrkPhx

iTrader: (15)

Is the battery bolted down and secured? Did you disconnect anything during the install? There's a small ground strap on the lower, front of the driver side engine block. There's another one on the same side but on the chassis (almost under the fuse box). Also check the main ground on the strut tower right by the battery itself. Don't forget to check the two alternator connections, starter connections and the AUX connection at the fuse box. Finally, I would try to wiggle the wires with the car idling (be careful and watch yout hands) to see if that causes the problem.

Z28ant

The battery is bolted down and those connections listed are good, i went to the chevey dealer and baught a new positive cable. After installed it I decided to make one final sweep and found the wire on the back of the head was BARELY connected I was able to pull it right away and another ground was being twisted because there wasn't enough room for the wire to move as the motor torqued. I'll be extending those tomorrow and testing it out, I believe I have probably found the problem in that though. I should have been a little more thorough the first time I checked them. Thanks for the help I'll repost with the outcome

Z28ant

problem solved, b/n the positive battery cable being coroded and a weak connection at the grounds behind the head. I extended the grounds so they could make it to the fender that way I can keep an eye on them. It feels good to hit 7k again