View Full Version : Late 2nd turbo latest
Ok dudes i think ive isolated this pesky problem to the fact that the EBV vsv is not getting a signal to it , can anyone confirm where/how this signal coes from , is it boost or rev related , when i fit the vsv with a switch i can bring the turbo on line at 4000rpm without the switch it is over 5000rpm .
John:flame Dev
The signal is rev related. It gets a signal from the ECU, the exact pinout escapes me :)
To clarfiy, is this the exhaust gas bypass valve (bolted onto turbo 2, looks like a wastegate actuator, controlled by the VSV nearest the brake fliud reservoir) or the exhaust gas control valve (bolted onto the downpipe, under the turbos, controller by the VSV at the front of the engine)?
Plus, check your intake air control valve as well, because that is switched at an RPM point, so if the ECU is somehow reading the RPM incorrectly this one should be affected too.
Well done on the diagnosis, I like the idea of plumbing in a manual switch, sounds like you've torn most of your hair out on this one to reach that level!
-Ian
Ian , it is the vsv nearest the brake cylinder , when the switch is activated the car works fine , checked the feed today and the trigger is by an earth , it has its live to it fine , if i have to i'll use an rpm activated switch to work them , but im thinking of going the single route to avoid all this hassle .
John:flame Dev
Terminator
18-05-03, 15:17
IMHO it will be turbo boost pressure sensor that feeds the ECU with the most important signal for the VSV's in question. RPM may be a component but not the sole source other wise turbo two would always come one line at the same rpm regardless of throttle position.
If the sensor is giving low readings this would cause the VSV's to be activated late. Have you got boost readings that correspond with your 5000rpm activation of the VSV’s.
Matt Harwood
18-05-03, 15:46
Not that I know anywhere near enough about the workings of the sequential set-up to comment or argue, but I thought the 2nd did always come on at the same point. For example, when you're cruising and slowly get to about 4000 rpm on a motorway, I'm sure you can feel/hear it changing over to both turbos....
Waiting to be corrected :innocent:
Originally posted by Matt Harwood
Not that I know anywhere near enough about the workings of the sequential set-up to comment or argue, but I thought the 2nd did always come on at the same point. For example, when you're cruising and slowly get to about 4000 rpm on a motorway, I'm sure you can feel/hear it changing over to both turbos....
Waiting to be corrected :innocent:
I think Matts right , whenever you read anything on the workings of the seq. set up it allways says about pre-spooling at 3500rpm and never mentions boost , just my thaughts and a few others on here .
John:flame Dev
Terminator
18-05-03, 20:51
I think the RPM figure is a red herring, we all see number two start building at roughly the same time and coming on to full boost at roughly the same time too. The engine manual makes no reference to RPM except for the ECV, EGC and waste gate valve being closed at low RPM. Everything kicks off when "charging pressure reaches a predetermined level" So it is the pressure sensor that control the boost.
How else could I achieve 6500 rpm and minus 0.5 bar at the same time. If it was RPM controlled, I would not have been able to stop number two coming on line at 3800 ish and hitting full 1.2bar boost by 4200 rpm.
High engine speed is mentioned in the context of the waste gate controlling boost at high engine speeds. So here it is explicit that pressure and RPM are used to control boost and keep it safe.
MINUS 0.5bar boost at 6500rpm? How did you acheive that?
The *plumbing* for the second turbo is all opened up at 3500-4000rpm, it'll "come online" if it's got enough exhaust gas going through it for it to produce boost.
If you can get to 6500rpm with no boost from one turbo due to a very light throttle opening, you can do it with both turbos. Your argument doesn't really make sense, you seem to be assuming that the moment the floodgates open, #2 will deliver 1.2bar no matter the throttle opening or load?
Also, you can hit full boost on #1 well before 3500rpm, so that's another indication that it's not pressure related.
I've also seen the IACV actuate when revving the engine while stationary...
