Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 19th February 2014, 12:59   #1
Senior - BHPian
 
DCEite's Avatar
 
Join Date: Sep 2004
Location: NCR
Posts: 3,048
Thanked: 486 Times
Default RPM drops after cold start, and engine shuts off

Hello,

I searched the forum but could not get a similar problem.

The issue:

Here is a 2012 Spark having run 8000kms and serviced regularly. The issue comes - during only cold starts in morning. Crank the engine, it fires up, but immediately revvs fall to 200-300 rpm and then engine shuts off. If i crank the engine again after a while, it picks up revvs this time and idle rpm settles to about 1000-800 rpm - after which i am good to go.

I suspect this is a sign of something going to fail soon. The nights are not so cold here in Bangalore, and this issue comes *only* during cold start in mornings.

What could be causing this.

Any suggestions?
DCEite is online now   Reply With Quote
Old 19th February 2014, 13:32   #2
Distinguished - BHPian
 
paragsachania's Avatar
 
Join Date: Nov 2007
Location: Belur/Bangalore
Posts: 4,262
Thanked: 10,567 Times
Default re: RPM drops after cold start, and engine shuts off

Generally during cold starts ECU must signal the IAC to push the RPMs to the upper limit (at least 1000 and beyond). This is the usual case with most of the Petrol cars today (Well, even when the ECU detects that the AC is on, to compensate the load, it will increase the RPM by 100).

Since there is something called as "Desired Idle" which is a static number set by the ECU to ensure the car doesn't stall and maintains the typical Idle RPMs, this feature will in the first place not allow the RPMs to Drop to that level.

I am suspecting things mostly related to Fuel and injection here along with bad spark plugs as well.

Get the following things checked:
  • If the spark plugs are firing well. Please check this for each and every spark plug. Clean the plugs, check for corrosion on ignition points of the coil etc.
  • If the Idle Air Controller (IAC) valve is not stuck in the throttle body - In fact, while the car is in Idle, pull out the IAC connector from the throttle body and immediately the RPMs will drop to almost 550-600. Connect it back and the RPMs will raise and settle to 850-950.
  • If there is enough pressure from the Fuel pump sending fuel from the Tank into the engine chamber, clogged fuel filter too!

Last edited by paragsachania : 19th February 2014 at 13:34.
paragsachania is online now   (1) Thanks Reply With Quote
Old 19th February 2014, 15:42   #3
Senior - BHPian
 
dark.knight's Avatar
 
Join Date: Apr 2013
Location: India
Posts: 1,115
Thanked: 2,963 Times
Default re: RPM drops after cold start, and engine shuts off

Tell them to do throttle body inspection+valve cleaning (most probable issue). They will also check injectors and clean if necessary. The car has not run much to have any major problems. Battery or alternator problem isn't possible as the car becomes normal post the cold start.

By yourself, check for kind of smoke coming out of the exhaust if anything is out of the ordinary. Also change the fuel station for precautionary measures. The throttle body cleaning should solve the present problem.
dark.knight is offline   (1) Thanks Reply With Quote
Old 19th February 2014, 19:40   #4
BHPian
 
im_srini's Avatar
 
Join Date: Sep 2006
Location: Portland
Posts: 956
Thanked: 369 Times
Infractions: 0/1 (5)
Post re: RPM drops after cold start, and engine shuts off

Quote:
Originally Posted by DCEite View Post
Here is a 2012 Spark having run 8,000 Kms and serviced regularly. The issue comes - during only cold starts in morning. Crank the engine, it fires up, but immediately revvs fall to 200-300 rpm and then engine shuts off. If i crank the engine again after a while, it picks up revvs this time and idle rpm settles to about 1000-800 rpm - after which i am good to go.
I'm speaking from experience with Maruti engines, I've faced this issue due to a few things:

A) Malfunctioning or "slow" Idle-Air-Control-Valve ( IACV ). Basically, the engine is run in an "open loop" by the ECM till the coolant reaches operating temperatures. As mentioned, this is basically set in the ECM as "Desired Idle" values - there's usually one for without A/C ( ~ 800 RPM ) & one for with A/C ( ~ 1,100 RPM ). The duty-cycle of the IACV is controlled by the ECM till the engine achieves the desired idle RPM. If the IACV is slow to react to the commands from the ECM, the engine could stall before the IACV is able to open enough to reach or sustain the desired idle RPM. I had this issue after Throttle Body cleaning by the M.A.S.S I frequent

B) Having a fuel "Conditioning" device in the fuel line to the engine. I had a "miracle" device from Australia fitted to my car for a couple of years. Rather than increasing performance by "optimizing" combustion it turned out that it was actually restricting fuel flow ! I had a persistent idle problem, particularly when cold, which did not go even after an IACV change. I had to use the manual tuning screw in the throttle body to artificially keep the idle rather high to get around the problem. But once I had the fuel conditioning device removed, the idle problem just vanished & I could return the idle screw to its factory setting

