Ecu and turbo control

[MLC]

After trying to track down info to fix my turbo problems i've found myself having to learn about the sequential turbo system, but something puzzles me.

I've read that the entire system of VSV's, wastegate control etc are entirely ECU controlled. It just puzzles me why have an electrical control system to operate other mechanical devices such as the VSV's without just having plain old solenoids for direct control over valves. It suggests that wipping out the EFI fuses for a few mins 'may' solve it (although i'm dubious about doing that while the car is running ok'ish, 'if it ain't broke....don't fix it' scenario http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/wink.gif )

Is it some kind of dual electro/mechanical control system that'll do my brain in if I dig any deeper or is the info I found just plain wrong?

TonyE

[Martin F]

Hmmm a VSV is very similar to a solenoid, just a solenoid that activates a valve. Yes the MKIV sequential system is very complex, but look at what it achieves on a stock car, a near as dammit flat torque and power curve.

IIRC i think the RX7 uses a more electronically based control system, but i'm not familiar with its operation.

Have you been reading the New Car Features info on the sequential system ? Its probably one of the better descriptions.

As for removing the EFI fuses to reset the ECU i wouldn't be too overly concerned about them making things worse. All it will do is cause the ECU to relearn so the car may run a bit rough for the first 10mins or so of driving as it relearns things.

Always worth a try.

[MLC]

Yup, read through all of the new car features which was extremely helpful since i know absolutely nothing above basic combustion engines.

I gave the ECU reset a go and managed to get the 2nd turbo to come in once while the car was almost warmed up so at least i know it has the 'potential' to work. After that it didn't want to know even at 5000 rpm. Blew a tyre and that was my lot for testing although the new exhaust did set off it's first car alarm ?http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/buttrock.gif

It might just be me but i'd swear the turbo will cut in a lot more frequently in cold weather. In fact the whole car has a lot more low rpm poke with a cold engine too.

[MLC]

Lil update on the turbo 2 situ which is becoming even stranger.

For the first time this year on the way home turbo 2 never failed to operate, the only thing different was the Air Con was on for the first time this year http://www.mkivsupra.co.uk/iB_html/non-cgi/emoticons/rock.gif So.. (after satisfying my boy race tendancies and grinning lots) I switched the AC off and lo and behold Turbo 2 didn't wan't to know again.

I can't find a single connection between the 2 systems as to why, anyone ever heard of this before?

[Martin F]

That is a strange twist of coincidences, but I wonder if its a red herring.

I know that Chris Wilson on here has come across a few of these intermittant turbo 2 issues now and its turned out to be the speedo converter.

Take a look HERE (http://www.mkivsupra.co.uk/cgi-bin/iB/ikonboard.cgi?act=ST;f=1;t=223)

[MLC]

I didn't think the speedo conversion would be an issue on a UK model.

I'll be playing about during this week if the weather holds out to be sure, but at 300 miles a week and the turbo worked as many times today as the rest of the year combined it was a very convincing herring.

Because the car has so much more go in it over the whole rpm range when not at full temp i'm replacing all the turbo piping and then gradually working through Ian's VSV/pressure tank tests he posted on 'the other forum'.

[Martin F]

Quote[/b] (MLC @ May 17 2004,23:36)]I didn't think the speedo conversion would be an issue on a UK model.
Doh!!

Never spotted that.

[Martin F]

I wonder if it could be speed signal related. The speed sensor on the back of the gearbox has been known to go intermittant occasionaly.

May be worth checking for any fault codes logged in the ECU.