chevy383

I will appologize in advance for this being so long and for making about the 10 millionth thread on this. So to start with when I went to buy car (98 civic coupe d16y7) battery was disconnected. Threw the cables on and fired right up ran great. Driving home ran perfect until about a mile from my house. Pulled up to red light and while sitting there the idle would surge from about 900 to 1500. Ive seen plenty of cars that when you disconnect the battery the throttle body and sometimes throttle body and IAC have to be cleaned before it will hold a steady idle again. So when I got home I cleaned throttle body and IAC with some carb cleaner a piece of scotch bright and an old tooth brush. Put all back together unhooked battery again for about 10 minutes to give it all a fresh start just like I would do at work. Also blead cooling system and topped off with my fill funnel. Well after this started her up and let idle for a good while when I was picking all of my stuff up. Ran perfect. Went around the block and first stop sign it started surging again. The temp was just under if not right at where the thermostat should be opening at this point. So I flipped the heat and cooling fans off to let it warm up just a little more and see if it would even out. When I turned the heater blower motor off the car idled down and almost stalled. Still surging just now at a lot lower rpm. I have CEL on and a code for both o2 sensors. These are the only 2 codes in the PCM. Get back under the hood to visually inspect o2 sensors and wirring. O2s look brand new but are the universal ones that you splice in. But whoever did them did it the right way by soldering the 2 wire ends together and putting heat shrink sleeves over each connection. While looking at o2s I spotted the PCV valve and took it off to inspect and clean also. PCV looks new also. The next thing I notice is that on the breather (more towards the driver side top of the breather box housing that sits on top of the throttle body) I have a sensor there. I would assume its a intake air temp sensor. But I have no plug whatsoever in my harness to go to that IAT sensor. I have a decent code reader that shows a pretty good live data stream. So I go into live data and go to the IAT sensor and the code reader shows that the IAT is reading 360 degrees Fahrenheit. Its about 40 degrees here now so there is no possible way that reading is right. Even in the desert still no way in hell it would be 360 degrees going into the throttle body. Im not even sure if a car would run with that hot of air being taken in. So my questions are.#1 Why do I have a IAT sensor but no connector in the harness. #2 could my o2 sensor codes be there bc the air being pulled in is missing part of the metering process done by the IAT and MAP sensor and mass air flow. #3 with no vaccuum leaks (brought smoke machine leak tester home from work) also sprayed carb cleaner around and deff no vaccuum leaks unless maybe an internal leak in the IAC. And a clean throttle body and iAC, coolant system air free and full what else coulf be the problem. I thought about fuel pressure and timming and even bringing volt meter home with me from my toolbox at work and testing the o2 sensors. And #4 if the problem was something with fuel/timming/o2 sensors then why is my idle having such a dramatic change just by turning the HVAC blower motor on and off. Any help for me to figure this headach out would be greatly appreciated. I am pretty well experienced mechanic but this is the first time ive really worked on a honda. And the first time I have seen an idle problem be so stubborn. Where would yall go from here after the info I have told you and how much is not having a IAT effecting the problem I have

JDMswagSerf

Holy Molly lol

Cut it up
State the important things
Too much n too lazy to read

B_Swapped93

Cliffs for others: IAT is reading 360* (degree's F) has IAT in intake but not plugged in cause no connector on the harness, and cel is on for both o2 sensors. however the o2's are hacked in via splicing

The HAS to be the remains of where the old one was split the loom open and grab the pigtail from a junk yard then splice it in, 2nd pic of intake stock intake or aftermarket ? 3rd did you correct the spliced in o2's with proper clip ones ?. I had one on my car and I mixed up the wires car threw a cel for it replaced with proper clip style all was good.

Former User

In the future, please create a thread title that summarizes the problem. "need help before I go crazy" is not adequate.

chevy383

This was my first ever post in any forum so i appoligize about title and length. Just wanted to well explain what i saw and tried. The o2 sensor wiring did not seem right to me so wanted to look into more before changing them. And i looked all under the corrugated tubing and saw no sign that there ever was a IAT sensor in this harness. The idle isue is my main concern. CEL can stay on for an o2 code as long as i can get it to run correctly also.

B_Swapped93

Well there's no way the car came from the factory with out one split the loom open and find a new connector. For the o2's replace them with non hacked ones.

chevy383

Know any places i could get a decently priced harness that is all factory? I would honestly rather spend the time and money to put in a new harness than to try and fix a chopped up one. And also do you know any reason why when i turn my blower motor on for the heat my idle increases about 700 rpm. Still surges but does it at a lot higher rpm

B_Swapped93

Here VERY good quality, I have the b-series one for DC integra's and love it http://www.rywire.com/catalog/dserie...d8256a6add0811. The heater operates off of the coolant heat I recommend bleeding the system.

chevy383

Thanks. And i did bleed the system. on an incline with front higher than rear with a fill funnel. I am a mechanic and have pretty good knowledge of how things work but i honestly think something with the wiring is causing my problems. I have great heat. It just greatly effects my idle with the blower on. Even running the ac it does. Its the actual blower motor that is changing idle. Doesnt have to be on heat. But other problems are the speedo jumps all around. Idling this morning was reading 120mph. When i turn ac compressor on cig lighter quits working. Its got a ton of electrical problems but the harness looks to be in good shape other than o2 sensors

chevy383

Thanks. And i did bleed the system. on an incline with front higher than rear with a fill funnel. I am a mechanic and have pretty good knowledge of how things work but i honestly think something with the wiring is causing my problems. I have great heat. It just greatly effects my idle with the blower on. Even running the ac it does. Its the actual blower motor that is changing idle. Doesnt have to be on heat. But other problems are the speedo jumps all around. Idling this morning was reading 120mph. When i turn ac compressor on cig lighter quits working. Its got a ton of electrical problems but the harness looks to be in good shape other than o2 sensors