justinCO

Been fighting this idle issue the last few days :/.

Current symptoms, during cold start, idle bounces between ~900rpm and ~1300rpm until it warms up. Once at operating temp the idle settles at around 850-900rpm. Once I am driving, the other problem is the car stalls often on deceleration. Say I'm coming to a stop sign/light and I push in clutch and brake to stop. Well, instead of the rpms dropping down to 850rpm and idle'ing, the rpms drop low, under 500rpm. Sometimes it stalls, sometimes it catches itself and gets back up to 850/900rpm idle. I can sometimes reproduce this just sitting here in my garage at idle, and blip the throttle, it will drop real low then come back up. I took some datalogs of this is anyone wants to look. When driving regularly it runs good and strong, just the decel' and cold start idle is being retarded.

Relevant info:
d16y8 block/z6 head, low compression ~8.8:1, new engine, ~350 miles on it.
y8 intake mani with b16 tbody
(new) 40 micron fuel filter, fuel pressure set to 38psi with pinched off fpr vacuum
Hondata s300 loaded with stock p28 calibration (min idle 850rpm)

What we've done:
-fixed bad vacuum leak, don't think there are anymore vac' leaks cause I can plug the tbody up with my hand and engine will immediately stall
-clean out iacv with carb cleaner (twice)
-measured/calibrated tps sensor per helms, ~.5v closed ~4.5v fully open I believe were the recommended @ ecu.
-adjusted idle screw with iacv plug still connected. If I tried to set the idle like the helms says, by unplugging iacv connector, the car just stalls. I cannot keep an idle at all with the iacv plug disconnected.
-reset timing after that
-re-adjusted throttle cable
-swapped in my Hondata 4bar MAP sensor to try, same problems (I also uploaded new calibration to the hondata to reflect MAP sensor change).

A few other things I cannot remember off top of my head but basically anything related to idle problems.

Really not sure what is causing this. I have taken everything apart again and re-cleaned iacv and tbody one more time. I noticed my tbody plate sticks a little, so tried to fix that. The throttle stop screw was not touching the throttle link arm, so I screwed it in a bit more enough so the throttle plate wouldn't stick but still appeared fully closed. I have yet to test after these changes.

Hondata datalog:
http://jackmoves.com/~justin/w...s.s3d

Justin

justinCO

Everything back together, same exact problems...wtf. Here is what I did this time:

-cleaned iacv again
-cleaned out tbody, idle adjust screw and hole
-set throttle stop screw
-new air filter (old one broke)
-verified resistances were correct on TPS sensor
-verified voltages were correct on ecu harness plug for TPS fully closed and fully open (.509v closed and 4.6v open)
-set timing in hondata using "set timing" feature (to 16 btdc) and then set dizzy timing to the center mark on the 3 mark set on pulley.
-set base idle successfully this time w/out iacv plugged in, it chugged along at 500/550rpm idle
-plugged iacv back in, checked timing again to make sure it was good

Let car sit for 20 mins to settle/cool a little. Start it up, idle bounces up and down and up and down between 600rpm and 1200rpm. After couple minutes it stabilizes at 850/900rpm according to hondata. Every other minute or so the idle will just drop to 200/300rpms and bog down, then idle back up normally, seemingly for no reason???

Blip throttle up to 3k rpms, the rpms come down and car nearly stalls, one time it DID stall doing this. Just sitting there in my garage.

Took it for a drive. Anytime I decelerate and push in clutch the car almost stalls, battery light flickers on/off and engine drops to 200/300rpm before catching back up to 800/900rpm. Other then this car is running strong and pulling hard (for stock low compression), I am at least happy about this.

That is where it sits...I'm friggin pissed. Oh, and turning on lights and heater full blast does nothing to idle, it stays normal @ 850/900rpm.

What could it be? These are remaining things I can think of to check/replace:
iacv
throttle body (one with stock positioned TPS)
fuel filter?? (I have one of those little "Trick" black filters, 40 micron metal cheese grater type filter)

Anyone, tips?

Justin

justinCO

Fixed! Had to make some changes in Smanager software:

To fix cold start idle bouncing = checked "invert purge valve" box in hondata under Misc. tab. Idle'd fine on cold start then.

To fix stall issue when bringing rpms up then letting off = adjusting iacv duty cycle in hondata to the right. Blip throttle up to 3k and it holds idle rpm when it comes down now just fine!

Road tested and car is running great now, no more idle or stalling problems yay!! Time to

Justin

ravigo60

Hi there,

I am having the same problem like you did on my 93 honda prelude (H22A engine). Can you please clarify how you were able to fix your idling problem?
What did you mean by 'Smanager'? Is this your ECU that you've adjusted?
I'm using P28 ECU.

Your help on this is greatly appreciated...

joelmatt89

wow way to bring a thread out of the dead but i am having this exact same problem when it comes to the dying on deceleration part if someone could get on here and explain what he did i would really appreciate it. Whatever he did by "adjusting the iacv duty cycle" i am wondering if that is my problem because i have tried cleaning and adjusting everything i can think of.

OliverV

wou same here, exact problem and want to find a fix for it!!! normal explain also, don't know about these fancy short-term names..

608_red_rex

seriously, i have the same problem when i de-cellerate, my car almost stalls, it has died a couple of times, and i have no idea what it could be.... any help would be great!

compdog694u

my h22a civic hatch is doing the same thing. any help would be great.

callmechad

read what he did guys. it may help you

accord_raffi

Why is it no one ever posts there answers to their problems? I have been searching and found a million threads on this and no one leaves a solution.

ekmushi_mushi

changing your "this and that" sensor wont work , especially the iacv , no matter what u do or how many time u clean it will still alway be dirty @ some point ..best bet is to get a new one , and to the dude above, people have solution but not every car acting the same when is come to symptom of being limb, I , myself have the same problem and solve it with new iacv , and still does it , it turn out that my ecu harness is loss from my engine and plug omn my ecu computer is loss also that why is having a shortage and act that way, i spend the whole weekend of turn on and off the car to see , after the fix, my starter went out due to just turning on and off too much EL o EL but good luck