:confused: Help !! Strange Engine Behaviour !!

[fitsandy]

Its a Suzuki 1.3 L swift MPFI.

I just got my engine rebuilt 3 months ago, spent about $ 1000.

Now there is a strange engine behaviour that I see. On starting the idling RPM never goes beyond 400-500 and reaches 900 or so only when engine is warmed up.

Also at time during heavy rainfall days engine power seems to be very very low and I sense something seriously wrong.

MPG falls drastically when engine power seems very low. Dunno whats wrong with the motor.

Have changed air filter and plugs, cleaned distributor terminals and rotor etc. Problem persists.

At times suddenly the engine becomes very smooth and responsive and gives very good pick up and power.

Whats wrong ??

Is it ECM gone bad ??

Is it some sensor gone bad ??

What can be the possible reason ??

Is it a partially choked fuel filter ??

I recently cleaned my throttle body, TPI and IAC also and added a catch can to the PCV-Breather circuit.

Help please in diagnosing the problem.

Thanks much.

[$400chevymetro]

You might check your plug wires. Since you mention that it seemed worse in wet weather. When it's dark start engine and look uder hood and see if you see any sparks around plug wires, you might mist a little water on the plug wires and see if that makes it worse.

[fitsandy]

the mechanic checked the plug wires by placing the screwdriver against the wires in diff positions to check cross firing but found none.

what can be the other reasons ?

[Johnny Mullet]

First off, is there a check engine light on or does it even work?

The "screwdriver trick" does not show the condition of the plugs, but you said you changed them. Wires OK?

You said it was rebuilt recently, but was it timed properly?

First steps....................

Scan for codes for check engine light.
Change fuel filter.
Fuel pressure test.
Check timing with a timing light.
Check compression in all 4 cylinders.

[fitsandy]

I opened the TB again and found oil+carbon inside. I cleaned it and IAC valve and reassembled. I loosened the TPS screws and advanced it a bit so that even with a small opening of butterfly the ECM will read as 8-10% more than that.

Also I disconnected the air-breather pipe of engine from air inlet hose and plugged the air inlet hose. But I just left the engine breather pipe open in the air to take fresh air. I will add a small filter on top of this and post pics soon.

This has sorted my problem 100%

This will stop any oil from entering the TB at all. I have already added a catch can between PCV and IM.

Lets see what happens.

I plan to add a Hyundai Verna stock air filter with assy in place of the round suzuki 1.3 L.

I also plan to add 1K ohm resistor in series with IAT sensor for timing to get a bit advanced to get an easy city driving and better fuel average.

Comments welcome.