cehcivic15

95 civic with b16a swap. my car started doing the whole idle surge a few months ago throwing code 14. so i cleaned it and it kept doing it. i bought a new one from oreilly auto parts and it would act alot better. but when i would come to a stop you could here it all of a sudden suck real hard and the rpm's would jump just a few times or so. after that one day my car died and wouldnt start until i opened the idle adjust screw all the way open and threw the code 14 again. i took the part back to oreillys and a friend gave me a used iacv. and it acted better and would still suck real hard when braking and jump in rpm's. last night my car started idling at 4000 rpm's throwing code 14 again. i took off the fitvalve and cleaned and checked it. if you put your finger over the bottom hole in the throttle body nothing changes (fitv) but if you put your finger over the top hole (iacv) it will die down and idle about right. also if you leave the iacv hooked up and unbolt it nothing changes unless you plug the hole with you finger it will idle better. im thinking the iacv is getting stuck open sucking in too much air like a vaccuum leak. uhhhhh i know long story.......but today i got another used one off of a 99si b16 and only one bolt hole lines up cause its different but now it idles right even tho i havent drove it.
so i was wanting to know if there could be somthing else causing all of this or if im right that i just cant seem to find a good iacv.
also i know how to set idle by unplugging iacv setting rpm removing back-up fuse etc...
timing is right there are no vaccuum leaks
also i have tried 3 differnt ecus with all the same results

cehcivic15

also have tried multiple map and tps sensors with no change

Former User

Did you calibrate the TPS output voltages?

Have you tested the ECT sensor?

When those tow sensors are working fine, then adjust the idle speed (see diagram in FAQs sticky).

cehcivic15

ronj you always make me feel stupid lol....i dont know how to calibrate tps and dont know what a ect is.
as for the tps do i just loosen the bolts and move it to where it reads a certain voltage at closed throttle?

Former User

Sorry, I don't want to make anyone feel stupid. We're all learning here.

Loosen the TPS bolts and turn the TPS sensor until its output voltage reads about 0.5V. Then check the TPS output voltage at WOT to verify that it is about 4.5V.

When the engine is fully warmed up, unplug the 2P connector from the ECT sensor (Grn/Wht and Red/Wht wires) below the distributor. The resistance across the sensor terminals should be 200-400 Ohms.

cehcivic15

key in the on position not running?

Former User

Yes for the TPS tests.

No/off for the ECT sensor test.

cehcivic15

okay ill head home and test these and report back....thanks ronj

cehcivic15

okay the tps tested out right. when i did the ect test, the only reading i could get was with it set on 20k and it read 2.11 or on 200k and read .211 so i think that is 211 ohms. as i backed out of the driveway and then clutched to put it into 1st, it started surging again with no cel

Former User

Set the multimeter to the 200 Ohm scale to take the ECT sensor resistance measurement.

cehcivic15

it just reads 1 as it does without touching anything as well....i guess i did it right, got it up to temp and unhooked the connector and touched the terminals on the dizzy side of the connector

cehcivic15

sorry wrong one

cehcivic15

the coolant temp sensor okay.... set on 200 the sensor read 1 with the connector not hooked up, set on 2k it read .331

Former User

Engine fully warmed up, right? The ECT sensor is toast. It's reading 1 Ohm but should be reading 200-400 Ohms.

It's the TW sensor in this diagram:

cehcivic15

yes that is correct i tried and tried and it is the right sensor, it read 1. how did you ever suspect that was the culprit of my weird symptoms

Former User

1) You showed that the IACV was bypassing too much air to the IM (by covering the IACV hole in TB with your finger).

2) One of the main controls for idle speed is engine temperature provided by the ECT sensor to the ECU, which uses this information to control air bypass to the IM by the IACV. If the ECT sensor is sending incorrect signals to the ECU, the idle speed will be abnormal.

3) A bad ECT sensor does not always throw a CEL code.

cehcivic15

i guess what i mean is how does that work in that it effects my surging like that

cehcivic15

thank you honda guru lol...how do you know all this stuff..do you have a pc made by honda for diagnosing problems or are you a engineer for honda lol

and not for just helping me figure it out but explaining it so that i can learn for next time

Former User

Neither. I just like solving tech problems. It's a hobby.

coupedragracing

wow! that was some good information.. you should sticky this. if not already a sticky in FAQs forum... i come across alot of honda's with idleing problems and surge problems too.. just one more way i learn to diagnosis problems.. thanks guys!

cehcivic15

okay repaced the ect sensor and started it up and let it run for a minute with no problems. played with the brake pedal for a few minutes while it idled. put it in reverse and let off the brake to coast backwards down the driveway and it started surging again. drove it around the block and everytime i clutched and braked it did the whole suckin sound and rpm jump. if im in first or second gear with foot barely on gas it surges a few times and my whole car shakes. doing the same thing with no cel code yet. so now im really thinking that it has to be that iacv

Former User

Did you reset the ECU?

cehcivic15

no, ill do it now

cehcivic15

reset and still doin it

cehcivic15

when i coast backwards with foot on brake it sucks and rpms jump and will surge for a minute