:( Very lumpy idle, backfiring

[tstrahonja]

Today i was on dyno and it was very horrible



Running super lean, low power, low torque...Leon is originaly auq, but has aguengine in, k03s, stage 1, forge fmic, TIP, decat 70mm exhaust...
And now my car wont idle smoothly, on my gauge usual vac level is -9, and it is -4-5, running very rich, u can feel the smell of fuel..when i am driving it seems normal, except very loud missfires when letting of throttle, and i mean after a gentle acceleration..

Checked DV (forge 007p), seems ok, when i push piston invards and put my finger on DV top nipple, it holds, when i let go DV piston pops back.
MAF seems ok, read 175 on dyno
I did n249 bypass
I have 3.6 bar FPR, and judging by graph, very bad fuel pump, can this be related?
I once had throttle position error on vag com, and today i had somethin saying Pressure Drop between Turbo and Throttle Valve (check D.V.!)
Thanx for your help guys.

 

[mty12345]

Hard to tell mate, i'd start looking for splits in hoses. Between the turbo and the inlet manifold, and also check vacuum and PCV hoses too.

 

[tstrahonja]

Used a bike pump to test most of vac hoses and one way valves...all good
I also tested vac hose to FPR, and i am not sure if this is ok...i can hear air escaping thru FPR..i also tried to make vacuum with my mouth and it doesnt hold vacuum...would that mean that the FPR membrane is broken, or this is normal behaviour?




I tried disconnectind coilpacks one by one...and there is not much difference? Engine runs almost exactly the same while 1 coilpack is dissconnected..
When i press throttle it works normal, reving is normal

 

[Hedgehog Dodger]

Looks to me like coil or plugs as you have major hesitation high in rev range. What plugs have you got and are they gapped correctly?

 

[tstrahonja]

I have new bkr7e, coils are ok, i think, i will check, but 90% they are fine
Today i tried anothet FPR, no luck.
Changed fuel pump, no luck.
Changed injectors, no luck.
Usual vac level is -9, now it is -4, car can barely idle..
Sparkplugs are white, like super lean, but there is petrol smell thru exhaust..
There is vag com code multiple cylinder misfires, and cylincer 2 misfire and p1297 pressure drop between turbo and throttle valve...
Tommorow i will try my friends throttle body, and maybe another ECU.
If that fails i just dont know what to do anymore...

 

[tstrahonja]

Well, today car ran almost fine, i installed my friend ibiza 1.8t PRV valve (next to DV) and car ran fine, almost perfect..i will buy new one and report back, maybe PCV valve is half busted too

 

[Hedgehog Dodger]

Poss. Why not just fit a catch tank instead of the hockey puck?

 

[ibizacupra]

log fuel request etc on blocks 001,002,031 under wot when its doing its problem.

this will show maf airflow, requested fueling and lambda adjustments its trying to do to achieve the request..
001 should be within 5% not more and if physically running out of lambda adjustment it will go up to 20% and afr on 031 will go lean.. as its out of fueling.
Look at maf readings also.. a heavily under reading maf will cause lean running also and big lambda adjustment.

Usually pump weak tho.

 

[tstrahonja]

Thanx for your help guys..
I ordered walbro 255 in tank fuel pump, and i also ordered new hockey puck prv valve.
I will also order new pcv valve, adn then we will see..
I am afraid to do wot logs at this time cuz i dont want to boost with 14 AFR..i just hope i didnt do any damage to valves and pistons so far..

 

[tstrahonja]

So, i tried different throttle body, no luck, although i didnt have vag com so i couldnt do TB alignment, but that TB worked just as mine...idle like crap, when above 1500 rpm engine works normal...

I changed PRV valve (hockey puck), no luck.
Now i dissconnected all those vacuums under inlet manifold



I tried blowing and sucking One way valves working ok, PCV also ok, no visible holes, leaks...
Can a very bad fuel pump cause this?
Bad pre cat lambda?
Dirty fuel filter?
Bad MAP?
Bad MAF?
I am running out of ideas

 

[Hedgehog Dodger]

Fuel pump?

 

[tstrahonja]

I think that my fuel pump is bad, but can bad fuel pump cause idle problems, but still ok driving?

 

[tstrahonja]

So, i removed entire PCV system, checked suction jet pump, pcv valve, one way valves..all seems ok.
My vac reading on idle id -0.9 bar, and when i engine brake vac imidatley goes to -1 cuz that is max vac that my gauge shows...but now i cant get less than -0.9 with engine braking..so it is definitley somwhere a huge vac leak, just dont know where to look...

I tried pinching both vac nipples under the intake manifold, blocked them, still idles like crap, tried blocking brake booster, nothing, tried blocking vac that is on TB, nothing

 

[Josephgiles29]

Can eny 1 help me I got a oil leak in my 03 cupra r looks like it's cuming from side of engine we're gearbox is as there's oil all over top of gear box and all pipes it's seems to leak more if u boost it eny 1 no we're it could be cuming from it's got a be towards bottom of engine just above gearbox as round rocker cover is dry it's below that or could be a pipe I don't no car boost sound and drives fine just got that leak

 

[mty12345]

Can eny 1 help me I got a oil leak in my 03 cupra r looks like it's cuming from side of engine we're gearbox is as there's oil all over top of gear box and all pipes it's seems to leak more if u boost it eny 1 no we're it could be cuming from it's got a be towards bottom of engine just above gearbox as round rocker cover is dry it's below that or could be a pipe I don't no car boost sound and drives fine just got that leak

You need to start a new thread, but i would imagine either the turbo itself or one of the oil lines, to or from it.

 

[tstrahonja]

Would this mean that my engine is dead? Seems like a blowby...

https://www.youtube.com/watch?v=xuFfF7dGX7Y&feature=youtu.be

https://www.youtube.com/watch?v=FBe7rDBvLR8&feature=youtu.be

 

[tstrahonja]

Well, it is more or less the same on my friends Ibiza 1.8 and audi 1.8t..it is definitley blowing from oil cap hole.

 

[ibizacupra]

compression test it and leakdown test it

 

[tstrahonja]

Well, i took the car to a mechanic this morning, but he is not 1.8t expert, no such mechanics here..
He asked me what to do, and i told him to do a compression check, temp sensoe change, fuel filter change, pressurize whole system from turbo to intake, chekc fuel pressure..
While i was driving to him, car acted almost normal...started perfect as usual, run smooth while choke is on, then started to run bad as idle dropw downo to 750-800 rpm and then while i was driving it vac got beter and better...got to -0.8 on idle, and usual is -0.9..i dont know what to think anymore..we will see

 

[tstrahonja]

Compressions are:
9 10 11 11 bars

Not so good on cylinder 1, but still in spec?