Mazda Rotary Club

General => General Technical => Anything Engine/Performance/Tuning related => Topic started by: TheJackal on July 13, 2004, 08:29:27 PM

Title: Why is my car running 15 psi boost
Post by: TheJackal on July 13, 2004, 08:29:27 PM
Hi, just fitted a boost guage to my fd and it seems to be running 15psi, there are no signs of a manual or electronic boost controller. Does this meand the ecu has been modded ?
Title: Why is my car running 15 psi boost
Post by: scooby_si on July 13, 2004, 09:15:27 PM
eek(http://smilies.jeeptalk.org/contrib/tweetz/scared.gif) that\'s 1.1 bar as i recall which if the ECU & fuelling aint modifed to be able to take that you could be asking for trouble, personally i\'d wana get that checked out to at least find out if it was all tickety boo by an expert ASAP.
Is it a smooth consistant 1.1 bar kinda thing or a bit of spike, sketchy or otherwise.
Mine did overboost>1bar & it turned out to have a FCD (fuel cut defensor) added to the standard ECU but also according to pip underboosted at certain times.
In the end seemed to be the ECU not communicating properly but 1 power FC later nice none OTT boost, i\'m only one i\'ve read about who had boost issues caused by that mind but er back on track & either way sounds like yers is OTT if standard ECU &/or fuelling (http://instagiber.net/smiliesdotcom/otn/shocked/Wow.gif)
Good luck
Si (hopefully not talking outa bung hole for a change...)
Title: Why is my car running 15 psi boost
Post by: TheJackal on July 13, 2004, 09:37:27 PM
Well running on the 1st turbo, the boost reads 11psi when the 2nd turbo kicks in it goes up to 15 psi (with heavy right foot) and stays there. The boost does not spike at all its quit smooth unlike my impreza which spikes up to 19psi and settles back to 15psi. When the engine is cold the boost does not go above 11psi coz of the dual butterfly throttle thingy I assume.

Although the boost needle is quite smooth the acceleration is a little bit jerky.
Title: Why is my car running 15 psi boost
Post by: scooby_si on July 13, 2004, 09:45:26 PM
blimey does yer scoob (classic?) not hit fuel cut thought that was set to 1.14bar on the scoob if >that for a few secs then total loss of power?
Anyway back to FD certainly sounds like more than yer average boost figures, what mods you got on that bad boy?
Si
Title: Why is my car running 15 psi boost
Post by: TheJackal on July 13, 2004, 10:06:41 PM
The ECU in the scoob allows the boost to spike when you change gear, yes the fuel cut off point is 15 psi, mine is set to just below this using a dawes device in conjunction with a boost guage (for setting up). If the scoob goes 0.0000001psi over 15 the fuel cuts off and you go through the windscreen, I had to do this a few times when setting it up, it was interesting, definetely a new underwear experience. My scoobs done 147,000 miles its running around 300hp and it still drives like a new car.

All the FD has so far is a twin cone HKS filter system and a bailey dump valve. It has a Jasma back box but it is what I would term gay as it is less than 4 1/2 inch. I\'ve got a stainless 3" downpipe and midpipe to go on asap and I was thinking about an intercooler upgd from rotechniks. After that I think i\'ll probably leave it alone. The car was imported less than a year ago with absolutely no mods whatsoever (unless it has an ecu upgrade which would explain the boost).

Where is the ECU anyway.
Title: Why is my car running 15 psi boost
Post by: Iwan on July 14, 2004, 05:49:33 AM
Hi all,

.... I\'ve got a stainless 3" downpipe and midpipe.....

well this should explain your "more of boost"

please remember, it\'s strongly recomendet to upgrade your ECU when decating your car. Othervise you will run lean.

