squrly97ex

whats up. on a previous post i explained the problem i have with my 97 honda civic ex. no power at low rpm, miss at idle and low speeds, etc. my cel was on so i got the codes.

PO113-INTAKE AIR TEMPERATURE SENSOR CIRCUIT HIGH VOLTAGE
PO122-TP SENSOR CIRCUIT LOW INPUT
PO108-MAP SENSOR CIRCUIT HIGH VOLTAGE
P1381-CYLINDER POSITION SENSOR INTERMITTENT INTERRUPTION

the car has an AEM fuel rail, dcsports header, aem air intake. i bought the car with a burnt up wiring harness, replaced the harness. ive replaced the dizzy, cap, rotor, spark plugs, wires. this is making my head hurt.

civic-4-ges

Holy ****, lots of errors...

Are you sure the replacement harness is ok??

You also say you burnt your last harness, were any of your sensor damaged in the process?

project_mercy

Sounds like your burnt up harness burnt up a buncha sensor, or burnt up a ground cable. There's test procedure for some of those sensors in the helms.

squrly97ex

i bought the car with the harness burnt up, the guy before me put the cobra led windshield washer lights on the hood. he spliced them into the harness wires by the connector near the brake booster, of course his shitty wiring grounded out on the firewall and voila! travis gets a deal on a car. i replaced the harness, which wasnt easy, and it has missed since the first time heard it run again. sometimes it runs better, sometimes worse. im almost tempted to get another motor if i cant figure this crap out. back to the burnt harness, there is no physical damage to any of the sensors, a fire extinguisher was used after the car flared up.

project_mercy

Yeah. Problem is, there's a wad of "blk/yel" wires on that side. They're all the same circuit. It's the Ignition (-) ground lines. They all run to various engine sensors and such. If dude tapped into that (which is likely), and it grounded, who knows what happened to various other things, including the ignition power wire that heads up to that header, or the sensors after that.

If you ground out a battery circuit, it's going to draw maximum current. Functionally 500-800 amps are going to burn through that circuit until something melts and breaks the circuit. Most of the car wires are 16-18ga, which, given the length of the wires, is only able to handle 8-15 amps. You can see how that can lead to problems.

Edit: Then again, to start an engine harness fire, you really have to mess something up. so there you go.

Another thing, molecularly speaking, in a DC system electrons flow from negative to positive, despite what the circuit may lead you to believe. So if path of least resistance is through your sensors.. they go bye-bye. He'd have really had to botch something up for that to happen, but I've seen worse.

squrly97ex

good times, huh? well, i have checked the spark to the plugs and in all the spark is weak, so maybe this ignition power source is what im looking for? it also seems to be worse when conditions outside are wet, broken wire comewhere exposed? i picked a friggin jewel didnt i?

project_mercy

Yeah. For future reference, if ever you get near a car under the premise to purchase it, and it has any electrical problems, you'll likely want to run away, promptly. As if the guy had a shotgun leveled at your groin...

with a bayonet attached.

and an attack dog.



You really need to get a full wiring schematic to do a full check. I heartily suggest you pick up a helms manual. It has all the wiring in the back. There's also an electrical supplement, but it's not totally necessary (it is pretty helpful though).

At the minimum, try to look at it from the car's point of view. It thinks those 4 sensors don't work. So, unplug those sensors, take a multimeter, and see if things work the way you think they should (such as sensor ground goes to ground with ignition on, etc). Then do a test on the sensors.

I wouldn't dive into the whole harness when you have some 'clues' as to what it is currently.

Edit: also, you really will need a cheap multimeter. Something that does does continuity, DC voltage, and measures resistance. Everything else is gravy.

squrly97ex

thank you for the info, im gonna go out and get a multimeter tomorrow as well as a scanner so i can clear these codes and make sure im getting hard faults here, cause im pretty sure that both the map and tp are fine, and i checked my wirirng and grounds earlier and all is well, so ill keep you posted and thanks again for the help.

squrly97ex

OK. i have checked voltage to all but 1 sensor, thats the cylinder position sensor, i have no idea where the hell that is. KOEO: MAP voltage is fine, KOER TP voltage is fine and IAT voltage is fine. KOER and unplugging these sensors dramatically changes the way the car runs, so im thinking the CYP is my missing link here.