This has been an ongoing discussion topic between me and DtheB and Prof for quite a while, but I thought I\'d put it to the board and see what people say.
Basically my car feels dead off boost, very little power at all (and pulling away is annoying, might need to bleed my clutch though - it\'s not been done since I got the car, partially the welded diff though).
She has:
R-Magic ECU
2.5" downpipe, decatted, straight through to the backboxes.
HKS mushroom filter
When she was dyno\'d (with a 3" cat-back exhaust at the time, which was stupidly loud, but feels like it made a slight power difference) she mad 222bhp at about 6900rpm. 170lb/ft torque at 6300rpm. Very smooth graph though but the graph only shows from 3500-7500rpm . (I can scan it in if people want to see it)
From what I\'ve gathered from others, this is definitely under what it should be, and the lack of torque has always made me wonder. She quite literally won\'t even spin the rear wheels up in the wet until about 5000rpm, and not at all in the dry!
Not really done a lot so far, but Prof told me how to run an error check, and it would appear that my error detection gubbins isn\'t working - connecting a bulb up and the bulb just stays on, no flashing, nothing, and only gives a 6v level of light, not 12v.
Replaced the OMP as the ond one doesn\'t appear to have been working correctly.
Anyone got idea\'s or suggestions? Any q\'s you want me to check? I have time and mechanical knowledge, but am crap with electrics. Bear this in mind!
Thanks
(of course, if everyones is dead offboost, then tell me so.)
(lastly, saw this on Wiki the other day, and thought \'naaaah, that can\'t be it!\' It\'s not something that can be closed is it? " The Turbo 2 uses a turbo charger with a twin scroll design. Engineered to cancel the turbo lag at low engine speeds is the smaller primary chamber.")
What turbo actuator do you have? An uprated one, or a 20+ year old tired actuator? Also, what boost controller do you have and what BOV do you have? I found that I had a minor air leak and the BOV slightly leaked meaning that not all the boost from the turbo actually got to the engine lol
The turbo (as in the series 4) had an extra exhaust flap that blocked off part of the exhaust meaning that it was channeled to the turbo more, the series 5 turbo IIs don\'t :)
Actuator - standard old thing. Prof has told me that I cannot just change the spring, so I\'m on the lookout for an uprated actuator unit. Unless someone (you) has one going because they are putting an external wastegate on? :p
No boost controller, I have a manual one to plumb in sometime though. BOV - whatever the standard thing is, gives a small tshhh when you let off. Engine was totally standard when I got it!
Also have Magnecor KV85 leads fitted btw.
Yeah the OEM ones are fixed, I did have a brand new one I sold about a year ago after my turbo got rebuilt, its not running Prof\'s HKS actuator now.
Does the boost stay liner and level and what boost pressure are you running it at? I have found that the OEM recircs leak after a certain level
Yay for leads lol
Do you have an OEM top mount then? I might suggest going round and tightening up all the clips and hoses on the intake, I did that on mine and found I had a mini leak somewhere, made a big difference to power.
Oh yeah, dyno sheet says 0.6 bar boost max too btw. The boost went from 0.1bar at 3500 to max at 0.6bar at 5700, and back down to 0.4bar at 7500.
It\'s not running it? Does that mean you have it for sale?
Yeah, OEM top mount. Those clips are definitely tight, I\'ve had it on and off a couple of times recently, and nothings changed.
Sounds like due to the better intake and exhaust the wastegate actuator can\'t cope with the extra gas flow and is letting the wastegate open meaning a loss of boost. Mine used to do that, it would boost up really well, then tail off as the OEM wastegate couldn\'t keep the wastegate closed against the extra exhaust gasses at higher RPM.
Ive sold it now, but I would suggest checking out an uprated actuator, its a shame it has a fixed arm as it could have been adjusted out.
Alternativly you could wait a bit and buy my rebuilt turbo off me with its full 360 degree bearings, decoke, ported wastegate and HKS actuator lol
0.1 at 3500..... thats gotta be the spring surely!!
Quote from: dthebuk;7712790.1 at 3500..... thats gotta be the spring surely!!
