Throttle position sensor
 

Okay guys, just bought a civic last week for a work car and it starts great, but idles up and down in park when a/c is not on, but not so bad when a/c is on. Someone said it is probably throttle position sensor. Haynes says itshould have 5v at terminals on TPS connector but there is no voltage at connector. It also doesn't show difference when connecting leads to sensor and stroking throttle.TPS or PCM????????????????????

Oh yea, the chk. engine light was on so I had Auto zone pull the codes and it read a PO302 and a PO117--misfire on no. 2 cyl and engine coolant temp. sensor circuit low input, respectively. Car hesitates when running down the road, but picks back up unless I'm at a stop then it dies.

It is a 1997 Civic w/1.6l and auto trans. (and 214k miles on it)[&o]

RE: Throttle position sensor
 

Before addressing any potential TPS issue, check whether plug/wire 2 and the coolant temperature sensor need to be replaced. Repair of these two CEL faults may solve most if not all of your current engine problems.

RE: Throttle position sensor
 

The unsteady idle could be related to either of those codes you have now. Generally if the TPS is bad you will get a TPS code. You probably didn't measure any voltage because you didn't get the probes in past the insulation.

First clear those codes, drive a few days, then check codes again to see which one, or both, reoccurs. If you get the misfire code again you should start with a basic ignition tune-up. The coolant temperature code can be caused by overcooling the engine (defective thermostat, wrong thermostat, or no thermostat). Does the temperature gauge go about halfway up and stay steady while driving?

RE: Throttle position sensor
 

OK-- cleared codes, FILLED RADIATOR to proper amt., ohmed out TPS(checked out fine)and drove. After 2 days got new code for IACV and has horrible hesitations while cruising, but when a load is applied it will straighten out. Will check IACV w/DVM and report back. Any help would be greatly appreciated.

RE: Throttle position sensor
 

The IACV won't cause problems while cruising. You get the "IACV code" whenever the engine won't idle properly, which is often something other than the valve. Really sounds like a misfiring situation. Check the ignition parts. If it has any sort of aftermarket spark wires, replace them with stock ones.

RE: Throttle position sensor
 

All right guys--- Checked the IACV last night and w/dvm it ckesked out ok. When I would unplug the MAP though, it would idle fine. This AM driving to work it really ran rough and died and put me on the side of the road. When I finally got it running I took it to the shop. Cant afford to miss work over a broke down car. Will let you know the outcome. mk378,-- I agree with you about the ignition idea and thank you for the input.

I have a 1997 Honda Civic DX. The car hasn't run in 1 year, the car was parked because while driving, all the lights dim and light up. The accelerator needle goes crazy, and the transmission doesn't shift when it should because the accelerator is going crazy. So I finally had the time to fire it up last week and the symptoms are the same but it is un-drivable. Now what's going on is, the car idel's at a very low rev, when I step on the gas, the engine rev's up but when I let go, it comes back down to a very low rev, almost at the point of stopping dead. it is so low that when I step on the break, the car stops dead. and when I try to shift gears, the same thing happens. I talked to a guy at work, and he says its the Throttle Positioning Sensor, but I want to 100% and need everyone's opinion. I'm no mechanic nor know much about cars, so anything would help.

Lights dim and bright, speedometer not working, various ECU codes, are all the classic symptoms of the fuse 15 problem. On the 1996-2000 they had a bad design where a wire behind the engine rubs through and shorts out, blowing the fuse and causing several electrical issues. Search for it here.