thaler4cuse

Hi guys, new here, new to Honda in general. I have bought a 99 civic with some issues to repair and make a daily driver. The car had a leaking power steering pump, brakes were very hard to push, TPS code, and surging issue. The kid that had it before I bought it installed an aftermarket intake and a header on the car, also claims he replaced the timing belt 10K ago.


What I've done thus far:


Repaired the PS leak


Replaced the brake booster, had to pull intake to do so, installed with new gasket and coolant. at first the brakes were still hard to push, I pulled the vacuum line off the booster and there was no vacuum from it. I replaced that hose and walla, brakes now, however when they are depressed the hunting gets worse like it's pulling too much vacuum?


Replaced the TPS and set it to per the specs in the manual.


I pulled the IAC and the TB off and cleaned them when I had the intake off, and actually would up replacing the IAC valve a few days ago thinking that it was it but it's not, money poorly spent...


The car didn't hunt that bad before I replaced all these parts. When it is warm it completely dies when it's hunting.


For poops and giggles, I unplugged the TPS tonight. at first it help a bit and stayed around 900 RPM, as soon as I started to load it (went for a drive) when I stopped it started to hunt again, not as bad but still hunting but the car did not stall.


I'm lost at this point. I've bleed coolant, checked for vacuum leaks, I fabricated a smoke tester from a youtube video I found and also pinched off the hoses off the intake with some pliers, still not luck.


Any help is greatly appreciated.


Thanks and have a great day.

ezone

Did you clamp off the vac hose to the brake booster?

Got codes?

Get it warmed up and surging.
Inside the throttle body, you can see the ports drilled in the side for the IAC. Plug the port with your fingers and see if the idle comes down to normal.

thaler4cuse

I have clamped off the brake booster line, no change.


My TB only has one port. with plugging it with my finger, it stalls immediately.


The codes I have with the TPS plugged in are P0131 Bank 1 Sensor 1 Low voltage. And a P1399 my reader has no definition for it and it says pending.


With the TPS unplugged I only have a TPS code.


Today it wasn't hunting as bad, it would hunt from 200RPM to around 1K, and would stall when it dropped from time to time.


Would an aftermarket TPS do this? Think the intake is warped? Could it be an injector issue? Fuel filter?


Thanks for the help Ezone.

ezone

So all the commotion is being allowed by the IAC, and controlled (or uncontrolled) by the PCM.

Low voltage.
Got freeze frame data to go along with this code?
Could be anything that causes an O2 sensor to read low, such as a lean condition or low fuel pressure.



Or a bad sensor.
Um......Unplug the O2 sensor, do a battery disconnect, leave the sensor unplugged and see if it runs any better.

Not defined in my info, but IIRC it means the same as P0300 random misfire.

A misadjusted one might.

What is your TPS voltage set at @closed throttle?

Did it start running bad after you replaced this?

thaler4cuse

I do not have any freeze frame data, not sure how to do that?

Here is what happened when I reset the ECM and disconnected the O2 sensor, the idle came up to 1200 at start up then stabilized around 800, I took the car on a nice long drive after it got warm, when I would come to a stop sign, the idle would drop very very low 100, 200RPM, wouldn't stall though, wouldn't surge either. but whenever a electrical component turns on, like the radiator fan, the RPM raises and then comes back down low and stabilizes.

Obviously I have P0135 for the O2 and I am still getting the P1399 probably due to the very low Idle.


When I adjusted the TPS I adjusted it to .5 closed throttle

It started running bad after I made all the repairs, I made the repairs at once. Pulled intake, replaced brake booster, replaced TPS, repaired exhaust leak right after cat, cleaned TB and IAC. After all those repairs I fired it up and it ran like that.


Thanks

ezone

Would be obtained from a good scantool. The cheapest code readers may not have the ability to give the info. Also, it's gone once codes are erased.

Kinda makes it tougher to decide which one may have had something to do with it.
1200 and higher sounds normal for a cold start, then the RPM comes down as the engine gets warmed up..

Have you let it do an idle relearn yet?

99% show on a datalist as 0.49v, this value is extremely consistent across the entire car line. Just a few hundredths of a volt off target can cause odd things to happen, this is one of the reasons Honda makes you buy an entire throttle body to get the TPS for so many of their cars.


Check the intake areas for vacuum leaks?
Vacuum port left open from the cruise line?
Gasket problem?

EGR sticking open?
Lean condition?

thaler4cuse

OK so I adjusted my TPS to read .49V, changed spark plugs, installed a new O2 sensor and installed a new fuel filter. No more CEL. After that I performed the Idle relearn. It seemed to help, car does not surge at all however the idle is still very low. Around 300-400 RPM. Why such the variation in IDLE? Does the idle relearn take a few key cycles to learn it. Where do Civics like to idle at?


Car does not have EGR. I've checked the whole system for vacuum leaks as well as an intake leak, none were found.


I have no more codes and the car runs great. Just an idle issue.