Cold Startup issue

civic4g · Post by **civic4g** » Sat Nov 29, 2008 1:52 pm

Well let me see if I can explain the problem and make it clear to all of you. I've only noticed this problem about a month ago so i think that it may be related to some modification in the rom code. I've tuned the duty cycle of the IACV to -68% (I have a OBD2 engine and IACV) since the beginning and never had issues, now when I cold startup the engine it takes to much time to reach cold idle rpm (1500rpm) and rpm keeps going up and down almost stalling the engine. To try to understand what was causing this i've set the DC correction of the IACV back to 0% and it starts perfectly. Anyone else has experienced this problem? I think only OBD2 engines will experience this because they don't have FICV. I don't think I can find a Duty Cycle correction value that will suit both situations (coldstart and idle after warm). Is it possible to have a IACV DC value for coldstartup and other value for \"normal operation\"? or disable IACV DC correction for first x seconds? I think this would solve my problem but if there is another way to correct this issue let me know. Datalog files below:

Post by **Bugermass** » Sat Nov 29, 2008 3:17 pm

u need to post your cal too

civic4g · Post by **civic4g** » Sat Nov 29, 2008 3:25 pm

Bugermass wrote:u need to post your cal too

Updated

98vtec · Post by **98vtec** » Mon Dec 01, 2008 12:28 pm

i cant view the cal on this computer but what are your fuel cut settings? I know that i made a mistake in that area once and it wouldnt get to the cold start RPM's and it would also bounce for a second while cold.

civic4g · Post by **civic4g** » Mon Dec 01, 2008 12:52 pm

I think it's not related with fuelcut, anyway i've fuelcut \"disabled\" by setting \"Below Load\" value to near 0 mBar. When possible take a look at my DL files. The only thing changed between them is the IACV duty cycle correction.

borat · Post by **borat** » Mon Dec 01, 2008 2:41 pm

civic4g wrote:I think only OBD2 engines will experience this because they don't have FICV.

My engine is OBD2, and it has both IACV and FITV.

hackish · Post by **hackish** » Mon Dec 01, 2008 2:51 pm

I have an H22 with the fast idle valve bypassed and it does exactly the same thing as yours. A little annoying... -Michael

civic4g · Post by **civic4g** » Mon Dec 01, 2008 3:56 pm

I have an H22 with the fast idle valve bypassed and it does exactly the same thing as yours. A little annoying...

Look like we'll have to ask Calvin to code something, I think either of the suggestions I've made in 1st post would deal well this issue.

hackish · Post by **hackish** » Mon Dec 01, 2008 6:43 pm

The best way to do it is actually a DC->RPM table with a CLT modifier. You can usually get away with skipping the CLT modifier. So basically if the ECU determines the engine is -5 and sets a target idle RPM of 1500 then it looks up 1500 and knows that it requires approx 68% DC to achieve that so that's it's starting point and any PID control it has is applied after that to fine tune and achieve the actual target. -Michael

greasemonkee · Post by **greasemonkee** » Mon Dec 01, 2008 7:53 pm

Way back, a few years ago, it was decided that the OBD2 IACV behaved differently than the OBD1. My engine is obd2 with the obd1 IACV, no fitv, no coolant lines to anything. Only problem I have is when it's real cold and the oil is thick, I have to give a little throttle to keep the rpm at a reasonable level right after crank. Within a minute everything is self sustaining and stable.

98vtec · Post by **98vtec** » Tue Dec 02, 2008 12:30 am

hackish wrote:I have an H22 with the fast idle valve bypassed and it does exactly the same thing as yours. A little annoying... -Michael

I dont get as cold as you do up there being in Florida, but i am running an s2k throttle body (no FITV) and it idles perfect.

Post by **Gaskleppie** » Tue Dec 02, 2008 2:19 pm

Are the base settings for the idle control ok? I mean, when the engine is warm you must be able to unplug the IACV valve and the engine must fall down to about 500rpm at idle. If it stalls, open up the idle screw till it keeps running at 500rpm, if it runs higher than 600rpm, close it a bit to get it around 500rpm. When the base idle is ok, plug the IACV in, reset the error code and try again.

hondagourou · Post by **hondagourou** » Wed Dec 03, 2008 2:16 am

Gaskleppie wrote:Are the base settings for the idle control ok? I mean, when the engine is warm you must be able to unplug the IACV valve and the engine must fall down to about 500rpm at idle. If it stalls, open up the idle screw till it keeps running at 500rpm, if it runs higher than 600rpm, close it a bit to get it around 500rpm. When the base idle is ok, plug the IACV in, reset the error code and try again.

This sound pretty good, but is impossible with S2000 throttle body (no idle screw) Mine is running pretty good when cold with the S2000 throttle body if i let it run few minutes without toutching the gaz pedal. Here in Canada is wery colt in winter. Lots of people is running OBD2 engine without FITV and eCtune. It is possible for Calvin to code someting for that please

Post by **Gaskleppie** » Wed Dec 03, 2008 3:02 am

I also run an S2k throttle body. You still have to do what I wrote. If you dont have an idle screw, you have to adjust the min throttle screw to get some air through and to get it running at 500rpm with a warm engine with the loose IACV plug.

Post by **Bugermass** » Wed Dec 03, 2008 3:25 am

How about set your AC IACV duty really high and when its cold start just kick the A/C button on.. Just a simple work around for now..

Cold Startup issue

Cold Startup issue

Re: Cold Startup issue