Fb 15 Idle Drop Issue

The Don · September 2, 2013

A friend drives a 2002 NissAN Sunny FB15 Super saloon auto gear. Recently the auto box was repaired, but since then an interesting problem has developed which is probably not connected to the gear box issues.

The car is perfectly stable most of the time. Idles nicely at 900 rpm with the AC on.

But when you drive for a while and stop with the gear in D sometimes the idle just suddenly drops and the car stalls

If you put the car into the reverse gear the same happens (this is from a standing stop)

This behaviour is also observed when the gear is in neutral.

Now a number of mechanics have tried to repair this and often they find it difficult to reproduce the problem. The last Lal Alawatte said he had replaced "some sensors" (my friend is not technically minded) and the car was ok for over 2 weeks. Then the problem returned.

When I had a look at the she was able to demonstrate the problem in the above scenarios (so clearly she hasn't gone cookoo).

Since this has already been taken to a number of mechanics I wasn't sure what to suggest. Any of you guys had the same problem or any ideas?

VVTi · September 3, 2013

Was the petrol filter/pump checked?

Edited September 3, 2013 by VVTi

The Don · September 3, 2013

On 9/3/2013 at 1:47 AM, VVTi said:
Was the petrol filter/pump checked?

From what I know yes. What I can't understand is how the problem can go away and come back after a number of weeks. The thing is you can sometimes go the entire day without the issue surfacing but then while waiting at the lights the idle will drop the engine will stutter and the anti stall kicks in but fails to stop the engine from dying.

Any other ideas? I first thought it could be the automatic gearbox but it seems to happen in neutral as well (all of this is not hearsay, I saw the problem with my own eyes and at least when I was there she managed to reproduce all the scenarios).

LashNeo · September 3, 2013

Probably a failing Idle Control Valve? Or else maybe substandard fuel in case the owner is pumping from the same place often?

maheshw · September 3, 2013

Anything related to TB or sensors ? as lashneo state cant it be a ICV ? what are the sensors that replced by lal alwatta ?

Rumesh88 · September 3, 2013

Hope there is no CEL indication. Was the TPS changed (or cleaned) at anytime recently?

jdnet · September 3, 2013

speed sensor on the transmission going bad?

The Don · September 3, 2013

JD that was my initial suspicition as well that a sensor in the automatic transmission was to blame. But to my surprise the issue raised its head when the car was in neutral.

I don't know what Mr Alawatta has changed or in fact he has changed anything. I don't like to take people at face value.

Substandard fuel is an interesting suggestion. Will suggest to pump from a known pump for the rest of the week. The car is in regular use.

There is no CEL or any indication of a problem. 95% of the time the car is absolutely fine. I did not drive it to check acceloration.

I've asked her to book a diagnisis session at A*W who in the past have helped a number of friends to get to the bottom of problems like this.

I think the throttle body was cleaned a little while back by Auto miraj as part of a tune up. I'm not sure the sensors changed but I think it might be TPS and/or MAF. Will confirm.

Anybody reliable to diagnose a niggling problem like this? About 50K has been dumped on various mechanics already which is slowly becoming a colosal waste of money.

k9master · September 4, 2013

Hi Don,

Think one of my friends had a similar problem, Is the Engine QG15DE or a older GA15DE?

Whichever one it is, think they have a nasty problem with the MAF where it fails to give the correct voltage. The check engine light will not be lit sine MAF is still technically operational. In such an instance the throttle body needs to be replaced as the MAF comes built in to it and sealed off.

Most of our expert mechs think that the TB doesn't need to be replaced. They break the seal and try to repair the MAF by cleaning re-welding the circuit board etc. This surprisingly sorts the MAF issue out most of the time, but start generating incorrect idle voltages randomly causing these stalls.

I've faced the same issue some time back in my GA-15DE and my friend has gone through the same with QD15 last year. This is just a hunch and A*W guys surely will be able to diagnose the issue.

Hope this helps.

Cheers,

K9M

jegank123 · September 4, 2013

On 9/4/2013 at 12:47 AM, k9master said:
Hi Don,
Think one of my friends had a similar problem, Is the Engine QG15DE or a older GA15DE?

Whichever one it is, think they have a nasty problem with the MAF where it fails to give the correct voltage. The check engine light will not be lit sine MAF is still technically operational. In such an instance the throttle body needs to be replaced as the MAF comes built in to it and sealed off.

Most of our expert mechs think that the TB doesn't need to be replaced. They break the seal and try to repair the MAF by cleaning re-welding the circuit board etc. This surprisingly sorts the MAF issue out most of the time, but start generating incorrect idle voltages randomly causing these stalls.

I've faced the same issue some time back in my GA-15DE and my friend has gone through the same with QD15 last year. This is just a hunch and A*W guys surely will be able to diagnose the issue.

Hope this helps.

Cheers,

K9M

jegank123 · September 4, 2013

Me too had the same problem, engine stop while driving and there was no any engine light indication too, Got it done from A*W , just changed the CAM , Crank sensors, better take to them its little expensive but job done

jegan

The Don · September 5, 2013

On 9/4/2013 at 10:41 AM, jegank123 said:
Me too had the same problem, engine stop while driving and there was no any engine light indication too, Got it done from A*W , just changed the CAM , Crank sensors, better take to them its little expensive but job done jegan

Jegan, how much did it cost. K9 and you have been quite helpful. Actually I've read about this problem in autolanka before but for the life of me could not find the thread via searching.

So the issue is probably the throttle body (which to be honest I can help source because I think the Almera 1.5 probably uses the same engine), or the crank and cam sensors which is I think the same problem sharkster had with his cefiro many moons ago.

A*W does not seem to want to give appointments and wanted the car to be brought in at 8AM.

One thing I've learned is you need to learn at least the basics of motor vehicles before you decide to own and buy one, and be willing to put the hours in sourcing parts and in garages. I went and bought a radiator fan for my sisters Swift and the price range was 8000-15000. Massive range and there are no prices for guessing what I bought.

cefiroA33 · September 6, 2013

well i aint an expert but i could say its got to be the MAF. I am using a cefiro and had a similar issue. but engine tune up from mario and MAF change helped to resolve the issue.

NRX · March 5, 2014

Don. Any updates ?

The Don · March 6, 2014

On 3/5/2014 at 3:50 PM, NRX said:
Don. Any updates ?

Well it seems a number of sensors were replaced and the situation has stabilised. I think the CAM and Crank sensors as some have commented and a new throttle body.