[Anonymous]

after doing some more research I'm now thinking of going down the ppe route.
Good proven power gains and lots of experience of people fitting them and cheap now with the weak dollar.
If only my insurance and tax weren't due - I'm going to be very skint for a while.

[GSB]

after doing some more research I'm now thinking of going down the ppe route.
Good proven power gains and lots of experience of people fitting them and cheap now with the weak dollar.
If only my insurance and tax weren't due - I'm going to be very skint for a while.

The PPE has some pretty fundamental flaws though, I personally wouldnt go there.

[northernalex]

"fundamental flaws" such as?   s:?: :?: s:?:

[Anonymous]

I've done a quick search on here and most people seemed fairly happy. Some mention of problems with the single 02 sensor but good performance gains and well made etc.

I'd be interested to hear what you think before I make a decision to buy.

[Chris]

how about this instead?

 m http://cgi.ebay.com/ebaymotors/TOYOTA-M ... dZViewItem m

(postage to europe 59 mecan dolla)

That seems absurdly cheap!!  but very tempting..  Around £150 shipped as opposed to around £400 for the h&s option   s:D s:D    Makes me wonder what the catch is...   s:roll: :roll: s:roll:  

On the one hand i think that mr t spent lots of time and money to come up with the design they did so i should just leave it at that, whereas on the other hand i'm now out of warranty and should probably look at loosing the precats and it makes sense to change the manifold at the same time if i'm ever going to...

[GSB]

"fundamental flaws" such as?   s:?: :?: s:?:

The manifold works well enough in terms of power gains at the top end, as a 4 into 1 manifold should do. But thats only half the story, and only in open loop operation. My main reservations about the PPE are in terms of its effects on the engine in closed loop mode. Not to mention its build quality, lack of bracing, and it's frankly laughable flexijoint.

The power gains in open loop mode are there for all to see, theres no doubt that you'll get more power withe the PPE. But the effect of the manifold's design in closed loop mode is up for question. My main issue is this: I cannot for the life of me see how the ECU can reliably control fuelling with only one O2 sensor... Toyota use an ECU that effectively runs the engine in 2 halves, or 'banks'. Bank 1 is cyliders 1 & 4, Bank 2 is cylinders 2 & 3. Using the O2 sensor in bank 1's exhaust manifold the ECU adjust the fuelling for those 2 cylinders, and it does exactly the same for bank2. With the PPE manifold in place, you are feeding the 02 content of the combined exhaust gas from both banks into the ECU. This is the sticking point. The ECU can no longer reliabley measure the O2 content of a particular bank, so how can it make valid adjustments? Essentially you are measuring an 'averaged' O2 content, so any change the ECU makes is going to have a minimal effect on the diluted gas stream, which will lead to over correction and instability in the control loop. The end result is that you could end up with one bank running rich and the other lean, and have no idea about it due to the fact that the average of the 2 streams is correct... You'll never know about it because as soon as you boot it, the ECU reverts to open loop tune, the engine makes full power again and all is seemingly right with the world.

The way the ECU is configured is not compatible with single sensor operation, but thats not all. The sensor location is also not as good as it should be. In order to reduce the delay in measuring the 02 content and making the fuelling adjustments, the 02 sensor should be placed as close to the cylinder head as possible. The further away it is, the longer the delay. The delay's here have a negative effect on emmisions control, and on throttle response.

[northernalex]

Grant, I would agree, they are very fundamental flaws!! The averaging thing worries me!

[markiii]

all true, but a compromise you make with most aftermarlet turbokits as well

[GSB]

all true, but a compromise you make with most aftermarlet turbokits as well

Except of course, the TTE turbo, which retains both O2 sensors.

[markiii]

and the HASS

however teh TTET manifold has 2 sensors but they sit in 2 pipes rather than a junction of 2 pipes each

TTE reckoned it would make a difference to closed loop but as long as you bore it in mind when diagnosing problems niot a big one. It will affect closed loop fueling though as 2 cylinders are never read at all

[GSB]

and the HASS

however the TTET manifold has 2 sensors but they sit in 2 pipes rather than a junction of 2 pipes each

TTE reckoned it would make a difference to closed loop but as long as you bore it in mind when diagnosing problems niot a big one. It will affect closed loop fueling though as 2 cylinders are never read at all

Oh yeah, and the Hass...  s:oops: :oops: s:oops:  

The ECU adjusts the fueling for both cylinders in any particular bank equallly, and is only looking for the combined result of both... By running on on the result of only one cylider you do increase the risk of poor control slightly, but assuming that a TTE owner is generally going to be taking very particular care with his engine, and isnt going to be running the engine into the ground, it should be fine. The only real problems that could occur would be if a spark plug went south in the unmeasured cylinder (but the ecu's misfire detection would pick that up from the conflicting accleration rates measured at the crank postition sensor), or a bad injector, in which case you could run the risk of running lean on one cylinder and not knowing it...

