G60 problems-my turn.

[Blown 0]

In a word-overfuelling.

The car is unwilling to start without a bit of throttle and idles ok.

Give a rev to around 2k and let it drop back and the thing drops right down,hunts for a second,then returns to a reasonable idle again.

Remove the blue sensor and the engine dies.

Remove the MAF sensor and there is no change-however,I have noticed that there's a boost leak around the MAF(lot's of white vapour/smoke)where it goes into the boost pipe.

I removed the plugs and they are soot black,so I changed them for another set and ran the engine,took them out and they were wet with fuel.

If I take the car out and drive it,there is a noticable "miss" which would indicate timing probs,but I have had the timing checked and it's ok.

Could the MAF be faulty?

I take it that if the BTS is removed and the engine dies,then it's doing it's job?

Would a boost leak cause this amount of overfuelling?

 

Have just had the oil seals in the charger replaced after the others failed and let loads of oil into the cooler system.I have removed and cleaned out all the pipes and I/C so hoping that has nowt to do with this problem.

The car has a 260deg cam and rebuilt head with stainless steel manifold,enlarged inlet/exhaust ports and a decat with new Lamda sensor.

I'm hoping that it's not needing a remap,cos there's no-one here who can do it-and I don't fancy driving the car 400miles to the nearest mapper in this condition either! :( :shock:

Any ideas? :?

[h100vw 0]

Without any load it should rev cleanly.

 

The BTS disconnect causing a stall would make me wind the tickover screw out, also the dropping right down and then kicking up points to this.

 

 

Have you got the vac pipes on the TB the right way round. ECU to the top one.

 

The next best one for overfuelling is the lambda probe/or it's wiring. Much has been posted recently about checking the output with a DVM. The output is steady until the engine gets to temp.

 

Gavin

[Blown 0]

Yep,the vac pipes are the correct way round.

How does the tickover screw work?

Is it similar to the idle screw on carbs-i.e. screw it out and the idle drops,turn it other way and revs increase?

[h100vw 0]

Out increases the tickover, bigger hole for the air to go through. Need to do it with the BTS disconnected.

Gavin

[Henny 0]

I'm with Gav here...

 

If you have a boost leak then it will make the engine run rich as all of the air that's supposed to be getting into the engine isn't which'll screw up the vacuum and boost systems. Change the rubber grommet that fits around the CO Pot in the boost tube if it's leaking, they do squish down over time and can leak....

 

Once you've replaced the grommet, run it up to temp (over 80degrees water temp) disconnect BTS and unscrew idle screw until revs are around 850rpm, rev upto 3000 and release three times then let it settle. Re-adjust the idle screw again to get it back to around 850. Repeat a couple of time as needed, then reconnect BTS which shouldn't make any difference to how it's idling...

 

See if that's any better... :)

[Riley 0]

lets see if ive learnt a bit from you guys? :)

 

as a rough guide,the maf sensor,should have somewhere near 500ohms across pins 1 and 3? (the top and bottom one) but you cant beat having it on a gas anyliser to set the c.o correctly.

 

sounds like the guys are onto your problem though. 8)

 

neil.

[Henny 0]

Riley, sounds reasonable to me... 8)

[Riley 0]

:D

 

good luck sorting it m8,us g60 owners need it!

[Blown 0]

I'm with Gav here...

 

If you have a boost leak then it will make the engine run rich as all of the air that's supposed to be getting into the engine isn't which'll screw up the vacuum and boost systems. Change the rubber grommet that fits around the CO Pot in the boost tube if it's leaking, they do squish down over time and can leak....

 

Once you've replaced the grommet, run it up to temp (over 80degrees water temp) disconnect BTS and unscrew idle screw until revs are around 850rpm, rev upto 3000 and release three times then let it settle. Re-adjust the idle screw again to get it back to around 850. Repeat a couple of time as needed, then reconnect BTS which shouldn't make any difference to how it's idling...

 

See if that's any better... :)

 

Well,I've replaced the grommet and that's cured the leak there,but I've found another leak on the return pipe-right where it's supposed to seal at the charger. :roll:

Have had a good look and it appears that the top screwhole on the charger has stripped the thread-so the allen bolt isn't seating,which is causing the pipe to "push" itself away from the charger and create a leak.

Ho-hum,it's out with the tap and die set then. :(

 

Oh,another thing,I've calculated that since all the major work was done and I taxed and insured the car in june,I think I've only driven it on the road for about,maybe,ten days.The rest of the time it's been sat in the shed in bits.

