Momar

Well, I just recently got my 350 running. I have it running pretty good right now. I got all of the error codes I had other than the vss(it was origionally a mech speedo and I am in the middle of converting) taken care of and installed a heated 02 sensor. It seems to run pretty good now. I was just curious about the rpms fluxuating slightly at idle. It is only about 50 rpms maybe, but it still does it. It isnt anything that effects driveability. This is the first motor I have had with an aftermarket cam. Will a cam cause this or should the tach still stay perfectly still at idle? If it shouldnt fuxuate at all, what should I look for? It has new plugs, wires, cap, rotor, and coil.

Thanks

Ben

flyway190

Mine does something similar, it seems to be more random than consistent. I finally got to install a zz4 chip, and it seems to have fixed my lean part throttle problem, but it didn't have any effect on the fluctuating rpm's at idle.

Momar

Do you have a gauge or how did you know you had a part throttle lean condition. I have not driven mine yet accept around the neighborhood but it seems to drive nice. Did you have any noticable effects from it being lean? I would think that that should have only occured in open loop because when it goes to closed loop it should go by the oxygen sensor right?

Ben

flyway190

The problem was that it was pinging, and I determined that it was running lean at part throttle in closed loop by hooking a multimeter up to the oxygen sensor. It came up as a 0.010 voltage only at part throttle. I installed the zz4 chip this weekend and the multimeter showed between 0.400 and 0.700 at part throttle, and the pinging is now either gone or not very noticeable. I don't know exactly why it was running lean, but I know that it changed with the chip.

Momar

So then was the pinging audible? I havent ever really heard a motor that was pinging to know what to listen for. I dont think mine is though. What was your base timing set at by the way?

Ben

flyway190

It was definitely audible, it sounds kind of like a bottle cap tapped on glass. Base timing was set at 6 degrees.

Momar

Man, my car is running a lot stronger than it was the first time I drove it. I am not sure what did it but I have cleaned and regapped the spark plugs, reset the valve lash, put a heated 02 sensor in, changed to synthetic, and hooked up the pcv system since I had drove it last. I would guess that it is the plugs because the first few times I ran it I was trying to set the timing way retarted because I was going by the wrong style timing tab. It spins the RE730s clear through first and kind of kicks out a little on the 1st to 2nd shift. Sure beats the heck out what the 305 would do. It only had the potenza 910s on it and I could hardly powerbreak. lol. It seems to pull really hard and I have only taken it up to about 5000 and the power peak is supposed to be closer to 5800. I actually kind of like driving with the stall. It kind of smoothed my part throttle shifts but my full throttle shifts are still nice and hard.

Ben

JP84Z430HP

Do you have the part number around for that ZZ4 chip? I would like to do something like that to get me by until I can put Fuel injection on it!

Oh, and yes an aftermarket cam can make it idle rough, or fluctuate. I don't know all the specs. of that particular cam, but the LT4 HOT cam I have lopes a little, and I liek it like that! Lopes a little, but not too much to be annoying!

Momar

Yes it lopes. I just didnt know if that would cause the tach to move or if it was something else. I think that my cam has a little more duration and slightly less lift than the hot cam.

Ben

JP84Z430HP

Well, my needle does move about what I would think to be 50 RPM's or so, therefore, it's probably just a result of the cam's duration and overlap. Also, are the wav files you have in your sig current? If so, I would say that the fluctuation is definately the cam. The HOT cam doesn't lope quite as much as that either! Sounds good though!

Momar

OK, thats good. I just wanted to make sure that was what it was and not some kind of problem.

Ben

JP84Z430HP

Just to be sure, you may want to check all your connections, pull the distributor cap and check all that out too. When I pulled the cap on the old LG4 Saturday, I got a big surprise. At some point, the screws in the rotor decided to back out all the way! The spring tensione from the rotor center tab must have been enought to keep it down on the shaft and turning, but the rotor had tilted and was destroying itself and the cap. I have no idea how the thing was able to keep running, but it was running great! I never had a problem with that LG4 other than a water pump about 4 years ago, and just before that, the converter had plugged.
The amazing thing was 215,700 miles, and it looked clean on the inside! The pushrods weren't even all black from oil residue! No synthetic oil either! I am going to check the numbers on it to see if it was the original engine. I had put about 50,000 of those miles on it, and they were all HARD miles!

Momar

Man, I just got it running right. I have been over the connections about 50 times in the last couple weeks. Also, I just had the cap off and its good. Its got a new cap rotor, coil, wires and plugs. I just cleaned and regapped the plugs this weekend because I was running the motor to retarted the first couple times I ran it. It runs good, dont get me wrong, but it just seems that the tach is not perfectly still. I just wanted to make sure it was the cam. I dont have any codes for anything in the computer. It did give me one for for no distributer signal but it was a loose plug and I took care of that.

JP84Z430HP

I wouldn't worry about it then! Mine isn't "rock steady" by any means, and it pretty much was before. I'm sure it's the cam, I just like to remember not to overlook the basics!

flyway190

Looks like the chip didn't fix my problem after all, it still pings. I had some emissions pass test stuff in my gas tank so I think that's why I didn't notice the pinging anymore. For some reason that stuff always makes my engine run better. I did pass emissions with this chip though (barely)!