Guest Roger NE Posted September 5, 2013 Share Posted September 5, 2013 (edited) Can anyone explain to me how the Mk4 Supra increases the engine revs slightly when you are parked and turn the steering wheel? (the Power Steering Pump puts extra load on the engine, so there's an "Idle-Up" system to increase the tickover revs slightly when you do this) I have read through the TSRM, but can't find an explanation. The reason I'm asking is, as some of you may know, I'm putting a 2JZ-GE in my Mk3 Supra . . . . complete with ECU and Mk4 PAS pump (but Mk3 Steering Rack) The idle-up system on the Mk3 is very simple - there's an air hose that goes via a valve in the PAS Pump - when it opens it just by-passes the Throttle Flap, thereby increasing the tickover slightly. But obviously this won't work when I fit the Mk4 Engine & PAS Pump. All the write-ups (from the USA) I've seen simply say the idle-up won't work . . . . but I'm wondering if there's something I can do? Hope somebody technical can help ! Edited September 5, 2013 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
Iky Posted September 5, 2013 Share Posted September 5, 2013 Can anyone explain to me how the Mk4 Supra increases the engine revs slightly when you are parked and turn the steering wheel? (the Power Steering Pump puts extra load on the engine, so there's an "Idle-Up" system to increase the tickover revs slightly when you do this) I have read through the TSRM, but can't find an explanation. The reason I'm asking is, as some of you may know, I'm putting a 2JZ-GE in my Mk3 Supra . . . . complete with ECU and Mk4 PAS pump (but Mk3 Steering Rack) The idle-up system on the Mk3 is very simple - there's an air hose that goes via a valve in the PAS Pump - when it opens it just by-passes the Throttle Flap, thereby increasing the tickover slightly. But obviously this won't work when I fit the Mk4 PAS Pump. All the write-ups (from the USA) I've seen simply say the idle-up won't work . . . . but I'm wondering if there's something I can do? Hope somebody technical can help ! I thought the Mkiv works the same way. Theres a valve which opens up and lets air bypass the t.b Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted September 5, 2013 Share Posted September 5, 2013 (edited) OK . . . then where is that Valve? And as it's NOT in the PAS pump (like in the Mk3), what actually tells it to open? Edited September 5, 2013 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
hodge Posted September 5, 2013 Share Posted September 5, 2013 It's a black plastic valve with 2 pipes coming from it. It's screwed into the banjo that is attached to the side of the PAS pump. 1 pipe goes to the bottom of the TB (negative vacuum), and 1 pipe to the intake manifold (positive vacuum). Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted September 5, 2013 Share Posted September 5, 2013 (edited) Oh right . . . . so it gets its "command" to open from the PAS Pump, like on the Mk3 then? And this valve, together with the vacuum lines, I'm presuming will already be on the engine I'm getting . . . . So I see no reason why the Idle Up won't work, even though I obviously have a Mk3 Steering Rack. Wonder why the guys in the USA who've fitted 2JZ engines in their Mk3 Supras say the Idle Up won't work, and just to blank it off? (maybe it's because they usually fit 2JZs from Lexus cars or something?) Many thanks for your help chaps Edited September 5, 2013 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
hodge Posted September 5, 2013 Share Posted September 5, 2013 Mines blocked off anyway. The car shouldn't cut out at all it just stops you revs dropping. Block it off and be done with it. It's only clutter after all. Quote Link to comment Share on other sites More sharing options...
straightsix Posted September 5, 2013 Share Posted September 5, 2013 The idle up should work on a 2JZ fitted to any car as the vacuum lines run into the stock throttle body and air intake (although you might have to modify a fitting if you're retaining the Mk3 intake pipework. When I fitted the V8 in my car, there were no issues with the 1UZ power steering valve. Looking on the net, most Toyota/Lexus models operate on the same design with the same valve across several applications. Quote Link to comment Share on other sites More sharing options...
Rich.2211 Posted September 5, 2013 Share Posted September 5, 2013 I did the same as Hodge and got rid of my idle up for the PAS and noticed absolutely zero difference. Quote Link to comment Share on other sites More sharing options...
hodge Posted September 5, 2013 Share Posted September 5, 2013 I did the same as Hodge and got rid of my idle up for the PAS and noticed absolutely zero difference. I think your RPM drops 200 or so on full lock, no other issues. Quote Link to comment Share on other sites More sharing options...
David P Posted September 5, 2013 Share Posted September 5, 2013 It's very handy for parallel parking maneuvers, I've changed many things on mine, yet idle-up gets a thumbs-up from me. Quote Link to comment Share on other sites More sharing options...
