View Full Version : Help: Fuel / Idle
08-04-2009, 09:55 AM
My car, now that I have the IACV check engine light fixed (re-pinned ECU wires), cleaned out the IACV, double-checked and re-soldered the MAP and TPS wiring (correct), replaced TPS, I’m still getting a sporadic idle up and down from 1000-2000 rpm, sometimes even 2500, when engine is warmed up or hot (190* oil temp). During cold start-up, idle sits between 2000-2500 rpm, a tad high. I tried lowering the fuel pressure at the FPR from 45 down to 32, 35, 40, but still, nothing. The wideband meter was reading 11-13 at 45psi (FPR), at 32psi, AFR ~17+ at 3000rpm @60mph, a bit lean, so I turned it up, kept going. AFRs are now at about ~15 cruising speed limit.
I have yet to get a multi-meter to test the voltage at the TPS, but I’m not getting any CELs now either, so I’m at a loss.
It’s also a bit annoying because in high boost I’m still getting boost cut at 4500rpm under full load. Doesn’t cut out in low boost. It only seems to like it in high boost when you’re in the car. I’ve looked at the settings in SManager, trying to understand everything, but nothing looks out of place to me.
Let me know if you have any ideas.
08-04-2009, 11:59 AM
More info on your build, please.
After tinkering a bit, I've gotten my idle smooth as butter, but only in closed loop.
Open loop, it still wants to bounce a bit. I'm trying to fix that (lowest load index is a bit lean, I think).
Did you go through the idle setting steps in the help file?
Warm the car up
Unplug the IACV, and adjust the idle screw until you're ~450 RMP (I actually had to go higher on my build due to the big cams)
Plug the IACV back in, and clear the error in SManager
Leave your fuel pressure close to stock (45-50 psi).
Check your timing w/a timing light, and adjust @ your dizzy. Advanced will bring the RPM up a bit, retard will bring it down.
You might want to tinker with the IACV duty cycle and minimum idle RPM in SManager.
Mine ended up at 1000 RPM, and dead center duty cycle, after I fixed the vacuum leak.
I also needed to adjust the stationary Idle spd vs. Coolant temp values.
I ended up with:
60 | 90 | 120 | 140 | 160 | 190 | 199
1552 | 1450 | 1300 | 1250 | 1101 | 1000 | 1000
Basically brought all of the idle values up, so the lowest one was at operating temp, and adjusted temps because I don't plan to drive in cold weather.
Lastly, you definitely need to lean out your idle values (first two or three columns, from bottom to ~1500 RPM).
Running as rich as 11-13 is definitely going to throw idle around a bit, likely high (probably explaining your 2500 RPM).
Putting it in closed loop should allow for the ECU to try to correct your idle, and it will learn it eventually. Make sure to set the target voltage as close to 14.7 as you can, and set your closed loop settings safely (like maybe limit how much it can pull off of the fuel table).
Where are you from?
I'm getting a pretty good handle on the whole Hondata thing.
EDIT: One other thing, adjusting the injector voltage compensation on the Fuel Trim on the Parameters window may help with idle, and other things as well. See if you can find out what it should be set at. I've found increasing my dead time from the stock settings has helped with both idle, low load, and sudden throttle close/fuel cutoff.
08-04-2009, 04:48 PM
Thanks for the detailed information.
81.5mm 9:1 CP pistons w/ coated skirts
balanced rotating mass
Skunk2 Pro manifold
ACT 6-puck unsprung
ACT 12# flywheel
top mount manifold
HKS SSQ bov
Greddy Profec B EBC
Hondata S300 p28 (Handcommand)
3" downpipe - 3" flex by VRD Garage
Apexi N1 bpipe to canister
Cometic HG .053"
Autometer boost, EGT,oil temp, oil pressure guages
AEM UEGO wideband
I'll have to print your info out and check my settings in SManager.
