Hello all,

84 Z28 shorty headers and cat back (cat delete)
EGR delete, air injection delete
hypertech thermomaster 180 chip

Car runs very well cold, but then after about 150 degrees and some driving it has erratic idle, 400-750 RPMs and driving it'll have a flat spot from 1100-1900 rpms but if i put my foot down further it'll obviously go away but always happens when car is warm.

I'm attempting to put some emission equip. back on seeing as I thought I knew what I was doing; but it never ran this bad till now.

I checked the 02 sensor and it seemed well; but sometimes get code 45 (rich exhaust). I'm thinking could it be a bad TPS sensor, Coolant temp sensor, baro?


I'm just pulling my hair out over this stuff and any thoughts would be appreciated thank you for your time!!

 

Hello, seen u posted this a little while, was curious if you found out what the problem was, as some of us are still searching

 

are you having a similar problem? If so, change your O2

 

After lots of headaches and struggling, I finally did figure out the cause of my problem!

Turns out, the cannister control valve (the very large can looking valve with like 4 or so hoses running and from it) was stuck, so excess fumes and fuel was being dumped into the intake manifold and carb thus making my mixture extremely rich with a rough idle!

Hope this helps anyone else, you can also contact me if you need any other support or have any questions!

 

I changed my 02 already, its working fine, also have a wideband hooked up and can see it going rich to lean like a ping pong ball, i will check out the canister!

 

Keep in mind that according to your profile you have TBI and I have a carb so it might be set up differently. It's not the cannister itself that went bad but the rather large looking valve that ran to/from the cannister, that's the part that went bad. It also ran to the PCV valve and what not. I'll post a picture if I can find the time

 

I posted an attached image of the part that went bad