nothing_shocking

My eg3 does a rpm jump sometimes when I shift to neutral and brake before a stop sign or light. Everything is going fine, shift to neutral and start braking, and it'll jump up to about 1500 for a second and then come back down to normal idle rpm. I recently cleaned the throttle plate, IACV, etc. D16Z6 turbo and it's only done this jump since I cleaned the stuff.

nothing_shocking

no idea's at all?

91blackEF

i had a problem sorta like this and it happened to be my main engine ground i replaced it with a thicker gauge wire and no more problems when i was in neutral if i let of the brake and tapped it real quick i would get a 500 rpm jump idk how but the ground fixed it

nothing_shocking

ok i'll check those, but any other idea's?

nothing_shocking

all the grounds were connected and looked just fine but it still does it.

orangemanja

Let me know what you find i have the same exact problem iv been trying to diagnose turbo b16a2 swap in my 99 civic ex. New iacv cleaned throttle body checked for vacume leaks.
I even took it to honda cause i was sick of messing with it and havent had time but honda said my car was to heavily modified for them to handle lol they just didnt want to **** with it.
anyways these are my next steps to check
TPS – Throttle Position Sensor bad
Check for cracked or bad vacuum hoses- spray carb cleaner if the idle changes you have a leak
Check pcv valve for leak

i have been searching this to and putting some possible notes and saving it to notepad
you may be able to use something ill paste it

iacv
there is a way to ADJUST it by turning a little 5-point allen bolt on the side of it.
TPS – Throttle Position Sensor bad
.Check to see if the nuts holding the TB and the IM on are tight

Check for cracked or bad vacuum hoses
. i know this thread is very old but did anyone check the map sensor because it sounded like your guy's problem. have you guys tried disconnecting the map sensor for awhile to see if it goes back to normal idle?


The PCV valve could also be the culprit. Take it out and examine it. If it is cracked it could be causing a vacuum leak.
Next cover both holes up with your fingers. The car should sputter and die (or almost die). If it does then the source of your crappy idle is the IACV. Replace it. If you want you can test the IACV. Shut the car off and put + battery voltage to the blk/yel terminal (on the valve) and momentarily touch ground to the blu/yel side. When doing this the valve should click, if it doesn’t, replace it.

If, when covering both holes the car still has a high idle, you have a vacuum leak somewhere. Again check the IM and TB nuts. You can spray carb cleaner around those areas and if any gets sucked in (the engine will rev) you have found your leak. Another source of vacuum leaks are where the FITV and IACV connect to the IM. Either replace the gaskets or use silicone gasket sealant.

FPRIVATE "TYPE=PICT;ALT=Cool" If nothing has worked you should test your TPS. Probe the middle wire on the TPS plug (with the key on but not running, and the plug still connected to the sensor) with the + probe on the volt meter, and the neg probe to ground. You should have .5v with a fully closed throttle plate and 4.8v with it wide open. If the TPS is off, replace it. My TPS was .425v to 4.55v and it idles fine now so I don’t know how big the margin of error is. Also, it is pretty rare for these to go bad.


Three things I know and have seen to cause a surging idle:

1) air in the cooling system - when hot coolant comes in contact with the AICV (idle air control valve) it gives the ECU a reference as to what to set for an idle. The ECU then lowers the idle because it senses that the engine is hot. When it does that the waterpump of course slows down with the rest of the engine and is not spinning fast enough to pump a sufficient and constant flow of coolant because there are air pockets in the system preventing it. When that happens, the coolant that used to be in contact with the AICV now retriets, the ECU then senses that the engine is cold, raises the rpms, the waterpump surges and speeds up, pushing coolant back onto the AICV, and the cycle becomes endless.
2) bad Idle Air Control Valve - on the back of the IM and should have a blue w/yellow and a black w/yellow wire going to it. Cleaning the filter screen inside the AICV will help restore a more steady idle. To do so, you must remove the valve assembly from the throttle body and clean out with brake cleaner.

nothing_shocking

Nice. I cleaned the IACV about a week or so ago and I'm planning on bleeding the coolant soon too. I'm doing a good bit of work on it this friday so I'll add this stuff to the check list. Thanks

orangemanja

Ya i did the same with the coolant i even flushed the system
i think my porblem is the timing is off but i might be wrong