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Old 14th April 2010, 21:18   #1
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Default Santro Engine Dies When Decelerating - NOT ALWAYS

Posting this on behalf of a friend who has a 2001 Santro LE.

He has been facing a weird problem of late - the engine dies when the rpm drops.The funny part is this doesn't happen always and does not show any kind of pattern.


Here's the story:
  1. The car runs fine - temperature is normal at ~45% of range.All of a sudden the engine stalls when the rpm drops to idle levels.Start the engine and rev up. Engine dies again whenever decelerating next.(This is similar to what happens if the slow running jet of a carb car gets choked)
  2. Shut off the ignition for sometime and restart - bingo - all is well
  3. Drive for as long as you want for 2,3,4 days,nothing happens
  4. All of a sudden,the weird behaviour starts
What has been done so far

Stage1 - Throttle body,spark plugs,air filter cleaned

No problems experienced for approx 2 weeks after which problem surfaced and disappeared automatically

Stage2 - When problem was faced next,the NRV connecting the tappet cover and the TB was cleaned

Again no issues for approx 3 weeks - same problem recurred but disappeared as well

Stage3 - When problem was faced next,the thermostat was removed and radiator flushed thinking that if this problem were due to temperature,this would take care

Same weird behaviour - kabhi khushi to kabhi gum

My Observations
  1. The distributor,coil,plugs,wires are ruled out as they are in good shape - also if they had been the source,they should have always misbehaved with ,say the engine hot
  2. All electrical connectons to sensors found good
Have you guys faced this issue? please help.
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Old 14th April 2010, 22:04   #2
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Just to add,the engine check light does not come on when the car is running - so that means the system detects all sensors normal,right ?
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Old 14th April 2010, 22:24   #3
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I am facing exactly the same problem with my M1000, car runs fine and engine cuts of when reducing speed and this happens only sometimes. And to add to my problem, whenever I take to mechanic, car works absolutely fine, one day mech. will think I am psycho. (not the tbhp member).
What I got got done till now is:
Carb tuned - no effect, problem arise again.
All spark plugs changed - again no benefit.
Today I got ignition coils checked, plug cables and one coil resistance changed. Car is running smoother than before now and I need to see if problem arise again or not.

So maybe you should check plug cables for any damage (rubber cracking) and I don't know santro have that "HT coil resistance" thing. If it has, get that replaced as its cheap part.
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Old 14th April 2010, 23:51   #4
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Seems to be a fuel flow problem - the fuel supply is cutting out at low revs. May be a pipeline/fuel pump vapour lock. Or muck blocking the fuel tank suction end filter net.

My suggestions:
1. Check and clean the tank and suction-end filter net;
2. Check the fuel pump for overheating when this problem happens;
3. Check if this happens when the tank is comparatively empty;
4. Check fuel pipelines manually by blowing compressed air through them after disconnecting both ends (both inlet and return pipelines).

Also check the HT voltage being generated at the spark plug end. I don't recall, but I think the engine has a CDI distributor unit. If so, check the distributor unit for any grease or muck inside the cap.

Hope this helps.
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Old 15th April 2010, 00:25   #5
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Get the idle air control valve checked, also known as the IAC or IACV.
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Old 15th April 2010, 07:16   #6
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Quote:
Originally Posted by SS-Traveller View Post

My suggestions:
1. Check and clean the tank and suction-end filter net;
2. Check the fuel pump for overheating when this problem happens;
3. Check if this happens when the tank is comparatively empty;
4. Check fuel pipelines manually by blowing compressed air through them after disconnecting both ends (both inlet and return pipelines).

Also check the HT voltage being generated at the spark plug end. I don't recall, but I think the engine has a CDI distributor unit. If so, check the distributor unit for any grease or muck inside the cap.

Hope this helps.
Quote:
Originally Posted by pranavt View Post
Get the idle air control valve checked, also known as the IAC or IACV.
Thanks SS and Pranav.

One more observation - when this problem occurs,if we start the engine and keep the revvs even a wee bit over idle,there is absolutely no problem. Seems to be the IACV or thereabouts to me.

Nevertheless,it is a good idea to check the distributor.

Thanks once again-watch this thread for updates
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Old 15th April 2010, 09:45   #7
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I do not think the Santro has a distributor! Also check if there is an air leak on the inlet manifold.
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Old 15th April 2010, 11:00   #8
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Have they tried cleaning injector and fuel lines? Then the idle control unit.
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Old 15th April 2010, 15:58   #9
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Quote:
Originally Posted by sgiitk View Post
I do not think the Santro has a distributor! Also check if there is an air leak on the inlet manifold.
There is a distributor on the Santro.

The inlet manifold leak may not be a reason since teh engine dying behaviour is erratic - not regular.Nevertheless,will be checked.

Quote:
Originally Posted by Jaggu View Post
Have they tried cleaning injector and fuel lines? Then the idle control unit.
Just checked with the guy - The injectors were cleaned approx 5000 kms back.The fuel tank and lines were cleaned three years back.
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Old 16th April 2010, 21:02   #10
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Quote:
Originally Posted by vigsom View Post
Posting this on behalf of a friend who has a 2001 Santro LE.

He has been facing a weird problem of late - the engine dies when the rpm drops.The funny part is this doesn't happen always and does not show any kind of pattern.


Here's the story:
  1. The car runs fine - temperature is normal at ~45% of range.All of a sudden the engine stalls when the rpm drops to idle levels.Start the engine and rev up. Engine dies again whenever decelerating next.(This is similar to what happens if the slow running jet of a carb car gets choked)
  2. Shut off the ignition for sometime and restart - bingo - all is well
  3. Drive for as long as you want for 2,3,4 days,nothing happens
  4. All of a sudden,the weird behaviour starts
We tried the car with a new Throttle Position sensor - same phenomenon - the car starts,runs normal for a few kms and suddenly it stalls when at idle.Restart revv up and she is fine.Again stalls at idle.

Shut off ignition and restart - all is well.

Since the throttle body was serviced only recently,am clueless as to what to check next.

Surprising thing is , shut off ignition and restart - all is well

Please help
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Old 22nd April 2010, 21:57   #11
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The problem looks resolved ; there is apparently an issue with the sensor at the intake manifold(the sensor upstream to the throttle body).

Two adjusting screws(one above the throttle body and one below) were adjusted to set the idle - no problem at all since then.

This is just weird.

watch this space for updates
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Old 11th March 2015, 15:04   #12
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Default Re: Santro Engine Dies When Decelerating - NOT ALWAYS

Quote:
Originally Posted by vigsom View Post
The problem looks resolved ; there is apparently an issue with the sensor at the intake manifold(the sensor upstream to the throttle body).

Two adjusting screws(one above the throttle body and one below) were adjusted to set the idle - no problem at all since then.

This is just weird.

watch this space for updates
Hi Vigsom facing same issue will appriciate if you can send a photo or location of the sensor & the screws you have mentioned
Thnkxs
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