Merry xmas and happy new year to everyone.

I know there are millions of threads regarding PPP and dp. There are many saying its great, some warning of running lean and overboost. Following John Bank's threads and others it appears that fuelling is not changed on the PPP ecu at all, i was under the impression it put more fuel in. Therefore I would like to know if anyone who has all the above i.e PPP, downpipe knocklink and afr have ever seen any knocking, overboost or bad fuelling.

 

Paul,

Perhaps the relevant questions are:

1. Does it really put more fuel in?????? (come on Mr Wood, help us out here )
2. If so, is it enough to counter the leaner running a catless DP will make?

The answer to point 2 on a standard ECU is yes, but I'm not sure how many people know the answer with regard to a PPP ECU. John Banks' efforts recently would indicate that all is well but he has yet to see what a Knocklink would tell him on the same car....

Anyone out there with MY99-00 with PPP + DP + Knocklink + AFR/Lambdalink that could tell us their results?

Matt

[Edited by mutant_matt - 03/01/2002 13:32:47]

 

There is no way mine is running lean or knocking with the levels of lambda and ignition advance I am seeing even with the boost yanked higher still than PPP. Unless you start telling me individual cylinders are leaning out...

The car has a perfectly good knock sensor and an ECU with a far more advanced knock correction facility in it than a KnockLink and a human observing it would ever help you with if you keep within its retard limits. If it is not retarding I don't believe it is knocking. Our sensors/ECUs are supposed to be hyper cautious hence some people's views on MY00 hesitations. Just my opinion. Just because the Bosch sensor with the Knocklink is wider in frequency response doesn't necessarily mean it is better.

I have FWIW monitored my knock sensor with various gizmos and not seen a dicky bird. I suspect the knocklink is just an LED voltmeter with a delay circuit on it letting you see it for long enough.

On a MY01 PPP without an uppipe the ignition is too retarded for comfort apparently, but on MY00 Pete Croney was happy to recommend a DP I understand.

But you have to decide how cautious to be with your own engine. I don't think I am excessively paranoid or gung ho. I do not want to have to get an engine rebuild, and by my nature I am cautious, although not as much as some. Some have worried about induction kits with DP and PPP but mine was fine, but the APS one apparently can lean you out with a lot of breathing mods even on std ECU.

Fit a lambda link or similar and see what advance you are running on Select monitor and get the DP on IMHO.

Edited to say that Mike Wood is actually saying that the PPP IS A REMAP OF ignition boost and fuelling and not a kludge (even though I reckon you could get almost similar results).

It maybe does not advance the ignition more or lean out the fuelling to get more power, or retard the ignition and increase richness to get more safety, it maybe just has a more accurate map that doesn't seem to be way off beam on fuelling and ignition if that makes any sense - ie it is not in a fixed way going to be more advanced or leaner or richer at any one point. It is mapped to go to over 17PSI in the midrange. It will do that in factory state on some cars. The OEM ECU doesn't. That makes me a little happier to have it.

[Edited by john banks - 03/01/2002 13:58:48]

 

I have been in john banks car and with his Dawes still holding fairly high boost at 6500 revs,I was concerned about det at higher revs,so he booked his car into AWD who put it on a select monitor,took it for a run at engine speeds up to 7200rpm and reported that ignition and fuelling are spot on,this can only be a guide as your car may not be.I have been in a few PPP cars with/without d/p and john's is by far the best for both performance and smoothness.

Mike Woods has replied on one of jbanks many threads stating that the PPP ECU has a different map from a standard ECU.

 

Forgot to say I have my99 in case its not obvious from my UN . Oh and Mike Wood says "Boost, fuel and ignition are all remapped to suit". Back to the questions.

 

Cheers john and T-uk, you replied whilst I was writing the one above.

Has anyone ever actually seen any problems with this set up????? Or are all the threads just warnings. I want some evidence that it has caused problems.

 

John,

I wasn't trying to imply that you were either "gung-ho" or that you hadn't done your research - the discussions we've had over many months now show that

The only thing that bothers me slightly is that the standard Knock sensor is apparently not actually that great and the real value in the Knocklink is in fact the aftermarket Knock sensor that you can get to go with it....I say apparently because I certainly don't "know" for sure.

