Hi all! After I go to a grocery store for 20 min. and try to start my car, it always starts but RPMs dip low to 500. Engine sputters for few seconds, and then restores to normal 800-900 rpm. I replaced IAC valve, EGR valve, spark plugs, checked ignition coils, added injector cleaners, cleaned EGR passage. Everything stock. Passed smog last summer. Btw I live in CA. No Check Engine light. Few times I had to press accelerator for the car not to stall. Never any issues on cold start or while driving. Also gas mileage aint what it used to be but oh well. Any ideas?

 

Try something easy like cleaning the throttle body and lubing the TB plate hinges with some all purpose oil and a q-tip. Also clean and lube the spring that controls the throttle wire. Hopefully something is just stuck.

 

tranny maybe?

 

Ive been pretty religious about tranny fluid changes. No issues with performance or shifting. I use Redline type F since it has been praised here on the forum. I will try to maintain TB with some oil tomorrow

 

It appears as though you have covered most of the basic causes for a rough idle. If it does it only while warm, it could be due to the winter blended fuel. Try a high octane fuel without the ethanol if it's available and add a can of Seafoam to the gas tank. If it continues, recheck your previous work and have the fuel pressure checked.

 

I just did seafoam treatment and my car accelerates better but still surges idle on hot start. I noticed when i pump brakes or turn the steering wheel upon start that rpms stay up. Otherwise rpm dips low and then comes to normal.Is this normal?

 

I had a 99 come to me with the same issue and turned out to be a failing coil.
Note: I couldn't find it with the unplugging method so your going to have to wait for the one of the coils to go. You'll know when the engine starts to shake and both CEL and TCS will illuminate.
Hows the redline doing for you? I kept away from it since our cars aren't DBW.

 

Redline is awesome. There's less overheating and I can feel it in the shifting. Whenever I drove for >1hr (DW ATF) it used to shift hard between P and D. Now, it shifts much smoother (Redline F) and I can feel more power from the engine

 

I got my issue resolved by loosing up the screw on my throttle body. I don't recommend to do this since I'm not sure if this will impact my idle in the long run. Nothing else seemed to work... Any input?

 

The screw I mentioned adjusts the idle speed

 

You might have a problem with fuel boiling issue.
A member on here advised to remove the plastic engine cover and if it alleviates the problem then you have the fuel boiling issue.
Just 4 10mm hold the engine cover.

 

Having the same issue, cleaned my EGR ports, changed the EGR, cleaned my throttle body & IACV and changed ALL my plugs and coils.


https://acurazine.com/forums/showthr...ht=fuel+filter

Maybe taking a look at this forum might help you.

 

My first thought was IAC. I had a Mustang 4.6L that wouldn't idle once warm. I cleaned the original IAC - no help. I replaced the IAC with a NAPA part, but it didn't solve it. I replaced it again with a different brand, and no help. I finally took it to my mechanic, and they said "it's the IAC no doubt about it." I let them install a factory replacement, and voila, it ran like new. The factory part cost 5 times more than aftermarket, but it actually worked.

If you installed an aftermarket IAC, you might want to try a factory one. Adjusting the idle air is the IAC's job.

 

That would be my guess as well. Someone on the forum also had success by disconnecting the vacuum line to the fuel pressure regulator and plugging the line. Two, no cost, easy, and fast things to try.

 

How did you check the ignition coils? You need special equipment to check those, not just a DMM...

Could also be a flaky PGM-FI relay.
Everything there is to know about your Honda/Acura main relay:
http://www.tegger.com/hondafaq/mainr....html#blueline
http://www.tegger.com/hondafaq/mainr...mainrelay.html