hello,

i have an issue with a surging engine. this happens when the car is warmed with an electrical load and only when stopped.

after much searching i believe i narrowed it down to the following problem: low voltage.

with the car off i get a reading of 12.5 (est.) volts from the battery.

upon starting the car, i get a reading of 14.4 (actual) and the idle is fine.

once the car is warmed, if i turn on my stereo, the voltage drops to 13.1 (actual) and remains there regardless if the stereo remains on. if i rev the motor, the voltage remains at 13.1.

after about 5 minutes the voltage dropped to 13.

i feel that this may be causing bad readings either to or from the computer (hondata s300) and therefor causing the idle issues.

i have recently cleaned all the grounding connections (three cables total) but this solved nothing.

perhaps these two issues are unrelated. understand, this thread is meant to be about the voltage issue first.

thanks for your help everyone!

 

Hmm. Have you considered your alternator? It sounds to me like it's not providing enough juice to keep your voltage output the same or thereabouts.

I don't imagine your computer would be causing a low voltage problem so much as just reacting to it. More like a symptom not the disease, you know?

Do an AVR test on the electrical system and check for problems in the alternator/battery area. That would be your best bet I think, then go from there

Dave

 

Correct me if I'm wrong...but isn't 12-14 volts normal when running the car? I unno. Maybe its just me and my electrical woe's I've had with this car (I'm on my 3rd alternator lool).

I highly doubt its your ECU. Do you have a sound system in the car? After market deck, subs, amp, capacitor. Any weird wiring that aint oem? Do as Dave stated above and maybe start from there. Check how old your battery is as well.



As for how low is too low....well. Imagine me driving in a thunderstorm in the evening with a really shitty alternator and as you drive your battery readings are going from 14 down to 9 volts....to 0. Loool.

 

Engine surges usually are caused by a misfire. What makes you think its the alternator? the readings you said sound normal to me. I would check out your plugs, wires and the distributer cap and rotor.

 

allow me to update. since my original post, i found that my voltage readings are just fine. my issue is partly due to three loose bolts on my intake manifold. i have ordered new cap, rotor, fuel filter and PCV valve. i know the valve needs changing and i haven't even looked at the other parts as they are years old. i will also change the plugs when the parts arrive. to add to this i have an afr gauge and tach. once all those new toys are installed, i will throw it back on the dyno for a good tune. i am confident that will solve my issues and then some.