Sorry, guv, I've gotta disagree all the way :)
-Ian
Aaaaand, I should add to the main point of the thread as well :)
That's the EGBV actuator VSV. The exhaust gas bypass valve serves two functions.
One, it bypasses some exhaust gas from #2 turbo through the downpipe of #1 turbo, allowing #2 turbo to spool up a bit. This is the 'prespool' we talk about and it's characterised on dyno sheets, that little dip in power at around 3500rpm
Two, by doing this, it acts as the wastegate for #1 turbo when it's the only one online.
The prespool doesn't allow #2 to reach full operating speed, it merely starts it spinning up so that when the EGCV opens it's not accelerated from standstill, rather a rolling start. The small amount of airflow the prespool creates bypasses the IACV via a one way pressure flap housed in the IACV unit, and enters the main induction flow.
So. If the EGBV isn't opening, #2 doesn't get prespooled, and when the floodgates open it has to a) get up to full operating speed while b) fighting the boost pressure from #1 that is trying to spin it backwards. So it may well take until 5000rpm to come properly on-song!
Also, if this valve isn't opening, you may have no wastegate control on #1 turbo. Now, the real wastegate may still open at a set pressure, 0.8bar, regardless of RPM, but as a bleeder valve on the EGBV VSV increases the max boost pressure of #1 turbo (I've seen as high as 1.0bar on #1 alone, not that I recommend this!) I think perhaps that is also only activated once both turbos are online.
If you have a boost gauge, see what it says #1 turbo is kicking out at WOT in 6th, around 2500rpm upwards. If it's more than 0.7bar or so, it reinforces the theory here.
Did you say that sometimes it works normally and other times it doesn't? You may have to try a horribly long bridging wire from the ECU to that VSV, see if it's a broken connection somewhere...
-Ian
Terminator
18-05-03, 21:38
I am only quoting what Toyota say about the operation of their turbos. Two only comes on line when boost pressure is high enough and the pressure is feed in slowly to smooth the transition from one to two turbos.
It also seems strange no mention is made of specific RPM in the whole turbo section, all the checks relate to pressure and voltages relating to VSV's. I would have thought there would be at least one check that involve watching or measuring operation of voltages or VSVs' at a specify RPM level if it was the controlling factor. AFAIK there is one check that involves RPM but that is at WOT in first above 5600 to check wastegate operation.
If (3800 and 4200) or what ever they are so important why is it not mentioned in the manual? They were often mentioned in magazines by test drivers, but I think these are just likely to be an observation as it is an easy reference point
Ian and Phil
now im really confused , 2 sound arguments but totally different results , if its any help with a switch on the vsv for the EBV and the vsv shut the car drove as normal but with the car locked in 2nd and accelerating and the switch operated at 3500rpm all appeared to be working right , go figure , trouble is the ecu harness is so tight testing any wires is a pain .
John:flame Dev
Matt Harwood
18-05-03, 23:18
Ahh, now I see why you wanted a Fields harness...
Have you got one? Or try posting a wanted ad...
Right, I've found the bit in the manual (EG-217) that I think you are referring to, and i think I've sussed the confusion.
"When the charging pressure reaches a predetermined level, the exhaust bypass valve opens progressively to supply the exhaust gas to the no2 turbocharges causing the no2 turbocharger turbine wheel to start rotating."
That's *prespool*, not *transition*, and yes, it's pressure related as you need manifold pressure to physically start opening the bypass valve. If the manifold pressure isn't there, the valve won't open.
The VSV that controls this valve is open when the valve needs to be shut, and closed when it needs to start opening (this traps the pressure in the actuator and thus opens the valve - the VSV is actually downstream of the valve's actuator) I know you know this already Term, I'm just going into the detail for the benefit of anyone else reading this :)
So, the default state of this VSV is open. It probably shuts at a predetermined pressure level as it also serves to control the boost pressure when only #1 is online, and that can be hit at varying rpms. OK, I may have got this over-simplified when I say 'it prespools at 3500ish rpm" previously :) Prespool begins when manifold pressure reaches 0.7bar (actually probably a bit earlier to allow for atmospheric variances but I don't know the exact figure).
