integra LS, engine stuttering and cutting off

[my integra]

Hi, searched the forum but could not find this problem. Engine starts up cold or warm. Stutters a bit when you just press the throttle upto about 1200 rpms once its warmed up. It will climb on up to the upper rpm range without stuttering and stay there for 30 seconds and beyond, but when you let off the throttle and let it idle for a few seconds and touch the throttle it will shutter and at timesquickly shut off. It will start back up right away or sometimes in 2 to 3 seconds. Seems as it nears idle and touch the throttle it studders most times and will studder then sometimesdies quickly. The engines revs nicely and is very responsive at high rpms but once the throttle is released for a few seconds and open the throttle a bit it stubbles. I can romp down on it and runs like a bat out of hell.
So what am I looking for here. Checked the fuel relay, and vac hoses. Replaced the fuel filter. Plugs are nice and tan. Have not checked fuel pump pressure, but usually fuel pumps either work or dont work. Pressure regulator? Would the regulator cause this? Checked the IACV and Fitv and ok. Sprayed injection cleaner and still no change.
1990 integra LS B18 auto
Thanks, hope some will reply here

 

[j13]

Make sure your air filter is not filthy blocking air. Do you have a CEL (Check Engine Light)?

Maybe your fuel pump?

 

[my integra]

Filter is fine. No check engine light on. thanks

 

[Prozon]

I've heard "fuel pumps either work or they don't" but that's not always the case.
I would tell you to check your fuel pressure but i'm pretty sure you can't on Integra's lol.
I don't think that's the problem anyways.

I'm thinking a sensor. Which one? Not sure. Fairly certain it's not the fuel pump though.

 

[my integra]

the integra has a threaded port on top of the fuel filter for a gage. I have a gage of 1/8 pipe thread, port thread is smaller. I would need to find out thread size and get a reducing fitting in order to use my gage

 

[my integra]

Btw, most electric in tank fuel pumps have a fine mesh strainer on the intake of the pump, does this pump have one, and if so anyone found it "clogging" up momentary if some trash/sediment was in the gas tank and causing my problem? Thanks

 

[Prozon]

Is it possible to keep the engine running? Are you able to just keep it revved up and keep it from dying?

 

[my integra]

yes. Even as I hold the engine running at say 3000 rpms it does not faulter.It will run at rpms over idle and never faulters. As I slow the engine down it still is ok. But when I let the engine idle at 1000 or so and feather the throttle it studders some and at times then idle may run smooth without a studder then quickly will die. Turn key on, starts right up and may idle for 10 minutes without a studder.
When I feather the throttle its like a flat spot, Never backfires or runs rough.

 

[my integra]

I had put this problem aside and now started back on it. I removed and cleaned both the FITV and the ICAV and reinstalled them and engine still has same problem.
Question, with the IACV not hunting and holding idle most of the time after warm up and then idle dropping and hesitating once the throttle is opened slightly, at times could the IACV be bad , even though it was cleaned, causing the idle to drop and engine hesitate and sometimes cut off when throtle opens. When driving ion the road it runs fine. It's when you come to a stop at times, it will sputter and or hesitate and cut off at times. Then at other times, even at stops, it will idle fine "except" sometimes there is a definite engine miss abrupty for a split second and 10 seconds or more another abrupt miss.
Looking at the the wiring of the internals of the IACV it appears the coils could become faulty or the valve stick and cause the IACV to maybe become inoperative. With the electrical plug of the IACV disconnected would'nt this eliminate the valve out of the loop if it was causing the problem? I have done this and of course the check engine light comes on and the idle is lower but does this eliminate the IACV, or if the IACV is faulty within it would/could still cause the problem?
thanks