Any ideas as to why my car feels like it is 'Choking' when I hit full boost. It is spiking to about 15-16psi and at that point you can feel the power fall once it settles back to about 13-14 psi it appears less noticeable. Occasionally it may hit fuel cut so I have back the EBC off slightly. I believe it maybe either the AFM or possibly the rubber intake pipes warping (sucking closed) creating a restriction, any other ideas?
Choking when on High boost
- Thread starter whiteleg
- Start date
leebutts
1 AYC Bar
Do you mean choking? As in, unable to breathe?
It could be the flexi pipes, could just be the restriction in the exhaust? Do you have a 3" cat converter?
cheers
Lee
It could be the flexi pipes, could just be the restriction in the exhaust? Do you have a 3" cat converter?
cheers
Lee
leebutts
1 AYC Bar
Hmm sounds like how I'd describe my car before I changed the exhaust, it felt "restricted" when on boost.
Maybe the dyno day will give you some hints.
Maybe the dyno day will give you some hints.
SiliconAngel
1 AYC Bar
Err, correct me if I'm wrong but doesn't the stock ECU automatically protect against boost over 1 bar? Is that what you might be feeling?
G
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Unregistered
You'll know if you hit boost cut, because you'll have a forehead mark on the windscreen 
Its pretty violent, and really not good for the engine..
If yours is more of a loss of power thing, then it might be a spark plug issue?
Also, its pretty hard for these cars in stock trim to sustain much more than 13-14 psi to the red line, it tends to peak mid rev range, and then level off. A good exhaust helps free that up a bit.
Its pretty violent, and really not good for the engine..If yours is more of a loss of power thing, then it might be a spark plug issue?
Also, its pretty hard for these cars in stock trim to sustain much more than 13-14 psi to the red line, it tends to peak mid rev range, and then level off. A good exhaust helps free that up a bit.
VR4Rocket
Leaving Skid Marks
- Location
- Queensland
- First Name
- Kevin
- Drive
- Was a Ralliart Colt, was a 1997 Toyota Aristo was a 1996 Legnum..Now an XR5 Turbo
I have just been noticing that choking a bit...I thought it maybe a boost leak but after reading this I am not sure....
- Thread starter
- #8
I know exactly what boost cut feels like, so does my wife and she doesn't like it. It won't hold that kind of boost to redline it simply hits it (3000 - 4000 rpm) where you can feel the power drop then boost levels down to 13-14 psi. I have 3 boost gauges in the car and the peak hold on my Greddy profec B and Defi unit has shown 1.28 which is actually about 17.5psi. It does only hit this for a very short time (basically hits then drops back). The plugs should be fine they were replaced less than 4000Km ago and are gapped to .8. Maybe I should stop trying to flog the little turbos and give them a break.
G
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Unregistered
The reason is as our data results have shown on the R&D car we were working on, the factory tune is so rich that as the boost / airflow increases especially with mods that the car is literally chocking on the fuel it is getting, which causes the boost to drop and the car to try to kill itself.
This is definitly not a good long term thing as it will cause ring wash and burn your cat converter out in no time. I suggest as a sticky, that most owners beware of just trying to raise boost above 12 psi without doing some tuning at the same time.
Check the following link to see what I am talking about
http://www.rpw.com.au/shop/index.php?option=com_content&task=view&id=221&Itemid=40
This is definitly not a good long term thing as it will cause ring wash and burn your cat converter out in no time. I suggest as a sticky, that most owners beware of just trying to raise boost above 12 psi without doing some tuning at the same time.
Check the following link to see what I am talking about
http://www.rpw.com.au/shop/index.php?option=com_content&task=view&id=221&Itemid=40
VR4Rocket
Leaving Skid Marks
- Location
- Queensland
- First Name
- Kevin
- Drive
- Was a Ralliart Colt, was a 1997 Toyota Aristo was a 1996 Legnum..Now an XR5 Turbo
Have a look at my thread
Real Problem.....HELP in the Workshop thread....could this possibly what is happening to my car?
Real Problem.....HELP in the Workshop thread....could this possibly what is happening to my car?
SiliconAngel
1 AYC Bar
Certainly sounds related doesn't it?
VR4Rocket
Leaving Skid Marks
- Location
- Queensland
- First Name
- Kevin
- Drive
- Was a Ralliart Colt, was a 1997 Toyota Aristo was a 1996 Legnum..Now an XR5 Turbo
I think I am going for a new exhaust system with a replacement cat converter and turn the boost down
Hi Matt,
You seem to have a few drama's with that car? From memory your car was in the low 10s with AFR's?? Most dyno's wont read below 10 (mine flat lines at 10 as well- now fitted with AFC)
Here's my 2 cents
I wrote somewhere on here about rich mixtures, but can't find it. Short version;
Most people think that mixtures on the richer side of ideal is "safe". The reality is that the engine can't actually burn the fuel in the cylinder when its really rich and the flame front actually burns at a slower rate and not all the fuel is actually burnt- so what AFR the engine is actually running is a mystery. On top of that your fuel use is just tragic.
