Idling Time during Morning Start for MPFI Vehicles

[adya33]

Topic is already discussed
http://www.team-bhp.com/forum/techni...ht=Idling+MPFI (Idling Time during Morning Start for MPFI Vehicles)

[navin]

Originally Posted by adya33

Topic is already discussed
http://www.team-bhp.com/forum/techni...ht=Idling+MPFI (Idling Time during Morning Start for MPFI Vehicles)

agreed so i merged the threads.

[passionpurple]

thanks guys.. that did help a bit.. but still not satisfied with the answer..

mostly the idling problems happen in cold weather. The place where I stay is much hotter now a days than it used to be ( approx 30 degC compared to the usual 25 degC). But this reving problem started just a few weeks ago and never before that.
why now all of a sudden?

Also, the increase in revs comes in sudden bursts ( which add ~+500 revs) is that normal?

PS- I searched some threads as adviced.. but most of them describe a gradual increase in the revs on startup which deaceases gradually over minutes.. my car's revs shoot up and down suddenly in episodes lasting 1-2 secs.

[SLK]

you mentioned it.. revvs.. as soon as you press the clutch....
if thats what you are refering to as episodes lasting 1-2 secs.... then again its normal (you disengage the gear and it revvs.... no issue)

My WagonR does not revv down untill I stop (PARK) the car... and let the engine idle for 30 secs... after its crossed the operating temperature.
Same happens with the Alto...
So its not revving down gradually... in my case too.

Also say... I do not park the car to revv down the engine...
I switch on the A/c and then park the car..... it idles at about 1000rpm.
now while remaining parked... I switch off the a/c..... the revvs SHOOT up to 1500rpm... and remain so for FULL 15-20secs.... then its comes down to 800rpm. (and this is normal)

[Roshun]

The revving engine during cold starts is a normal phenomenon. Happens with my WagonR as well.
I usually start it, wait for about 1 min, while I adjust the mirrors, seat, put on glasses etc... and then gently drive off. It usually warms up by the time I reach the first traffic light. When I stop for the light it still revs for about 20 secs, before gradually settling to a whispering 800 rpm.

The reason this happens with most MPFI cars is this... since they have no choke (carburetted cars rev when the choke is pulled), the ECU senses a cold engine - and makes the fuel slightly richer - while opening the throttle flap marginally. Once the engine is warm it settles down.

The only thing I find odd about the ECU's logic is that if the car is moving, it does not reduce RPM (even if you let the engine idle and let the car roll in neutral, while slowing down).

Cheers,
Roshun

[SLK]

Originally Posted by Roshun

The only thing I find odd about the ECU's logic is that if the car is moving, it does not reduce RPM (even if you let the engine idle and let the car roll in neutral, while slowing down).

Finally.... someone notices this!... I have been crying about this since eternity!

You are lucky to have a first traffic light close to you!.... BUT for me sometimes I end up driving 20kms.. non-stop!... and still find the engine revving hard. (and all those 20kms without engine braking is no fun)

happens on both my WagonR and Alto Vxi....
now i make it a point to stop by the side of the road to... let it idle!

Maruti Service centre guys did not have enough IQ/EQ/Common Sense to understand.

But does not happen on my MPFI 800DX.....

[chetanhanda]

Originally Posted by SLK

Finally.... someone notices this!... I have been crying about this since eternity!

You are lucky to have a first traffic light close to you!.... BUT for me sometimes I end up driving 20kms.. non-stop!... and still find the engine revving hard. (and all those 20kms without engine braking is no fun)

happens on both my WagonR and Alto Vxi....
now i make it a point to stop by the side of the road to... let it idle!

Maruti Service centre guys did not have enough IQ/EQ/Common Sense to understand.
But does not happen on my MPFI 800DX.....

It used to happen to my MPFI 12 valve, but I didnt drive for 20 KM with the engine at high RPM.I used to stop after 5 minutes of driving , turn off the ignition wait for a few seconds, start the ignition , the RPM in this case settles down to normal much quickly.
(Make sure u stop the car and dont put the car in neutral and turn off the ignition - the power steering and brakes become tough to operate or totally inoperable when ignition is off, u may not be able to steer the car in traffic, so its better to stop on the side for a few seconds)

Dont know why the car used to behave this way.