Now, on the same page it says that no1 is only online during 'low engine speed' and both are online at 'high engine speed', so here is your (rather vague!) references to using rpm as the deciding factor as to when to open the floodgates. Also consider, #1 turbo reaches it's peak boost quite quickly, so if it was all pressure related, surely #2 would be brought onstream as soon as #1 hits its maximum boost...?
-Ian
I'm with Phil on this one, i think the pressure signal is the determining factor on when the the EGBV activates and the various other VSV's to bring on the second turbo. I wouldn't be so blinkered to say that this is the ONLY factor as our sequential system is quite complex and there may be various safety parameters programmed into the ecu.
I think this may well be the answer to Johns problems as he has already mentioned having 0v coming back from the MAP sensor when the ignition is on, the TRSM states a value closer to 3v. I think it would be a good idea to bypass his AFC and see if this cures the turbo two coming online problem, but obviously there is the potential for a disaster if the car runs lean at the transition especially if he uses WOT. Hence why i don't want to recommend this for somebody else to do on their car.
:cool:
Martin
after talking to pete betts i tested the map sensor at the plug and it seemed fine , if i disconnect the afc it will over fuel not run lean so maybe this is the next step .
john:flame Dev
also remember ive tried another map off a diff. car, and it was the same , ecu as well .
John:flame Dev
Originally posted by dudersvr
Ian and Phil
now im really confused , 2 sound arguments but totally different results , if its any help with a switch on the vsv for the EBV and the vsv shut the car drove as normal but with the car locked in 2nd and accelerating and the switch operated at 3500rpm all appeared to be working right , go figure , trouble is the ecu harness is so tight testing any wires is a pain .
John:flame Dev
With the VSV shut you'll get the equivalent of a non-VSV'd wastegate. That is, the EBV will start opening as soon as manifold pressure gets to a high enough level. This means the buildup of boost will tail off as the valve starts creeping open. With a VSV working as it should, the bypass valve stays shut until the VSV shuts and suddenly the bypass valve bangs open, immediately controlling boost.
That's why we have the EBV VSV and the wastegate VSV - makes boost buildup faster and more linear. So you will probably be experiencing a slightly laggier response by having the VSV shut all the time. Whether it's noticeable or not is irrelevant to this discussion though :)
As this VSV defaults to "shut", can you verify for me that what you consider shut really is shut? :) I don't know if this valve defaults to shut and needs a voltage applied to open or vica versa! Could paint a different picture depending on which way it operates...
As for testing the ECU, you need pin 38 on terminal E9. It goes straight to the VSV so there are no multiplug connectors you can tap off, unfotunately. Try a map pin or needle edged into the insulation of the wire?
-Ian
Matt Harwood
18-05-03, 23:35
John, as you know, I've got a similar problem to yours, something that Ian just posted;
simplified when I say 'it prespools at 3500ish rpm" previously Prespool begins when manifold pressure reaches 0.7bar (actually probably a bit earlier to allow for atmospheric variances but I don't know the exact figure).
What's your first turbo pressure reaching? - Mine only seems to get to 0.5 bar
Still clutching at straws...
Ian by shut i mean you cant blow thru the pipes , this is how it is with the plug off or ign. on or idleing , it has a 12v feed to it and wire 38 is green/ and is a switched earth , when you look at the pin outs on an ecu diagram there are 2 lots of 38 & 40 i take it the one we want is on the front plug (double with 10mm bolt holding it in ) .
John:flame Dev
Matt mine gets to .8 or .9 but if i kick down that can tale off to .4 or .5 before no2 comes on line , its better going up the box but even then there is a very slight lag at gearchange .
John
Originally posted by Martin F
I'm with Phil on this one, i think the pressure signal is the determining factor on when the the EGBV activates and the various other VSV's to bring on the second turbo. I wouldn't be so blinkered to say that this is the ONLY factor as our sequential system is quite complex and there may be various safety parameters programmed into the ecu.
