Over Fueling Aygo 2012

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Hi all, im at my wits end ere' i would like aome help please! Ok so my Aygo aeems to be iver fueling, done a compression test and getting over 12 bar so thats ok, ive changed the following as a measure of tests as i thought it was more if an ignition fault.

MAP sensor

Idle Control Valve (ICV)

Throttle Position Sensor (TPS)

X3 Coil Packs

VVT valve + mini filter

Did service the car over a month ago and spark plugs are new.

When i took out the spark plugs today to carry out a compression test all 3 spark plugs are what the look like in the picture.. and details of the cylinders test. sometimes the car idles nicey but then fluctuates up and down and you can hear the engine when driving it hesitates to more then you have to press acceletrator abit more to try pickup some speed..

Id like to know if the Temp Sensor sends the signals to the ECU when cold to run rich for cold start if so can it send signals to run rich most times if the switch is faulty? Running out of ideas... 

Thanks In Advance!

J

 

[Vandals01]

I think you should get a real OBD2 scanner before shooting more parts at it, i.e: scanner that can read generic OBD2 data.

Bring up the data for:

• Fuel System Status (Open Loop/Close Loop)
• Injector duration (for how long is the injector fire for in milliseconds)
• Coolant Temp
• Short-term Fuel Trim for Bank 1 Sensor 1
• Long-term Fuel Trim for Bank 1 Sensor 1
• Air-Fuel Sensor Voltage for Bank 1 Sensor 1

I mean yes, the spark plugs seems to be burning rich (too much fuel) but you need know what data is feeding into the ECU to made this happen.

(BTW, I hope you are not using Super Market Fuel...)

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1 hour ago, Vandals01 said:

I think you should get a real OBD2 scanner before shooting more parts at it, i.e: scanner that can read generic OBD2 data.

Bring up the data for:

• Fuel System Status (Open Loop/Close Loop)
• Injector duration (for how long is the injector fire for in milliseconds)
• Coolant Temp
• Short-term Fuel Trim for Bank 1 Sensor 1
• Long-term Fuel Trim for Bank 1 Sensor 1
• Air-Fuel Sensor Voltage for Bank 1 Sensor 1

I mean yes, the spark plugs seems to be burning rich (too much fuel) but you need know what data is feeding into the ECU to made this happen.

(BTW, I hope you are not using Super Market Fuel...)

Hi Vandals01, thanks for your reply back! i use Shell V-Power in both my cars. Ok i do have an OBD2 scan tool no errors showing! 

Also as for the data you stated how would i know what data on a correct working car to comparing it to mine thats causing this over fueling issue if i make sence? Wouldn't the pressure regulator on the fuel pump be faulty, causing this, etc?

Thanks in advance.

J

[Vandals01]

This video sums it up very well.

Generally speaking, you want to know:

• Is the car determine itself to be in Open loop or Close loop (Any attempt to control the fuel)
• Fuel trim - is it Positive (ECU adding fuel) or negative (subtracting fuel) - which is also reflected on the Injector duration e.g. when it subtracts fuel, injector duration decreases.
• Air-Fuel Sensor Voltage - senses how rich is the exhaust gas after burn.  Above 3.3v means it's lean (low on fuel), the ECU will thereby add more fuel by open the injector longer.  Below 3.3v means it's rich (computer senses too much fuel), thereby it will shorted the injector duration, subtracting fuel going into the engine.

Yes, it could be the fuel regulator.  As for Aygo, I believe it is part of the fuel rail.  But I would place my bet on the Lambda sensor.  (if the Lambda sensor is faulty, you'll see it goes the Air-Fuel Sensor voltage reacts very slowly.)

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Hi Vandals01, thanks for your reply back an the link to the video! I have forgotton to mention that i have a 3 branch manifold on my Aygo 2012 so the Lambda sensor is at the bottom where it joins the middle down pipe opposed to the top where it would be on tje cat. the lambda sensor is bolted on to adaptors which is kind of an extension away from the boss of the 3 branch, it avoids the engine light coming on as there is no Cat! Now no errors come up on the OBD2 reader stating that the Lambda Sensor is faulty, i know there are 2 sensors, which one would normall be the culprit for fueling/overfueling issues as both sensors would be instructed to do different things if im correct?

Cheers..

J

[flash22]

Plugs look about right, No cat and the location of the A/F it will not trim correctly especially when cold - tbh it will need mapping to get it to run correctly, to allow for the reduced back pressure and adjust the fuelling

is the manifold a 3-2-1 or 3-1, unless the ecu is mapped a manifold will not do a lot, a manifold with a high flow cat will be a better option

Please don't tell me you have a sub £100 "tuning chip"

 

It seems you have loaded the parts cannon without any diagnostics

 

[Vandals01]

That's why dealers do not touch modified cars.  As modification especially around engines will create many abnormalities, makes it impossible to diagnose in a "Normal" manner.

Its not like it didn't happened before:  Mechanic reverse the modification, the car no longer acting strange.  All the problem disappeared like magic.

I certainly agree with Bob on this one:  with the CAT deletion, the car needs a remap before anything else.

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44 minutes ago, Vandals01 said:

That's why dealers do not touch modified cars.  As modification especially around engines will create many abnormalities, makes it impossible to diagnose in a "Normal" manner.

Its not like it didn't happened before:  Mechanic reverse the modification, the car no longer acting strange.  All the problem disappeared like magic.

I certainly agree with Bob on this one:  with the CAT deletion, the car needs a remap before anything else.

Hi, thanks for your replies back! the problems seems to get worst at little stages, a mate who makes videos on you tube using his car for mods etc done has the same, 3 branch and runs perfectly well, no faults like what what  mine has although with a 3 branch it has a flatspot at a certain rpm then its ok to which is when you have to put on rollers to map it out. My issue is over fuelling, 3 branch has no effect to whats going ...  me mate took the var for mapping the the flat spot had been mapped out and drives smoother and abit quicker.. i havent had any mapping done or tuning chip. The 3 branch is a 3- 1

Thanks.

J

[flash22]

pre and post cat sensors control the fuel you need to look at live data and see what the CTS is reading, what air filter are you running ?

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52 minutes ago, flash22 said:

pre and post cat sensors control the fuel you need to look at live data and see what the CTS is reading, what air filter are you running ?

Hi, thanks flash22 for your reply, can i ask for a good working 02 sensor, what reading am i to expect to compare with mine if faulty?

Thanks.

[flash22]

It depends on the conditions, you need to be looking at live data, or cold engine, engine off, sensor unplugged - see below, not sure what year your mate's car is, but late 2009 onwards is euro 5