C) Weak spark - although I doubt this would be an issue in a barely run car such as yours. In my case, the DDLI ( Dual Distributor-less Ignition ) coils in my engine had cracked housings & the sparks were short-circuiting to the valve cover. Best time to notice is at night when the "jumping" of the sparks can be seen clearly. Once I replaced the DDLI coils the idle went back to normal
im_srini is offline   (3) Thanks Reply With Quote
Old 19th February 2014, 20:22   #5
BHPian
 
motionfreak's Avatar
 
Join Date: Jun 2006
Location: Thane
Posts: 184
Thanked: 54 Times
Default re: RPM drops after cold start, and engine shuts off

might not solve the problem at all, but try disconnecting the battery for 30-60 mins. (FIAT owner )
if problem persists, then go to service station
motionfreak is offline   Reply With Quote
Old 20th February 2014, 13:15   #6
Distinguished - BHPian
 
dhanushs's Avatar
 
Join Date: Oct 2009
Location: Bathery/BLR
Posts: 3,446
Thanked: 4,057 Times
Default Re: RPM drops after cold start, and engine shuts off

My guess is the O2 sensor.

Please get it checked. Actually, you can plug in an OBD and check for yourself.
dhanushs is offline   Reply With Quote
Old 18th March 2015, 08:16   #7
Distinguished - BHPian
 
Sheel's Avatar
 
Join Date: Jul 2006
Location: Purnea(Bihar)
Posts: 5,210
Thanked: 4,846 Times
Default Re: RPM drops after cold start, and engine shuts off

Quote:
Originally Posted by SAJEESH View Post
The reason why I was worried is because I had read on the internet that revving a cold engine is not good as in this condition, the oil would not have fully circulated inside the car's engine providing full protection to all its vital components.

On that day morning after starting my car, the RPMs went high upto about 1500 RPM and then dropped to somewhere around 800-900 RPM. This is a usual occurence as you might know.

I waited for the RPMs to drop and then started to move the car as i normally do. But then the car got stuck just after about moving the car for 5 meters.
What you read is true.

But this time, you are not manually revving the car.

In cold starts, especially in winters, rpm's do shoot up. It is the fuel injection at work with inputs from the electronic module unit (ECU) of the car.

No need to worry if it was a one off case. Secondly, if you feel, the rpm's are shooting too much off, read Parag Bhai's reply on this thread. Reply no. 2.
Sheel is offline   (1) Thanks Reply With Quote
Old 18th March 2015, 08:20   #8
Senior - BHPian
 
humyum's Avatar
 
Join Date: Feb 2006
Location: Leicester/Mumbai
Posts: 2,306
Thanked: 2,188 Times
Default Re: RPM drops after cold start, and engine shuts off

Quote:
Originally Posted by im_srini View Post
I'm speaking from experience with Maruti engines, I've faced this issue due to a few things:

A) Malfunctioning or "slow" Idle-Air-Control-Valve ( IACV ). Basically, the engine is run in an "open loop" by the ECM till the coolant reaches operating temperatures. As mentioned, this is basically set in the ECM as "Desired Idle" values - there's usually one for without A/C ( ~ 800 RPM ) & one for with A/C ( ~ 1,100 RPM ). The duty-cycle of the IACV is controlled by the ECM till the engine achieves the desired idle RPM. If the IACV is slow to react to the commands from the ECM, the engine could stall before the IACV is able to open enough to reach or sustain the desired idle RPM. I had this issue after Throttle Body cleaning by the M.A.S.S I frequent
According to me, as im_srini mentioned, THIS is the problem.
humyum is offline   Reply With Quote
Old 7th May 2017, 23:49   #9
BHPian
 
Jag4's Avatar
 
Join Date: Mar 2014
Location: Delhi
Posts: 129
Thanked: 108 Times
Default Re: RPM drops after cold start, and engine shuts off

A little OT:

Hello all,

Seem to be having an issue with my i20 crdi lately, whenever the car is between gear changes or while stopping at red lights or while making a U-turn (basically when the car is in neutral at a speed of 20-30km/hr) the Tacho needle goes crazy, Rpm fluctuates in the range of 500-1500 rapidly after which the needle drops to 500 Rpm and the engine dies. Any pointers as to what the problem could be ?

I just got my car serviced, Engine oil was replaced and the filter was serviced according to hyundai's service schedule. Also Filled fresh fuel but the problem is still present.

I couldn't go to the service centre again but I talked to a mechanic who said suggested using an injector cleaning additive.

Any help on the issue is appreciated.
Jag4 is offline   Reply With Quote
Old 8th May 2017, 02:33   #10
Distinguished - BHPian
 
Join Date: Oct 2012
Location: Delhi
Posts: 3,069
Thanked: 6,246 Times
Default

Quote:
Originally Posted by Jag4 View Post

I couldn't go to the service centre again but I talked to a mechanic who said suggested using an injector cleaning additive.

Any help on the issue is appreciated.

Don't listen to the mechanic. This is not a problem you are going to solve with injector cleaning. Find a place that has a manufacturer specific OBD analyser. It is very likely to give you exactly what the problem is.


Jeroen
Jeroen is offline   (1) Thanks Reply With Quote
Old 8th May 2017, 10:02   #11
Senior - BHPian
 
ashis89's Avatar
 
Join Date: Aug 2011
Location: Hyderabad
Posts: 1,314
Thanked: 1,050 Times
Default Re: RPM drops after cold start, and engine shuts off

Slightly off topic.