It would be interesting for Bob Rawle's comments as he's seen excactly how good the OE Knock sensor is as he maps cars and also sometimes (always?) uses det cans as well. Bob? can you help?

Also, Pat or Mark, have you any nuggets you could share with us RE: the quality of the standard KS?

Ta,

Matt

 

john,do you ever leave your computer ?

if you fit a d/p to a PPP car you may find that the boost solenoid will start to kick in,this can be sorted by changing the in line restrictors but this is fairly crude and can also loose you any gains,I am sure that this was the main reason jbanks got a Dawes.he really is the best person to comment.

 

...no I'm aware of that. I've been following John's Restritor drilling, replacing, bleed valves, Dawes, Bleed Values + Dawes, Digital Volt Metering of the LS etc. etc. etc. with much interest over the last six months.

(with no offence meant) I still think that my point is valid though....

Matt

 

Matt, chill man! My offenceometer had not even registered. And it is not as sensitive as any knock sensor so don't worry! I'm not like some of the mardy ****ers on here who take offence at a change of wind direction. Offence had not crossed my mind. Some people you just disagree with them and they go ballistic. I would not survive long as a GP with that attitude.
Tell me I'm a ****wit and you are about to stab me and I'll get interested though But only if you are in the same room!

Anyway, people seem to think that the Bosch aftermarket knock sensor is somehow better just because it picks up more on a Knocklink. Pretty shallow thinking to my mind. One lesson from medicine with any test there is a sensitivity, specificity and a positive and negative predictive value. The same can be applied to knock sensors. Now just because the OEM one is a tuned rather than wideband device does not mean it is crap. I can't see Subaru fitting a crap knock sensor. It someone shows me that the std sensor does not pick up **actual** knock when the Bosch one does then I'll be interested. Until then people think it is better because it shows more signal more of the time. Crap I say. Prove me wrong and I'll buy a Bosch and knocklink

The sophistication of the OEM ECU is huge compared with most aftermarket ones. Just because it makes a slow car doesn't mean it isn't safe or advanced. Look at the level of Subaru warranty claims for engines compared with other PERFORMANCE turbocharged cars...

I would trust my engine to an OEM ECU with a functioning origial knock sensor when the system was running healthy advance with plenty of retard available - that is what it is there for!

[Edited by john banks - 03/01/2002 14:40:50]

 

All good points John which was why an input from Bob would be most interesting as he uses the only sure fire way of telling - Det Cans.....

If you can "hear" the Det through the Cans and the OE sensor is not telling you there is Det, then there is a case that the OE sensor is not up to the job.

Also, if you can hear Det, the Knocklink says there is Det, and the OE doesn't, that's also a case for the Knocklink...

Come on Bob, help us out

Matt

 

Exactly Matt. And that is what no one has yet shown as far as I have heard. When they do I buy. Until then I trust the ECU. I wouldn't trust the ECU if it did not have plenty of retard left, but I would rather a chip watches a sensor and reacts more quickly than I would be watching it. I am supposed to watch the road.

[Edited by john banks - 03/01/2002 14:46:53]

 

I too think that the standard knock sensor will be up to the job but the good thing with a knocklink+sensor is you can see the lights,I mean how do you know your standard knock sensor is 100%,or that last tank of fuel was good.your car may not pull well one day and not boost as high,so you adjust the Dawes thinking it is temp. related.IMO for a small expense it may save you a fortune.

I have,after being in jb's car,sourced a Dawes but will not fit it until I have some sort of fuel and knock monitoring in place and also will get it checked on a select monitor.

 

so if its not knocking/retarding can you conclude that the fuelling is o.k? or do you need to make your afr John to check it? Actually on that note why does the ecu go into this closed loop mode at all? Why don't the sensors keep monitoring fuel etc all the time through boost? Surely if the fuelling is a "written" amount in closed loop mode then one car with ppp and decat would fuel the same as another (providing boost is controlled) unless there was something wrong with injectors and like?

is it closed or open loop?

