When gassing it through the gears, my Scoob hesitates momentarily after I mash the gas again. I always thought this was turbo lag and lived with it. UK00, PPP, full Scoobysport decat exhaust.

But I've just had a go in an Evo 6 Mak. It's got a sweet box and turn-in to die for, but when pressing on the engine doesn't hesitate at all and revs just like a normally aspirated engine. Gear changes are much smoother and quicker.

Any thoughts? Does the Scoob's ECU cut boost on purpose?

Thanks.

Richard.

 

Dunno m8...but mine did the same till I put a SS downpipe on

 

Richard

Have you got a boost guage? My my00 with PPP and decat used to overboost so much that it then underboosted before getting to the correct held value.

This was subtle, but noticeable on performance after a gear change.

If you've no boost guage, try using half throttle after the gear change and then slowly put your foot down. If it feels better, it's likely the same thing. I slightly opened out the restrictor to fix it.

Richard

 

Hoppy, does it last for a split second? It feels like its coming from the back? I have been told that this could be the rear diff winding up.

I dont have a boost guage at the moment so dont know if my car is overboosting. It is rather annoying though.

Ian

 

Thanks guys. I've been suspicious about boost levels for a while now and have ordered a Defi gauge from ScoobyMania. It was going to be fitted last week but Mike decided to move premises so I'm still waiting.

I guess the gauge will tell me quite a lot, and I've been following John Banks' fun and games with restrictor sizes and have a Dawes Boost Controller on order. Frightened to death of fitting it though! I'll let the good Dr John blow his motor up first

Ian, I'll see if I can detect anything transmission related. But if it is I guess I'm stuck with it.

Cheers,

Richard.

 

Hoppy,

When my car was completely standard (it's almost that now, just a different BB), it did this and still does. I don't *think* it's a boost control problem because I've got a boost gauge and when I'm full throttle gear changing, I get this but I'm not overboosting (pretty certain anyway). I'll have to find a nice empty long stright bit of road and get a passenger to watch the Boost gauge like a hawk whilst I try this out....

Anybody know what this is for certain?

Matt

 

I've got a MY00 turbo, standard apart from the back box. When I first got it I used to get massive hesitation when I changed gear. Now I'm used to it a bit more the changes are much better (slower = smoother) but still get a slight delay in the power when I change up (it goes then it GOES!)

Optimax improves it as does trying to be as smooth as you can - ON-OFF-ON the gas really fast seems to confuse it, ON-LIFT-ON works better but is hard to do.

Richard

 

Yep, my MY00 is does the exact same and it does feel as if a tremendous stress is being put on the drive train during that nano second of "brick wall" hesitation! I have the defi kit but haven't spotted it over-boosting yet. Although it has registered 1.4 bar as a peak within the last few days. It normally goes to 1.1 bar approx and eases back to hold at a reasonably steady 1 bar during accelleration. So, is 1.4bar over-boosting?

One "cure" that does work is raising the revs higher than normal as you let the clutch out so that on re-engagement, the clutch contras the revs. This avoids the problem but I suppose it cant be wonderful treatment for the clutch. I will also mention it to the guys at Powerstation tomorrow.

Jerome

 

Quick update - I've had this problem from new. Dealer first cleaned then replaced the boost control solenoid. Problem still existed.

Dealer then referred to IM technical dept. who 2.5 weeks later have come back to say it's overboost and the restrictor size needs changing. But, dealer doesn't stock restrictors, so is toying with whether to order a set of restrictors or buy a set of small drill bits to modify the restrictor that's already fitted.

This all seems to tie in with the previous posts in this thread, so makes sense. Dealer also has a P1 with the same problem that they've been trying to cure.

On a related point (ie boost control), can anyone tell me what teh "pressure sources switching solenoid valve" does (LINK manual description of the valve on the driver's side inner wing next to the boost control solenoid and the MAP sensor). Also what is the £1 size plastic disc surrounded in foam which sits in the boost pipe between the manifold and the above switching solenoid - as I understand this is not the restrictor which is between the turbo outlet housing the the T piece before the actuator.

Thanks for any help

Dave
MY00

 

Hoppy,
I have a fully decatted my00, mine does it too, the answer is in trying to drive more PROgressively, and not so AGGressively, try it, it works, treat the car like it's a big old yank, ie; change gear at a sensible pace, not too fast, you'll still get where you're going, but a nano-second later.
Ron

 

My MY99 was the same, I now change gear slower and it helps. But fitting an aftermarket BOV helped the most, its almost none existent now

Edit bit: Just a thought but could it have something to do with the injectors shutting down when you release the throttle, then when you hit the throttle again there is a slight hesitation as the ECU sorts it out. The BOV on mine would overcome this because it causes overfueling since its a dump to atmosphere one. As I said just a thought....

DaveW

[Edited by DaveW - 11/15/2001 10:04:56 PM]

 

Dave

Don't think that's what's causing the problem on mine, since the engine cut is very shortly after mashing the throttle - ie not the instant you mash it. Hence I think the overboost scenario is more likely.

I know I could drive more gently, but if I'd wanted a shopping trolley I'd have bought one!

I'll post on here to let you all know if the restrictor change fixes it.

Dave