From what I've been able to find out regarding the tuning of these cars and Im sure Dave Mitsiman could offer some insight here, but when the boost is turned up on these cars from the already rich map, they go even richer which just kills power.
I would highly recommend that if you're going to up the boost then get the miniceptor mitsiman offers. You can adjust the fuel AND timing and i think we'll see that the car will respond quite well to this- yours in particular!
Fit the biggest exhaust you can live with. Front pipes- i think 2&3/4 inch will be the biggest you can fit- my exhaust guy said 3inch will be a pain to fit.
I will be fitting a miniceptor to mine but its not high on my list of priorities ATM
You seem to have a few drama's with that car? From memory your car was in the low 10s with AFR's?? Most dyno's wont read below 10 (mine flat lines at 10 as well- now fitted with AFC)
Here's my 2 cents
I wrote somewhere on here about rich mixtures, but can't find it. Short version;
Most people think that mixtures on the richer side of ideal is "safe". The reality is that the engine can't actually burn the fuel in the cylinder when its really rich and the flame front actually burns at a slower rate and not all the fuel is actually burnt- so what AFR the engine is actually running is a mystery. On top of that your fuel use is just tragic.
From what I've been able to find out regarding the tuning of these cars and Im sure Dave Mitsiman could offer some insight here, but when the boost is turned up on these cars from the already rich map, they go even richer which just kills power.
I would highly recommend that if you're going to up the boost then get the miniceptor mitsiman offers. You can adjust the fuel AND timing and i think we'll see that the car will respond quite well to this- yours in particular!
Fit the biggest exhaust you can live with. Front pipes- i think 2&3/4 inch will be the biggest you can fit- my exhaust guy said 3inch will be a pain to fit.
I will be fitting a miniceptor to mine but its not high on my list of priorities ATM
G
Guest
Unregistered
Hmm I wrote something bt it disappeared. You have stated exactly what we have found - major changes plus boost makes an already tuned rich car now run a whole lot richer.
The moral is that tuning on these cars is not a luxury, its a necessity. I would wind the boost down and then save up for a piggy back ecu package.
For those wanting our dump pipes, I can provide the Miniceptor units with a a baseline tune for those not wanting dyno time, with no ignition tuning but just running some minor fuel changes on stock boost levels. This will be suitable for exhaust and dump pipe modifications only.
The moral is that tuning on these cars is not a luxury, its a necessity. I would wind the boost down and then save up for a piggy back ecu package.
For those wanting our dump pipes, I can provide the Miniceptor units with a a baseline tune for those not wanting dyno time, with no ignition tuning but just running some minor fuel changes on stock boost levels. This will be suitable for exhaust and dump pipe modifications only.
bradc
1 AYC Bar
yep, thats what they do The more mods you add onto them such as exhaust, boost, hard pipes, the richer they run until you get something in there to sort out the fueling.
The more mods you add onto them such as exhaust, boost, hard pipes, the richer they run until you get something in there to sort out the fueling.Here is a link Matt to help you understand what is most likely happening.
http://express-press-release.net/29... VP of Engineering, Innovate Motorsports.php
Glad to hear Dave that i'm not spruking shit. look forward to seeing your hearing when you kit is ready for release and am now following your VR4 upgrade.
http://express-press-release.net/29... VP of Engineering, Innovate Motorsports.php
Glad to hear Dave that i'm not spruking shit. look forward to seeing your hearing when you kit is ready for release and am now following your VR4 upgrade.
- Thread starter
- #17
I would love to put a full engine management system in it. Unfortunately my wife doesn't understand why you could possibly need to spend that kind of money on a car. She used to be an accountant (can't spend money) and now she is a paramedic so she cleans up bodies from car crashes, I just loose every time.
G
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Unregistered
Its not a full engine managment system, its a piggy back system.
as for justification thats fairly simple, I can garauntee with a piggy back your fuel economy will improve.
Let me state this again for everyone, no matter the level of modifications on the vehicle, even if it is completely stock
YOUR FUEL ECONOMY WILL IMPROVE with any piggy back tuning process because these vehicles run SOOOOOOOO rich on the factory tune.
Haltech Miniceptor $1250.00 tuned and fitted on average is a great option.
as for justification thats fairly simple, I can garauntee with a piggy back your fuel economy will improve.
Let me state this again for everyone, no matter the level of modifications on the vehicle, even if it is completely stock
YOUR FUEL ECONOMY WILL IMPROVE with any piggy back tuning process because these vehicles run SOOOOOOOO rich on the factory tune.
Haltech Miniceptor $1250.00 tuned and fitted on average is a great option.
SiliconAngel
1 AYC Bar
Matt, explain the economics of using less fuel. I'm sure she'll understand that.EDIT: DAAAMN YOU MITSIMAN!!!
Cheeky Dave you snuck in while I was reading something else >.<
G
Guest
Unregistered
Excellent my sneaky tactics worked for a change