Depends if you are on WOT, but yeah it does seem like a tired actuator
A couple of things I keep seeing on the rx7club site:
TPS - it get\'s talked about a lot - but if you adjust your throttle cable / throttle assembly in any way - then the TPS will probably need adjusting to avoid a \'deadspot\' - usually around 1500 RPM where it will hunt up and down - proper adjustment of the TPS should almost completely eliminate this hunting - which is caused by the ECU alternately cutting and then re adding fuel because it get\'s confused. There is also some relationship between the TPS setting and the ECU you\'re running - I set mine on the stock and then found it was out on the chipped ECU.
CAS sensor - this is the main timing pickup for the Turbo rotary - it has a pair of geared wheels - one with 2 teeth, and one with 24, and it has 2 pickup coils. On the RX7club site - people have had the following issues:
- Bad/missing teeth - usually on the 24 tooth wheel
- Pickup coils too far away from the cogs, resulting in missed ignition events at higher rpm
- Bad/insulation cracked wiring for the CAS sensor - causing shorts whilst driving - again resulting in screwed up ignition timing when you hit a bump in the road, or in Pete Taylors case - a car that would not even start
The symptoms are loss of power at the top end, loss of power during acceleration, hickup/dead spots in the acceleration
I\'d also suggest doing the following things too:
- Change diff and gearbox oil, if they\'ve not been changed in a while
- Oil change - should be doing this every 3000 miles
- Spark plug change - plugs get a little \'lazy\' after a year or so - I always get a marked improvement after changing - usually I do it for the MOT - so once every year
- Check alternator is pushing out the correct voltage when engine running / under load - loose or too tight a belt can cause some weird behavior - lose belt can cause a really bad power loss when accelerating including backfiring, spluttering - goes as soon as you let off the gas
And our old favourite - the fuel system:
- Fuel pump
- Fuel filter (there\'s the low pressure one on the sock on the pump, and the high pressure one on the bulkhead down the bottom on the passenger side - supposed to change this every 4 years or so - can make a difference if it\'s been on a while
- Rewire of the fuel pump - the stock wiring is attrocious - voltages at the pump when you short the yellow connector (near drivers shock tower - makes the pump run full voltage for testing) can be as low as 9-10 volts - should be 12\'s or better when engine running, and 11-12 when engine off and pump running (yellow connector shorted, ignition key to 2nd position)
I\'ve had a lot of these issues in the +100,000 miles I\'ve put on the car -and still get some (TPS) now.
Quote from: m1tch;771281Depends if you are on WOT, but yeah it does seem like a tired actuator
surely you would be on a dyno run?
Do you have an AFR gauage installed? Before i replaced all IC silicone joint and clips the AFR goes quite lean to 16,17 in low rev due to air leak and an obvious lack of power as well. hope it helps :)
Quote from: m1tch;771278Sounds like due to the better intake and exhaust the wastegate actuator can\'t cope with the extra gas flow and is letting the wastegate open meaning a loss of boost. Mine used to do that, it would boost up really well, then tail off as the OEM wastegate couldn\'t keep the wastegate closed against the extra exhaust gasses at higher RPM.
Surely that only affects it at the top end, WOT and at the top of rev range, not below 3500rpm? (which is what I am disliking)
Uprated actuators are hard to come across :(
Prof - I have had my car \'hunt\' like that at 1500, after 1 min or so from starting and sat in traffic, before it was properly warm. Depressing the clutch makes it stop briefly, then when it starts again, letting the clutch off and it stops again briefly. Very odd.
How do I rectify? How do I adjust the TPS \'properly\'? (Since I don\'t know what I\'m doing)
Where do I find the CAS sensor on these? I\'ll get checking the car later.
Since I bought it I\'ve also (from your list):
Replaced the diff oil
Changed engine oil roughly every 3000 miles
Changed spark plugs (when I got it, now over 1 year ago)
Changed high pressure fuel filter for a much larger 300ZX one
I guess I need to add the other items to that above list by doing them asap?
