NAC

Just got back from the Dragon. On the way up, I got a CEL light and vtec became non-existent (like trying to vtec with only one temperature bar lit). The car wouldn't shut down, but would slam up against the 6k RPM wall. I pulled over, restarted the car, had the CEL stay on, but vtec was fine....until 5 miles down the road- no vtec. Also, idle would dip below 800rpm when out of gear. The problem kept going away temporarily when I'd shut down and restart the car.

When we got to the hotel, we plugged in a laptop and got P1259 as the code- vtec system malfunction-rear bank "vehicle speed idle control and aux. inputs". Lastly, I could tell that the car was going to not have vtec, because it started to feel sluggish- even before vtec. I have the following mods:

Comptech supercharger (no aftercooler)
T1R test pipe
Apexi VAFC

Any ideas where to start? Thanks to my fellow Atlanta S2kers and Wisconsin S2k for their assistance up to this point!

xviper

First thing to do is to check the 2 wiring harnesses by the VTEC solenoid and pressure switch. Disconnect them and wiggle them back on. Have you been diligent about changing the oil and filter since the supercharger has been put on? Have you been using a good oil or even a synthetic as Comptech recommends? There is a filter screen between the VTEC solenoid and the engine. This screen could also be clogged. It would normally not be a problem if oil changes have been done using the "severe" schedule.
If the problem repeats itself and the code returns after you've cleared it, then you need to double and triple check all the wiring where you spliced in the Comptech ESM (if you have one). This is a common glitch (or failure) on Comptech S/C'd cars. Did you use the crimp connectors? Comptech has issued a memo to say not to use these but rather, all connections should be soldered.

Slows2k

Check the Oil level 1st. VTEC needs oil to work. Then start looking at all of your splices to the VTEC signal wire with the VAFC.

The low RPM limit is normal with a P1259 stored. It's the PCM's way of saving the motor from high rpm use if there is little to no oil in the pan.

Wisconsin S2k

check those connections! let us know what you find out.

Utah S2K

DTC P1259 is a problem in the VTEC oil Pressure switch circuit or VTEC solenoid valve circuit.

1) Reset the engine ECM
2) Check the engine oil level...as previously suggested
3) Warm the engine to 3 bars and then until cooling fans come on.
4) Road test the car-
-- Accelerate in 1st gear to 6,000 RPM. Hold that RPM for at least two seconds. If DTC P1259 is not repeated during the first road test do the terst 2 more times.
5) Only if you repeat a code set need you worry about loose wires.
Make sure all connectors are secure.....

Utah

NAC

Thanks for the input guys. I had the oil changed on Thursday using the same type- Mobil 1 synthetic. I will get with my tuner, get him to clear the code, check connections etc. I'll post what happens.

NAC

hondamanwill

NAC it is conections on you vafc. I have seen lots of conection problems with these controlers MANY. Look there first.

NAC

I talked to my tuner, and he promised to double check all the soldered connections. Thanks for the reply! NAC

Wisconsin S2k

NAC, hondamanwill is the one I called friday and had look up the code.

NAC

Just wanted to update this thread. I took the car to Knowledge Performance and had them clear the code. They then raised the Vtech back to 6k, and the car made it through SESM without any trouble. I took it back to Knowledge and had them do some additional installation and tuning. As it turns out, there was a wire that was not soldered in that should have been. I'm not that technical, but needless to say, no mor CEL light since. Kudos to Knowledge- Kevin and Joey are good guys.