Okay... 97 accord SE 2.4 4cyl, FB122? 178k miles, rebuilt auto tranny.

When i first start the car it will idle 2500rpm and start hopping between 2000 and 2500 (I believe the computer is shunting the fuel injectors in an attempt to control engine speed).When car is fully warm, idle drops to 1500 (the hopping quits).

Cold start, finger in FITV hole, idle slows some, strong suction. Once engine is warm, FITV hole takes over four seconds to put any draw on finger, and even then it is weak. However, IAC hole will still pull a blister, so to speak. With finger in IAC hole, idle drops to 1100rpm, unplugging it is the same.

No codes, no mil/cel, no codes on my scanmaster and elm327 obd2 reader.

Sometimes, in what I believe is a related problem, during driving, car will stumble, and if you press the gas, get even weaker before backfiring through the intake, usually twice, then launching at full power. Power is weak overall and varies unpredictably during regular driving. This problem first appeared as weak power and got progressively worse over time.

I've had three different IACs on the car, they all act the same,
I've redone the cooling system (FItV valve closes),
replaced the ECT sensor with a new one, changed the two other ones with used sensors, no change, replaced:

fuel pump, filter, regulator

entire ignition, including crank and cam sensors and distributor, plugs, wires

map sensor and both o2 sensors

TPS sensor

a lot of vacuum tubes (all four that come from the intake manifold).

swapped a test pipe for the cat

cleaned egr channel, replaced egr with a new one, replaced egr solenoids

sprayed highly flammable brake parts cleaner over the hoses while praying for it to ignite - no joy. (no vacuum leak that i can tell)

replaced master relay

pulled pcv valve, it rattles, plugging it with a finger does not change idle speed

Unhooking every vacuum and electrical device on the firewall, including brake booster.

dug through alldata (no electrical load sensor in underhood fusebox), youtube, forums.

flung my hands in the air and gave up, several times, and tried enjoying driving my old dodge spirit for a while before coming back to the Honda and trying something else...


Any ideas as to what could be causing the IAC to stay wide open? Any ideas as to why the idle still stays so high even with the iac unplugged and the fitv closed?

Thanks, Ernie

 

Welcome to HAF.

Was any of this happening before the trans change?

Need to be sure the cooling system has been bleed of all air. Next be sure the small coolant lines to the IAC are clear and allowing coolant to flow. Do the same for the FITV just to be sure.

 

Trans change 50k miles ago, i don't think I was noticing power loss then. I had a heater hose rupture when I changed the timing belt at 160k so I went through the system then, and have re-burped the system (radiator cap off, on steep incline then additionally on car ramps) when changing the iac and ect sensors, when pulled iac the first second and third time I was rewarded with nice fresh green antifreeze spurts.

I haven't pulled the lines from the FITV but it is closing near perfectly and the car still idles at 1100rpm with both the fitv hole and the iac holes plugged (and electrical unplugged from iac), so I guess I was thinking I had eliminated coolant as part of the issue... I wasn't real thrilled with my burping technique as compared to one of those funnels like they use on youtube videos. Do you think the putting car ramps on a hill to do the burp thing was good enough or do I need to take it to a shop?

Thanks man, Ernie

 

On the 5th gen's (94-97) there is a bleeder on the t-stat housing.

I've never used one of those funnels. Just the factory shop manual procedure and never had an issue.

I'm sure you have given the TB a good cleaning - get both sides and the edges of the butterfly. Want to be sure it is closing all the way and not getting hung up on "build up". Also be sure there is a bit of slack in the throttle cable.

I'd also do additional checks for a vac leak....intake manifold, ect.

 

Welcome to the forums..enjoy your time in here.A lot of guys to help with your answers..

Merry Christmas WheelBrokerAng

 

That is a very high idle considering when both FITV and IAC ports are blocked. Did you do any work on the vehicle right before you started having this problem?

You have to have a pretty big air leak. Since you looked for leaks by spraying cleaner around the engine, I'd start looking at the throttle plate.

Clean the throttle body bore and both sides of the throttle plate. Verify that there is some slack in the throttle cable and that none of the cables are preventing the throttle body from closing completely.