WTK: FLAT SPOT DURING ACCELERATION FROM STANDSTILL

[Rory Phoulorie]

Car: Mitsubishi Lancer CK1

Model Year: 1997 (Local)

Engine: 4g13 carburetted

Transmission: 4 speed automatic

I am experiencing a flat spot during acceleration from a standstill to about 30 km/h. Once the car crosses that speed, it starts to accelerate as normal.

The carburettor has already been completely dissassembled, cleaned and seals replaced. The engine timing has also been checked. The fuel filter was also recently replaced.

Could anyone provide some advice as to what else could be the problem.

Thanks.

[-blazing-]

timing?

dist may need adjusting.

[Rory Phoulorie]

[X2Board]

sounds like youre experiencing a vacuum leak..
check all the lil rubber hoses and vacuum lines that connect from the carb to the manifold.

the principle behind it is the car isnt pulling significant vacuum at this speed to temporarily "seal off" this leak so air is sucked in and upsets the mixture, causing a rough idle and flat spotting.
at higher speeds/rpms, the amount of air being ingested by the engine is so much thet the leak becomes negligible....

you can go about checking for this leak 2 ways....

get yourself a spray bottle with water and start the engine .. whith the car idling , squirt water all around the carb , hoses vacuum lines , (dont forget the booster, pcv valve and vacuum advance to the distributor), if the idle drops off or teh engine cuts off the leak is in this area .. spray smaler areas to pinpoint the leak

the other way is to do the same thing with carburettor spray... and listen for an increase in idle .. jst be careful yuh doh spray the exhaust manifold & cause a fire....lancer is crssflow so u doh have to worry too much ..

Another culprit may be the vacuum diaphragm in the distributor.. if it burst the timing will not advance on acceleration and you'll flat spot .. chck this by pulling out the hose going to the carb and with the dist cap off , pull thru the hose like a straw and look for movement in the cap ( cant remember offhand how the inside of the mitsu cap made up eh.. but you should see movemnt) ..
if not, the diaphragm buss....

check your pcv valve.. make sure flow is in one direction..

i assume your plugs have been rrplaced as well. if not do so asap ..or atleast clean the ones installed right now and gap them to the proper specs.. 4g13 should be 32 .... electronic ign 36 - if i remember corectly....
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[Rory Phoulorie]

X2Board, thanks. Will try what you recommended.

[tensei]

my 2002 cs3a lancer experiencing the same flat spots
just that the engine is 4g18 with 5fwd gb
any ideas suggestions
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