Boost spike problem ?

[Dr1ft_King]

Hi all,
 
OK, bought car, 1 week later water seal failure ! Grrr
 
Bought recently rebuilt engine and installed OK. On new engine tho I boost fine on primary, but when 2nd turbo kicks in I get a boost spike from 1 bar to up to 1.2 bar !!, Now I know this isnt good and the ECU isnt mapped for it so obviously Im not booting it around.
 
Its a 93 \'L\' which has filters, de-cat and rear box. The new engine was from a 92 \'J\'. Ive tried the ECU from my original engine and replaced the cat back on it but still has the problem. Checked all obvious hoses and they are all OK.
 
Any ideas ?! because I daren\'t put my foot down for fear of blowing this engine !!!
 
Could I have done any damage to it on the few occasions it has spiked or is it a case of it either goes pop or it doesnt ? It still starts fine, and idles fine so Im hoping there hasnt been ay damage ?
 
Thanks for your help !

[oscrx]

hi mate, a bit off topic but if you still have your dead engine could you email me at:
 
oscar.andrews@solodesigns.co.uk
 
i would be interested in buying it!
 
sorry i cant help with your spiking!

[leon]

I doubt you have done damage by the sound of it, But there is a chance of it if you keep doing it.  when you say obvious hoses do you mean the vac hoses under the plenum chamber and the ones down the left hand side above the turbo\'s?

[gsb876]

Check the boost controller as sometimes they dont hold boost correctly and spike. Just be careful until resolved a quick spike to 1.2bar might be ok on ocassion but dont let this continue bud.

Also check the boost controller wires in the engine bay for wear - depends of course if you have a boost controller

[rmagictastic]

Hi all,
 
OK, bought car, 1 week later water seal failure ! Grrr
 
Bought recently rebuilt engine and installed OK. On new engine tho I boost fine on primary, but when 2nd turbo kicks in I get a boost spike from 1 bar to up to 1.2 bar !!, Now I know this isnt good and the ECU isnt mapped for it so obviously Im not booting it around.
 
Its a 93 \'L\' which has filters, de-cat and rear box. The new engine was from a 92 \'J\'. Ive tried the ECU from my original engine and replaced the cat back on it but still has the problem. Checked all obvious hoses and they are all OK.
 
Any ideas ?! because I daren\'t put my foot down for fear of blowing this engine !!!
 
Could I have done any damage to it on the few occasions it has spiked or is it a case of it either goes pop or it doesnt ? It still starts fine, and idles fine so Im hoping there hasnt been ay damage ?
 
Thanks for your help !

dont worry its a common problem!!

are you still on stock ecu or an un tuned powe fc??

either way the additional flow from your de cat and filter will cause over boost, which in turn can easily cause leaning out of the mixture..

DONT BOOST THE CAR!!!

get a power fc and get it mapped asap to avoid popping your seals matey..

cheers

Rmaj

[Grizzly]

have you put the pill in the vac pipe? if its missing you will get mad boost spikes, the Decat pipe will 99% sure be the problem but i had this problem and found a Profect B2 boost controler really helped.

out of intrest what other mods have you got? 1 bar of boost is quite allot to be set as a target boost on a fairly stock fuel system.

[Grizzly]

bottom left of the Diagram (Prespool control), Worth a look.

[gillard28]

sounds to me like the boost pill is missing

[Dr1ft_King]

Thanks for the advice, I dont have a boost controller tho and ive put the cat back on it and its still doing it ??
 
So at the moment all I have diff from standard is the air filters and a backbox, surely that wouldnt be enough to cause it to spike ?
 
Whats this boost pill thingy then ??

[Dr1ft_King]

Using the stock ECU, tried 2 standard ones to make sure that the new one didnt have any piggybacking done to it but it made no difference.

[gillard28]

The restricter pill will limit the boost. I think it will hit 1.2 bar with no pill in but dont quote me on that. The exhaust is a red hearing. The boost issue is charge control related not ecu. The fd runs a open loop system.
If all else fails i would suggest talking to a rotary minded mechanic
 
S

[Grizzly]

Thanks for the advice, I dont have a boost controller tho and ive put the cat back on it and its still doing it ??
 
So at the moment all I have diff from standard is the air filters and a backbox, surely that wouldnt be enough to cause it to spike ?
 
Whats this boost pill thingy then ??

You can cheat a bit, just fit a Greddy Profect B2 (best way around it)

[Grizzly]

Thanks for the advice, I dont have a boost controller tho and ive put the cat back on it and its still doing it ??
 
So at the moment all I have diff from standard is the air filters and a backbox, surely that wouldnt be enough to cause it to spike ?
 
Whats this boost pill thingy then ??

You can cheat a bit, just fit a Greddy Profect B2 (best way around it)

Hope it helps.

[Grizzly]

The exhaust is a red hearing.

What you mean is the Decat with a stock ecu would not hit 1.2 bar (which by the way is .2 bar over the max stock fuel system limit the weather is proberly the only thing stopping your motor dropping a seal at that pressure.) Standard Target boost is something like 8-6-8psi (about .6 bar max) thats way off 1.2 (about 17psi) with a Decat you would see one of these faults, you would find it would boost ok but is you put it in third at 30mph going up a hill it would creep past the target boost or if you floored it in second and third it would spike past the Target boost then drop back to just over, ether way is not good. But what you are describing is more constant so is more likly to be a fault.

[Dr1ft_King]

So where is this boost pill ?