307 Hesitation/no power at low RPM

M

Marcel B

New member
Tadpole
Joined
Jan 20, 2018
Messages
6
Location
Perth, WA
I have recently purchased a 2007 307 with the 2.0 16V petrol engine EW10A/RFJ. that has developed a hesitation and lack of power at low RPM (800-1500) particularly with sharp throttle openings off idle. It is much worse when cold and will sometimes stall. It doesn't seem to have any issues until about 5-10sec after staring from cold (guessing it is when the car is operating in closed loop). If I hold the revs at around 1200rpm then snap the throttle open it will misfire and stumble then rev as normal. It accelerates and revs normally once above 1500rpm. It will do this when in neutral also so not likely to be transmission related. It does not show any fault codes.

It is staring to drive me nuts and cost me a small fortune as I have replaced a number of parts that could cause similar symptoms. This is what I have done so far with no success.

Spark plugs (Bosch)
Ignition coil (old one had hairline cracks in it)
Engine flush (liquidly engine detox) and oil change
Fuel filter
Fuel pump
Coolant temp sensor
Crankshaft position sensor
Removed and cleaned injectors (not professionally cleaned but flushed them thoroughly with carb cleaner while cycling them on and off and removed any deposits)
Cleaned throttle body
Cleaned intake with Liquimoly Petrol engine intake de-carb
Full tank of Liquimoly injector cleaner
Checked ECU wiring for water damage
Checked injector resistance at cold (#1-12.5ohm,#2-13.1ohm,#3-12.5ohm,#4-12.4ohm)
Can't find any obvious vacuum leaks


Has anyone come across similar issues with this engine or model that could give me any advice?
 
A pretty comprehensive list, but did you look at the aging secondary air pump? If not functional the air/fuel ratio can get upset. If the computer notices you'd get a fault shown.
 
Does this car have an idle air control valve on the intake ?

The one on the 306 played up a few times. If it sticks the air flow off idle will be incorrect.

Cheers

Justin
 
Thanks for the response. I don't think this model has a secondary air pump fitted but I will double check and don't think it would still affect it when warm. Doesn't have an IAC valve idle is controlled by the throttle plate.
 
Black domed thing with the hose, front left.
307-ewmotor-2litre.jpg

Something is affecting your cold fuelling, or the computer's interpretation thereof.
 
Upstream oxygen sensor was the first thing I replaced with no effect. Don't think the downstream one has any input on the fuelling so have not changed it. It seems to affect low rpm fuel mixture or timing but is far worse when cold. seasink I think you are looking at a different engine (that looks like the EW10J4 not the EW10A) I can confirm there is no secondary air injection on mine. Could injectors be causing this? i.e as the engine warms up fuel is easier to ignite so is less sensitive to spray pattern? Or something to do with variable valve timing being affected when the oil is cold?
 
Google this issue as it is a common problem with all EW10A motors. There is no secondary pump or idle control valve. It just requires a cold start reset. Must be left overnight & be dead cold and the engine management adaptors need to be reset via a computer. My C4 requires it again & my C5 is just starting to do it again after 18 months. Once done it's like a new car.


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Last edited:
For those interested this problem turned out to be related to the variable valve timing. It seems as though when the car was cold the solenoid or depahser was sticking or had the incorrect oil pressure causing the cam timing to be out. Solved by putting some liquimoly taper stop noise (which claims to clean out oil ways and lubricate lifters) in the oil and replacing the oil control silenoid valve. Thanks for the input.
 
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