Jump to content

Tuning help - v3 STI (Overseas)


Andrew Smith
 Share

Recommended Posts

Hi, Just wanted to know if someone could provide some tuning help for my v3 sti with a link g3 /adaptor? I am located overseas and i got the link ecu tuned in nz but i think it was done on 98 octane. Our fuel here is around 95 with octane boost. I gave the IIguy a list of my mods and he tuned it accordingly. I think he has a v3 sti with similar mods. The problem im having is that when i run 1-1.2 bar of boost, the engine starts to lose power and seems to be detonating. There's like popping noises through the exhaust. I currently set the duty cycle on the boost solenoid map to 0 and its on spring pressure now which is around 0.6-0.7 bar and it doesnt detonate or miss like before. I will gradually increase the numbers and see where it starts to detonate. My air fuel ratio at idle is 13.1 (operating temp) and 11.2 at full power. Is this ok or is it too rich? Also, what would af ratios be when the engine starts to detonate and what will the lambda reading be? It would be much appreciated if you guys could help me out here as there are no dynos here and i have to tune the car myself on the road. My mods are: 3" exh (no cat), FMIC, Pod, BOV, LINK G3, Will spark plug gaps cause detonation, i havent adjusted spark plug gaps and im not too sure what they are currently. The vehicle was running perfectly with my factory ecu on 1.2 bar standard so i think the fuel isnt too bad otherwise it wouldnt reach 1.2 bar. What do you guys think? I have done all the mods to the car myself but i have very little experience with tuning aftermarket ecu's. Your help will truly be appreciated. Thanks guys.

Link to comment
Share on other sites

OK, The biggest change between running 98 and 95 octane fuel is the ignition timing.  I would think that you will need to reduce your ignition timing at full load to prevent detonation as you AFR sounds plenty rich enough.  At cruise, light load and idle you should be able to run around 14.7:1.  What type of AFR measurement are you using?  You could pull about 5 degrees timing out at full power and see how it goes.  11.2 is reasonably rich, but not too rich for 1.2bar boost when detonation is a problem.

There are two possible causes for the popping that I can think of, one is trigger arming voltages, but reducing boost would not prevent that.  The other is spark problems.  A large spark plug gap, poor HT leads, incorrect dwell time could cause the spark to be missing at high power.  As you increase boost, more spark energy is required.  The quick test is to significantly reduce your plug gaps and see if it helps, if it does, upgrade the ignition.

Just a warning, playing with high boost and detonation can lead to some pretty bad consequences like blown engines!  Start low and slowly work your way up in boost.

Link to comment
Share on other sites

Thanks for the info bro. Much appreciated. Im slowly turning up the boost and its currently on 0.9 bar. I have adjusted the the fuel map for idle and its now at 14.7. Light throttle its around 13 and full boost its around 11.2. I am using an Innovate LM-1 for the air fuel ratios. From experience, are these ratios fine and can it do any damage. At full power, what ratios should i watch out for? I think i figured out what the seemed to be detonation. It was the rpm cut. I have learnt how to adjust the rpm cut properly and its nots cutting in at around 7200 as before. Regarding the MAP cut, can i change this to 240 kpa or should i just leave it at 230? Thanks.

Link to comment
Share on other sites

Typically you would run the engine at around 14.7 at cruise and light throttle.  Pretty muchly all town driving will be at 14.7:1.  It will be a little richer under acceleration, but any time you are holding constant speed on the flat you will usually be araound 14.7 or sometimes higher.  Full power AFR doesn't sound too rich...

You can set the MAP limit to whatever you want.  The important thing to remember is that if you get boost higher than the map limit the engine will cut...  Usually you run it just above your boost level plus a bit extra to allow for any boost variations...

Link to comment
Share on other sites

Hi Ashley, Well i decided to plug in my factory ecu and boost solenoid to see if the misfiring stopped but guess what? It still misfired @ 1.1 to 1.2 bar! I took out the plugs and they were a bit worn. Like 1mm of metal was missing from the centre electrodes and had welded it self onto the earth electrode. Put some new plugs in and gapped them to .8 mm but the misfire is still there. I did a comp test and it was 130 psi in all cylinders. Tested my coil and its within specs. Just the primary winding is over by.5 ohms. HT Leads are within specs as well. I guess the only thing i can do now is bite the bullet and change my coil and HT leads because its very hard to diagnose without a dyno. Is there anything else you can suggest that i should check/ change. Really appreciate your help.

Link to comment
Share on other sites

It may be that you do not have enough spark energy to fire the plugs with that much boost... I dont think the coil will be the problem, but the leads definitely could be a problem.  If the plugs have been worn out, the high energy required to fire them could have caused the insulation to break down and blow holes out the side of the leads usually down the spark plug tubes...

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...