I've gone and depressed me now.I think it's time for beer. :cry: :lol:

[W3RKD 0]

the boost return pipe will make no differance to the poor running of your car.

[Blown 0]

Yeah,but it's leaking.

I would've thought that a leak,albeit in the return side,would still cause an imbalance in the pressure as the charger draws air in from the opposite end of,what is basically,a hollow tube? :scratch:

[andycowuk 0]

Yeah,but it's leaking.

I would've thought that a leak,albeit in the return side,would still cause an imbalance in the pressure as the charger draws air in from the opposite end of,what is basically,a hollow tube? :scratch:

 

I dont have a pipe on that side.....its got a blank; that side of the boost return butterfly has air flow in it, but is efferctively as atmosphere.

 

I dont think a boost leak would cause overfueling. The ecu considers MAP and RPM to refernnce the injector pulse width. So if you should acheive say 15psi at full chat, but because of your boost leak you only have 10psi, you car will fuel for 10 psi at that engine rpm IE cross-reference an injector pulse width lower down the fueling map. On WOT the map has fixed values, with the CO pot controling the baseline that the fueling values are reference from, for non WOT values, the map is more dynamic, with feedback from the lambda probe.

 

The connection between the probe and hte main loom on mine was really terrible, so i stripped each of the 8 wires back and inch or so and reconnected with spades. see if you can take the shrould of the ECU wire harness, get the car running and check the voltage that the lambda pin is seeing (purple wire). low voltage represents lean to the ecu 600mV and it will flick between the two like a toggle switch. A bad connection in this part of the loom will result in a significant voltage drop over the loom connection, so that the ecu might always see 300 - 400mv less than the lambda is telling it.

 

Also..

 

What value is your CO pot at?

 

Do you know how your injectors are performing? when were they last tested?

 

Incase you have accidently began to trust me...... I am going up to wick some time in the next 6 weeks to fix my mums husbands scirrocco.... I may well me buying a wideband lambda sensor and data logger to help with the mapping of the vsam in it.... I might be able to help you out if you can handle getting the boat across to me?

[W3RKD 0]

blown, also to consider is if you have pumped lots of oil over the lambda when you blew your oil seals it has most proberly damaged that too. I would go back to the start again and check the fundimental area's which can often get overlooked. Earths' harness/sensors etc would be my first port of call.

[Henny 0]

yup, with you all the way there Daz... Unusual over fuelling on a G60 is normally due to a sensor or vac pipe, be it a new one or not, that's not doing as it should...

[Blown 0]

Well,I think I have finally gotten to the root of the problem-I think the head gasket has a small hole in it. :cry:

I've cured the leaks in the boost pipes,which I think has corrected the overfuelling problem, played with the dizzy to advance/retard the timing to get rid of the misfire and checked the lamda and wiring,then started the car,without too much throttle this time,then let it warm up.

Went back to it and it was idling away nicely,with just the merest hint of a misfire,barely noticable in fact.

It wasn't until I raised the revs to around 2k that I saw quite a lot of blue smoke from the exhaust. :x

Thinking the oil seals had let go yet again,I pulled out the CO pot from the boost tube and had a look,but no oil was present inside.

So I took out No4 plug and it was clean apart from a slightly oily looking film on the end.

So I think I'm right back at square one and will have to replace the HG.

Again.

 

I'm giving serious cosideration to giving it all up as a bad lot and selling the thing as parts,or to someone who wants to do the work. :cry:

[Henny 0]

Blown, did you have the head skimmed last time you did the headgasket?

 

Sounds funny to me that it should have blown the head gasket again so soon after you've already done one... :|

[Blown 0]

The head was taken off and sent off for a rebuild with gas flowed ports and enlarged manifold inlet/outlets and generally cleaned up.IIRC the company said that it was in fairly good condition before any work was carried out,so no,it hasn't been or needed,skimming.

It just seemed wierd to me that the exhaust smoke was still coming out blue with oil vapour,even after I had cleaned out all the boost pipes.

The only other thing it could be is oil lying in the inlet manifold that is still to be burned off.

What's really confusing,is the fact that there doesn't appear to be any emulsion inside the oil cap or inside the rocker cover.

I did however,notice that the water level in the expansion tank goes down,but that might be due to a leak somewhere........so most clues point to an HG failure.

Think I'll take the rocker cover off and make sure.

I can see I'm going to have to go over this with a fine toothcomb... :roll: :)