rsn932

my 87 305 tpi has been having problems idling when started, but runs perfectly fine once it has warmed up a little bit. i replaced the cold start valve thing and it didnt help. i was reading through some different threads here and somewhere i read that it could be related with the MAF, so i unplugged it, and the car started and idled perfectly. now the question is, what needs to be replaced? the whole maf? the wiring to it? the relay?

Maverick H1L

iTrader: (8)

I'd start with the cheaper parts (the relay) and work my way up to the most expensive parts (the actual sensor) in replacement. Usually one of the relays goes out long before the actual sensor does and causes problems.

Vader

Your diagnosis may be flawed. The ECM maintains a relatively close monitor of the MAF input, since it is relied upon so heavily by the system. If the MAF output is out of the acceptable range for more than 600 mS (6/10ths of a second), an error code will set.

Unplugging your MAF simply created a fault, and set the ECM into Backup Fuel and Spark Mode. In this mode. fuel mixture is highly rich (down to 10.7:1), and spark advance is minimal. The excessively rich mixture may be masking what the initial problem actually is, such as low fuel pressure, clogging injectors, vacuum leaks, intake duct leakage, or other possibilities.

Take a mV reading of the MAF output at normal hot idle RPM and see of it is in the normal range. If so, you're barking up the wrong tree. If not, you still have other possibilites to eliminate before replacing any MAF circuit parts and STILL having the same problems.