Warning: Illegal string offset 'html' in /home/nissansi/public_html/forums/cache/skin_cache/cacheid_1/skin_topic.php on line 907
Lossing Power Under Full Throttle - Hardtuned.net

Jump to content


Lossing Power Under Full Throttle 

9 replies to this topic

#1 Burak Besiktepe

  • Joined:09-November 16

Posted 09 November 2016 - 09:14 AM

Hi all,

I've been looking on the forum for awhile about this issue and can't seem to find anyone with the same symptoms as mine. My S15 has a weird problem where it'll feel strong and linear in power delivery untill I apply full throttle, and after 5000RPM it feels as if the engine looses 50% power.

I've found modulating the throttle after 5000RPM helps (75%-90%) and the car feel strong and powerful. My question is, is the fuel delivery that's crapping out (dodgy fuel pump) or ignition (coilpacks) or the car has a shit tune.

The car is a JDM S15 with stock turbo but HKS waste gate actuator, Apexi-Power FC, HKS Dump-pipe & full 3" exhaust. Thanks in advance all.

#2 Dose Pipe Sutututu

  • Joined:19-January 05
  • Location:Australia NSW
  • Car:Boat Sutututuutu

Posted 09 November 2016 - 05:01 PM

could be blocked cat, crappy tune too (so you're hitting cells with extremely low timing), insane lean outs because your fuel pump is cooked or the oem pressure relief valve is still there and you're bleeding off heaps of fuel pressure.

easiest way is to hook up a wideband or load up the car on the dyno followed by a map trace.

#3 Burak Besiktepe

  • Joined:09-November 16

Posted 10 November 2016 - 12:04 PM

View PostDose Pipe Sutututu, on 09 November 2016 - 05:01 PM, said:

could be blocked cat, crappy tune too (so you're hitting cells with extremely low timing), insane lean outs because your fuel pump is cooked or the oem pressure relief valve is still there and you're bleeding off heaps of fuel pressure.

easiest way is to hook up a wideband or load up the car on the dyno followed by a map trace.

Thanks for the advice, I was planning on taking my car to chequered tunning as they're close and heard good things. Would you advise a new fuel pump (i.e. Bosch 040 or Walbro equivalent) before a tune as it's a 17 year old pump? I do often feel like it's leaning out as the car operates a lot better in the high RPM in hot weather as opposed to the cold (correct me if I'm wrong but warmer weather requires less fuel in the ARF as the air is less oxygen dense).

I'll check the car for the OEM fuel pressure regulator and see if it's been upgraded. I've bought the car off my brothers friend, so with little to no info on modifications and maintenance on the car I haven't been able to figure out what's wrong.

Edited by Burak Besiktepe, 10 November 2016 - 01:08 PM.


#4 Dose Pipe Sutututu

  • Joined:19-January 05
  • Location:Australia NSW
  • Car:Boat Sutututuutu

Posted 10 November 2016 - 07:52 PM

no bosch 040, they're a horrible old pump get a DW300 or a Walbro 460

Trent is good, he's one of the better tuners out there, I've seen his tunes and they're decent, unlike other big name shops in Sydney that just punch in 888888888 into the ignition maps

#5 Burak Besiktepe

  • Joined:09-November 16

Posted 11 November 2016 - 08:44 AM

View PostDose Pipe Sutututu, on 10 November 2016 - 07:52 PM, said:

no bosch 040, they're a horrible old pump get a DW300 or a Walbro 460

Trent is good, he's one of the better tuners out there, I've seen his tunes and they're decent, unlike other big name shops in Sydney that just punch in 888888888 into the ignition maps

Thanks for the advice! Is the DW300 a drop in, in-tank fuel pump?

I do hope that the symptoms are of a crappy tune and nothing mechanical. As a quick side note, I noticed in the "Let's Talk Brake Pads!" thread you were a reseller of the Intima pads. Could I PM you about a bundle deal as I need pads and rotors all round?

#6 boost_bus180

  • Joined:18-December 05
  • Location:Australia ACT

Posted 11 November 2016 - 10:14 PM

to me it sounds more symptomatic of an induction problem. If it were the cat that was blocked, you would have 50% power all throughout the rev range, not just at the top at wide open throttle.

First place I would consider looking at is whether or not the rubber intake pipe connecting the airbox to the turbo is collapsing under the high loads and choking the engine. This is a bit tricky to test yourself, but easy enough to modify it with an alloy tube in the squishy part. After that I would consider looking for boost leaks in your intercooler piping.

Trent is a quality tuner and will be able to give you a good assessment of issues and a probably a few good tips on what your engine would benefit from next. Upgrading the stock fuel pump should be one of the first mods you make when chasing extra power.

#7 Dose Pipe Sutututu

  • Joined:19-January 05
  • Location:Australia NSW
  • Car:Boat Sutututuutu

Posted 14 November 2016 - 11:16 AM

View PostBurak Besiktepe, on 11 November 2016 - 08:44 AM, said:

View PostDose Pipe Sutututu, on 10 November 2016 - 07:52 PM, said:

no bosch 040, they're a horrible old pump get a DW300 or a Walbro 460

Trent is good, he's one of the better tuners out there, I've seen his tunes and they're decent, unlike other big name shops in Sydney that just punch in 888888888 into the ignition maps

Thanks for the advice! Is the DW300 a drop in, in-tank fuel pump?

I do hope that the symptoms are of a crappy tune and nothing mechanical. As a quick side note, I noticed in the "Let's Talk Brake Pads!" thread you were a reseller of the Intima pads. Could I PM you about a bundle deal as I need pads and rotors all round?

Sure thing!

I'm in Japan at the moment but send myself and the team an email sales (AT) trak-life.com and someone will sort it out :)

yes the DW300 is a drop in

#8 Burak Besiktepe

  • Joined:09-November 16

Posted 20 November 2016 - 08:41 PM

Thanks for all the advise guys! I'll be taking the car to get tuned within the fortnight. I'll have a look at the turbo piping and see if I can find any spongy plastic or leaks.

#9 Burak Besiktepe

  • Joined:09-November 16

Posted 29 November 2016 - 05:27 AM

Hi all, the car has been sorted out a the tuner. I ended up taking my car to ETUNER out at Campbellfield. The crew there were super good with the car. Went for a test run and the tuner new the car had a horrible tune. Got the car on the rollers and he found a boost leak. For some reason there was a t-piece in the pipe that connects the boost controller solenoid to the wastegate.

Once he got into the Power FC he found that it had no tune, the O2 sensor wasn't turned on in the ECU, injectors set to 100%.... suffice to say it was difficult to get a base figure before tuning; 132kw was the base line with 260nm. By the end of the tune he got it up to 188kw and 370nm at the wheels. Car drives a crap tonne better now. All I have to do is change sparkplugs as the tuner said the previous state would have lunched them. Should I go for? "BCPR7ES" a good idea as I'm at 20psi apparently.

Cheers.

#10 ColS15

  • Joined:13-June 12
  • Location:Australia NSW
  • Car:S15

Posted 30 November 2016 - 08:44 PM

Yes, you can go a step colder at that boost.
Plugs are Bkr7e





1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users

Common Links

  • About Us
  • Privacy Policy
  • User Agreement
  • Help & Support Forums
  • Advertise
  •  

    By your continued use of this site, you agree to follow all Rules & Guidelines and abide by the User Agreement outlined in our Terms & Conditions.

    Hardtuned Network is hosted by Sanity Technology

    Design, Site Management & Hotness provided by Loz.

    Big thanks to all our members and volunteers for making this network what it is today!