grafx

First off about a couple weeks ago I was having a weird idle problem and no codes were showing until finally one did and pulled the code manualy and turned out to be CTS...replaced and car runs fine. Today I gave my car a tune up at a freinds shop...cap-rotor/ plugs/ oil change. I also checked the timing cause Monday I'm going to go get the car smogged turned out to be good so no adjustment was needed.

After I finished the tune up I hooked his Snap-On Scanner up to my car to see what kind of readings I could get. I found the following. 2 service codes
#23-Manifold Air Temperature too low
#42-Electronic Spark timing(EST) Problem

Now I'm pretty sure that the code #42 is because I disconnected the bypass when I checked my timing but what is the code #23 for, what would cause a code like this?? Could it be from my CTS problem?? I don't see how since the code I got from that at the time was a code #15=coolant temperature sensor circuiit (low temperature indicated), and I cleared it afterwards.

Here's the vehicles actual readings when I had the vehicle plugged into the scanner, tell me if you guys notice anything out of the normal. This is a 91' 305 TBI Camaro by the way.


RPM__1000 O2(Mv)___577 INTEGRATR__129
OPEN/CLOSED LOOP___CLSD EXHAUST OXYGEN__RICH/LEAN
TPS(v)_____0.58 BLOCK LEARN______145
IAC POSITION______27 A/F LEARNED_______YES
A SYNCH PULSE_____NO PROM ID__________1091
COOLANT(c)_______105 MAT(c)____________59
MAP(KPa)_________27 MAP(v)__________0.92
ESC COUNTER______0 KNOCK_____________NO
CLEAR FLOOD______NO BATTERY(v)________13.8
HIGH BATTERY______NO LOW BATTERY______NO
AIR DIVERT SOL_____DIV AIR SWITCH SOL___CONV
VEH SPEED(MPH)_____0 P/N SWITCH______P-N___
TCC COMMAND_____P1 TCC APPLY CKT_____NO
4-3 DOWNSHIFT____NO HIGH GEAR________YES
A/C REQUEST______NO

Nixon1

You live in California so the climates shouldnt be that extreme.....if the computer tells you there's a problem with the manifold air temperature, I would tend to believe that that sensor has a problem. That sensor isn't necessarily a VITAL sensor, but it tells the computer what the temperature of the incoming air is, so it can adjust the a:f ratio accordingly because air density at different temperatures varies. I disconnected mine once and lots LOADS of power..... Might try replacing it, say with an Autozone one. Reset the ECM and see if the code comes back, or if the car runs better. If the code returns or no difference is made, just return it. I did that, but with an IAC valve assembly. I stole the motor off the new one and installed it on the old valve assembly, and returned the new valve + old motor for a full refund. Sssshh, don't tell anybody.

Vader

Your results seem to be contradictory, since the scanner is reporting a reading from the MAT. 59°C should be acceptable at that CTS range. Try clearing the ECM again and see if it repeats. You might want to check the MAT wiring and connections just for grins.

Dave Y

I would like to see the MAT reading when thye engine is cold

the ECT and MAT should be the same after sitting overnight and before starting the car

grafx

by ECT you mean the coolant temp right?? I was thinking last night after posting this topic and realized that when I was checking the timing I had the air cleaner off the car which means the MAT sensor which is mounted in the air cleaner was disconnected. So I guess that would be the cause of the trouble code right?? sorry guys my car has been having a little bit of a stumble at idle was just hoping that this might be it or maybe something would show up in the read-out