Has anyone else had a similar problem? Very rich! Short term fuel in the area of 98 to 108! O2's 200 to700mv. long term fuel at 112 to 118. Vacuum at idle at 15.5". Also very rich at crusing speed. GM Hot Cam with 1.6 RR and LT4 springs, adjustable fuel pressure regulator, now set at 42Lbs. New Opti spark new gears and chain. MUCH POWER at WOT but almost unpleasant to drive around town. Can anyone help? Other mods include plugs and wires,CAI, and air foil. 93Z Ted

 

Well, Im not too sure, but from my experience with 5.0s, speed density doesnt handle cam changes too well. Your 93Z is speed density, not mass air, correct? I could be way off here though.

 

Try this thread.

 

You must tune a 93 after doing any camswap to make the car drive right. Your just fouling plugs and washing cylinder walls right now.

 

Forget about a cam install, I was running very rich after I took off the catalytic converter. Car was popping and stumbling from 1000rpms to 2500 rpms. Changed opti, O2 sensors, Idle valve, plugs, wires, ignition coil no change in symptoms. Decided to do a PCMForless tune and now the car runs great, no stumbling, just smooth power delivery. I'm guessing since we don't have a MAF, an increase in volumetric efficiency has to accompanied by a tune.

 

Yes it is a speed denisity, MAP sensor, based system. I checked wires for burns ,like I said ,new plugs and wires. MAP voltage is 1.9 to 2.02v at idle slightly higher than the 1 to 1.5 GM spec for this engine (at idle). Throttle position sensor (TPS) is .58v within specs. I realy appreciate the thoughts so far. If I "tune" this engine as was suggested what else could be done? THANKS 93Z

 

You can remove the speed limiter, set the rev limiter to 6500 since the Hotcam makes power up to 6200, remove A/C trouble codes just in case you decide to ditch the A/C, desensitize knock sice we don't have the option of buying an LT4 Knock Module, set the fans to come on early with a 160 T Stat. Dyno tests have shown hotter engine temps can rob you of 3-5 RWHP.

 

I don't know too much about computer tuning, my father does, but I also have a 93 with a cam. I did notice a big difference in the motor after we tuned my car. I believe you have to pull out spark knock.
Maybe do a Craig Moates search for computer tuning, thats how we went.
Good luck