Overboost In 4Th & 5Th?!

[GT4 James]

Hi all, just wondering if anyone has any ideas what this may be, when on full boost 1st through to 3rd all fine (averaging around 15psi) 4th & 5th gear in high rpm (apprx 6000rpm+) she keeps hitting fuel cut, have tried turning boost down but just cuts down overall in all gears but still hitting fuel cut in 4th & 5th. Any ideas, im hoping is not actuator as looks like a pig to change, could it possibly be a boost leak somewhere, did notice on the inlet pipe into chargecooler that after a drive im seeing a small deposit of oil being left on it? could there be a leak on the chargecooler would that cause this to happen, any ideas would be great. Thanks all...

[Fawbs]

Most likely the turbo oil seals, as for over boosting i'm not sure, it might be the cold weather as i think it can make it over boost

[GT4 James]

Hi there mate long time no speak hope your good. Turbo oil seals you reckon for the oily deposits, am i looking at a new turbo then or can you replace them?

[Fawbs]

No im pretty sure you can get it refurbished, if you leave it idling for 10-20mins and it starts smoking out the exhaust then i think that can indicate the turbo oil seals, something to try.

[GT4 James]

The only time she ever smokes is a small puff if youve been driving nicely for a period of time then suddenly put your foot down, but ive always thought this was quite normal on turbocharged cars...? Never smokes on idle. Mate can i ask you a favour if you have any pictures of your engine bay mainly the setup of all your boost/vacuum hoses associated with the turbo, ive never seemed to have much luck with the boost on mine and really want to make sure how ive got things is right...

[Fawbs]

well my car is by no means standard i have pictures of when it was standardish though but my current setup isn't 100% hooked up yet.

Thing is when its colder the car over boosts thats why people turn their boost down in the winter.

[Fawbs]

Standardish

and current

Just search celica st205 engine bay on google, will give you a better picture

[GT4 James]

well my car is by no means standard i have pictures of when it was standardish though but my current setup isn't 100% hooked up yet.

Thing is when its colder the car over boosts thats why people turn their boost down in the winter.

Tell you what then mate ill try turning boost down a bit more again and see how i get on...

ps i want your engine bay please lol looks fantastic mate good work!

[Fawbs]

What have you turned it down to? if you are running 1.1bar its worth turning it down to about maybe 0.9bar.

Ha i didn't go for presentation its not that great when you look at it in person.

As for the puffs of smoke its never a good sign is it using much oil??? It will probably get worse but you may get away with it in the short term but i would try find out where the oil is coming from but would definitely look at the turbo oil seals.

[GT4 James]

ok well will see how i get on with turning it down, its running about 1.2 bar if im honest so ill try under a bar to start with. Mate its not about how it looks its how it goes! Im guessing shes fairly nippy looking at her ;) lol thanks for your help again mate

[Fawbs]

I'm not even sure you can run 1.2bar on a standard car thought it was 1.1 ha but yeh thats definitely why its over boosting cause of the cold weather. When you get into summer you should be able to turn it back up.

It will be once its done next month ha

[GT4 James]

Right just turnt boost controller alllll the way down, doing exactly the same is spiking at 17 psi, im starting to think its one of 2 things, 1 has the actuator failed...? 2 full de-cat system turbo back has the exhaust system become too efficient and now i need one of them restrictor gasket things?

[Fawbs]

What size decat and exhaust do u have? It sounds weird if you have turned it right down and you are still hitting 17psi :S

[GT4 James]

http://www.japspeed.co.uk/Toyota-Celica/Exhausts-and-Manifolds/c-1-25-72/

This is link to what i have, is 3" all the way through. I feel to cry sometimes with the boost issues im getting just dont know whats going wrong anymore

[Fawbs]

Its very weird indeed if you have turned it right down, i'd imagine you may get boost creep if its 3" all the way through but still may not explain everything but then again i'm not sure how much creep you get in these things. The hose hasn't split to the actuator or anything like that?

