60 replies to this topic

[migoreng]

Cheers for the advice.

The car has been boosting fine for a week...yesterday I found the maf sensor was covered in black dust and ive given it a clean...
The sensor was actually only black from the direction of the air flow. I could clearly see the red sensor and wires on the other side.


Maybe it just needed a good flogging?

[migoreng]

Looks like a clean maf sensor gave me better fuel consumption.

9.5L per 100km down to 9.3

[Zac]

Looks like a clean maf sensor gave me better fuel consumption.

9.5L per 100km down to 9.3

Maybe I should do that sometime too.. just another thing to add to the list... LOL!

Think I'm getting about 11.5... thats with mostly stop start driving... maybe 30% highway

[migoreng]

tgyrtuftyyhdg

[migoreng]

Finally got around to recording the boost problem.

 

 

http://www.youtube.c...h?v=JSLUeFjWN2s

 

 

 

 

[TSG]

That is really weird, even after changeover it maintains 7psi. I thought 7psi was the limp mode boost limit.... has to be a vac line or bbod issue if its not ECU related. Seems like something isn't actuating.

[migoreng]

Its weird huh?

But why does the boost drop just before 5000rpm? Is it the intake air valve opening up?
When the engine is boosting normally, valley of death starts at about 4200rpm.

[migoreng]

Any more idea guys?

 

Can I confirm that it's safe to spray Upper engine cleaner through the black box solenoids and vacumm lines? I will also use an air compressor to spray any junk that is stuck in hoses...then will let everything to dry overnight.

[Cam.]

I would be using UEC followed by contact cleaner to insure you don't have any UEC residue sitting on any solenoids.

[migoreng]

Well I bought a can of contact cleaner and cleaned out 3 solenoids:
exhaust gas control valve positive and negative and the exhaust gas control valve duty solenoid.

I dont think anything is wrong with the intake air control valve or the supercharged pressure relief valves so I left them for now..

ill see how the car drives tomorrow. It was boosting fine on the way to places today then got stuck at 7 psi again on the way home. 60km round trip...

negative on right



Positive pressure exhaust gas control valve solenoid



exhaust gas control valve duty solenoid

[tmh983]

i found the primary wastegate bleed line completely blocked on my car, it caused pretty much the same as what you are seeing.  After I cleaned it out it went back to normal boost.

But that doesn't explain why yours does it only intermittantly...

It is the primary wastegate that more or less controls the boost level (when not in the changeover), so i would be checking everything around that.  Maybe the solenoid is developing an intermittant fault?

Got a SSM2 scanner?  it can tell you exactly what is happening with all the solenoids.

Its not just a fault in the gauge itself is it?

[migoreng]

Its not a fault with the gauge. The car takes off fine from idle but doesnt pull hard once boost gets stuck.

where is the boost control solenoid?

no I dont have a scanner.

[tmh983]

the primary solenoid lives behind the passenger side guard.  You can trace the lines going to it starting at the primary turbo.

[migoreng]

Yes. Ill get around to cleaning the rest of the bbod later on.

[migoreng]

Hey everyone.. did some more reading but havent had a chance to clean the bbod yet.

does Ignition Advance Multiplier have anything to do with my 7psi boost problem?

Apart from my catback exhaust I think my car is stock. Is there an easy way to find out if it has an aftermarket boost controller/ecu and anything else?

[migoreng]

Ill check out scanner tools...one thing I have noticed is the engine makes some scraping noises when im starting to give it a hit...ie...building up boost to 7psi and higher......is the engine pinging and going into limp mode?

I rotated my noisy feathered tyres to the rear which probably explains how I can now hear certain noises...no more of that whoopwhoop tyre noise...my exhaust is not that loud but I guess it does make it a little harder to hear things under load..a while ago I also replaced a noisy wheel bearing...so theres quite a bit of stuff I haven't heard during the first few months of owning the car...
lol :S

[migoreng]

Sounds similar to this guys car... a few tick tick noises when he revs past 6000rpm..


https://m.youtube.co...h?v=_K5rxhTVUuc

except I get those noises randomly as early as 4000rpm..only when im starting to give the car a hit.

[TSG]

I've got a similar thing at the moment. I think its a bad batch of fuel for me, dad thought he was doing the right thing during the BP fuel shortage and put V-Power in it, just when I was getting past the fuel issues! 20deg outside temp. If I do a standing start, it will drive relatively normal (up to 15psi etc). But if I cruise on the freeway at a constant speed (say 80), then hammer the throttle to get it to leap to 100. It will build 7psi 3000rpm, and hold that indefinitely, the car does not kick back (being an auto) and feels like I am hauling arse up a giant hill. I had a mate with me too... it still built up speed and was driveable... but not in the sense it should be.

 

My best guess, is that the car is picking up the knock, and putting it into Limp mode to protect itself. But it goes on and off randomly, its only a recurring thing when I am at cruising speeds. I got it down to a quarter of a tank today, so after another decent run babying it, I will fill it up with the usual, and see if it helps. If a little octane booster doesn't help either, it'll be mechanic/tune time.

 

EDIT:

 

Ok. After thinking on it for a while, and driving the car around doing various test. I got this feeling that it was airflow related based on throttle response, and how the car improved when I drove over to the coast.

 

After close inspection we notice a pinched vac line - when the car is hot on top of the manifold. So I free that up. We popped the air filter out of curiosity - to find a Repco Air Filter. I asked for genuine at the last service... This filter looks visually restrictive - and cheap. So we decide that it might just be that, and a dirty MAF. Pick up some CRC MAF cleaner, and a Genuine Air Filter - took us all of 5 mins. Went back out for a drive after resetting the ECU (something I've done a couple of times during my tests). Suddenly - the car is SO MUCH more responsive, and no more pinging. The car was boosting as good as I remember when I bought it!

 

We get carried away and do a genuine upper engine clean, oil filter and throw in some fresh oil. I've not driven my car this responsive in ages. Cheering. I'll need to do some long freeway runs on a hot day again to confirm, but so far its promising