Google has not helped me resolve my problem. I recently bought a 2003 accord lx 4 cyl. It didn't seem to have any issues when I bought it but I left it in my garage for about two months and when I went to drive it the battery was dead. No big deal I just threw the charger on it. After it was charged and I started it I noticed that the idle was fluctuating wildly. It would bounce between 2500-3500 rpm. There was no CEL at this time. The almighty google suggested multiple things. I checked for vacuum leaks but couldn't find any. One forum suggested tapping the throttle body with something to see if the idle dropped. I did that and the the idle would stop fluctuating but would stay high around 2500 rpm. They suggested changing the IAC which I did. I also cleaned the crap out of the throttle body. After putting it back together it wasn't fluctuating any more but the rpms stayed at about 2300. I tried the idle learn procedure but no change.

Eventually the CEL finally came on and it was popping 3 codes: p0685, p0123, and p2227. Somewhere in the process I must have cracked the TPS because when I removed the connector the top part of the sensor came up with it. I replaced the tps but still have the high rpms. I had disconnected the battery during the process and since then the CEL hasn't come back on.

The car still has issues though. The RPMs are still around 23-2500. I can't shift the car out of park without pushing the shift lock release. Once I do the rpms drop to about 1200 in gear. They spike back up to 2300 in nuetral. The car can get up to over 40 mph without me even touching the gas. I also noticed that while in park if I turn on the heater or A/C the rpms drop to about 1800. Not sure what to make of that. I drove the car about 30 miles and got up to about 70 and the CEL hasn't come back on but I know the car still isn't right. Anyone have any other suggestions? I've searched the forum and only other thing I can really find is to adjust the idle screw but I've been told that just masks the real problem. I'd like to fix it properly. Any help would be appreciated.

 

Current issue may still be the TPS. The voltage needs to be at less than .5 volts (this essentially tells the PCM the accelerator pedal is not depressed and the throttle is closed). If it is at a higher voltage, the PCM thinks the accelerator is depressed and the throttle is open and prevents the shift lock solenoid from energizing (you won’t be able to shift out of Park).

You may be able to adjust the TPS with instructions that are not part of the service manual. People have posted instructions on the internet on how to adjust Honda's TPS.

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This is how the Shift Position Interlock works:

Shift Position Interlock
Battery voltage is supplied at all times through under-hood fuse 13 to the brake pedal position switch. With the Ignition Switch in ON (II), battery voltage is supplied through under-dash fuse 21 to the Shift Lock Solenoid. When the Brake Pedal is pressed, a battery voltage input is supplied to the PCM and the MICU. If, at the same time, the accelerator pedal is not pressed, the PCM provides ground to the Shift Lock Solenoid. The solenoid is then energized allowing the Shift Lever to be moved.

 

Thanks for the info redbull. I checked the voltages and everything seems within tolerance. After putting everything back together the CEL came back. I haven't taken it to get the codes checked again yet. Something did change though. Somewhere in the process I did something to allow me to shift out of park again with out having to do the shift lock release. I guess that's progress.... Any other ideas?

 

New update. I went to go get the codes checked again. Now the CEL was gone again and I was unable to shift out of park again. Drove it to shop to have codes read and was all of a sudden able to shift out of park. Although the CEL wasn't on anymore it still popped codes: p0113 and p01222. These are different codes than before so I guess change is progress. When I went to leave I was unable to shift out of park again. This is getting super frustrating. Ideas?

 

With the changing trouble codes, this may be an indication of an issue with either the battery, PCM, or wiring connection.

You may want to get the battery tested. You can also visually check the area of the PCM (behind the center console) to see if there may be rodent chew on wires, water from the evaporator drain hose leaked and damaged the PCM, etc.

Next time you can't shift out of PARK, disconnect the TPS. You'll get a Check Engine Light; but, see if you can shift out of PARK. If you can, it is TPS, wiring, or PCM related. However, a low battery may also be the cause for electrical gremlins.

 

Ok I finally got frustrated and took it to the dealership. They ran diagnostics and suggested I replace the entire throttle body which includes the IACV and TPS. They wanted my first born kid for it which I can't afford right now. The technician was really cool and gave me a throttle body that he had just pulled off another car that just had the hook for the throttle cable broke off. Everything on it was stock. I cleaned it up and changed it out hoping for the best. I started it up and it idled even higher!! It was up over 4k now. Messing around I just started pulling connectors off while it was running.

I pulled the TPS sensor off first but there was no change so I put it back on then for some reason I pulled the connector off the MAP sensor. The idle dropped immediately to 1300 from over 4k. I left it off and then pulled the TPS sensor connector again and the idle dropped to about 900-1k I noticed that it was now rumbling a little with a rough idle and there was a foul egg smell coming from the exhaust with a lot of smoke. I reconnected the sensors and the idle stayed low but idle was still rough and egg smell and smoke was still there. Turned it off and then back on again and idle was back over 4k. I pulled the connectors in that order again and had the same result as before. So I pulled off the junk tb from the dealer and threw mine back on. Idle was back above 2k so I pulled sensors in that order and this time idle dropped to 6-700!!! Still with smoke and foul odor.

What does this mean? Do I have a bad MAP sensor? Is this supposed to happen? It's the closest to being fixed as I have been....

 

Unplugging the sensors will cause the PCM to detect the signal interruption. The PCM will probably go into pre-programmed limp mode, which ignore inputs from engine sensors. That may explain why the idle changed.

Since the dealer's diagnostic points toward the TPS and possibly the IAC valve, there are aftermarket TPS available. For the IAC valve, you can try cleaning that. The IAC valve is separately available from Honda; but, it may not need replacing.

 

I've already replaced those two parts though.

 

Hi I don’t know how to use this forum but I also have a 03 accord and had the starter replaced by a mechanic and the rpms are up to 3000. What could be the cause??

 

It could be anything he forgot to do. Have home check to make sure everything was plugged back in and the accelerator was put back correctly if he moved it out of the way. It's hard to give you a pin point because the starters are done multiple ways so no telling what he removed or moved out the way. Start at the accelerator though. The cables may not be right