I think this may well be the answer to Johns problems as he has already mentioned having 0v coming back from the MAP sensor when the ignition is on, the TRSM states a value closer to 3v. I think it would be a good idea to bypass his AFC and see if this cures the turbo two coming online problem, but obviously there is the potential for a disaster if the car runs lean at the transition especially if he uses WOT. Hence why i don't want to recommend this for somebody else to do on their car.
:cool:
See the post I made just before you wrote this one, I'm with you on the EBV being pressure related, but the actual instroduction of #2 is rpm related. As the symptoms seem to match #2 not being prespooled, and #2 wouldn't be prespooled if the EBV didn't open, and this wouldn't open if the ECU didn't see any manifold pressure, we may be on to something! Teamwork :)
I also didn't know that an AFC is involved. This intercepts and alters the MAP signal to the ECU, which involves wiring, specifically the MAP signal! If that's ending up at 0v, we could be onto a winner here. Especially as it's not the MAP ensor or the ECU, so it realy does point to something on the wiring front.
Testing the car without the AFC in the loop would seem like the next step. I would be more concerned running the car as it is rather than without the AFC because if the ECU isn't opening the EBV because it isn't reading any boost, then it's probably not fuelling for any levels of boost either! Could be running dangerously lean...
-Ian
Originally posted by dudersvr
Matt mine gets to .8 or .9 but if i kick down that can tale off to .4 or .5 before no2 comes on line , its better going up the box but even then there is a very slight lag at gearchange .
John
I'm playing catchup with all the posts here as I'm writing effing long ones :p
There you go - #1 is overboosting as it's getting no wastegate control as the ECU can't see any boost and so doesn't open the VSV.
It tails off when #2 is struggling to get up to speed from a standing start, facing nearly 1bar of manifold pressure coming the other way already.
I would forget about the VSV and it's wiring for now and concentrate on checking that the ECU is getting some sort of boost pressure value being sent to it. And I'm increasingly concerned about the fuelling, if the ECU isn't seeing any boost pressure, WTF is it going to be telling the fuel injectors to do?! It's hardly going to be opening all the stops...
-Ian
Ian
i dont think the car is running lean cause it was doing this when leon set it up with his wideband and he even set it up a bit rich to be safe cause of a bit of det (i reckon MINES related ) when this prob is sorted its going back for another tune and fitting of a timing controller , but i need to sort this problem , i think before i go cutting any more wiring i need to fit a fields harness so as i can test voltages to the ecu easier .
John
ok so i need to test voltage at the black/yellow wire (62) at the ecu , but where do i test it as its cut , either side of the incision i suppose ???
John
Originally posted by dudersvr
Martin
after talking to pete betts i tested the map sensor at the plug and it seemed fine , if i disconnect the afc it will over fuel not run lean so maybe this is the next step .
john:flame Dev
Do you mean the plug at the MAP or at the ECU ?
Doh.....didn't think about the fuelling logically. As both Ian and yourself stated it will overfuel with no AFC not under fuel. It's getting a bit late in the day for me for these type of conversations.
Have you monitored the MAP voltage at the ECU when driving along yet ?
Martin see above , lol . i tested the map at the map plug not the ecu .
John
Originally posted by dudersvr
ok so i need to test voltage at the black/yellow wire (62) at the ecu , but where do i test it as its cut , either side of the incision i suppose ???
John
Would be best to test it both sides, the more information the better. But its essential to test it at the ECU side as this will then tell you what the ECU is seeing and in turn you can try to guess\predict what it will do when it see's that type of signal.
Sorry guys forgot to ask what voltages in relation to specific boost reading should i be looking for on the map wire???
John:flame Dev
Originally posted by dudersvr
Martin see above , lol . i tested the map at the map plug not the ecu .
John
Need to test at the ECU, what you've done just tells you that the MAP is working.