David P Posted September 5, 2013 Share Posted September 5, 2013 I did the same as Hodge and got rid of my idle up for the PAS and noticed absolutely zero difference. That means it wasn't working. Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted September 6, 2013 Share Posted September 6, 2013 It's very handy for parallel parking maneuversI agree, although it's not essential, it's worth keeping . . . . and I can see no benefit in removing it ! When I turn my Aircon on, the idle revs increase even more (from about 750 to 1200) . . . I've no idea how THAT happens . . . and I suspect getting THAT to work with the 2JZ engine might be harder! Quote Link to comment Share on other sites More sharing options...
straightsix Posted September 6, 2013 Share Posted September 6, 2013 Probably not as hard as you think.... The aircon system on a JZA80 Supra relies on a signal to the engine ECU when the aircon compressor engages (again, the same system is used on a vast range of Toyota/Lexus models) You should be able to trace this properly when you start your wiring Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted September 6, 2013 Share Posted September 6, 2013 (edited) Oh it may be OK then . . . . as you say, the fact that it's Toyota means they tend to do things in a similar way, even though it's a later model. It's certainly an easy thing to just try dabbing a wire on to see if the revs increase! I think I was put off about this because, as I said before, the US websites said the Idle Up wouldn't work! Many thanks I do have lots of notes about all the connector wiring and cable color codes (most cables are even the same colour on the Mk3 & Mk4) . . . and plan to fit Mk4 Body connectors on my existing cables that will then plug straight into the 2JZ Engine Loom . . . it's just that SOME of the notes I have are a bit vague or unclear exactly what they do ! (when I've got it all working I'm going to do a really clear write-up, as none seem to exist!) Edited September 6, 2013 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
straightsix Posted September 6, 2013 Share Posted September 6, 2013 (edited) It shouldn't matter that you have an earlier car - you'll be using the mkiv ECU with a 2JZ. You will need to run a wire from the air con circuit to the relevant pin on the ECU. It will probably make sense more when you have it all laid out in front of you I would have thought you'll be cutting your chassis wiring plugs (the orange and white ones on the 2JZ loom) off completely and soldering in your Mk3 chassis plugs? Obviously the grey plugs connecting to the ECU will be left well alone.... Edited September 6, 2013 by straightsix (see edit history) Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted September 7, 2013 Share Posted September 7, 2013 (edited) I would have thought you'll be cutting your chassis wiring plugs (the orange and white ones on the 2JZ loom) off completely and soldering in your Mk3 chassis plugs? Obviously the grey plugs connecting to the ECU will be left well alone.... That was my ORIGINAL plan . . . . But then I thought that I (or anyone else) would never want to put another 7M in the car (when 2JZs are available and so much better) So, calling the ones on the Engine Loom PLUGS and the ones on the body they plug into SOCKETS, I thought it would be better to do it the other way round, cut off my Mk3 Body Sockets that have to connect with the 5 Engine Loom Plugs and replace them with the Mk4 Sockets. (I have a source from a scrapper) Then if ever I have to replace the engine again with another 2JZ it can be done with the Engine loom left on the engine (which is far easier of course) Edited September 7, 2013 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
straightsix Posted September 7, 2013 Share Posted September 7, 2013 Ah! I see.... A plan so cunning you could pin a tail on it and call it a weasel Quote Link to comment Share on other sites More sharing options...
Ian C Posted September 7, 2013 Share Posted September 7, 2013 Mines blocked off anyway. The car shouldn't cut out at all it just stops you revs dropping. Block it off and be done with it. It's only clutter after all. Removing stuff because you want as empty an engine bay as possible for show-and-shine reasons is one thing, but advising normal people to remove useful systems for no reason other than it's "clutter" isn't really on. It's not clutter, it's very useful, deleting it will affect aspects of driveability. Much like fannying around hiding wires and putting fuse boxes the wrong way up in the path of rainwater will one day affect driveability as well. Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted September 7, 2013 Share Posted September 7, 2013 (edited) I agree . . . . and I certainly want to try and keep all the Stock features . . . even though some of them have needed a bit of sussing out So even though I'm replacing my 7M-GE with a 2JZ-GE it looks like I should still have Progressive PAS with Idle Up, Aircon with Idle Up, and still have a working Oil Pressure gauge (crazy to me that Toyota didn't include one on the Mk 4 Supras!) And to be honest, the two N/A engines look SO similar (both having Distributors in the same place, those Y-pipes after the Throttle body, etc) the engine bay should still look quite original The one thing I WOULD have removed is the EGR System (removed it all on my 7M) . . . but I gather the Jap market 2JZ-GE engines don't have it anyway! Thanks once again for all the help and advice guys . . . I'll let you know how the Transplant goes (still waiting for my Engine to arrive, but I've been told it should be this week!) Edited September 7, 2013 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
straightsix Posted September 7, 2013 Share Posted September 7, 2013 Nope - no EGR system on the 2JZGE Quote Link to comment Share on other sites More sharing options...
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