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Engine start very very difficult when cold. I can start the engine only using ether. Once started during warmup I can maintain only using the accelerator. To summaryse a lot of sympthomes makes me suspecting srongly the IAC valve not working properly. This valve was used on my previous engine and mecanically checked. But data in VEMS play an important role and I am now investigating on the VEMS parameters to control well this valve. I recorded log and did initial analysis. I saw that the IAC duty cycle is always 100% I saw a frequency of 200hz and PID of 255, 25, 10. I saw in other config that some are using lower frequency and different values for PID, warmup etc... How to set or get good reference parameters for a quick start of the engine and warmup available for Audi 5 cylinders ? Many thanks in advance. Laurent. -------------------------------------------------------- Hi Erikk, Thanks for your advise and I have complemented some additional info for you --------- /Erikk Is it a Bosch 3-pin IAC ? If so, 100hz seems to be the correct freq http://www.vemssupport.com/forum/index.php/topic,1900.0.html Chech that Dual Solenoid is Enabled Check wiring and that Higher DC% == More air into engine, not viceversa (forget this in case of a 2-pin IAC) -------------------------------- LoloQuattro It is a 2 pin IAC so is there something I should do ? * No. /Erikk -------------------------------- /Erikk PID values of 50/25/50 seems OK. You have to set the IAC Reference curve vs CLT to reasonable values. -------------------------------- LoloQuattro OK I will change the PID value to 50/25/50 and 100hz frequency my IAC reference curve versus CLT start at 75% for -40°c and finish at 45% for 69°C. -------------------------------- /Erikk Under "Start/Idle -> Idle Crankning, PWM" you can set DC% at crankning. 85% is probably OK at cold engine, same or lower at warm engine. -------------------------------- LoloQuattro OK, I had something very close 70% and 42% but will change ------------------------------- /Erikk Remember the fueling at cranking must be set correctly also. First set Crank VE% when warm and laborate with "Start/Idle -> Crankning Enrichment Curve" -------------------------------- LoloQuattro Erikk could you develop this point? My crancking enrichissment curve is: -20°c 300% 0°c 281% 30°c 200% 70°c 163% * This is wrong, put 100% at 70c, now you have 63% enrichment on Crank VE% value when already warm. You probably have to lower all values a bit, do you use Ethanol/E85 fuel? Too much fuel causes bad starting behaviour/Erikk ------------------------- -------------------------------- LoloQuattro What values recommanded for PWD Idle control ? -------------------------------- LoloQuattro I saw from Reidar some configuration file and this is very kind of him. I notice sometimes very different pwm frequency for the IAC. sometimes it is around 20hz for the 670hp and 478hp and 250hz for the 634hp. I am not clear why such change in values ? http://www.vems.hu/wiki/index.php?page=MembersPage%2FReidar --------------------------------------- LoloQuatro OK, thanks for all, idle is working much better. I have changed nearly 700 values, the whole ignition table as I had 33° advance for the ignition at idle and that was too much. I imported the ignition table from Reidar with 16° that is much better. Also made many update in other area as suggested by Erikk, there was still some not to go above 100% for the crancking enrichssment curve. 100hz for the pwd iac frequency and 70,40,50 for the PID. I removed the remaining oscillation by setting the decrease integral limit to 5. Starting hot was perfect. I will continue to adjust some values and see how it goes even if sometimes this is not obvious due to the effect of combination betqeen parameters and their side effect. My next concern is the cold start that is still a problem and need ether, I will open a new page for that.
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