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bdw18_123 · 10-07-2011

Problem is FIXED!!!

Holy crap, you guys aren't kidding! When these things are running right, they do indeed pull like a freight train! I mean, it did have power before, but I could never get past 5K before the CEL came on. My ZR-1 now has the full 375HP on tap 100% of the time, with no stupid 'Check Engine Light' to shut down the fun!

Did a quick blast to 6500RPM & 140MPH in 4th (had the laptop hooked up, taking a Datamaster recording). Still gotta hit that magical 7000 number, though I was within 500RPM of it that time!

So what was the cause of the codes 44 & 55? Bad left O2 sensor! Before I replaced it, I had taken a Datamaster recording and I noticed that the left O2 sensor kept dropping to 0 volts, especially during hard acceleration. The long term fuel counts were also high on the left side at lower throttle openings (like 150-160 or so), indicating that the ECM was trying to richen the mixture on that side to compensate for what it thought was the left bank being too lean.

I showed that recording to my buddy Evan (who I work for at his performance car shop) and he agreed that it was most likely a bad left O2. I just wanted to make sure that the sensor was the issue before I went spending more money I don't have. That's why the CEL kept coming on shutting the secondaries off every time I got close to around 5K RPM. I also ohmed the left O2 sensor harness to the ECM and didn't find any issues - grounds were there and the signal line was good and not grounded.

So, I'm taking my Z on it's first Corvette Run that my other friend Pete (PLRX from the 'other' forum) is doing with a bunch of C5 & C6 people, Evan is going too. It is going to be in the mountains in my area. So there will be 2 C4's and 1 C4 ZR-1 there to remind those guys where their cars came from!

10-07-2011	#18
bdw18_123 Join Date: Apr 2009 Location: Prather, CA Posts: 804	Re: 1990 exhaust manifold issue... Problem is FIXED!!! Holy crap, you guys aren't kidding! When these things are running right, they do indeed *pull like a freight train!* I mean, it did have power before, but I could never get past 5K before the CEL came on. My ZR-1 now has the full 375HP on tap 100% of the time, with no stupid 'Check Engine Light' to shut down the fun! Did a quick blast to 6500RPM & 140MPH in 4th (had the laptop hooked up, taking a Datamaster recording). Still gotta hit that magical 7000 number, though I was within 500RPM of it that time! So what was the cause of the codes 44 & 55? Bad left O2 sensor! Before I replaced it, I had taken a Datamaster recording and I noticed that the left O2 sensor kept dropping to 0 volts, especially during hard acceleration. The long term fuel counts were also high on the left side at lower throttle openings (like 150-160 or so), indicating that the ECM was trying to richen the mixture on that side to compensate for what it thought was the left bank being too lean. I showed that recording to my buddy Evan (who I work for at his performance car shop) and he agreed that it was most likely a bad left O2. I just wanted to make sure that the sensor was the issue before I went spending more money I don't have. That's why the CEL kept coming on shutting the secondaries off every time I got close to around 5K RPM. I also ohmed the left O2 sensor harness to the ECM and didn't find any issues - grounds were there and the signal line was good and not grounded. So, I'm taking my Z on it's first Corvette Run that my other friend Pete (PLRX from the 'other' forum) is doing with a bunch of C5 & C6 people, Evan is going too. It is going to be in the mountains in my area. So there will be 2 C4's and 1 C4 ZR-1 there to remind those guys where their cars came from! Last edited by bdw18_123; 10-07-2011 at 04:49 PM.