Yiug - I don\'t have an AFR gauge, got a boost gauge. (anyone got an AFR gauge going cheap?)
That vacuum leak issue will affect idle and low revs, but once you pick up rpm\'s it will just leak a bit of boost (depending on how big the leak is of course)
I found that if one of the bolts on the back of the turbo compressor comes off (the ones that are removed to allow the actuator bracket to fit on), then there is an air leak straight into the compressor housing - yep - sounds daft - but there it is - it also means you have to be mega careful with replacing these bolts - as they obviously can intrude into the compressor and make contact with the blades if too long.
Regarding TPS - you\'ll hear lots of different ideas about adjusting this - the adjuster is behind the alternator - at the bottom of the throttle mechanism - look for the 2 pots - dark blue grey things with plungers - the outer most one is in contact with the adjustment you make. You need to warm the car up fully - take it for a run for 10 mins or so, then shut the car (you may need to take the intercooler off for the next step) Locate the 6 way connector that plugs into the 2 TPS sensors, you want to measure the wiper to ground contacts (which I believe are the 2 wires on one edge of the 3 pairs of contacts) - you\'re looking for the wires coming from the outer most sensor. Then adjust the wiper until it reads 1Kohm on a multimeter, by adjusting that screw on the bottom of the mechanism. If it\'s taken you a long time to set this, it will be slightly out - so you may have to repeat this excersize.
CAS sensor - looking at the front of the engie - this is to the right and lower than the alternator - it\'s a big round thing about 3-4" in diameter (usually black). It\'s where the timing is set on the rotary - it\'s locked by a single 10mm nut on the bracket - loosen that and you can rotate the CAS back and forward - only do that if you\'ve got a timing gun and a warm engine idling below 1000rpm. Check the wires coming out of the sensor and the wires on the loom - if the insulation has got old and hard it can crack off causing shorting.
Sounds to me like the actuator arm has come off the gate flap. Same symptoms as mine had the other week. 0.6 bar of boost all day long and laggy when off boost. Mine is great again now.
Thats a lot to read ( or skip over ;) )
Humm i would expect more boost that that to be honest with the exhaust - i would have of expected around .9bar
and the torque .. that seems WAY off to be honest :(
Does the ecu have a FCD fitted ( i assume it has or you would hit fuel cut ) - but prob not at those levels of boost ?
i used to run that exact exhuast and put out more than stock boost. No idea how much though
Hence me thinking the actuator arm has popped off :)
OKay then Tiddles, want to run through checking the actuator arm, and potentially putting it back on? (if possible) photos pointing out where to do whatever are good too :p
Grinder, yes it does. It certainly should do!
Prof - have you got a photo or diagram of the bolts you mean? If I can get there I\'ll certainly check them! Any photo\'s/diagram of adjusting the TPS too?
I\'ll leave the CAS sensor for now!
Thanks guys, lots of input from you all, it\'s really appreciated!
If I can get a photo of it I will but it\'s a bit hard to see down there. Basically from the drivers side of the engine bay. look down under the brake master cylinder. You will see the turbo right at the bottom of the engine. If you\'ve still got the air pump etc this will be even harder to spot. With the exhaust down pipe on the left of the turbo and the actuator on the right. The actuator has shaft coming out of it that runs under the turbo heat shield towards the back of the car. This the actuator arm that came off on mine and on other peoples also. If you can get your hand in to feel if it moves from side to side that will indicate if it has come off or not. If it moves from side to side then it has popped off.
I\'ll post up a few pics for you :)
The first shows a turbo off the car - I\'ve labelled the bits that go iffy.
The next set of photos show the TPS - from above, showing the one on the outer side which is the narrow TPS - the one youre adjusting - you can also see the adjustment screw at the bottom - when adjusting this be careful not to push it as it will skew the setting.
The next shot shows the wiring - and a closeup of the connector showing the 2 wires that need adjusting (green and black). All these photo\'s were with intercooler removed.
It appears we have our answer! The actuator arm wobbles back and forth!
Will get onto stripping this down and sorting it tomorrow - sounds like a full day event really, as I\'ll need to strip a LOT of things out of the way won\'t I?
