High Idle, then fluctuating, now high then stall? Getting Pissed!
 

OK, I have done alot to my friend's 1998 Honda Civic LX, d16y7 engine 190K miles. The things I've done are as followed. Clean TB plate, replace IAC valve, TPS, spark plugs, and air charge sensor. I forgot all the codes but one was p0505 and the others were TPS and air charge sensor the one that goes into the airbox. The idle went high like around 2-3K rpm after replace the TB gasket to put in the IAC valve gasket that the substandard "mechanic" failed to put in as he reused the old gasket and put silicone to doctor it a little bit. I also adjust the throttle cable linkage to reduce the slack. topped off the coolant and yet idle fluctuates after starting up high at 4K rpm then goes down to 2 and 4 as it fluctuate. I know everyone has seen posts like this all the time, but this time its very serious, I really need help! This is not my car but my friend's car. She is on fixed income have a child to raise and bills to pay so she just about had it with throwing money and parts into fixing. If anyone can give me a good solution, that has been proven will end this problem, please let me know. Thank you.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

Is the TPS code fixed?
MAP code fixed?

Check for vacuum leaks

Use your fingers to block the open port(s) in the throttle body opening to see if the idle speed comes down to or well below normal RPM

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

P0122, P0108, P0505 were active and recommendation was to replace throttle body, which was done, still the same but a little bit better. I disconnected the battery and let it sat for 15 minutes, still the same. The throttle body was replaced with one recovered from a salvaged vehicle. In regards to the opened port, I did cover it idle did went down, hissing stop, but I didn't think anything much of it since it appears normal to have an opening on the throttle body wall. Hmm maybe im wrong. but please check out the video I uploaded.

https://www.youtube.com/watch?v=dPmA...ature=youtu.be

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

Aaaaand what valve is attached to that port? (follow the paassage) Maybe the IAC on your new used unit is stuck wide open?

Did this new used throttle body fix the TPS code or is that still a problem?

P0108 is for the MAP sensor. That code and TPS code must be fixed.

(Earlier you said "air charge sensor" so I figured you meant the IAT sensor, but P0108 is for the MAP sensor, which is critical for fuel control)

Also...Video unavailable fail.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

Everything on that used TB was original.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

#1, that tach looks broken AF. It's got to be reading far higher than the engine is actually running.

A typical idle surge will repeatedly cut in and out from 2000 to 1200 RPM.
But I can't HEAR the engine in your video.


#2, you said you replaced the throttle body.....but didn't answer the questions.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

Yes it was replaced but still aint fixed the effing problem. getting really angry now.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

id wipe all codes and repair -check all codes showing.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

Is it still setting a TPS code?
Is it still setting a MAP code?
(oh yea AFTER erasing the codes do they set again)

And didn't you follow that one passage like I said--to find where it leads? The IAC on the new used throttle body is probably stuck wide open.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

Yes I did earlier, but not throughly due to heat. However, tomorrow, I will investigate the problem again, but placing my finger on the hole leading to IAC valve and see if that stops the issue. Earlier, I did replace the IAC valve on the previous TB and didn't fix the issue also the TPS, which I didn't calibrate on that one since I don't have a multimeter tool, and air temp sensor, again same problems. I'll keep you posted as new leads come about.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

OK, sorry I been busy lately with work and stuff. So what we did was replaced the intake manifold gasket, and MAP sensor. Still does the same thing. However I was given several codes. the codes are P0108, p0122, and P0113. It still has the fluctuating idle and also it hesitates with the accelerator pedal being pressed. Car also dies at times.

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

P0108: https://www.autocodes.com/p0108_honda.html
P0122: https://www.autocodes.com/p0122_honda.html
P0113: https://www.autocodes.com/p0113_honda.html

Seems like these combined with other issues are leaning towards a faulty ECU or harness?

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

A good scanner and a voltmeter could answer a lot of questions..

Re: High Idle, then fluctuating, now high then stall? Getting Pissed!
 

Maybe the OP can look into this one that's been mentioned on a few threads: