Serious lag issue

Went to Surrey rollers yesterday to get the car mapped, started out ok, got 420 at 1.5 bar but there's a lot of lag, nothing really happens until 4500rpm then it takes off.

Car has a 3071 and all usual supporting mods.

Apparently this should kick in around 3000rpm not 4500.

Been told it could be the cam timing but has anyone got any other ideas?

I checked for boost leaks up to about 10psi and all good.

Also something happened on the way home, I was giving it some stick when at around 6000rpm the power dropped to about half with my foot still down to the floor and heard a big release of air and a bit of a whistle, I then lifted off, put my foot back down and realised the BOV stopped working, no high pitched chirp, just the sound of the turbo spinning.

Could the issue possibly be the BOV had a bit of a leak and upping the boost made it worse causing the massive lag? This kind of makes sense to me. The BOV had been on the car nearly 10 years but it was a genuine hks BOV.

Any other ideas?

Thank you please

It could well be... Same thing happened to 1 of my Renault 5 turbos...

Take DV off & bung the inlet pipe where the DV fits in to & put a tight fit screw in the vac pipe & try it... Atleast you have ruled that issue out then

I run the same turbo mines starts coming in at about 3000 but don't come in full boost till 4000

Yeah will give that a go tomorrow hopefully, absolute pain in the arse coz I will probably have to get it re mapped again!

Don't think mine hits full boost til 5k!

Yeah not great lol

Checking for boost leaks upto 10psi is as much use as nothing aron as that's just around standard boost pressure
You need to raise the pressure on the test to around 25psi then see what happens.
Could well be the dv causing the prob, we had one in 2 days ago that was leaking so fitted another and all was good and car was so much quicker in both spool and mid range when turbo comes on

If you raise the pressure on the leak test you'll soon see if it's that which is leaking

I can't coz it's a home made tester and pops off the turbo after 10psi. Got a 4" intake so how else can I do it?

Don't test it from the turbo intake try taking it from the outlet to the ic pipe just use a round bit of plywood fitted in a silicone connector with a tapping to fit the connector to airline into

Okekoke

Just watch your face becuase if that fooker pops off its going to hurt .... you can get rubber bungs and plastic caps for 4" inch (100mm) pipework from any plumbing place as that is the same size as house waste pipe for toilets etc ...

I blanked the inlet elbow off with a can of wd40 years ago and it shot up fucking hard like Lexington Steele, hit the bonnet and closed it on my head! That made a big bang

Lmao lex steele

the impaler

I couldn't get hold of my mate the other day and when I did I asked where he had been and he said I'm sorry but I was in a meeting with carmella bing

Lol now she was hot piece .... shame she let herself go

DV, our escort leaked like an OAP until I replaced with a stonger bailys one then boost kicked in at 3.4k instead of 5000, 251bhp at 67000rpm

Got the thing off today and bunged it but couldn't take.the car out as I noticed I have run out of tax! Will get my mate to take the BOV apart and see if the diaphragm is split. Then when it's taxed will take it for a blast.

Really hope it's just that, cam timing wouldn't be so.bad but does anyone know if I need adjustable verniers if it needs changing? I have hks 264 cams.

Got told the worst case scenario is the turbo could be damaged but I checked the blades and all looks ok. Plus its only done 6000 miles and is a genuine garrett

Tbh aron I can't see Karl building an engine and getting the timing out so would be amazed if it were that

Yeah that's what I thought too. Jez did have to adjust the timing slightly though on the other bit not the cams. He used one of those guns that light.up blue

Well if the engine timing had been out he wouldn't have managed to get the ignition timing set, even one tooth out would have put the dizzy off the slot if you know what I mean

Karl's a damned good mechanic he wouldn't have made a mistake like that, will be something much more simple such as major boost leak.

Can you post up the Dyno sheets and especially the one showing afr's

I can't but can take a pic on my phone and.send it to you if.you can post.it up for me?

Send it me fella ....

Yeah leightons the man I've not got a clue lol

Can you pm.me.your number mate, thanks

gtir_pimp wrote:Got the thing off today and bunged it but couldn't take.the car out as I noticed I have run out of tax! Will get my mate to take the BOV apart and see if the diaphragm is split. Then when it's taxed will take it for a blast.

Really hope it's just that, cam timing wouldn't be so.bad but does anyone know if I need adjustable verniers if it needs changing? I have hks 264 cams.

Got told the worst case scenario is the turbo could be damaged but I checked the blades and all looks ok. Plus its only done 6000 miles and is a genuine garrett

Unlikely the diaphragm although not unheard of. Usually it's the spring not able to hold the pressure. Does it sound like an asthmatic Darth Vader when you're under load from low down? If so there's your problem, boost leak.

Not sure.about the Darth Vader thing, don't think so tbh