REgards
Iwan
Title: Why is my car running 15 psi boost
Post by: TheJackal on July 14, 2004, 11:14:03 AM
I\'ve not actually fitted the 3"downpipe and midpipe yet. It could be that there is a restrictor pill on the feed to the boost sensor, I know where this is on the scooby but have no idea where it is on this car. Anyone got a pic/drawing or something ?
Title: Why is my car running 15 psi boost
Post by: TheJackal on July 14, 2004, 08:09:47 PM
See the boost sensor, which way should that black round thing be facing, you can see here the arrow points toward the sensor is this correct ?
Title: Why is my car running 15 psi boost
Post by: TheJackal on July 16, 2004, 07:40:33 PM
My car was running at 15psi boost because of a kinked vacuum pipe that goes to the second recirculating valve.  I found it myself today when I was checking the vacuum lines. The car is now normal running 10-11 psi boost.

Thanks anyway.
Title: Why is my car running 15 psi boost
Post by: TheJackal on August 15, 2004, 08:12:15 PM
Heheh my cars running 15 psi boost again, at least ths time I know its because the 3" stainless straight through exhaust is fitted. Its apexi pfc time.
Title: Why is my car running 15 psi boost
Post by: scooby_si on August 15, 2004, 08:49:52 PM
Get it done soon bud the scoob can take a bit of det the rotary wont like it & will prove more costly than a PFC.....
Si
Title: Why is my car running 15 psi boost
Post by: yonner on August 15, 2004, 11:55:15 PM
whare in scotland are u???
Title: Why is my car running 15 psi boost
Post by: Andyp on August 16, 2004, 12:07:12 AM
can you actually tell if it\'s running lean or not? does it jerk as if you were running out of fuel?

mine was running so rich before the decat think it should be normal now hehe.. still waiting to put the FC in :(
Title: Why is my car running 15 psi boost
Post by: TheJackal on August 16, 2004, 02:05:22 PM
Hi, you can tell its running lean coz I get 93 miles to a 1/4 tank of petrol. I got Pip at WGT to put it on the rolling road on friday and he put a wideband lamda sensor in it and linked it to a fuel/air meter and he could see it was really lean so I\'m on 5psi boost or less until the Power FC gets fitted.
Title: Why is my car running 15 psi boost
Post by: TheJackal on August 16, 2004, 02:06:44 PM
Oh, I\'m in Edinburgh Andy.
Title: Why is my car running 15 psi boost
Post by: TheJackal on August 16, 2004, 02:11:02 PM
I forgot to mention aparently for every 2 mods you need to increase or at least check the air/fuel ratio.
Title: Why is my car running 15 psi boost
Post by: Donato on August 16, 2004, 02:41:19 PM
Nice to see another one in Edinburgh! nd red too, my favourite!!

:D
Title: Why is my car running 15 psi boost
Post by: TheJackal on August 17, 2004, 03:53:09 PM
You know what donato I think I\'ve seen you 2 or 3 times going up towards the wisp, does that sound right.
Title: Why is my car running 15 psi boost
Post by: Donato on August 17, 2004, 04:02:22 PM
Yeah but not for a few months as my engine hasn\'t been in the car for 3 months..:(

Im currently going through a complete rebuild and non sequential conversion, then a respray...

Hows the car then mate?

Cheers

Donato
Title: Why is my car running 15 psi boost
Post by: TheJackal on August 17, 2004, 06:41:54 PM
The cars getting there, have already had a respray as the paint was fading I got it done at speedliner at the bottom of leith walk. I\'m going back down to WGT in the next week or so to get the Power FC fitted and tuned by Pip. I am thinking about getting an AVC-R as well. Yeah it has been a few months since I saw you at the craigmillar crossroads right enough is that the way you go home or something I cant remember if it was in the morning or evening I used to see the car.
Title: Why is my car running 15 psi boost
Post by: Donato on August 18, 2004, 09:08:58 AM
No mate my Gran lives at gilmerton.

Pip is sending my engine back this week so thats me a busy boy from the weekend onwards.. I keep going into my garage and looking at my FD, she looks all sad with no engine :(

When i get back on the road we will have to have an Edinburgh mini meet!
Title: Why is my car running 15 psi boost
Post by: TheJackal on August 18, 2004, 09:33:04 AM
Sounds good to me m8 lol.