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ecu keeps putting boost into limp mode.....why??

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Old 28 June 2002, 09:53 AM
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UkLegacyT
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Hi,
got a problem at the moment with the car. the ecu puts the boost into limp mode say every 2 days or something, im assuming its doing this anyway, as an ecu reset puts the boost back to normal.

question is, what could cause it to do this, what is it possibly sensing?
could bad plugs/coils cause it to do this?

any other ideas?

thanks
Old 28 June 2002, 10:30 AM
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spen
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Could be the boost control valve (right hand suspension turret, three pipes, two wires) is sticking or blocked with oil?

Or you could be running too much boost?

Do you get an ecu 'check engine' light? If not it sounds like the first idea - these were my symptoms and I fixed it by cleaning the valve with brake cleaner.
Old 28 June 2002, 10:44 AM
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UkLegacyT
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Hi spen, hows the car going, back onto the mods yet?

i think i'll try cleaning that boost solenoid, and also the bleed valve.
whats the bests way to clean it, just remove and spray the brake cleaner into the holes?
how could too much boost cause it to reduce the boost? what would it sense?

cheers
Old 28 June 2002, 11:32 AM
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john banks
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Could it be detting - are you running 1.4 bar?
Old 28 June 2002, 01:36 PM
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UkLegacyT
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john, thats a point, maybe it is detting

its only happened since fitting the TDo5 turbo, but i havent altered the fuelling whatsoever, so maybe its running lean??

im running 1.5bar through the gears, and its 1.7bar in fourth and fifth.

thanks

p.s. have got an afr meter, and that always shows full lights when accelerating though.
Old 28 June 2002, 01:39 PM
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UkLegacyT
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forgot to mention, reset the ecu yesterday, and all was fine. after trying it, was boosting fine.
however, after that, i have just been pottering about, and not booted it once.
jumped in the car this morning, and its not boosting properly again! the boost doesnt build up as fast as it should either, like driving a milk float
Old 28 June 2002, 01:41 PM
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john banks
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Have you been reading, "Cars I quadrupled the power of" by Mr A Forrest I've got to slag you off for running 1.7 bar because it is more than me a lot more. Are you angling for a rebuild or something?

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Old 28 June 2002, 01:48 PM
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UkLegacyT
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yep thats the one ive been reading

seriously though, ive been considering whether to put it back to standard as i realise it may just go pop any minute.....but its too much fun

however, ive just got the s-afc and avc-r units brand new, so the 'back to standard' thoughts have just exitted through the nearest window :P
Old 28 June 2002, 01:48 PM
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ustolemyname??stevieturbo
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The boost is way too high, for a virtually std car. Check that the chargecooler pump is actually working, and circulating water, as couple of times on my car when it was not working, A blast down the road, would see the ecu reduce the boost pressure, for an undetermined time. No idea how it knew to reduce the boost, unless inaudable det was detected, as there is no air temp monitoring by the ecu.. The std pump wiring on my car had never worked for some reason, and I just ran a new supply to it. It maybe a similar problem to yours, altho probably not...Also, get rid of the bleed valve, they are crap. It is only a matter of time before those boost levels will **** a psiton, especially when you are getting surges. I doubt it goes much better with 1.7 bar than it does with 1.5 due to air temp rising.
Old 28 June 2002, 01:55 PM
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UkLegacyT
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hi steve

yes, the pump is working, can hear it whirring in the left wing.

ive got the apexi afc and avc units, so will fuel it a bit more to keep it a bit cooler aswell, and limit the boost to 1.5bar max.

cheers

p.s. fitted the sti pistons yet?
Old 28 June 2002, 02:04 PM
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Pavlo
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Ian, you are a mentalist

Andy actually found more power running 21psi (1.4bar) at peak revs than 24psi (1.6bar), mainly due to inlet temps.

I think you really need to sort that AFR meter out, and get it working.

I feel scared if the boost goes over 16psi at the moment, so 25psi is just ott.
I know it feels good, but having to walk (again) because you car is off the road (again) with a big mechanical problem (again) is not as quick as running only 1.4 bar. Do you see a pattern forming?

If you want more safer power, sort your charge cooler out. Get a davies craig pump from www.merlinmotorsport.co.uk get some Redline Water Wetter, distilled water, and have a look at getting a bigger/second radiator.
Reducing inlet temps from 60'C to 40'C equates to about 19bhp increase in power if you are already at 300bhp. You will also be reducing piston crown temps by running cooler inlet and more fuel to burn.
Seeing as a S-AFC and AVC-R cost about £700, that would have bought you the following instead:

£135 Uprated fuel pump
£100 Uprated Fuel pressure reg
£135 Uprated water pump
£50 Second chargecooler rad
£100 Stainless uppipe
£150 EGT gauge
£30 Exhaust wrap
---------------------
£700 total (how convenient!)

An arguably more effective shopping list for now.

Paul



Old 28 June 2002, 02:07 PM
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Pavlo
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Forgot to add, noisy tappets gave the exact same symptoms as you are experiencing (I was cruising lightly in the middle of the night, nice and cool still).

But if the ecu no longer has any control of the boost solenoid, it can't be the det that's reducing the boost.

Paul
Old 28 June 2002, 02:16 PM
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UkLegacyT
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hmm, that is a shopping list

ive actually picked up them for £475 inc postage, which is a bloody good price eh (private sale-boxed/brand new).

the fuel pressure regulator, you on about an FSE? i have one lying in the shed....
right, cooling mods next then!
i like the cheap idea of a second charge rad......however, would a second one restrict the flow to the main water rad too much?

how about fitting 440cc injectors too?

Old 28 June 2002, 02:21 PM
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UkLegacyT
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ive shortened the list

£135 Uprated fuel pump
£135 Uprated water pump
£50 Second chargecooler rad (maybe lower cost?)
£30 Exhaust wrap
---------------------
£350 total

thats more like it
Old 28 June 2002, 02:24 PM
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Pavlo
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I have an aircon rad too, and don't see any water temp problems. My plan was to get a second identical rad, and mount them over the top of each other, hot water flowing though the inner one first, then the outer (series plumbed). That way you get the benefit of the coolest air still.

Something you may want to try straight away is seeing if you can fix the pump to run at full speed at all times; i think if goes from 15L/min to 30L/min when boosting, but it would be nice to get 30 all the time.

Nice price for the Apexi stuff, scrub the egt and FPR from my list then.

Paul


[Edited by Pavlo - 6/28/2002 2:25:27 PM]
Old 28 June 2002, 02:29 PM
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UkLegacyT
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yeah, i will wire the pump to run at full speed, should be pretty straight forward eh...

i'll wrap the downpipe aswell, as i can get discount for this stuff from demon tweeks :P

cheers

Old 28 June 2002, 02:32 PM
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Pavlo
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I just got a 5m roll from merlin motorsport for about £10

Rallydesign do a 15m roll for about £33

Paul
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