If the car is swinging all over the road as you suggest, then it might be related to the Hicas Bonded Bush in the rear steering mechanism. If this bush wears out/fails, it will allow the rear of the car to wander a small amount & this could be what is happening. Just my 2 cents worth. Cheers Kerry
Plenum bolt snapped off after only 3 small turns. Felt like no grab then "POP". The bolt was slightly warped (thats enough when dealing with plenum bolts) and was not noticeable unless you REALLY inspected it. Bolt must have come out of a heat damaged motor because it was EXTREMELY weakened. We used an extractor (eazy-out) which snapped off in the bolt. Impossible to drill again, we tried for a whole day and got maybe a few mill into it because of the hardened eazy-out. It may be just a hunk of alloy but unless someone has ever attempted to install a lower plenum or remove a lower plenum then they have no idea. It is connected to a pulley wheel. To get out the lower plenum you have to . . - remove the timing belt - remove the pulleys on the left of the motor. - remove the rear section of the timing cover. I was making an example pertaining to his exact situation. I was saying that without the turbos working, all he has is a "naturally aspired" engine (i.e. not force induced) with poor compression (stock compression of a TT being 8.5/1 rather than the 10.5/1 of an actual NA) The compression being to low for "NA conditions" would cause excessive fuel consumption. Therefor it is not a bad way of saying it . . . . it is SPOT ON the money. Peace
Which bolt on the plenum? From upper to lower? Sure you didn't just cross thread it? And why did you use those bolts rather than your original ones? I know full well what is involved in removing the lower plenum. I've done it start to finish, including removing cams and changing lifters in a day. It's not too low, it's just less than ideal. 8.5:1 was quite acceptable 50 years ago. Remember that the ECU injects fuel on RPM and airflow only. In the low airflow sections of the maps the TT tune is actually LEANER than the NA in parts. No boost = less airflow = the right amount of fuel for that particular condition. The ECU doesn't just inject a ton of fuel at 4000rpm because it expects there to be 12psi of boost up it's arse. Most of these 'tootling' around sections of the maps are closed loop as well, so the ECU should be getting feedback from the 02's and adjusting to suit aiming for a target of 14.7:1. Not having turbos connected wouldn't cause the sort of fuel consumption issues that this guy is having. It will be the usual O2/fuel leak/boost leak/dirty connector issues that cause most zeds to have bad fuel consumption. If it's not that then I would be guessing something much more sinister, and IIRC this zed was dirt cheap so that is likely.
that much unburnt fuel should be coming out black out the exhausts right? its certainly not making the power to burn all that fuel cleanly. hows the exhaust smoke looking slapstickz?
supersonic theres no black smoke its just white, smoke i see, but its not the white smoke you would see if i had my turbo seals broken. Its only showing very little white smoke, i suspect maybe the PCV need to be changed for that white smoke to go away. If not any smoke sometimes. My head gasket isnt blown or anything as it does not overheat at all.
LOL. Yes I am sure I didnt cross thread it. Yes one of the plenum bolts from upper to lower as was mentioned previously. Of course not, you are still failing to understand what i've said. If that is the case then why have others and myself fixed this same problem. I totally agree that the usual culprits should be checked and checked well but you cannot tell me that running the car constantly with the wastegates disconnected will not cause unusual problems including the ones mentioned. If you have a mild boost leak what happens? Multiply that to something that can never reach boost because of the leak . . . Peace
Forgot to mention . . . Air drawn in is metered. Boost/vac leak occurs. ECU fuels to what it thinks that volume of air needs (14.7:1.) That same volume of air is no longer there because of the leak. Cylinder now has an incorrect air/fuel mix to deal with with too much fuel for the amount of air provided being the result. Peace
You're not thinking this through properly. In the open loop sections of the map with a vac leak present some of the air will be metered, with the air leaking in being unmetered. So metered air + leaked air = too much air = lean running. Vac leaks mean lean running conditions, he is not making boost so he will not run lean In the closed loop sections the ecu should be able correct for a small vac leak. Remember in this section of the map (which is targeting 14.7:1 AFR) that it has a constant feedback from the O2 sensors saying either lean or rich. If it's lean, it will chuck more fuel in, if rich, it will take some out. If the leak is sooo bad that the car cannot make boost then the car would idle like an absolute pig. I would go as far to say that it would drive better with the AFM removed. I don't think that having the wastegates wired open would cause many of these problems. As Eric said it should still make boost with the wastegates open. There is a hell of a lot of air coming out that has to go through a 1" diameter hole so you would expect some to go through the turbine and make boost. For all we know one or both of the turbos are seized, or have lost wheels or snapped the shaft. This bloke might even have a NA engine with a Twin Turbo sticker on it. I'd love to have a look at this Zed and see what's going down.