I have been observing this on my ~6 year old, 45k km run WagonR K10. When the car is idling, the idle RPM falls below the normal 850-900 (to 500-600) range for a second or more before regaining the idle RPM. The car struggles for that moment but never stalls. This happens once in while and is mostly on a warm/hot engine irrespective of whether the AC is on or not. Also this occurs while the clutch is depressed completely (I can't remember any occasion where the clutch was not depressed/car was in neutral).

The first time I observed this was about 2-3 months back after I got my car from a waterwash. The observation was much pronounced and frequent. I assumed that water was the culprit and decided to let it dry. It was gone the next day when I used the car and I dismissed it as a water issue. After that my car has hardly seen any water till date but the issue is still observed once in a while. As if I am slowly letting go off the clutch with the car in gear and the handbrake applied.

Any idea what could be the cause?
ashis89 is offline   Reply With Quote
Old 15th May 2017, 01:42   #12
BHPian
 
Jag4's Avatar
 
Join Date: Mar 2014
Location: Delhi
Posts: 129
Thanked: 108 Times
Default

Quote:
Originally Posted by Jag4 View Post
A little OT:

Hello all,

Seem to be having an issue with my i20 crdi lately, whenever the car is between gear changes or while stopping at red lights or while making a U-turn (basically when the car is in neutral at a speed of 20-30km/hr) the Tacho needle goes crazy, Rpm fluctuates in the range of 500-1500 rapidly after which the needle drops to 500 Rpm and the engine dies. Any pointers as to what the problem could be ?

I just got my car serviced, Engine oil was replaced and the filter was serviced according to hyundai's service schedule. Also Filled fresh fuel but the problem is still present.

I couldn't go to the service centre again but I talked to a mechanic who said suggested using an injector cleaning additive.

Any help on the issue is appreciated.
Quote:
Originally Posted by Jeroen View Post
Don't listen to the mechanic. This is not a problem you are going to solve with injector cleaning. Find a place that has a manufacturer specific OBD analyser. It is very likely to give you exactly what the problem is.


Jeroen
Okay so, Went to the service centre today to collect my car but the car had the same issue still.

Ended up going for 4 rounds and 20kms worth of Road testing to finally find out that a Neutral Switch was being shown on the GDS (OBD SCANNER) as the error.

The neutral switch was replaced by them, costs 1820 Rs. And was a 20 minute job after 2 hours of roadtesting.

Tip: If you experience any issue in your car and the mechanic or the advisor tries to pass it off at normal as they did with me, ask them to take a similiar engined car for a Roadtest and observe it for similiar behaviour.

I did the same thing today and that led to the final diagnosis within 5 minutes after 2 hours of them trying to fix it by themselves.

Last edited by Jag4 : 15th May 2017 at 01:46.
Jag4 is offline   Reply With Quote
Old 21st May 2017, 09:23   #13
BHPian
 
Join Date: Aug 2013
Location: Vadodara
Posts: 60
Thanked: 76 Times
Default Re: RPM drops after cold start, and engine shuts off

Quote:
Originally Posted by Jag4 View Post
A little OT:

Hello all,

Seem to be having an issue with my i20 crdi lately, whenever the car is between gear changes or while stopping at red lights or while making a U-turn (basically when the car is in neutral at a speed of 20-30km/hr) the Tacho needle goes crazy, Rpm fluctuates in the range of 500-1500 rapidly after which the needle drops to 500 Rpm and the engine dies. Any pointers as to what the problem could be ?
Hi, just curious. While this problem persisted, did you also notice any weak battery symptoms? Weak cranking or any other stuff? Just want to know as the same crazy stuff used to happen in my old 2001 Pulsar which was ultimately a weak battery issue. Although, I do understand car electronics are to a different level altogether.
Racer911 is offline   Reply With Quote
Old 28th May 2017, 01:33   #14
BHPian
 
Jag4's Avatar
 
Join Date: Mar 2014
Location: Delhi
Posts: 129
Thanked: 108 Times
Default Re: RPM drops after cold start, and engine shuts off

Quote:
Originally Posted by Racer911 View Post
Hi, just curious. While this problem persisted, did you also notice any weak battery symptoms? Weak cranking or any other stuff? Just want to know as the same crazy stuff used to happen in my old 2001 Pulsar which was ultimately a weak battery issue. Although, I do understand car electronics are to a different level altogether.
Nope battery worked absolutely fine !
Jag4 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Engine shuts off in neutral gear 2cents Technical Stuff 24 25th September 2013 20:44
Switching ON headlights shuts OFF the engine aargee Technical Stuff 35 21st July 2013 23:09
Jazz - RPM drops to 500 white_vdi Technical Stuff 27 5th May 2012 22:50
Cold start vs warm start, is there a difference? Shan2nu Technical Stuff 6 18th May 2010 18:32
How many KMs after cold start the car will feel better sreenivass Technical Stuff 30 13th November 2009 12:14


All times are GMT +5.5. The time now is 13:06.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks