Engine Pining On Low Load

[GAPAUTO]

Hi All,

While I was driving last week, I start to hear a engine pinning on low load. Well if I describe it more, its like when I drive around 50kmh and I just step on the gas pedal a bit to increase the speed I hear a pinning sound. Well when normally if we accelerate the car suddenly we hear this sound, but it goes away once the car is in the required speed. But this doesn't go away like that till I release the pedal a bit. Well what could be the problem for this ? timing advanced ?

Gayan.

[Rohnd]

Hi All,

While I was driving last week, I start to hear a engine pinning on low load. Well if I describe it more, its like when I drive around 50kmh and I just step on the gas pedal a bit to increase the speed I hear a pinning sound. Well when normally if we accelerate the car suddenly we hear this sound, but it goes away once the car is in the required speed. But this doesn't go away like that till I release the pedal a bit. Well what could be the problem for this ? timing advanced ?

Gayan.

What's the car Make , Model and YOM ?

[GAPAUTO]

Well Sorry i forgot put the car information . Well it's Lancer station wagon, Engine : 4g12 Orion, YOM : 1978.

[Rohnd]

Well Sorry i forgot put the car information . Well it's Lancer station wagon, Engine : 4g12 Orion, YOM : 1978.

Since the Car is fairly old several factors could lead to this.

1. Incorrect Ignition Timing adjustments.

2. More carbon deposits in the upper chamber.

3. Low Air/Fuel Ratio

4. Sticky or wear in Distributor components

5. Use of improper heat range rated Spark Plugs.

[BLu3HaZe]

Hi Gayan,

You also wanted to tune or do something with the carburetor right? You sure it's not a problem with that? Though I'm not too familiar with carburetors other than in motorcycles, afaik, there are about 5 different modes for it right? As you say this comes when accelerating, maybe it's that mode not giving enough fuel making the engine lean, leading to pining? Just a thought...

[GAPAUTO]

Well I tried with retarding the timing a bit (around 1mm distance) that got rid of the pinning sound. But now the idle doesn't run smoothly. So I have to increase the idle speed from the card. Well there are some vacuum lines which goes from the carb to different components, but all are blocked by putting small iron balls inside other than the vacuum advance line. I'm not sure about the five stages, i just read from the Internet about the basic stuff and the experience I had with my VW Bug. And I remember the last time my carb was tuned by a Mech he did the same. Please can any body give some information about the 5 stages ? And I notice that if i press the accelerator deep I see a light black smoke after few seconds. Is that normal or some thing to do with timing ?

[BLu3HaZe]

Before anything, I should tell that my knowledge on carburetor engines is very limited, so you should ask your mechanic or some expert in that field on AL on that subject. I'll just try to answer that question regarding the 5 modes, cuz it came from what I said nah? We've had a 70s Lancer wagon at a time, but I didn't pay much attention to that, as I was more interested in the EFI Tercel.

When the engine is cold, you need more fuel to start the engine so you got the choke for that. Then you got the idle mode, which you were trying to tune in the other thread? And then a normal operation mode, for what the name says. Then an acceleration mode where more fuel is put in again. And a full throttle mode for which it's calibrated for proper air:fuel ratio. So guess that makes up 5 parts, which you can tune individually. But you better ask a mechanic how to do that stuff.

Edit - About the black smoke, that's probably soot or carbon from a mixture which is too rich. Maybe the timing or the carb, but by now it's quite a mess as it seems, so would be easier to get it tuned by a garage or whatever. Or if you're adventurous, try doing it at your own risk You may damage the sparks plugs at the least if you get the ratios off, and at worst cases of a lean mixture, may even damage the engine. Please be careful, as it's not a VW Beetle and more advanced as the environmental rules were different in 78, so more complex carb.

Edited September 27, 2010 by BLu3HaZe

[GAPAUTO]

I think we can only adjust the volume control and the adjustment on throttle lever which will adjust the idle mixture. Other said modes I'm not sure where to adjust. But I have herd that there are pre defined jets and mechanisms which will work on OWT (open wide throttle) to rich the mixture. But one thing i'm not sure is, on sudden OWT situations i get a light gray smoke and goes away. i'm not sure whether this is normal or not ?