Fuel pump rewire etc will be on the cards for the weekend after next (since next weekend is Cornbury festival, which I\'m working at).
Now Prof, if you\'re able to come up with photos/labels/diagram of how to plumb in a manual boost controller, then I can do that too, so that when the arm is back on (and hopefully everything works properly) I\'ll have a modicum of control!
Might not sell the car if I get this fixed, as it might well drive like I want it to, and I\'ll be happy. I can\'t imagine the MPG improving though :p
Yay for actuator problem lol its why I said that it was silly it wasn\'t adjustable, if it was you could \'dial out\' the wobble lol
You should be able to get to it from underneeth? There is a tiny circlip on the flapper arm - either don\'t lose it or get a replacement one. Although if you are going to plumb in a MBC then its probably easier via the engine bay, it should be easy to get to the turbo, you just need to remove the air box (few bolts) and then there is the huge S shaped OEM intake hose which when you get that out the way you will have lots of space in the engine bay lol
Splendid :) The easiest way to fix it I found was from underneath. But you have to loosen the turbo heatshield from the top first. Think there was just one nut (M10 socket) from the top the then one from underneath. The heatshield should then split in two and you have to find a way of getting it far enough out of the way to get to the actuator arm. It can be a PITA if I am honest. So much so I never put mine back on when it came off! I did however shear the bolt that you loosen from underneath so that contributed to the decision. I will put it back on again soon when I get chance. If you need any more help just ask.
Ade
Yeah don\'t sell man you love your FC! Good luck and Hope you sort it out quickly!
Heatshield removal - there are 2 10mm bolts that secure it from the top, and one on the back facing forward towards the front of the car - securing the heatshield to the exhaust manifold - remove those 3 bolts, and if you want an easy life - take the O2 sensor off (22mm spanner) - then you can get the heashield off easily and as others have said - access to the circlip :):)
Don\'t sell it - you\'ll miss it too much !
I\'ll see if I can dig out destructions for boost controller.
I had the selling thoughts quite a few times before as well, but when the rotary is properly up and running, the joy it gives is amazing!!!!! even better than driving in an Italian super car with the stupid paddle shift IMO :)
Im never selling my FC, no other car can get almost 900bhp out of a 1.3 litre engine lol more air + more fuel = more power, don\'t want to have to shell out on expensive forged internals!
4.4l of German V8 was really beginning to tempt me, they have SO much grunt and torque and STILL give better fuel economy than the RX7!
BUT me and my mate got the actuator arm back on! What a pig of a job (especially when there\'s lots of oil on the bottom of your gearbox - you end up FILTHY!) but it\'s now done.
WHAT A DIFFERENCE!
BUT, new problem. It won\'t boost past 0.5 bar :( Feels like a mild fuel cut (no big jerk, just lots of small ones, it refusing to go further) Nice that 0.5 bar is being hit just after 3000rpm though!
So, idea\'s? I\'m running an R-magic ECU I got from Liam,who imported it from Jap-land for me. Why would it be cutting? I\'m not pushing it, because fuel cut lots = engine damage.
Good news and bad news all rolled into one aye! I guess its time to start trying the other things mentioned earlier in the thread. Start at the cheapest and work upwards is my advice. Check all connections for boost/vac leaks, fuel filter, plugs etc next.
Without a boost controller its just going to keep it at stock boost, so 0.5-0.6 bar.
Isn\'t a boost controller to limit the amount of boost, without one it\'ll just boost to the maximum it can?
Quote from: papercutout;771773Isn\'t a boost controller to limit the amount of boost, without one it\'ll just boost to the maximum it can?
There is an OEM solinoid that measures the boost, the wastegate spring is set to about 5psi, the OEM boost solinoid then bleeds off a set amount of air/pressure so that the wastegate stays closed for longer (as in the boost might be 10psi, but the actuator is only \'seeing\' 5psi. My AVC-R boost controller has its own solinoid to bleed of the correct amount of air electronically, the manual boost controllers do this by bleeding it off using a needle valve. The car will boost up due to boost creap if its free flowing but thats not something that can be controlled, you need to control the amount of boost getting to the wastegate to be able to increase boost. The turbo on the FC is a wastegate turbo, its not a VNT turbo like on my Volvo that is ECU controlled.
