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Alan Roehrich · 04-18-2007, 11:29 PM

Almost all of the sensors are 0.0 to 5.0 volts. The O2 voltage is 0.0 to about 0.99.

The TPS voltage should be around 0.46 at idle, and around 4.6 at WOT.

The O2 sensor should switch back and forth across 0.500 volts, usually varying from around 0.300 to around 0.700.

At idle, the MAP sensor should be either about .50 volts or 4.5 volts, I cannot remember whether that particular model read high voltage with high vacuum or low voltage with high vacuum. It should swap either from about .50 to about 4.5 or from 4.5 to .50 when you take the vacuum hose off of it.

The fuel pressure should be around 24-25 pounds.

I can tell you that coolant temp sensor failures are very common, and if it is dead, it defaults to -40 degrees, which commands a full rich signal. The coolant temp sensor works like the MAP sensor in that it reads from .5 volts to about 4.5+ volts. You can check it the same way, when it's cold, it should read opposite of warmed up.

Make sure it is full of coolant, and if it does not have a "chip" in it that the thermostat is rated at 195 degrees.

In order of common failure, the coolant temp sensor is first, the O2 sensor is a close second, the MAP sensor is third, and the TPS is fourth.

Ground issues are VERY common, especially when work has been done, particularly engine swaps or replacements. ALL of the grounds MUST be perfect, they need to be clean and tight, with no paint or rust on the ground wire or stud. Also check for pinched wires.

Finally, make certain that you use genuine GM parts when servicing the computer, fuel and ignition systems. The cheap aftermarket stuff is nothing but trouble. Yeah, it's more expensive, but buy your parts from the dealer. You can usually use MSD stuff in the ignition, and good wires like you'd use on your race car. PREMIUM aftermarket fuel system parts, like MSD or Holley, or maybe Accel, are okay, if you're looking for a little power.

P.S. If you've put headers on it, make sure the O2 sensor is not too far from the engine. If it is, either move it close, or convert to a heated O2 sensor.

Alan Roehrich

Bring "AA" classes to NHRA Stock Eliminator!

04-18-2007, 11:29 PM	#7
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,116 Likes: 1,573 Liked 1,831 Times in 415 Posts	Almost all of the sensors are 0.0 to 5.0 volts. The O2 voltage is 0.0 to about 0.99. The TPS voltage should be around 0.46 at idle, and around 4.6 at WOT. The O2 sensor should switch back and forth across 0.500 volts, usually varying from around 0.300 to around 0.700. At idle, the MAP sensor should be either about .50 volts or 4.5 volts, I cannot remember whether that particular model read high voltage with high vacuum or low voltage with high vacuum. It should swap either from about .50 to about 4.5 or from 4.5 to .50 when you take the vacuum hose off of it. The fuel pressure should be around 24-25 pounds. I can tell you that coolant temp sensor failures are very common, and if it is dead, it defaults to -40 degrees, which commands a full rich signal. The coolant temp sensor works like the MAP sensor in that it reads from .5 volts to about 4.5+ volts. You can check it the same way, when it's cold, it should read opposite of warmed up. Make sure it is full of coolant, and if it does not have a "chip" in it that the thermostat is rated at 195 degrees. In order of common failure, the coolant temp sensor is first, the O2 sensor is a close second, the MAP sensor is third, and the TPS is fourth. Ground issues are VERY common, especially when work has been done, particularly engine swaps or replacements. ALL of the grounds MUST be perfect, they need to be clean and tight, with no paint or rust on the ground wire or stud. Also check for pinched wires. Finally, make certain that you use genuine GM parts when servicing the computer, fuel and ignition systems. The cheap aftermarket stuff is nothing but trouble. Yeah, it's more expensive, but buy your parts from the dealer. You can usually use MSD stuff in the ignition, and good wires like you'd use on your race car. PREMIUM aftermarket fuel system parts, like MSD or Holley, or maybe Accel, are okay, if you're looking for a little power. P.S. If you've put headers on it, make sure the O2 sensor is not too far from the engine. If it is, either move it close, or convert to a heated O2 sensor. Alan Roehrich Bring "AA" classes to NHRA Stock Eliminator! __________________ Alan Roehrich 212A G/S