Car is throwing codes:

13
33
43
55

Ive read what all of it means, but generally, expeciallly on the code 13, what usually causes this on the lt1?

Thanks,
Nick

 

13 usually comes from not having the wires to the O2 pulled back and secured and it burns the purple or tan wire on the header. Chances are, that caused the 55 also.

The MAP failure has to be wiring, like maybe your latch on the connector is broken like the rest of us and the connector came off. The shop manual is indicating the only wiring problem likely to cause the error is on the black wire providing ground to the MAP or the MAP itself. MAP's are bullet proof, well let me qualify that and say GM MAPs are. They very rarely go bad.

The last is only one wire to deal with going to the KS. Pull the wire off the KS and with KOEO, measure for 5 volts to ground at the connector. The other thing to check for is the resistance of the knock sensor to the block. Measure the resistance to confrim it's between 3.3K and 4.5K ohms. If the resistance is higher, the KS could be grounded improperly since it gets it's ground through the threads. Be careful what you use to seal the threads, no teflon here. If the resistance it too low, the sensor is bad.

A couple of last thoughts. First, I find it odd that 2 of the problems you have (the MAP and O2 failure) are all within 3 or 4 pins all in a row on the PCM white connector. BIG NOTE HERE. I may be wrong cause I'm looking at a 94 book and these circuits on a 93 may be different. But it doesn't take long to pull a connector so I would look at those pins on the PCM and the connector on the harness before you do anything else.

Last, the alternator can cause wacky S@#T to happen to the PCM if it's leaking AC past the diodes and that is easy to check for. Set your volt meter to AC and measure from the negative terminal of the battery to the ouput post of the alternator. The reading should not be higher than 0.03 volts AC. if it is, the diodes are defective. When this AC gets high enough (I don't know what high enough is) it can cause the PCM to do weird stuff.

 

Have you re set the computer yet to check if any of those codes are old stored codes?

ZMAN

 

Pull the "PCM BAT" fuse for 30 seconds.

There is a complete list of LT1-specific trouble codes on Shoebox's Tech Pages:

http://shbox.com/1/Dtcs.htm

 

code 13 ended up being the drivers side oxygen sensor was bad, I replaced it and all the codes but the knock sensor code went away. I bought a new sensor and connector and will install tommorow. thanks for the help so far