Maruti 800 5 Gear MPFI problem

anoovis · 22nd February 2007, 15:24

Hai,

I have a 2003 model M800 5 Speed model. When I start the car after a long time (like in morning) engine speed is normal. But after a little run, say about 2 km, the engine idle speed is very high, we may think the accelerator is pressed. And the Hazard indicator shows some error in engine working .
I showed the car at maruti service station, they told it is some problem with Throttle sensor, and they tried replacing the sensor. but that also failed. Then i showed at a local car workshop and they told it may be because some stuck in the throttle 'float' ( i didnt understand 'float'). What do you guys think ? Please suggest me. I already lost about 4000 rs replacing the sensor..etc.

Anoop

mithun · 25th February 2007, 23:15

A vacuum leak maybe the probable cause. I assume so.....

The powertrain control module (PCM) will maintain normal idle speed and compensate for a small vacuum leak by closing down the throttle body air bypass. But if the leak is too large and the idle control system cannot compensate for the extra air, the engine may idle too fast. Common leak paths include the throttle body gaskets, intake manifold gasket, any of the engine vacuum fittings, hoses or vacuum-operated accessories. It is even possible that leaky O-rings around the fuel injectors may be allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft.

The important thing to keep in mind about vacuum leaks is that they have the most noticeable effect at idle.

shibujp · 25th February 2007, 23:33

Idle in MPFI engines are controlled by and Idle Control Valve. In the M800 mpfi this is located just behind the throttle body on the firewall side..well more of less opposing the TPS...it has a couple of narrow rubber pipes leading to it from the air intake manifold.

The Idle Control Valve usually open only when the car is idling...sometimes dirt might get into it...you might try cleaning it at a garage. However in this case i guess you should have problems at the start itself.

I used to have a similar problem when my engine rpm seemed to continuously surge and fall at idle. But switching the engine off and switching it back on usually solved the problem. Later i figured out that it was related to the load perceived by the ECM. I could replicate this by revving the engine up an a low gear and move forward but never completely releasing the clutch.

drive on,
Shibu

anoovis · 28th February 2007, 10:07

Thank you guys I'll check these out at garage and revert back soon

22nd February 2007, 15:24	#1
anoovis Newbie Join Date: Sep 2006 Location: Cochin Posts: 3 Thanked: 0 Times	Maruti 800 5 Gear MPFI problem Hai, I have a 2003 model M800 5 Speed model. When I start the car after a long time (like in morning) engine speed is normal. But after a little run, say about 2 km, the engine idle speed is very high, we may think the accelerator is pressed. And the Hazard indicator shows some error in engine working . I showed the car at maruti service station, they told it is some problem with Throttle sensor, and they tried replacing the sensor. but that also failed. Then i showed at a local car workshop and they told it may be because some stuck in the throttle 'float' ( i didnt understand 'float'). What do you guys think ? Please suggest me. I already lost about 4000 rs replacing the sensor..etc. Anoop
	() Thanks

25th February 2007, 23:15	#2
mithun BANNED Join Date: Jan 2006 Location: Cochin Posts: 2,195 Thanked: 268 Times	A vacuum leak maybe the probable cause. I assume so..... The powertrain control module (PCM) will maintain normal idle speed and compensate for a small vacuum leak by closing down the throttle body air bypass. But if the leak is too large and the idle control system cannot compensate for the extra air, the engine may idle too fast. Common leak paths include the throttle body gaskets, intake manifold gasket, any of the engine vacuum fittings, hoses or vacuum-operated accessories. It is even possible that leaky O-rings around the fuel injectors may be allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft. The important thing to keep in mind about vacuum leaks is that they have the most noticeable effect at idle.
	() Thanks

25th February 2007, 23:33	#3
shibujp Senior - BHPian Join Date: Mar 2005 Location: Trivandrum Posts: 1,788 Thanked: 3,364 Times View My Garage	"Idle" reply?? Idle in MPFI engines are controlled by and Idle Control Valve. In the M800 mpfi this is located just behind the throttle body on the firewall side..well more of less opposing the TPS...it has a couple of narrow rubber pipes leading to it from the air intake manifold. The Idle Control Valve usually open only when the car is idling...sometimes dirt might get into it...you might try cleaning it at a garage. However in this case i guess you should have problems at the start itself. I used to have a similar problem when my engine rpm seemed to continuously surge and fall at idle. But switching the engine off and switching it back on usually solved the problem. Later i figured out that it was related to the load perceived by the ECM. I could replicate this by revving the engine up an a low gear and move forward but never completely releasing the clutch. drive on, Shibu
	() Thanks

28th February 2007, 10:07	#4
anoovis Newbie Join Date: Sep 2006 Location: Cochin Posts: 3 Thanked: 0 Times	Thank you guys I'll check these out at garage and revert back soon
	() Thanks