Unless it is trying to boost (which this is) this means that a certain amount of air will be lost at the wastegates. (a 1" hole will loose a lot of air) not suck air in. It would be . . Metered air + loss at wastegates + normal amount of fuel introduced for that metered air = overfueling. O2 corrects it, New air is introduced, ratio gets closer until new metered air is introduced and the loop starts all over again causing overfueling once more. Exactly, he will not run lean . . . . he will run rich. I agree. The closed loop will work to a point for small vac or boost leaks. disconnected wastegates is not a small leak however. Again I agree totally. It probably would work a lot better with the AFM removed. This happens with some of the cars we play with. There is one turbo with a smaller leak that we are playing with at the moment that does what you describe but only because it is a smaller leak. Air will always look for the closest point of Zero pressure. The wategates are the closest point of Zero pressure. Some will go through the turbine but the loss of pressure "may" be to great causing fluctuations. Therefor if its making like 1psi and he is using a stock gauge then it may not even register (assuming he is using the Zed gauge, I do not know if this is the case or not) Yes, a huge possibility that the turbos are actually stuffed. I would love to see it also, but I live too far away. (PS, Im not disagreeing to be difficult. I rather like this debate actually and it is interesting to look at things from a different way and see other opinions. I love to learn new tricks and information regarding Zeds. Thank you for having this debate with me. ) Peace
You won't loose/gain air at the wastegates. They are just a flap that opens to let exhaust bypass the turbine wheel and thus control boost pressure. No intake or metered air goes anywhere near them, only exhaust. Oppsies! I meant he will not run rich. If there are vac leaks and no boost then there will be a surplus of air, hence running lean. There will be no leak with the wastegates open shut or any combination of open and shut Not a problem I think you may be getting a little confused as to how the wastegate affects the entire system. This is a external wastegate system, but is easier to follow IMO. It still has the standard internal wastegate, as this picture is advertising a aftermarket extrernal gate for a standard WRX turbo. So normal turbo operation we have the exhaust coming out of the engine and into the turbo (from the pipe at the bottom of the picture). It goes into the turbine wheel, then out the back. This spins the shaft, rotating the compressor wheel which sucks air in from the centre and shoots it out the side (into the page in this picture). Now so we don't get into a weird runaway condition where more exhaust gives more boost, and more boost gives more exhaust which gives more boost we need some way of limiting the boost. The old school way of doing this (looking at you Buick) was to run a restrictive exhaust system so that the back pressure on the turbine limited the speed that the shaft could rotate at. This is a really crap way of doing it. So some clever people thought why not just get rid of some of the exhaust gas? They set up a actuator system that opens a bypass valve at a certain boost level. The bypass valve allows exhaust to completely avoid the turbine. This gives less restriction which gives less lag, less heat in the turbine housing and wheel which allows for much longer service life and allows for accurate adjustment of boost levels. Now some more clever people came along and said, why don't we put it in the turbine housing rather than having this big awkward hot thing cluttering up the engine bay and being all expensive to make? So they did. And it was good. You can see the internal wastegate actuator on top of the turbo in the above picture. In this picture it shows the wastegate flap in the turbine housing. These internal wastegates are nice for cost and packaging purposes, but for accurate boost control or very high exhaust flows you really need an external gate. There has been some aftermarket fiddlings with boost control using electric blow off valves in conjunction with a normal wastegate (R34 GTR BOV's can work if you want to do this). This allows the turbo to run in it's maximum efficiency zone and just bleeding off the excess charge air into the intake. Clever but fiddly. Sorry if I'm talking down a bit to anyone, but it never hurts to take a step back to the basics
LOL, why are you having this argument chrispy? Samuri, you're wrong, it is that simple. Just because his boost guage goes to almost zero doesn't mean it is trying to make boost, it just means the manifold pressure is very low ie throttles wide open. Yes the air is metered though the afm, but it isn't drawing in more air and going into that part of the fuel maps, it is running like an na. It wont meter the same ammount of air if the turbos dont exist, so it will not inject that ammount of fuel. If the gates are wide open, there is no air leak, as chrispy said that is waste gases getting expelled, the ecu kmows nothing about this, it only cares how much air is metered at the front, once again, no boost = no high air flow values = no extra fuel. Now, if he drives his car with the pedal mashed, then yes his fuel consumption will be high whether he has boost/vac leaks or not, the engine is lacking dynamic compression and is deliveriong very low power, so he puts his boot in more, more tps, more air flow, more rpm, sfa more power. If this car actually has turbos( still awaiting pics) then we need to sort out why it is showing 0 boost. If it has no turbos, well put some back on. A boost leak would be absolutley huge to show 0 boost, gates wide open will still give some + pressure. Thread fails until pics are delivered.
Not at all, i just needed to understand it which is why i was stating how I thought of it. Thank you for the information. I was thinking of a totally different thing and applying it to this Agreed to the other member also. We need pics . . .
