exhaust and turbo pressure

[khubner1]

ok so basicly the story is i have a full 3" system mated up to the stock dump pipe with what i think is a stock wastegate actuator on a td04l and im seeing 16-17 psi before the engine has a nice big miss (i think it might be boost cut). so i was wondering would running the larger free flowing exhaust see the boost pressure rise. i know i need a tune but im trying to learn the reasons behind such a large boost number.

 

[3zercrowd]

(i think it might be boost cut)

Definately!
The free flowing exhaust is allowing the gases to flow better and the turbo wants to do more work and its easier too....

Time for a boost controller and a few supporting mods

 

[khubner1]

like 560's and an ecm link? recomendations.

internaly stock. electronicly stock - boost controll solenoid(running waste gate pressure vac hose direct from j pipe to wastegate) 2.5" ic piping with a quite large 700X600 intercooler (yes i know over kill) running the larger tr magna tb with ported manifold to suit.

td04l(i beleive it to be stock)

i'm not chasing big number from this setup it still gives me a massive grin when i manage to hit the sweet spot via throttle control

 

[J MAN]

I used to have something like this happening on my GSR. I'm running 15 PSI but whenever i'd gun it; it would go up to 17PSI; Then once i'd shift to a gear it would like cut out and cut back in and a cloud of smoke would be behind.

It happened prior to me getting the Crank Angle Sensor amended. Also had the VAC lines checked and found that my BOV was put on fairly 'dodgily' <- That's right i created my own word. Also had the spark plugs replaced with 'premium' ones; which made it run a whole lot harder.

Don't know if that's what you mean by a massive Engine miss; but yeah .

 

[JETGSR]

you need to be more spacific cut or miss

cut is like you put your foot on the brake

miss is a splutter and the car still pulls - also check and see what revs you are doing? It might suprise you you could be hitting the rev limiter
your dash tacho is really just a mud dial they are not that accurate.

plug gap! adjust to .75

there are so many things that can cause this! usually the simplest!

 

[khubner1]

it'smore like a cut all most as if i've slammed my foot on the break engine sounds like it's stoped for a split second car hessitates severly once pressure is released continues. i'll try get a video of it happening. but latly the been more traffic around so getting it to that point hasn't been possible.

 

[moi]

As above try gapping the plugs smaller. If it is indeed a boost cut then you will not be doing any favours by adding a more free flowing exhaust system as it will effectively make it worst. I would not advise getting rid of boost cut unless you get some dyno time to check air/fuel ratio's - cheaper than a rebuild.

 

[khubner1]

the larger exhaust is alreay on plugs were regapped at time of instalation as i could not get correctly gaped plugs. so they were gapped according to manufacturers recomendations.

(jsut so theres no confusion this is a gsr 4g93t in a lancer coupe with a free flowing 3" mandrel bent exhaust system. with what i beleive is everything stock except said exhaust.) question relate to would the larger exhaust see the increase in usable boost pressure that i am currently experiencing. i am told 10psi is normal not ~17

the plan has always been to give it some dyno time. but i'd rather safly use what boost i'm being given rather than add more the car is no track star and is my daily so reliability is key.

you know what they say chose 2 of the following
budget.
power.
reliability.

im hoping to chose budget / reliability

 

[moi]

Yeh 17psi is not normal for our older generation of 4g's. The larger free flowing exhaust on your very small turbo most likely has caused your excessive boost pressure, due to less restriction your wastegate cannot control the flow. Either upgrade turbo or add a restrictor of some form such as a less free flowing cat converter.

 

[4piknup]

or port the gate/ bigger flapper

 

[moi]

or try that.. simpler options are harder to think of doh!

 

[Dean]

What fuel pump are you running? What plugs are you running?
I wouldnt think the larger exhaust would create a 7psi increase.. stock boost is only around 10psi isnt it? something else doesnt seem right.

 

[Gianni]

Could it be problem with actuator/waste gate not opening properly so not releasing correct pressure. Resulting in extra boost?

