Hey all.
I have a 1994 Efini 2 seater which I love. I'm slowly getting through the list of bits and pieces that need doing to get it to a good level.
One thing I've noticed is from what I've read about the place, I believe it's not boosting as hard as it should. When holding it at WOT, you can feel the first turbo start to boost and it produces approx 0.3bar (5psi). At around 5000rpm there is a noticeable lull and the boost drops off, then soon after build back up to 0.5bar (7.5psi). There is a huge difference in performance between 0.3 and 0.5 bar!
From what I've read, I should be seeing more like 0.7-0.8 bar on both turbos, with the lull in the middle. Is this correct? If so, what could be causing the consistently low boost levels?
Modifications: Fully decatted, 4" exhaust system, standard ECU, ARC Induction box.
Any help/advice much appreciated :)
Your only looking for 10 8 then 10lbs as the correct boost pattern so the boost levels your seeing would be about right
1 Bar or 1.1 bar and you will need mapping plus the twin turbos never seem to like living very long at these boost levels
Hope this helps
10psi - 8psi - 10psi is what I've read. So to confirm these are the stock boost levels for a 94 Efini? I believe it's the 254hp model.
So I'm right in thinking first turbo 10psi, 8psi is lull as second turbo comes online, second turbo 10psi?
I'm only getting 5psi - boost drops right off, maybe 2-3psi - 7.5psi. Seems a bit low to me?
Yes this pattern is for your model.
Unless you make enough boost on the first turbo it won't change over to the second
Start by looking for a boost leak on inter cooler pipes
No no no 0.3 and 0.5 bar is too low for your model. Standard oem boost is 10psi or 0.68bar. A rule of thumb in bar is look for 0.7-0.6-0.7 to redline.
The dip is the transition to both turbos being utilised. I would definitely advise reading and reading to gain knowledge of the sequential operation.
In short the primary turbo builds boost from 1800rpm giving 0.68bar by 2500rpm. This will hold solid until 4400rpm until 4600rpm where it will quickly dip to 0.60bar. At 4600rpm both turbos are now spinning giving twice as much airflow but still at 0.68bar which in turn makes more power until the 8k redline.
The straight through exhaust on a standard ecu is one of your problems and is a sure way to run lean and pop your motor aside from that Clive is probably right with a split ic pipe somewhere.
Hth
Cheers for the help guys. It's been a bit of a struggle to find a straightforward description of what to expect and when with regards to standard boosting.
I have an Apexi FC and Commander to put on at some point. I intend on fixing the few little bits and pieces, replacing the standard IC with an aftermarket SMIC, maybe a hard pipe kit before fitting the PFC and getting it mapped properly.
By the sounds some investigation into solenoids and boost leaks will be the way forward to.
Any opinions on how safe the car will be until mapping for just general driving? No racing/ragging etc. Or is time of the essence?
Had similar issues long way back when I first got my FD. Had to replace some solenoids in the rat nest but eventually gone single turbo and got rid of all the headaches.
Quote from: Eclipsed4ever on February 06, 2015, 09:27:02 PM
Cheers for the help guys. It's been a bit of a struggle to find a straightforward description of what to expect and when with regards to standard boosting.
I have an Apexi FC and Commander to put on at some point. I intend on fixing the few little bits and pieces, replacing the standard IC with an aftermarket SMIC, maybe a hard pipe kit before fitting the PFC and getting it mapped properly.
By the sounds some investigation into solenoids and boost leaks will be the way forward to.
Any opinions on how safe the car will be until mapping for just general driving? No racing/ragging etc. Or is time of the essence?
It's pretty straightforward and shouldn't be struggle if your asking in the right places. Register on fduk for all the answers on this specific model.
Before any major changes it's best to get it running right and tbh the standard ecu is to slow to cope with the increased exhaust flow. This in turn raises your boost slightly and your ecu cannot adjust the Fuelling quick enough so goes into limp mode.
Put your pfc on and get it mapped mate many many people make this mistake then wonder why it blew blaming an engine instead of the owner for not taking advice.
It may last it may not, get it mapped and you will probably find your sequential operation works just fine. Either or the tuner will help you diagnose what's up.
Quote from: Eclipsed4ever on February 06, 2015, 09:27:02 PM
Cheers for the help guys. It's been a bit of a struggle to find a straightforward description of what to expect and when with regards to standard boosting.
Standard boosting is as described above regardless of model, as said I would suspect a leak on the intercooler circuit
Also look at the big short pipe that goes onto the inlet manifold,
Have a look in the general and tech section and you will find full boost circuit diagrams that were put up at the start of MRC many years ago.
I would stick with you stock ECU till you sort out you problems as an Apexi whilst an excellent upgrade will sometimes mask problems.
With your cars specification once your ready to fit your Apexi , if this is a new boxed unit that has never been on a car, simply plug it on and start it up with all lights and electrics turned on and let the car idle for 5 minutes and it will learn. (Not Internet talk as I have done this to quite a few FD's over the years )
Hope this helps
I think I'll go through all the intercooler/inlet pipework to try and eliminate any boost leaks. As I said I'm trying to get everything working, as it should, before moving forward with modifications. I think the rats nest is on the list to do so that may help getting things working properly.
Unfortunately my PFC is a second hand unit. I've not tried it on the car yet but it was sold in full working condition. I'm yet to look at any manuals for it with regards to resetting it to factory default as I have no idea what mapping/settings are in there at the moment. Do you know if the self learning can be initialized on a used unit Clive?
Quote from: Eclipsed4ever on February 07, 2015, 07:44:14 PM
. Do you know if the self learning can be initialized on a used unit Clive?
So you know you can safely plug it onto you car , any of the Rotary tuners would have a base map on file that they can
load into it for you.
Talk to them and you should be able to post it to them to get your Apexi back to the settings it was born with
There is a huge wealth of info in the tech sections and when I was starting out with my rotary I used the archives regularly.
It's worth learning the system as best as you can as it helps in the long run.
If your going to stick with the standard ecu then at least get a restrictor plate or a cat put back in at least for the short term.
I'm hoping to get some time this weekend to search for some boost leak. I'm hoping it's something straightforward :)
With regards to the ECU. I've been doing a bit of reading on the PFC bits and pieces. I've found tables for the older 'base' PFC base and the newer 'base mod' PFC base maps. I was thinking I can fire up my PFC and put the newer base mod settings into it. This should make it safer to run until I can get it mapped on some rollers. I've had a bit of experience with other mapping softwares in the past, but not for a long time. Would there be much risk in doing this?