What voltage did you get at the MAP ?
Originally posted by dudersvr
Sorry guys forgot to ask what voltages in relation to specific boost reading should i be looking for on the map wire???
John:flame Dev
Take a look here :-
http://www.mkivsupra.net/vbb/showthread.php?s=&threadid=8563&perpage=15&pagenumber=2
I have no specific pressure vs voltage data for the MAP sensor but the voltage can only go one of two ways as the pressure increases.
:D
I believe it was 2-3volts as the engine was revving , it was about what pete said to look for .Thanks for the help guys just dont desert me know as we seem to be getting somewhere but right now its a bit late to talk this much invloved tech stuff , if i get a chance tommorrow i will try to test the volts down at the ecu on wire 62 and report back , thanks dudes.
John:flame Dev
didnt get a chance to test today but did notice one thing if i let the revs rise in 2nd then just before 4000 really nail the throttle ive got mega boost by 4500rpm , this worked every time , any thoughts
John:thumbs:
THOR Racing
20-05-03, 08:16
Is this a standard ECU? or a replacement? (like Mines, AEM etc)
Did it ever work properly?
How sudden was the change to it not working? Gradual or abrupt.
Maybe I've missed some history here. It's like the speed and load calculations inside the ECU etc are mucked up. (probably due to some sensor failure)
Ummm... getting more diffifult as time goes on.
Pete
Matt Harwood
20-05-03, 08:47
Originally posted by dudersvr
didnt get a chance to test today but did notice one thing if i let the revs rise in 2nd then just before 4000 really nail the throttle ive got mega boost by 4500rpm , this worked every time , any thoughts
John:thumbs:
Sounding even more similar to my problem now...
No.2 rarely come's in 1st gear, but after that, it's ok, albeit not coming in until 4500rpm. Or, if changing down a couple of gears, no.2 won't make an appearence until either I back off and gun it again, or let the revs build up and change up... Odd :conf:
Not that this helps you...
Right guys , the next stage ... tested the map wire at ecu and it is giving out the correct voltage , about 1.2 on no throttle in drive and then rising as manifold pressure rises , i think it got up to about 4volts on full boost , but the more i drive it the more i realise that if i 'punch' the throttle to the floor i can make the turbos come on full boost by 4500rpm , could this be a throttle or rpm issue now as we know the map is giving the ecu its signal .
Pete ,its a MINES ecu, the car has allways been like this since i got it on the road but like i said it was the same with another ecu/map/vsv's , i believe the revs and throttle position wires are fine TO the ecu as they seem to tally up on the display on my s-afc which i unplugged and ran the car with it off but the map wire joined back up to make a circuit .
Ideas guys if any of you want to test it at bracknell thats cool , if leon hadnt mentioned the problem i would just think they are a slightly laggy car so prehaps some of you can give me an opinion .
John:flame Dev
MONKEYmark
20-05-03, 20:56
you dont think you have the laggy UK turbos fitted do you?
just a thought.when you drive and hold revs at 3000rpm then floor car there is a slight pause then second turbos should kick in about 4000revs with a big kick.
mine seems to go ok on first turbos then second turbo comes online with loads more pull its mad.
do you think it could be anything to do with the big intercooler you have on car, sure there has been threads about you can have too big an intercooler. and dont you pick up a bit of lag on fmic too.
hope you get it sorted.
Ooh! That sounds familiar............ I had a similar problem when my HKS SLD played up.
The OD off light was flashing too ........
Probably bollocks , but kinda backs up Petes theory on the speed / load calc thang?
Do you have a seperate De-limiter ? Or is it sorted by the Mines?
If it is de-limited by the Mines ECU , you can probably ignore the above:innocent:
De-limited by the Mines :( :( :(
Still runs sub 13 second 1/4 miles on the Blitz power meter though :p
John:flame Dev
vBulletin® v3.7.3, Copyright ©2000-2008, Jelsoft Enterprises Ltd.