Alright I just got through pulling the codes from the 87 Z28.

12. No Reference Pulses to ECM (From What I understand this code is supposed to show to tell you the computer is functioning properly.)

32. Fault in BPS sensor circuit OR Fault in exhaust gas recirculation valve diagnostic switch OR Fault in electronic vacuum regulator valve. (Previous owner seemed to have attempted to block off the AIR system. Could someone show me the proper way to disconnect it or how to hook it back up, which ever is prefered.)

33. High voltage at MAF

34. Low voltage at MAF

36. Burn off at MAF sensor OR Problem in transmission shift OR Fault in direct ignition system OR Missing pulses in electronic spark timing signal. (Could this be caused by bad spark plugs or wires? I notice a small miss in the exhaust like a bad spark plug.)


So what do I look into in correcting these problems? I plan to get a new set of plugs and wires for it tomarrow. Should I reset the computer and see which codes come back or is that a bad idea?

 

Personally, I'd recheck the grounds, especially the one at the back of the cylinder head(s). Then, disconnect the ECM power to clear the codes, and start it up again. See what it shows, and go from there. I don't think some missing would set a code off either. I am using my SD system as reference though. Good luck.

 

Alright.. Replaced the plugs and wires and attempted to clean the MAF with the CRC Electrical cleaner. Reset the computer and the only code it throws now is 12 and 34.. How would I check the voltage at the MAF? I noticed the previous owner ran another ground wire from it to the aluminum throttle body. Also I try to check the engine ground when I get a chance.

Thanks

 

The MAF uses a 5 volt reference signal.

I dont have the maf diagrams in front of me so I cant tell u what pins are what.

U should have 5 volts at one with the key on, grd at another and the actual signal line.(what the sensor changes the 5 bolt reference to so the ecm recognizes it)

Believe the 4th wire will be for the burnoff relay.

later
Jeremy

 

Not much for poking and prodding with a VOM.. If ya can find a diagram that'd be very helpful.. I'll search around the net and see if I can find any more info on it. I checked everywhere for vacuum leaks and came up with nothing. Read somewhere that unmetered air such as a vacuum leak could throw this code..

Thanks

 

Search for posts by Vader involving MAF sensors.

Almost positive he has made a cpiture of it and which wires are what. He is great for that stuff

later
Jeremy

 

Woohoo Vader is the man! And thank YOU for pointing me in the right direction! Found this topic: Code 34

Pulled all of the connectors in that area. Just so happened to have some CRC QD Electical Connector cleaner left over from cleaning the MAF.. Used the rest of the can to clean off all of those connectors and relays.. Let it all dry while I removed some previous manual horn button bs installed by the previous owner. Wasn't a bad job.. But I don't like extra wires in the engine bay cluttering things up.. Anyways got finished with that, hooked it all back up.. Started up.. No SES light! Took it for a test drive and it didn't throw a single code. Idles MUCH MUCH MUCH BETTER! Took it out on the high way and was quite impressed at how healthy this little 305 still is. In drive in pulled cleanly up to 5500 before shifting to second without a problem.

Thanks again!
Matt

 

Ok I thought it was fixed.. And well almost is.. But still got a couple more questions.. First off threw the 34 code tonight when I got off work. Started the car up and it imediately stalled and died.. Checked the codes and it was another 34.. So finally got the car started up and get it home in limp mode. Anyways.. Got it home checked the connectors and such to the relays to no success. Started doing some more research and many people have been saying that the MAF Burn off relay and MAF power relay are the same.. So I swapped the connections and it runs fine again. So these 2 relays ARE the same correct? And will this be an alright fix for a day or 2 until I can find a place to purchase the relays? I took it around the block a few times and it didn't throw any codes and idles fine at stop signs instead of surging and wanting to die.

Also another question I have is this. The previous owner installed an "extra" wire onto the black wire w/white stripe on the connector that conects into the MAF Sensor. He grounded this wire to the Throttle body. Should this be removed? Maybe it was his attempt at solving the problem? I'm not sure...

Oh.. And one last question.. With the relays.. the 2 harnesses for burnoff and power.. From left to right are the first two wires on the power Orange, Blue and the Burnoff orange, orange? This car just seems an ongoing project of correcting things from the previous owner..

Thanks for the help,
Matt