Thanks for the reply, I suppose it's worth a shot. I seafoamed it last month. Put it in the intake and in the gas tank. Weird thing I'm not throwing any codes. Wouldn't a bad o2 sensor throw a code??

 

Also it could be an exhaust leak but I doubt it, i just installed a 2.25 welded catback with magnaflow muffler. It could be leaking at the headers though.

 

A lack of codes is often an indication of problems on the fuel side, which the computer can't usually see. Fuel filter is the easy check, or check the pressure is up to par.

 

I See. Yah i just changed the fuel filter and it seemed to help maybe a tiny bit but definitely didn't solve it. My next step is to check fuel pressure.

 

Seafoam is only good for checking for an exhaust leak due to its smoking ability when gently poured into the brake booster hose on a cold start when its automatically idling higher.

A bad oxygen sensor rarely throws a code.

 

How's it going guys, haven't posted in awhile but I have some updates on the issues I've been having....... so I recently got back from vacation, drove my little hatch 1700 miles to cali. And back!... didnt get the best mpg because of the issues but it ran like a champ for the most part..... anyways while I was out there I had my buddy who's a mechanic take a look at it and we found a pretty big exhaust leak where the two peices of the headers connect. So we threw on some stock headers that he had. It ran a little better after the leak was fixed but not by much. We also fiddled around with the throttle body and throttle cable, and got the idle a lot more stabilized then how it was before. Now it stays fairly steady and where it should be even when under electrical load....... the thing is on my way back during the last 250 miles of driving, the cel came on (first time it's come on throughout this whole ordeal)...it stayed on until I turned off the car to get gas, then when I turned the car back on it went away until about 30 more minutes of driving. When I got home i checked the ecu and the little led was blinking once repeatedly. I looked into it and found that, that's the o2 sensor code right?.... ok so the weird part is today, just for the hell of it, i unplugged the o2 sensor and went for a drive and it actually ran better! The problem didn't entirely go away but it hesitated less taking off from a complete stop and it felt like I got a little power back. But also what's weird is that there was no CEL with the o2 sensor unplugged? Is this normal??..... and what does it mean that it runs better with the o2 sensor unplugged?.... Also I was wondering what would be the repercussions of just running it without the o2 sensor plugged in?.... thanks in advance for any advice/help on the matter!

 

 

So you think that replacing the o2 sensor would solve it?.... why does it not throw a code when unplugged?

 

exhaust leaks kill oxygen sensors and catalytic converters

 

I gotchya so the o2 sensor is probably shot. But what i don't really get is why the car runs better and there's no cel without the o2 sensor plugged in?

 

CAP AND ROTOR

Is prolly arcing inside, check it out for burn marks
Make sure to inspect the plastic shield behind the rotor.

Just replace it, but good luck finding the plastic behind the rotor. If it has a hole or crack clean it up real good and use electrical tape to repair it. Keeping in mind the rotor is spinning right next to it, so tape it up real clean and flush.

 

It may not throw a code until the car is warmed up, but the fact that it runs better with the connector disconnected should point to the sensor being bad.

 

Thanks for the tip, I'll check out the cap and rotor. Yah that's what's weird is ive been driving with it unplugged for the past couple days. Even when the engine gets up to operating temp. There's still no cel for the o2 sensor being u plugged?

 

It's possible your check engine light bulb is burned out or someone removed it. Does it turn on when you turn the ignition to start position but without starting the car ? If you jumper the blue service connector on the passenger side floorboard the light should turn on solid.

 

No its definitely there and does work. It comes on then goes off when the key is in the on position. I looked around for a jumper wire on the passenger side but there isn't one. Then did some research and (correct me if im wrong) according to everything I read there's isn't one for ef's, just the little red led on the actual ecu. The only jumper wire connector I know of is the one you use when adjusting ignition timing. The one with the yellow cap on it, thats on the drivers side in the engine bay.

 

So the other day I took off my distributor cap to inspect the cap/rotor/plastic shield. As i was pulling it off i heard a rattling sound coming from inside, so I pull it off and find two smaller screws loose inside the cap just sitting in there!! I don't have any idea where they came from, I checked the distributor internals and nothing seemed loose or like there was a hole where they might have fallen out of. Needless to say I was very perplexed! The only conclusion I could make of it was that last year when doing the engine swap, I swapped the internals from another distributor and somehow the loose screws got left in there?!..... After finding those screws and inspecting the cap and rotor, I put the cap back on and started it up and went for a drive, to see if it made a difference. It didnt seem to be running noticeably any better, but could this be what's been causing the problem? Maybe arcing off the screws that were sitting there in the cap, if they were in fact just loose inside there?..... anyways the cap and rotor both look fine, and there's no cracks or anything on the plastic shield behind the rotor.........

Also yesterday I just installed a new Denso O2 sensor and it seemed to help a tiny bit, but it sure didn't fix the problem. Any more ideas?

 

Anyone else got any other ideas??

 

Bump for any other suggestions?

 

Does anyone think it could be a bad iat sensor not reading the intake temp right? Or possibly a bad ect sensor, not sending the right temp back to the ecu and making the engine run to rich, causing the low end bogging/stuttering??? It would explain why the problem doesn't appear until the engine gets to operating temp...... any got their .02 to throw in????

 

Its possible. Just test em for ohms. Ect should be 2000-2500 cold and 180-250 completely warmed up.

 

Awesome, thanks for the info!! I will test it first thing tomorrow morning!

 

So checked the ect sensor today. Set the multimeter on 20k ohms and this is what i got:
engine completely cold - 1.29
Engine completely warmed up (After 30 minutes or so of driving) - .19

Cold value seems out of spec but warm value is slightly within spec. What'd you think? Also I was wondering what range the intake temp sensor should be at?? And how would I test the map sensor??

 

Any thoughts??

 

Since you don't have an autoranging meter you need to set it to whatever setting is above the reading you appear to be getting to get the most precise measurement. You should use the 2k setting for the cold test and the 200 setting for the hot test, but it would appear those values are fine. Test again tho.

For the iat test, you will need to wrap a wire around it and suspend it in a saucepan of water and heat it up while using a thermometer, but the readings should be the same for the ect sensor. The hot reading should be measured around 195 degrees.

 

Looking over this thread again, you never responded if the car ran better with the oxygen sensor connected disconnected.

Also this could be egr related, provided you have egr. I'm not a civic expert. You can disconnected the egr valve connector if you have egr and test then.

Both of these are more likely than the iat being the cause of your issues so i would do these both first.