Annoying overboost

[boosh]

It's got a brand new genuine maf. Only about 2000k's since I put it in.

How much does the exhaust factor in? It's the stock exhaust but it's in pretty bad shape.

When I know it's about to overboost, if I really put my foot into it and max out the dawes valve, it doesn't overboost, or at least takes longer. Taking this into account, I've just gone for a drive where I closed the dawes slightly and opened the needle a bit. I got slightly higher EGTs but they settled quite quickly... I didn't have any limp mode issues, maybe it was just a lucky day, maybe I'm on to something.

I think it's just going to take me a while to get it right. Like I said, it's a new motor with new turbo and a few other things and it's just slightly different than the previous motor so it's taking a while for me to get used to it...

[Mud Gecko]

I think you may have your terminology mixed. Overboost suggests (for example), if you have your dawes set at 14psi, when you accelerate you 'overboost' and hit 16/18 psi before it settles at 14. When limp mode happens you will have max 10psi with virtually no acceleration until you lift off the throttle then power will return.

Limp mode in my experience is a combination of too high MAF voltage and/or too high boost. If you have ECUtalk its easy to see it happen.

Overboost on the other hand is fine tuning dawes and needle. I still get a slight overboost on mine but I like the quicker spool-up rate With my setup I will 'overboost' to 19/20 under WOT then settle to 17psi.

[critta11]

The car could have collapsed causing back pressure and stuffing everything up.

[mudski]

^^^^ Eh?

Also the MAF still could be faulty. Unlikely but it does happen. I have sold around 100 OEM MAFs in the last 12months and only have had one faulty one. So while its not common, it does happen. You don't have your old MAF to try? Just for the sake of trying...

[Mud Gecko]

I think Critta may mean 'cat', which is entirely possible and a great excuse for a shiny new exhaust

Boosh, is your EGR blocked?

[mudski]

Lol yeah.

[boosh]

I think Critta may mean 'cat', which is entirely possible and a great excuse for a shiny new exhaust

Boosh, is your EGR blocked?

Yeh my EGR is blocked.

That's an interesting thought about the cat... The previous owner fixed/welded it up at some stage. I do plan on a new exhaust, just don't have the funds yet. Is there a way I can check that?

I might put the old maf in to test it mudski.

[critta11]

^^^^ Eh?

Also the MAF still could be faulty. Unlikely but it does happen. I have sold around 100 OEM MAFs in the last 12months and only have had one faulty one. So while its not common, it does happen. You don't have your old MAF to try? Just for the sake of trying...

Yeh I did mean CAT haha my bad