[GT4 James]

Its very weird indeed if you have turned it right down, i'd imagine you may get boost creep if its 3" all the way through but still may not explain everything but then again i'm not sure how much creep you get in these things. The hose hasn't split to the actuator or anything like that?

Nope was first thing i checked, all hoses look good, checked bungs for the vsv valve as thats disconnected and they look fine, if the actuator had failed would it do this, could the wastegate be sticking?

[john905]

http://www.japspeed.co.uk/Toyota-Celica/Exhausts-and-Manifolds/c-1-25-72/

This is link to what i have, is 3" all the way through. I feel to cry sometimes with the boost issues im getting just dont know whats going wrong anymore

hello mate think you prob is the 3 inch de cat they are prone for boost spike with a 3 inch de cat, what controller do you have?

[GT4 James]

http://www.japspeed.co.uk/Toyota-Celica/Exhausts-and-Manifolds/c-1-25-72/

This is link to what i have, is 3" all the way through. I feel to cry sometimes with the boost issues im getting just dont know whats going wrong anymore

hello mate think you prob is the 3 inch de cat they are prone for boost spike with a 3 inch de cat, what controller do you have?

Is just a brass bleed valve. Tried relief valves and they dont work with it for some reason, boost went mad when i tried relief valve...

[john905]

its up to you mate, i would get an electronic controller or try a resrictor in the exhaust 99% sure the 3 inch exhust is your problem though

[GT4 James]

its up to you mate, i would get an electronic controller or try a resrictor in the exhaust 99% sure the 3 inch exhust is your problem though

The exhaust restrictor is one option I was considering...only thing with it is would it still explain why the bleed valve seems to just be able to hold a higher boost pressure rather than actually adjust it... ie ive turnt it right down and its still hitting easily over 1 bar (16 spiking 17.5psi)

[john905]

not sure why mate, sure others on here will no more then me, but 3sgte engines are prone to boost spike with 3 inch de cat

[GTForbes]

Your 3inch system will be a cause of your boost creep, this is because there is not enough back pressure in the exhaust system to keep the speed of the exhaust wheel under control.

As for your boost control, are you sure you set up the relief valve was set up right? They are proven to be more effective than bleed valves at controlling boost.

As for still hitting 17psi with it screwed in, I'd try running without it, it sounds like one of the actuator lines are punctured or your actuator is sticking. Any performance garage worth it's salt will be able to test your actuator for you

[aderiley]

boost creep means the boost will keep increasing at higher revs thats why your hitting fuel cut, i had similar problem just fitted restrictor place 2.25 inch and its fine now got mine from eBay

[GT4 James]

ok guys thanks for the advice im going to buy restrictor gasket and look at electronic boost control me thinks, ive tried relief and bleed valves and could never get relief valve to work properly just used to boost like a !Removed!. Am getting worried it is actuator as it does look like a pig to change but hey ho gives me something to do the next few evening if it is lol. Also guys completely seperate question but Im in need of advice on what you might consider would be the next step in tuning, my friend has recently got his hands on a mazda 3mps (2.3 turbo) and although the four is quicker im fearing its not going to be enough once he goes for a remap...this cant be the case lol age old story of needing to be the fastest haha. At the moment my current list of mods stands at obviously full 3" de-cat system, walbro 255l p/hr fuel pump, blitz induction kit, high capacity leads, Iridium plugs, millers fully synthetic oil, stage 1 paddle clutch, and apprx 17psi boost on the bleed valve (hopefully can be more accurate soon ;) ) Any ideas where I should be going next, i seem to have shed loads of low to mid range power but not as much as what I would like higher end, 152mph is max I can get on track of course and I do hear stories of other fours doing 160mph+ so really where should I be looking to go for better high end power...?

[GTForbes]

The gearbox is not the limiting factor in top speed runs, it's power. Running 17psi with an uprated induction and exhaust you'll not be far off 300 bhp. To go further safely you'll need management to enable you to get a remap