08-04-2009, 04:59 PM
Idle set at 925
Idle vs Coolant Temps
40 | 67 | 87 | 106 | 141 | 177 | 302
1623|1632|1471| 1315 | 1009 | 936 | 936
40 | 67 | 87 | 106 | 141 | 177 | 302
1601|1601 | 1450|1300 | 1000 | 840 | 840
IAC duty cycle is at Normal, IAC error is unchecked.
Right now it's in open loop, with 02 Heater enabled..
I'll try the IACV/idle adjustment, and push the fuel pressure back to where it was, 45.
I have not tinkered with any of the settings except the IACV disable. Everything is as is when I got the car tuned. But since I fixed the IACV CEL, the idle has been stupid.
08-05-2009, 09:29 AM
Ok, did a bunch of stuff last night. Didn't touch any of the settings in SManager.
1. Tested the IACV/idle adjustment, didn't do much.
2. Set FPR back to 45psi, where it originally was.
3. Tested each vacuum line at the vacuum manifold.
a. Turns out, the vacuum line going to the PVC could be the culprit. Seems like the
rubber line is too thin. I will replace that line with a thicker line and a new PCV
08-05-2009, 10:39 PM
new PCV and line didn't fix problem. TPS calibrated to .5v at idle.
When I pinch any of the vacuum lines, idle seems to settle at about 1000rpm. The only vacuum line that stalls the engine when pinched is the one going to the purge.
any help would be greatly appreciated.
08-06-2009, 02:36 PM
Have you adjusted the idle screw yet?
Is the PCV flowing in the correct direction (should be from crank to intake)?
My idle was terribly high when my valve was missing.
How do your AFR's look?
08-06-2009, 04:06 PM
well if you've checked all those stuff.. sounds to me that there is a air leak somewhere.
08-06-2009, 04:07 PM
I have tried to adjust the idle screw with the IACV unplugged. That didn't do anything so now the idle screw is closed. Opening it up just raises the sporadic idle rpm range.
PCV is flowing : crank, to black box, up through pcv valve, vacuum manifold, where all the other vacuum lines are plugged in, except the BOV, which goes straight to the intake manifold.
AFRs are still anywhere from 11.7-16, FP is at 45psi.
If any one of the vacuum lines are pinched, the idle sit steady at 1000rpm. I understand vacuum is the root cause, but I can't seem to find the source.
I also posted this in two tech forums at H-T, but people there just seem to care about opinion threads rather than tech.
08-06-2009, 04:10 PM
The common/easy way to check for vacuum leaks is to get a can of carb cleaner (because it won't hurt if some gets sucked in), and start spraying around.
Spray where the intake meets the head, wait a few seconds to see if the idle bogs down.
When you hit a spot where it bogs down, it's because the carb cleaner is sealing up the leak for a moment.
Check all of your vacuum lines, and anywhere air is flowing into the motor.
08-06-2009, 05:58 PM
Very well, I'll go ahead and pick one up on my way home from work tonight.. granted I'm out of here sooner than later. Thanks for the suggestions.
08-10-2009, 01:44 PM
Bump for more help.
Sprayed some carb cleaner around and on vacuum lines, vacuum manifold, nothing.
I unplugged the vacuum line going to the boost guage and boost controller. When unplugged, car seems to idle better. If I remove 1 of the vacuum lines and leave the port open on the vacuum manifold, then car idles fine. as soon as I plug the open vacuum port, car idles funny again.
08-10-2009, 03:59 PM
So, does the idle clean up if you unplug the IACV?
It could be faulty, I guess.
Also, did you try running it idle in closed loop for a bit to see if it evens itself out? (give it maybe 5 min or so)
08-10-2009, 04:55 PM
The IACV could be going bad, I don't know. I have another one I could try I guess.
Doesn't seem like a vacuum leak though because when i left one port on the vacuum manifold open, idle settles.
I'll have to change to closed loop and see.
Crazy Mofo just doesn't seem to like anything anymore...
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