todd5854

Just what the title says. Low idle, backfires every now and then, and when you give it gas, it stumbles and sometimes stalls. Once it warms up, it idles around 1000. I replaced a few vacuum hoses, inspected the MAF, cleaned the MAF terminals, and removed the IACV and cleaned it out, and it got a little better. Maybe it's just time for a new MAF? Would the aux air be worth cleaning?


its a 300zx 1985 t-tops 2+2 5 speed, analog dash. 276,000 miles

rogerz

fairly classic symptoms of chts being bad. Oxygen sensor possible. Maf usually doesn't go bad unless someone stuck a screwdriver in there. it is a very simple device. here is some other tips that will at least make things operate better:

Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion.

todd5854

So far I replaced the battery terminals, and sanded down a few grounds. Car seems to run slightly better. CHTS isn't an expensive repair, I believe. Shouldn't be hard to get to, its next to the thermostat, right? Is there a possibility my alternator is going bad, and needs replaced? I'll replace the o2 sensor as well. I didn't even look at my TPS yet so I'll look there too. Are there any vacuum hoses that would cause it to run funny?

rogerz

vacuum leaks are the bane of an FI engine. TPS not your problem. google chts replacement there are some instructions on the web. not complicated just slightly tricky. i just cut the wires at the oval connector on top the engine and solder in a new set with connector to the sensor itself. same as injector connector. Only ground really important is the one the negative cable goes to first before going to the starter. You can also run some 10ga wire from negative post to an M6 on either fender well (there are plenty). Take car to a REAL (not Walmart) battery shop and they will test your system for free in hopes of selling you a new battery. I have found Interstate batteries to be the most reliable. If you replaced the terminals and not the cable you probably used those wretched clamp on fit all type. They will give you trouble in the long run.
GET YOUR BATTERY LOAD TESTED when they check the system.
You cant just disconnect the O2 sensor and see if that clears your problem. If no change probably OK