3barboost

Help all

yip its me again looking for advice

My mates MY00 GT only runs 102 fuel with a VF23, unichip, samco hoses, wrx cooler 3 inch zorst and headers with about 35 000 miles suddenly started billowing black smoke and exhibit very rough running and idling. when one gets the car underway its drivable (slowly) on a very light throttle whenever any accel is called for its splutter city. HELP the driver atthe time hit a bump on entry to a filling station could this have anything to do with it or is it a red herring ?

On examination cyl 2,4, plugs are badly fouled - BLACK
cyl 1,3, are 100% and look fantastic
Heres whats been tried:

checked cooler for leaks - no problem
Disconnected/bypassed UniChip - no difference
Swopped ECUs - no difference
2 different MAFs - no difference
disconnect of lambda - no difference
check air hoses - no leaks
swopped coil pack - no difference
checked knock sensor - no problem
checked cam position sensor - no problem
Took injectors out for a visual - all fine
Swopped injectors for another set of yellows - no difference
Swopped injectors for a set of 2.0GX normally aspirated injectors and the idle began to stabilise (obviously ther are smaller and produce less fuel)
checked fuel delivery to all injector buckets - all fine (made a helluva mess...)
Plugged Delta Dash in - apart from a very fast moving AFR ratio and the ecu working at top speed to try fix it......the only error codes were MAF - to be expected after so many hot swaps and the ISC I presume this is idle stability control - on plugging and unplugging this in it makes no difference, I think it only gets affected on cold starts ? diffcult to fool the engine into a cold start

HELP what can I check to find the gremlin responsible for 2 rich rich rich cylinders causing this rough running ? and extreme power loss ?

Thanks guys
!!!!!

Jolly Green Monster

iTrader: (4)

Are the coolant fans running all the time? - coolant temp sensor faulty

failing that it sounds like one of the vac pipes is split.. try replacing them..
or a cracked / leaking manifold..

or obviously more serious problems.. have you checked the compression?

3barboost

Hi

Fans work as normal

did a comp test about 10 mins ago

all cyls within 3% of each other

I am now thinking MAP sensor - perhaps stuck giving a high boost reading ? causing the ecu to think its boosting 1 bar at idle ?????? sounds silly but all I got left are straws....

Jolly Green Monster

iTrader: (4)

MAP sensor is possible..

but unlikely..

David_Wallis

if you have a maf error code then try another maf.

3barboost

I tried another MAF (3 in fact)

Delta Dash shows no errors

This is insane

I have now checked cam timing all ok

Then I had the brain wave of holding a socket extension bar on the injectors and listening to them

the left bank (drivers side 1-3) on the affected car injectors click half as often as the passenger side 2-4....

Taking the same socket set to my 00GT all injectors sound the same (ie the same as the passenger side 2-4 on the affected car)

Now to me this means that the drivers side injectors are running lean, the ecu via the lambda is telling the injectors to open wider (overall) to provide more fuel - hence the rich bank on the passengers side (2-4)

So now the inlet manifold came off - coolant sensor unplugged - fans come on - runs the same as before

lambda replaced with a known good one - no difference

wiring harness checked and retested

got an oscilloscope onto the injector wires and it confirms the click click click evidence of the socket set

what else could be at fault ?

what could cause the driver side cyl 1-3 to run half as lean as the other bank ? according to the scope its exactly half !

changing ecu doesnt make a difference


HELP

I have even resorted to rubbing and tickling the inner fender hoping it will start purring.....

Jolly Green Monster

iTrader: (4)

Edit to change passenger and drivers side references as you are noty in the UK and might be lefthand drive?

Fuel pump not supplying enough fuel pressure.. 2 and 4 are fed first.. so gets enough fuel.. 1 and 3 are fed last so lean.. check the fuel pressure.. or switch fuel pump.. imho..

Jay m A

iTrader: (2)

If 2-4 are twice as fast as 1-3, then perhaps injectors 2 and 4 are receiving each others signal, ie injector 4 squirts as it should, but also squirts when 2 should, same goes for injector 2.

This suggests wiring, perhaps the injector feed for 2 and 4 are shorted together?

3barboost

Hi

Car is right hand drive as per uk spec

I thought some people may get confused thats why I was trying to put cyl nbrs in as well as sides of the car

I have learnt the following about the injector wiring

There is one common shared amongst all 4 and 4 seperate (control) so in total 5 wires enter the ECU for injectors, I have used a multimeter to check for shorts on these wires and definetly there are none !

Next step is to check the back of the cam pulley where the cam position sensor goes maybe something on the pulley is interfering with the sensor

I hope no one objects to this journal of fault finding, as it has me stumped

Jolly Green Monster

iTrader: (4)

My money is on fuel pump..

3barboost

Solved

problem = cam belt obviously whipped around somehow and hit the "plate" behind the centre main crank end pulley, this plate was then bent out of alignment and interefering with the signal to the crank position sensor, the ecu was not picking up anything in terms of error codes once this plate was sworn at sufficiently perfect smooth running order along with my mates and my sanity was restored along with a new cambelt !!!

Jolly Green Monster

iTrader: (4)

excellent!

Jay m A

iTrader: (2)

3barboost

I am ecstatic to have found this one, in all my years of fiddling this is the worst and most difficult and funny troubleshooting I have ever had the pleasure of going through !!!

I wonder how long a dealer would have taken ?

TARManiAC

A dealer would have taken as long as the customer kept paying.

Most dealers that is. Think 90%.