Mg7marine

So, I have checked the boards and they have led me to some of my fixes. My wife drives a 1999 Honda Civic DX 3-door hatchback. About a month ago I was coming home from work in it and all of a sudden I had a loss of power, surging idle and the CEL came on. I took it to the parts house the next day and the code that was given was for the IAC. I went home did some research (as I said in my intro post... I can do wonders with old cars [read Carb'd] but these new fangled gadgets you whipper-snappers have these days can be a mystery) and looked where I could get one. I went with a Honda parts dealer on EBay. It arrived a few days later and I installed it. I did a short test drive... the CEL was gone... so I drove it to work the next day. About 15 minutes to work the CEL came on again and the surges started once more... Now... to make a long, long, long story short... I have at this point had error codes for the MAP sensor (changed) and the TPS (changed). I have a new/used TB because the damn breakaway bolts for the TPS... well... broke away with part of the TB housing. I would like to commend the person that posted about scoring the bolts (found the post too late) and just getting a screw driver to move em out. I have checked to make sure I have enough coolant and that I do not have air in the lines. I do not have any vacuum leaks that I could find. After I changed the TPS the CEL went off, but the idle still was a problem. I took the car to Tyresplus to get them to scan it and they said the only thing they could find was possibly a bad IAC (95% sure he says) or the ECU was going bad (doubtful). I ordered a brand new, not reman/tested IAC thinking maybe I had a bad part... I put that on today and I still get the surging idle. I still do not have a CEL light after letting it idle for 10 minutes. I also have reset the idle computer. I am kinda at whits end here.

W95civicEXcoupe

How are your gaskets.

I know this sounds stupid and I might get a flame, but... I only had surge idle issues (once was so bad it did so IN DRIVE) when the HG was definitively blown. Blue Devil solved.

Not saying Blue Devil is what you should do, just that something in my engine needs Blue Devil on it or the engine dont work right. Including surging idle as you say.

1995 Civic 1.6L

09chaplak

Put your finger over the hole in the throttle body going to the IACV. Does the surging stop?

Mg7marine

No flames here, mate... Any idea is good for now. If the HG had been blown it would have shown up on the diagnostic as a misfired cylinder. Also you usually have a temperature problem with anything bad with the head. Thank you for the suggestion though. As I said... at this point... I am open to about anything.

Mg7marine

I will check again... but I believe the idle settles out (I have done so much some of it is beginning to get fuzzy).

Former User

Which IACV code? There are two different ones.

Are any CEL codes currently thrown?

Did you voltage calibrate the TPS?

Mg7marine

As mentioned earlier... I have no CEL or codes. I checked the voltage TO the TPS... I am not sure what you are talkin about other than that...

Former User

When you install a new TPS, it must be voltage calibrated. Loosen the TPS bolts and rotate the TPS until the output voltage to the ECU reads 0.5V at closed throttle. Then tighten the bolts.

09chaplak

I forget the exact colors, red and yellow maybe, but it's the middle wire of the three. Don't need the car turned over just have the key turned to the ON(II) position and you can calibrate it from there.

Travlash

If you have cruise control , there is a hose that runs from the cruise control module on the driver side and plugs into the back of the intake manifold , it may have popped out . Check that , my friend just had the same problem as you are describing and did everything you did. However we found out the hose from the cc to the intake fell out .

Mg7marine

Ok... I just put the new one on... and had it what looked like in the same position as the old one. Will give that a shot.

kngcrx

Double check your coolant level. If it's low and/or have an air bubble in the IAC, the vehicle will surge. Make sure you bleed the coolant system.

Mg7marine

Ok... adjusted TPS to 0.5V at closed throttle. I drove the car for 50 miles... no CEL, no problems. I stopped at stop lights and everything. When I stopped it would give a mild surge (about 3 times 1000 to 1200 RPMs) and would go back to regular idle. I figured it was relearning the idle. I had no problems at all while driving. I came to a red light that is one of the longer lights in town... and CEL came on... rapid surging...

I took the car to the Advance today and I got the P0505 error. I have a new IAC to put on... so... I will recheck voltage and then put the new one on. I will let you guys know how it goes.

In response to Chaplak, if I put my finger over the IAC hole in the TB the idle does definitely settle with no surging. In response to Travlash... what is cruise control???

Former User

Clean the IACV and Ohm test the ECT sensor.

Mg7marine

The IAC is brand new... right out of the box. I have also cleaned (you could eat off it if you want) the TB and the IACV port in the TB. I will have to check the ECT sensor. How would that make the idle surge? BTW... I really appreciate all you guys giving me a hand on this...

Former User

The ECU uses coolant temp to decide what the idle speed should be. Obviously, if the ECT sensor sends bad info to the ECU, the idle will have issues.

Mg7marine

Sorry in the delay in me getting back... been sick off or it has been raining. I put in a new ECT (just as easy to buy one as to check it). I have bled the coolant again after changing the ECT and for a while it idled fine... then it went back to dipping... surge x3, regular idle... surge x3... regular idle (with heater on the bleed coolant). I turned on the air and decided to take it for a spin... It started with the rough idle about a mile from the house... I took it to Advance again and it flagged 4 errors... all 4 were P0505 (IAC). I have changed that part out 2x... so I know it cannot be the part. I did also noticed that when I turned off the air/heat, when I got it home, that it started rapidly surging...

Travlash

Hey man, i have posted on this thread once before. Seriously think about checking under your intake manifold. there is a hose that runs of a little nipple on the back of the intake manifold. the hose runs into the cruise control. Make sure the hose is on there. If there isn't cruise control, make sure it is blocked off.

Former User

Remove the intake. With idle surging, use you finger to cover the hole inside the throttle body leading to the IACV. Does the surging stop?