 

[khubner1]

yeah i'm not 100%sure on the waste gate it could be a 1bar actuator which means 15psi. stock fuel pump from le coupe and before you query it's the same as gsr.

all in all it's not that much of an issue latly even when i boot it im only seeing 13psi. that and moderating the right foot = boost control. so yeah until i can put it on a dyno i know what needs to be done to keep it healthy.

oh and she's deff running nice and rich lots and lots of 4g poo on the rear. (soot from unburnt fuel)

 

[khubner1]

http://www.ebay.com.au/itm/Mitsubishi-Upgrade-TD04-19T-Compressor-Housing-Wheel-/150658932444?pt=AU_Car_Parts_Accessories&hash=item2313f8dedc
http://www.ebay.com.au/itm/Turbo-Actuator-VOLVO-850-S70-TD04L-TD04HL-0-8Bar-11Psi-/270807642114?pt=AU_Car_Parts_Accessories&hash=item3f0d64b002
http://www.ebay.com.au/itm/Turbo-Actuator-VOLVO-850-S70-TD04L-TD04HL-0-5Bar-8Psi-/280730618654?pt=AU_Car_Parts_Accessories&hash=item415cd94b1e
will the above fit on my turbo

 

[evo-gsr]

What fuel pump are you running? What plugs are you running?
I wouldnt think the larger exhaust would create a 7psi increase.. stock boost is only around 10psi isnt it? something else doesnt seem right.

I dont really see how a fuel pump or plugs, would have anything to do with an increase of boost either?? It would explain the excess unburnt fuel on the arse end though.

I would be checking the wastegate actuator if anything.......

 

[Dean]

I dont really see how a fuel pump or plugs, would have anything to do with an increase of boost either?? It would explain the excess unburnt fuel on the arse end though.

I would be checking the wastegate actuator if anything.......

Yeh nothing. However earlier in the thread he said there was a miss at higher rpm.
khubner are you sure the coupe's fuel pump is the same as a GSR?
Def agree theres something wrong with the wastegate, but I dont think your fuel pump is up to the task either.

 

[khubner1]

yeah went to get a new one and the part no's are exactly the same. in the links above i've found a 19t conversion compressor housing and a pair of wastegate actuator anyone confirm if they'll fit?

 

[Smutt]

For your miss... Gap your plugs down as previously stated & Change your spark plug leads to (not topgun), i went through 3 sets and one set only lasted 3 weeks, number one lead kept breaking down, changed brands and all sweet!

Agree your fuel pump (standard 1.8lt gsr one) wont be up to the task for increased boost, get a walbro in tank.

Point to note, the standard gsr Air Flow Meter will violently cut out 20psi at above 6000rpm (maxed out) from experience (have mods to suit) so I dont believe your AFM is the issue. But in saying that if your car CUTS OUT VIOLENTLY with a large cloud of black smoke out your exhaust as mentioned previously then its your AFM.. as this is what happened to me.. solution, upgrade to the EVO 1-3 range and computer and injectors

If your having boost stability issues I believe its because your are running a TD04L, it cant flow more than 12psi all the way to 6500rpm. Yes it will spike to 16-17 but pulls back at 5000rpm every time with the increased revs because your going "off map".

Check for leak in the hose to the waste gate actuator, AND..

Remove the vac line to the waste gate actuator and test for operation at pressure via a compressor and a pneumatic regulator set to 10psi then 15psi to check its opening, the diaphragm may have a pin hole in it also.. but it does sound like its not opening at all if its a 15psi actuator because its on a TDo4L (off compressor map)

Do not increase back pressure in your exhaust via a restriction... you want to lose power?

Get a split dump pipe for the TDo4L to 3" as I did, easy horsepower is made with a free flowing dump..

 

[evo-gsr]

Dont you think it would be a smarter idea to fix your issues before upgrading anything?
Eliminate not aggravate the problem would be my theory.......