Ok - put a picture up of a stock Turbo and it\'s plumbing.
The stock system has a spring that gives 5 psi with stock intake and exhaust - assuming you plumbed the actuator into the output of the compressor. What Mazda do to get a bit more is to bleed off some of that air through a solenoid which results in just over 8 psi.
OK - so now assume that you\'ve not got Mazda\'s funky solenoid but just the straight connection from compressor to actuator and you put a freer flowing exhaust and intake on - the boost will now be much higher - probably about 12 psi unchecked - and you\'ll get boost creep. The stock solenoid can\'t really understand what\'s happening now - so the ECU will try and do stupid things - unless you\'ve got a chipped one which should handle the unexpected extra boost.
HOWEVER - you\'re best bet is to take the stock boost solenoid off and block the pipe that was feeding it so that you\'ve got the simpler plumbing.
Then you have a choice of how to put a boost controller in:
Manual boost controller - pill type - this goes in series with the pipe from compressor to actuator - this type doesn\'t bleed off air.
Manual boost controller - bleed type - this would go where the stock boost solenoid plumbed into
Electronic boost controller - follow the instructions from the manufacturer - but basically these have a 2 way valve that allows compressor boost to go to actuator or be blocked off, and the actuator to see the compressor or vent to air. The valve operates several times a second as the boost controller works out the desired amount of boost to operate the actuator.
NOW FOR THE CAVEATS:
A boost controller cannot lower the standard spring boost - that\'s the lower limit of control.
A boost controller cannot stop boost creep either - boost creep is the inability of the wastegate to lose the extra boost and thus higher revs / higher gears you see more and more boost - \'creep\'. The only solution is a bigger wastegate - basically that means porting the stock one
Porting the wastegate increases the area that exhaust gases are acting on the flapper - so now the natural boost will be lower because the actuator can\'t keep the flapper shut because of the extra exhaust pressure - so you\'ve controlled boost creep but lost a little boost. The up side is you can now control a wider range of boost - by replacing the actuator with an aftermarket one with better spring.
Prof, this is the MBC I have, what type is it? :
http://www.driftworks.com/shop/dw-manual-boost-control-valve.html
As I said, I have an R-magic ECU, which is why I\'ve been surprised, surely it should have just upped the fuel to cope? It\'s meant to cope upto 0.9 bar. I\'ve just dropped Liam a message so he can check the specs for me again)
So you are telling me to:
take off the stock boost solenoid
fit MBC
(check ECU too)
Those ones on DW are ball and spring - so they are a restrictor type (pill type) so they go in line. Basically one barb of the MBC goes to the outlet on the compressor, the other to the actuator - simple as that.
By adjusting the MBC you are moving the sprung ball to allow air to pass - the amount is adjusted to suit your desired boot. Imagine it like a variable resistor for air. By restricing the amount of boost \'seen\' by the actuator, the engine must create more boost to operate the actuator - hence boost control :)
These things are very reliable.
So just cut the t-pipe in the middle, plumb MBC in, and remove/block off stock solenoid thingummyjig?
Quote from: papercutout;771920So just cut the t-pipe in the middle, plumb MBC in, and remove/block off stock solenoid thingummyjig?
I\'d be tempted to take the T pipe off altogether - and connect two thick walled silicon hoses one on the actuator and one on the compressour outlet and take the 2 free ends onto your MBC - ideally you want to keep the pipework short too.
hi hi, i think im ment to be here.
the r-magic ecu was for 3" exhaust, aftermarket intake and allows higher boost. think was stock ic. only some re amemiya ones (type a i think it was) was for larger ic
sorry if this is bit random. im tired.. its the weekend x.x
maybe actuator arm not tightened up properly?
as everyone else check vac lines etc.
to check the fuel cut on the ecu i guess can plug in a fcd into the stock map sensor and see if you still have the \'mild fuel cut\'
i just sold one but not sure if i have a spare, need to have a poke around through all my rubbish.
