help needed my mp9 conversion is extremly heavy on fuel

[Brandon200]

Hi guys. Dont know if im in the right place but here goes. I have a 1.8 cti that was converted to mp9 in march 2014. After a few months my fuel consumtion just started getting heavier and heavier from 680km on a tank an now im getting between 200-250km on a tank and at the same time it has a misfire. ive replaced the map sensor, temp sensor, throttle body, injector seals, distributor, plugs and wires, fuel rail, fuel pump had the ecu checked showed no faults on the vag had the injectors tested an it was ok. did compression test and compeession is fine. Its struggles to start when cold and once it starts i get a heavy fuel smell coming out of the exhaust can anybody give me some advise im really tired of struggling im so close to fitting a flipping carb on the thing. The motor is standard no mods on it my last hope is taking it to dynotech on monday and if they cant find the problem im setting it alight. Thanx in advance hope someone has a solution for me except the carb lol

[HannesG]

Hi Brandon, yip you are def in the right place.

you checked all the usual culprits. it's obvious that it's over fueling.

[mike65]

I had a polo classic 97mod it had the same prob,some1 tld me 2 change the water sensor nd redo co settings...it turned out the temp sensor was the prob...try it mayb it helps

[Brandon200]

Hi guys thanx for the reply. its defintly not the cold start have about 3 new ones its killing my pocket because i travel to work everyday and the best part is it drives like crap no power at all and timing is fine

[-=sT3V3=-]

while connected to diagnostics check the temp reading, if the sensor is faulty you should see the temp reporting incorrectly.

if you can, take it for a drive with the diagnostics connected you can track the readings and something should stick out...

could be a wiring issue with the temp sensor being good but a poor earth giving a higher resistance than expected.

otherwise i would think stuck injector.

Who did the conversion, homemade harness or what?

[Brandon200]

its a home made harness yes. Ill try and do that im suspecting an injector. Would it give the same symtoms if its sucking air somewhere?

[Brandon200]

another thing if i pinch the return line on the fuel rail the misfire goes away but doesnt have an effect on the fuel consumption still gets its 200km on a full tank but drives much better but dont wanna keep it pinched all the time because the pressure might crack the rail

[-=sT3V3=-]

An air leak generally is just miss fire related and not heavy fuel.

maybe put a pressure gauge on your fuel line and check it is in the 3 bar range.

[Brandon200]

Hi Steve my fuel pressure is 4 bar. Im going crazy im might aswell fit a carb on it:'(

[fmn716]

What isyou had to fit a piggyback chip

surely you could change the fuel maps ?

[maranou]

Alen mp9 box? Polocup or 2l or 1.8l map?
if u pinch the return and car idel write then ots feul pressure too low,if it high on feul ot kan be cracked rail....and if heavy on feul then plugs is dead, if u fit vagcom and take a drive I should be able to see if the sensors are all ok.

Need to take the car to someone that knows mp9 and to diagnose it....go to dynotech and speak to sakkie

[SebastianS]

I had a polo classic 97mod it had the same prob,some1 tld me 2 change the water sensor nd redo co settings...it turned out the temp sensor was the prob...try it mayb it helps

the O2 sensor adjusts fueling and also idling, make sure that sensor is tested (by some1 who knows what they are doing). good luck.

[Shawn S]

Hi i have a vw 1.4i velo that has 276 cam but is running verry rich what can i do

[HannesG]

Hi i have a vw 1.4i velo that has 276 cam but is running verry rich what can i do

remove cam.

[fmn716]

1. Dont Hijack threads
2. Get an A/F ratio guage and install it to see how bad it is from there and troubleshoot

Things to consider when modifying a car is always get your ecu remapped to ensure safety of your motor and gain the maximum hp from the upgrade

[Deniboy]

was this ever fixed?

[Funkymunkyman]

Was it fixed?