aeon117

Have a Honda that cranks and starts normal on cold starts (left sitting a while, or overnight, etc), but when driven for a few minutes or more, will have a sluggish/slow start. Will crank normal, but engine will seem to have a hard time firing, where the rpms will slowly increase to 1000 ish, and then idle normal.

On cold starts, if I don't let the car hit normal temp or idle before driving, the engine will have very low RPMs at the next stop where it comes to idle speed. And by very low, I mean like 200 rpms on the tach (first line above the bottom), it will bounce around the low 100-200s, for about 10 seconds, and then will shoot to about a 1000 fairly fast. From there, slowly decrease to about 700-800, and idle normal. Once here, no low idle for the rest of the trip.

In short, car cranks, but slow startup when engine is warm. When cold, very low idle if driven before car warms, but self adjusts idle after a handful of seconds, and will be fine for rest of trip (unless turned off and started again, where the slow start will occur).

It happens with a 100% recurrence. Will always have the cold start low idle after running until self adjusting, and warm slow starts.



Just needing a check list of things to look at to help diagnose, narrow down the problem.
I have already checked distributor timing, air filter, and air intake at the throttle body. I do not have a FITV, and have cleaned out the IACV about a year ago, so have assumed it is not this. Plus, engine does not behave correctly if I unplug the IACV connector, so it appears to be working as it should.



Hopefully some genius can pop in here and suggest the right problem area to check/fix.

fcm

Check ECT sensor, you may be running rich.

Symptoms of a bad ECT sensor...

1 Easy starting when cold.
2 Hard starting when warm.
3 Poor fuel milage.
4 Poor performance when warm.

Pull the spark plugs and check color to see if your running rich, or just huff some exhaust fumes and if it stinks of gas your most likely running rich. 94

aeon117

If it was that sensor, would it cause the low idle before (i assume the ecu) corrects?
I don't run a cat converter, so exhaust always smells a bit like gas, usually not overwhelming, but sometimes noticeable

fcm

The ECU/ECM adjusts A/F ratio with info from the ECT sensor, if it is not working and your running rich, the exhaust will smell of gas with or without a cat. 94

holmesnmanny

just test it .. should be 2000-2500 cold ... 180-250 warmed up

3kvr41998

stuck on closed loop
?

aeon117

checked spark plugs and ect today. Plug 2 had a bit of oil, took off valve cover and found that there was some debree between the seal and head, so cleaned it up. Weird, though, because there was no oil on any of the plugs last week when I checked. Other than that, plugs just looked naturally aged, not bad or anything. To best explain it, the plugs had a bit of browning/burning, on the top part of the threads. Like I said, just looks like its something that has aged with frequent heat being applied.

have warranty on the ECT, so just replaced it real quick. The old one looked kind of tarnished compared to the newer one.

went to start car, and started up fine. Smelled exhaust, and smells the same as I always remember it to smell (after new exhaust system). It does smell a bit of fuel, but its not a crazy amount, and there is no noticeable smoke at all.

Drove around, and still have the low idle on first stop. Seemed like the idle was lower than normal this time, I was surprised the engine did not stall. Again, just after this initial first stop (and being automatically adjusted after 10 or so seconds), it idles normal (as far as I can tell). After reaching operating temperature, stopped in a parking lot and shut off engine while I ate lunch for 10-15 minutes or so. Tried starting car, and started up fine, but slowly died/stalled. Tried starting again, wouldn't start, but would crank fine. Took key out for couple seconds, and tried starting again, started fine, but died near instantly. Took key out again for a couple seconds, and tried again... Started and died near instantly. Repeat, and tried again, and got car to start and put in gear/put gas, car rolled out of parking lot fine, and proceeded to idle and run thereafter.


Long story short, doesn't seem like plugs or ect is the problem. With new information, what else should I be looking at/for?

fcm

Ign. switch is what I would check next...
http://techauto.awardspace.com/ignitionswitch.html

aeon117

the symptoms listed on that page you linked don't seem consistent with my situation.

5.Car stalls then can be restart, then stalls after driving or idling.
6.Once started the the car starts for a second and dies after letting off the key.

those are the closest matching. For 5, never stalls while driving, after driving, or idling, only just shortly after startup. For 6, doesn't seem like it is linked to me letting off the key... Everytime I start the car, I hold the key to the start position till car is running just to make sure.


Even if it was ignition switch, would that be causing the low idle?

aeon117

Messed around with car again this morning before heading to work... Cranked and started fine. Just for kicks, wiggled key around after starting, and no noticeable effects, so do not think it is ignition switch related, but i could be wrong.

Also loosened idle air screw on throttle body to set idle speed at roughly 800. The needle points to last marker just before 1000. Coming to the first stop/idle after driving, rolling idle was higher than before (1300ish vs 1100ish before), but engine did not dip to low idle once fully stopped. Went to about 700-800, then after a handful of seconds, shot to 1200, and then slowly dropped to 850ish and idled there.


tl/dr: I don't think it's ignition stitch, but could be wrong. Loosening idle air screw seems to have stopped low idle, but ecu seems to still want to make some sort of adjustments for some reason.

What is rolling idle typically supposed to be at, and does the adjustment the ecu is still making mean that air fuel mixture is off?
haven't messed around with warm starts again, yet.

JoeBlue

You don't have a multi-meter?

I assume that when you adjusted the idle that you did it properly with unplugging the IACV. If this is accurate, what did the engine do when you unplugged it?

fcm

Poor currant through the ign. switch can cause a number of problems from outright stalling to "random" idle problems and can be very "random" and temperature will have an effect

Engine running until you release the key from the start position is tyipical of ign. switch problem. 94

aeon117

I do have a multi meter, it is a cheap one, though.

I've tested starting car with out holding key, still starts and doesn't stall. I've also jingled the key around while engine running, and no noticeable effect. So far seems like it was just that one time.
Should i still take the ign apart to examine?


I adjusted the idle and timing per Chilton book. Get engine to operating temp, jump service connector, check timing with light, verify idle is 750 +- etc. i don't believe there is mention of disconnecting iacv, I'll check again, though.