Okay ladies and gents, lets see how things go shall we?
I nicked the \'long\' pipe that ran from the stock solenoid to the metal tubing round the turbo, cut it in half, and put the MBC in the middle (this sounds really easy, it wasn\'t at all - got several new cuts on my hands!) then used another piece of pipe with a big bolt in to block off the stock solenoid pipe. See photos.
To get to it all I had to remove the air pump. I didn\'t have this \'connected\' anyway (I\'d removed the belt) so it wasn\'t running. But I still have a big pipe open, the one that goes from the pump to the rest of the air pump gubbins. I plan on getting block off plates sometime, but will this affect things at all? Draw warm air into the engine etc? (I know with the pump disconnected it shouldn\'t, but no harm in asking).
What do people think? Everything OK? I know the MBC is in an awkward place to adjust, but I had to use what I had, and I had very little!
Thanks
(http://i765.photobucket.com/albums/xx295/3d_cutout/My%20RX7/DSC00104.jpg)
(http://i765.photobucket.com/albums/xx295/3d_cutout/My%20RX7/DSC00105.jpg)
Okay, update (questions from the last post are still 100% relevant though!)
No difference today! So once I got home this evening I have wound the boost controller a lot further out, so it is active at a much lower boost level.
Lastly (for now!) I am getting lots of turbo whistle on boost, is it that it\'s finally working properly, or is it on it\'s way out? Sounds pretty awesome really tbh :D
That wistling could be a vac leak of course - :D
Okay, then please can you drop me a pic of where to look, and what to look at? I\'m still used to N/A engines, so you have to show me everything once turbo wise, then I\'ll get it and not ask again!
Anything else regarding my other q\'s? :D (I know, I know, I ask lots of questions, but please excuse my ignorance)
Wait till I get mine.... Prof\'s going to be hiding behid his keyboard :D
Glad your starting to get to the bottom of the problem (hopefully)
I also get a lot of turbo whistle. I just thought it was gonna take off! Maybe it\'s cause the wastegate is still being opened because of the boost pressure. The actuator is trying to hold it back but can\'t after 0.5-0.6 bar.
Ben - if I keep it up then I\'ll probably be able to answer them for you when you get your car, and we can give Prof a rest!
It starts about 2600/2700rpm, but only when I\'m driving, there\'s no whistle if you rev it with the car stationary.
Yeah but you don\'t make boost when stationary (well not proper boost, yo!). Like I say I put it down to the wastegate opening slightly when on boost causing the whistle. Is your wastegate ported (Oo err!)? I did mine a while back.
Okay, my fiddling last night limited me to 0.4 bar boost today, no hesitation or cutting, boosts cleanly. Obviously feels a little strangled, because it\'d happily do more, but probably as fast as it was with the actuator arm not connected before, BUT with much more low down power now too.
What vac pipes shall I inspect?
Is my block-off of the stock solenoid piping OK? And now this is blocked off and the MBC fitted, why am I still getting boost cutting with my aftermarket ECU fitted?
Is that air pump pipe (can just about see it in the top pic) being open like that OK?
My in-line fuel filter should be fine - it\'s a 300ZX Z32 item, bigger and flows better than the stock RX7 one.
Just checked the in-take sock filter, and it\'s not perfect, but it\'s pretty clean really, certainly OK to flow enough fuel for more boost!
Will organise a fuel pump rewire now.
I would not have thought that the air pump hose being free would cause an issue - it should be \'valved\' off by and large, but you might as well go the whole hog, get the block off plates and remove the ACV and split air pipe too.
As for vac leaks - they can occur at gasket joins with the manifold, or from un attaced pipes/hoses that carry vacuum / boost.
If you get a whistle that increases as you rev, it does sound like a boost/vac leak.
I use carb cleaner to find mine, after checking for obvious ones first (hose off, obvious leak somewhere), but you need to be careful spraying flammable stuff around the engine bay.