Hey guys desperate for your input here. 97 Z28, I just installed a fresh 2,000 mile 95 LT1 with the hot cam kit with the 1.6 rockers, adjustable fuel pressure regulator, ported stock heads, ported intake, and bottom end work. Emissions are deleted. I converted it to OBD11 and re used all my stuff from my 97.

Heres my issue. its got a slightly rough idle and it hesitates when I punch it or try to accelerate at low RPM's like below 2000. Once I hit 2k, it opens up and screams. I replaced the coil, didnt check the ICM. I pulled the plugs and saw they were gapped at .060! I brought them down to .045 and reinstalled them but they did look kinda fouled out. The car actually ran better but I still feel iffy about putting those plugs back in. the wires are moroso wires which came with the engine, I havent tested them yet. The Opti also has 2k miles like the rest of the engine.

Fuel:
fuel pressure key on engine off 36psi. Engine running about 34psi. Is that too low? It holds that pressure steady, and the fuel pump has only 7k miles on it. It did sit for about a year when the engine was out, dont know if thats an issue. I read about adjusting the fuel pressure, and I played with it a little and got it to 38psi. My pressure isnt low enough to cause an idle issue is it?

I checked my o2's I have simulators in the rear, but one is disconnected right now. Bank 1 the o2 is constantly fluctuating going up and down the graph from 0 to 1 volt. Bank 2 the o2 is still fluctuating, but barely, staying right in the middle, around .5 v I guess. is it bad?

Ive waited a year and a half to get my car back on the road, and I cant tell if this is fuel or ignition related? THe motor was built by a machine shop and balanced. Eagle parts. Ill take any input at this point. I do have the Proscan OBD11 scanner software and LT1-Edit. Thanks.

 

Fuel pressure, pump energized, engine off, should be 43.5 psi with a range of 41 to 47 Start there.

Before replacing the oxygen sensors, get the fuel pressure corrected. The lack of response could be related to an improper fuel to air ratio. The sensor on Bank 2 is probably bad but fix the fuel issue first.

I'd run a tighter spark plug gap on any modified engine....in this case 0.038" should be fine.

I didn't see it in your description, but was the computer tuned for the Hot Cam? Even though it's fairly mild, it would benefit in both performance and driveability from an off-the-shelf aftermarket tune....unless you can tune it yourself.

Good luck!

 

I had Brian at PCMforless send me a tune to use with my software. the FPR only runs when the engine is running right?, so if Im showing 35-36 with the key on engine off, it can only be the pump correct? I replaced the fuel filter, it did have gas sitting in the tank, but Ive burnt through that by now.

 

go turn the regulator up engine off and primed it will go up to 42-45... your pressure is too low.

 

The fuel pressure regulator is active all the time. WHen the pump is turned on by turning the key to on, the pressure should read 43.5 psi. The engine doesn't have to be running for that part. The engine vacuum does have a roll in what the pressure is under load...Rob has a good procedure written up on his website, www.shbox.com

SO, adjust the fuel pressure to 43.5 psi and see what you get...

 

Adjust it with the engine on or off?

 

Either way, really. Doing it with the engine running will make sure the pump runs when it needs to...

So, connect the pressure tester to the fuel rail. Start the engine and remove the vacuum line from the fuel pressure regulator and cap it off. Adjust the regulator so the pressure is in the range of 41 to 47 psi, 43.5 target. Reattach the vacuum line. That's basically step one.

To be sure things are alright with the fuel system, snake the fuel pressure test gauge under the hood and tape it to the windshield. Go our for a run and observe the fuel pressure under a full throttle run. The pressure should be in the range of 41-47.

 

Check the fuel pressure with the engine running. At idle, pull the vacuum compensation line off the fuel pressure regulator (plug the end so you don't have a vacuum leak) and set the fuel pressure to 43.5psi. Reconnect the vacuum compensation line, and the pressure will drop proportional to intake manifold vacuum. A drop of 8psi from the no vacuum pressure would be OK with a stock cam, but with a more radical cam, the pressure is going to drop less. Then continue on with the full load test outlined above.