TII lag/response - mine vs other people?

[papercutout]

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.")

[m1tch]

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

[papercutout]

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.

[m1tch]

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.

[papercutout]

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.

[m1tch]

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

[dthebuk]

0.1 at 3500..... thats gotta be the spring surely!!

[m1tch]

0.1 at 3500..... thats gotta be the spring surely!!

Depends if you are on WOT, but yeah it does seem like a tired actuator

[Prof]

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.

[dthebuk]

Depends if you are on WOT, but yeah it does seem like a tired actuator

surely you would be on a dyno run?

[yiug412]

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

[papercutout]

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.

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?)

[Prof]

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.

[TiddlesRX7]

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.

[grinder]

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 ?