Engine Rev Up And Down And Fuel Problem

[idoari 10]

Hi,

 

my 1.6 GTI engine running perfectly BUT i have a problem that bugging me.

when i rev the engine and leave the acceluration pedal the RPM goes don't under 1000 rev and the engine feels like it's going to stall but then it recover to steady 1000 RPM or so again . this happent even when the engine is up to temperature.

 

what can be the problem, bare in mind i replaced almost everything (not because of this problem - i'm restoation the car) : new AFM , new ECU water temp, new HT leads , new cap , cleaned rottor , new coil , new ignition amp , clean fuel injectors , new filters ( Oil, fuel , air) , new timing belt and water pump,checked the SAD - all good, re-done all the engine loom (clean the contacts , tested everything)

 

the only thing i think it's could be it's the TPS sensor or the fuel pressure reg .

what do you think?

 

i have another problem , when i re-fuel the car today , the tank was half empty and i put the nozzle in and started feeling. suddenly the gas station pump clicked (to tell me that the refueling is done) and i put another 1-2 liters and i look under the car and it was dripping fuel everywhere (after a few minutes it stopped). i didn't have a problem before.

is it some kind of safety mechanism that protect from overflow ? the leaks seams to come from the top of the tank not from the bottom. how can i fix it that the gas station pump will click at the right time and not overflows.

 

thanks

Ido

 

[Tom Fenton 1,542]

Revs, adjust the throttle stop open a small amount to open the position of the butterfly at rest. Adjust the bypass screw to bring hot idle speed back down to where it should be. Finally readjust the TPS switch.

 

Fuel should not leak. There are two pipe connections on top of the tank, one of these could be incorrectly fitted, also check the fitment of the fuel pump and the sender unit.

[idoari 10]

I did all that but it was before i bought the AFM. i will check again.

when i drove today and press the accelerator pedal steady the car rev up and down , like an hesitation. it felt like the car get my pressing signal than don't, than gets the signal again than don't - this happent very rapidly.

 

since i replace almost every component i think it's the TPS. if the TPS is built like the AFM it's most likely the contact inside wear out.

can you confirm?

 

it could be the clutch?

[jackherer 543]

The TPS is just two switches, there is no variable resistor/potentiometer. It is very easy to test it with a mutimeter but it doesn't sound like it will help the problem you have.

 

Since adding the new AFM have you checked the air:fuel mixture using an exhaust gas tester?

[idoari 10]

if the car overfueling, what are the simptoms of that?

i'm asking that because i have a different fuel injectors than the standard 1.6.

i have now on the car the 0280150703 injectors which are a little larger capacity than the 0280150211 that sepposed to be.

 

can this make that of a difference? the 703 is 165cc/min @3bar which the start i think it's 150 cc/min @3bar.

[jackherer 543]

Overfueling can definitely cause surging under constant throttle as you describe.