The stats are with you on this though. First, you have a 50/50 chance of the failure affecting a cylinder with no O2 measurement. Secondly, injectors rarely fail. An electrical failure would still be picked up by the ECU, so that leaves you with a mechanical failure, which is generally caused by foriegn objects in suspension (poor filtration) or in solution(contamination), both of these would tend to affect more than one injector though... That leaves you plain bad luck. But lets face, if you've gone for the TTEt you've already ditched you're precats, so the your bad luck factor is a fraction of what it used to be!

As you say, the biggest issue is one of diagnosis. The diagnostic charts in the BGB will no longer be quite right for some faults. It no big deal though if you aware of it...

[markiii]

The ECU adjusts the fueling for both cylinders in any particular bank equallly, and is only looking for the combined result of both...

aha, looks I was crediting teh sysem with a bit oo much intelligence

[Anonymous]

very interesting thanks very much.

So the PPE setup may reduce throttle response, I've already heard about problems with the flexijoint.

what would be the long term consequences of one bank running rich or lean and going undetected. Poor performance and response in close loop mode but any long term damage?

TBH it seems whatever manifold you change to there are always going to be pros and cons. I'll PM a few people who have fitted the PPE and see what their opinions are

[markiii]

in which case simply buy the PPE and have an exhaust shop weld you 2 02 bungs in the primary runners high up liekon the TTET

based on Grants explanation thats gives you teh best of both worlds, assuming you can live with the flexi joint

[Anonymous]

Sorry a lot of this is over my head  s:oops: :oops: s:oops:  

How high up on the runners would you weld theses, and on which Pipes?

[markiii]

about 6" to 8" down from teh head (comparable with teh stock manifold)

as to whhich pipes TTE use 2 and 4 (note thats when counting from teh left and doesn't neccesarily correspond to cylinder number as I can't remember which side they start from)

[Anonymous]

Right I reset the Ecu earlier and now heading for lunch (the long way!). I'll Let you know if theres a difference once I get back

[Anonymous]

Right Just Back, God I love this Car.  s:twisted: :twisted: s:twisted:  

The Car definitley feels better, but whether thats because of the sunshine or not I dont know  s:D s:D  

It does feel better, more urgent and I think it sounds better. I'll be keeping an eye on this and perhaps resetting the ECU more reguraly

[GSB]

about 6" to 8" down from the head (comparable with the stock manifold)

as to whhich pipes TTE use 2 and 4 (note thats when counting from the left and doesn't neccesarily correspond to cylinder number as I can't remember which side they start from)

On an inline engine cyl.1 is usually at non-drive end of the engine, counting up to 4 (or 5, or 6) at the drive end where it mates to the gearbox. On V, or a Boxer, or any other configuration, its down to the manufacturer which way he numbers his cylinders, but 1 is usually down at the pulley end.

[Anonymous]

So on our engine are we counting from the left then?

[GSB]

So on our engine are we counting from the left then?

Looking at from the rear of the car, number 1 is on the right.

[markiii]

so they are in 1 and 3 by Grants definition

[Anonymous]

Thanks,

Now for the extra dumb question?

Can you explain what you mean by "open" and "closed loop"?

[markiii]

I will but then we should split this off to anotehr topic as we havedrifted well off topic here.

closed loop is when your just pootling around and the ecu uses both teh o2 sensor reading, MAF signal and throttle position to determin teh amount of fuel.

as it learns it store this info in what is known as teh short and long term fuel trims.

when your at WOT (Wide Open Throttle) too much is happening too quickly so it can't use all this info

at this point it essentially forgets the 02 sensors and uses best guess, but a little rich for safety. (open loop, i.e it use no feedback from the 02 sensors)

[Anonymous]

Can we move this stuff to another thread or how do we just continue this stuff in another thread?