Throwing 4 codes....help

[CodyBrown]

I bought this car on Monday and drove it 8 hours home. First off, it's a 96 240sx. Sometimes when you would accelerate, it would get up and go fine. Other times it would bog down and seem to have no power. Anyway I got it home and plugged it into my scanner and got P0110 - IAT, P0120 - TPS, P0105 - MAP or MAF, and P0325 - Knock Sensor. The first thing I did was replace the plugs, cap, rotor, and fuel filter which were way over due. It seemed to help quite a bit, but it's still got the intermittent lag. Where's my next step? Nothing that I know of can make all these codes pop with an individual thing, but this is my first time wrenching on one of these cars. It's my 5th 240, and also the newest. I'm trying to stay cheap for now. The car will eventually be a SR20DET, but I want to upgrade the suspension and everything else before I do the motor and tranny swap.

[orion::S14]

The bogging down sounds related to the knock sensor code...

When the ECU senses knock, OR a bad KS...it will retard 8-degrees of timing under load. Makes for a S-L-O-W car.

If it revs over ~2500rpm, chances are the MAF is OK...maybe needs cleaned.

IAT...is a usless OBD sensor, no effect on power or driveability.

TPS has as much to do with driveability as the MAF..you'll need to check out the FSM procedure on that one, it's rather specific. But in a nutshell, it needs to be around ~0.5v closed, and around 4.5v when wide open.

...

First things first, however...have you reset the ECU, cleared the codes? Did they come right back?

MAF and IAT are common if someone had the airbox off and turned the key on.

- Brian

[I LUV MY S13]

replace them

done.

[aznpoopy]

p0105 is map, not maf. its a little box somewhere on your intake with a few tiny vac lines coming out of it. test it per fsm; replace if necessary.

[mxexux]

Hook up your DVM to the TPS measuring resistance. Slowly move the throttle open and close; the ohms should rise and fall smoothly. If the ohms spike up or down somewhere in the middle it means your TPS has a worn spot in it and needs to be replaced. I had the same symptoms on my car and it was the TPS.

[CodyBrown]

Well I cleared the codes, and got P0325, P0120, P0105, and P1105. The car seems to run a lot better and has lots of power. I have noticed it lag a tiny bit very rarely, but otherwise running good. Should I start replacing sensors, or am I missing something. I'm going to test the TPS tonight.