[frankmehta]

Originally Posted by aah78

MPFI cars do not require to be idled for long periods during cold start to reach operating temperature - however.....

if you notice, when you first start your MPFI car after leaving it off over night or a couple of hours, the engine always revs at a higher speed for a short while. during this time, your engine management system pumps in extra fuel into the engine to help it reach optimum operating specifications. after a minute or less, the revs drop down to regular idling speed.

a good time to start driving is when the high revs have dropped to regular idling revs. ofcourse, allow the engine fluids to begin flowing before you start revving hard or you're bound to damage the moving parts.

you can begin driving before the revs settle down but the motion will be jerky as the engine management system conflicts with inputs from the accelerator.

waiting for the revs to settle down also provides enough time for the oil to do its work in lubricating the movie parts.

in very cold temperatures (around and below freezing) its always recommended to let the car warm up for a short period before moving off. this is because as the external temperature drops the engine fluids become more viscous and hence, do not do their lubricating job effectively. driving off immediately in very cold climates will automatically cause your car to jerk & stall - this Very Bad for your car!!!! lots of friction between moving parts...

very very welll said...in fact i clicked on this thread to give the EXACT SAME ADVICE that u did due to my experience with my mpfi esteem......very well put!!!!!!!


the car when started stays at 1500 rpm and takes about a min to get to 800-900 rpm.....thats when i start driving off...
if i dont wait(sometimes wen im in a hurry) the car stays slotted at 1700 rom even after driving it for a hour.....not exaggerating.....this has got to do something with a hitch in the ecu software that gets confused if we drive off without running in the engine in the morning

one of the ppl has made a very valuable point by talking about the gear change......one minute MAKES A HELL OF A DIFFERENCE in the smoothness and ease of gear shift(esp in slotting it into reverse)

[turbo_c]

Originally Posted by SLK

My WagonR does not revv down untill I stop (PARK) the car... and let the engine idle for 30 secs... after its crossed the operating temperature.
Same happens with the Alto...
So its not revving down gradually... in my case too.

Also say... I do not park the car to revv down the engine...
I switch on the A/c and then park the car..... it idles at about 1000rpm.
now while remaining parked... I switch off the a/c..... the revvs SHOOT up to 1500rpm... and remain so for FULL 15-20secs.... then its comes down to 800rpm. (and this is normal)

Don't sweat it SLK ... I think we can safely put this down as another "Maruti Phenomenon". My MPFI Esteem does exactly what you have described!

I read somewhere that Maruti has cut some corners with the engine management sensors / ECU and that's why we see this issue.

Here's a tip to all Maruti MPFI owners: In case you need to drive off immediately (before the engine has reached operating temp), you can avoid the "over-rev" problem by not using the accelerator. It's ok to let the engine get loaded (release the clutch slowly and drive in 1st / 2nd) but DONT even tip the accelerator... somehow, when the ECU is in "warmup mode" using the accelerator confuses it. This works for my Esteem and a couple of Wagon R & Alto owners I know.

Interestingly, the Swift has not inherited this problem...

- T u r b o C -

[SLK]

Originally Posted by turbo_c

Don't sweat it SLK ... I think we can safely put this down as another "Maruti Phenomenon". My MPFI Esteem does exactly what you have described!

Hey, I know its a normal thing in Maruti MPFIs.... and I noted it the day I got hold of my Wagon R. But interestingly hardly anyone notices it!. Even now 4 people on the forum... out of so many Maruti owners.

I have driven continously for 20kms after cold start just to test the thing and not unknowingly.

The solutions I have found till now:-
1) PARK it and let it idle after its warm
2) while its rolling on a straight road put in neutral..... and restart the engine (might remind some of Microsoft Windows).

[normally_crazy]

I just shot a small video of my vRS on cold start. the display is showing ltrs/hour .

I press the clutch and give it the crank. Watch how the figure jumps up and then settles down.

ps - I could not finish the video but it settles down around1.0 ltrs/hour which takes about a minute and only after that I start rolling.

Cold start on the vRS

[headers]

Originally Posted by nitrous

Another variable here.

What if we're using synthetic/super-syn engine oil??

Whatever the oil..including the magnatec..It is a good practise to idle the engine atleast for 10 seconds at cold start..

Nitrous..its like you gettin up in the mornin and runnning @ full speed to the bathroom.. or do you do a slow dance to whatever.. cars are like humans too..remember

[nitrous]

OH GOD!
I warm up my engine more religiously than my prayers,Vikram.
I give all my cars exactly 60 seconds idling time (not 10) before I gently warm her and cross 2000 rpm only after the temp guage shows operating temperature.

[jaibir]

Any suggestions on what should be the warmup time on CRDI engines? Presumably it would be longer.

[headers]

Originally Posted by nitrous

OH GOD!
I warm up my engine more religiously than my prayers,Vikram.
I give all my cars exactly 60 seconds idling time (not 10) before I gently warm her and cross 2000 rpm only after the temp guage shows operating temperature.

Good..I was dazed for a moment..jus cant imagine u up out of bed and running..