[Edited by paulwadams_my99 - 03/01/2002 15:49:14]

 

How about a stethoscope on the block?

STUDENT DOCTOR:
"The patient has a systolic murmur sir."

EXAMINER:
"I think you'll find it is a detting engine stupid. Get out of my sight. FAIL!"

 

"so if its not knocking/retarding can you conclude that the fuelling is o.k?"
NOPE

"or do you need to make your afr John to check it?"
YEP

You may not be detting but could have 3% CO and be at risk of doing so for example. If you are not detting and have 7-8% CO this is much better, nay essential.

Fuelling is controlled by MAF. It goes open loop because closed loop would give you AFR of 14.7:1 with the rocking behaviour around stoich for a petrol engine. The mix needs to be much richer like 11.5:1 on full boost for cylinder cooling and knock control.

 

So surely if the afr is tested at install of DP its not going to change after, once again providing boost is controlled. Is this tested at the likes of scoobysport post fitting?

 

You hope the system adjusts to suit. I am not an expert on downpipes (or anything for that matter), but I understand they increase the volumetric efficiency of your engine by removing a restriction. Hence for the same boost the airflow will be a little better. So a car mapped by MAP would be leaner. Hopefully a car's fuelling being controlled by MAF would adapt. But then MY01 PPP with a downpipe is showing a lot of ignition retard unless you do an up-pipe as well... why I don't know. Perhaps someone clever will explain.

A downpipe can be beneficial in that improved gas extraction could lead to lower in cyclinder temperatures.

But we all talk about out car's fuelling being a very passive system, whereas metering out the fuel based on a MAF map is quite an active system and you would really hope it adapts. Maybe the ECU has a limited amount it can veer off the standard map to compensate for dodgy sensor inputs?

 

right i am way out of my depth so try and help me out. I understand that more fuel is injected at higher boost for cooling and knock control. What I don't understand is I thought in "open loop" mode the sensors were ignored and a defined map was used. If thats the case then at high boost the fuelling isn't adaptive and therefore passive. Or is fuelling not part of the open loop??

Still no-one actually has stated any problems but I wonder how many people are monitoring the knock/afr?

 

John, just from what I understood : the separate bosch sensor makes sense in the way that you can leave the OEM system alone, so you don't have to splice wires, forcing the OEM sensor to supply the voltage to 2 devices (ECU & disco lights )

As far as I understood it, the sensor is just a piezo microphone that is tuned to specific frequencies (which appear when you have det). I don't think a broader spectrum does you any good actually. Maybe I should dig out my old Radio Shack PZM piezo mike and bolt that to the car

I bought the Knocklink so I could see (and believe me, you DO see the flash) what's happening, especially at revs where it's almost impossible to hear... I know the standard sensor/ECU will do their job, but there is no use in pushing it when you see det happening.

The ECU can retard ignition, but when there is a real problem (injector failure for example), the ECU can only do so much (to be precise: I think retard 8° IIRC). I'm more clever than the ECU in that I can take my foot of the throttle, go to the dealer, and see what the hell is wrong...

One other thing: to be sure that fuelling is OK, I guess EGT temps would probably make things clearer.

That said, I would be *very* surprised if your car would be detting. But then you are lucky to have a MY99/00.

Theo

 

Paul, to answer your question ... I think the only problem you could see with a DP is - according to Mike Wood - a fuelcut here & there.

You should always check your own car just to be safe, but I'm pretty sure your car will not det or run lean.

 

Theo -

Paul - open loop is actually a bit of a misnomer. It is controlled by MAF still. However, it is no longer controlled by the lambda sensor, but ironically that is the thing we are reading when we use our AFR meters, but you cannot use it continuously and the sensor is way outside its most/only accurate range around stoich.

I'm not rubbishing the KnockLink certainly. I would sing its praises if I had one!

 

Paul - open loop is actually a bit of a misnomer. It is controlled by MAF still.

This I can confirm with 100 % certainty. When my MAF was knackered, it still performed OK at higher revs, but my car stalled at tickover.

Irony of reading lambda sensor while not using it ... true, but if anything, a lambda sensor underreads when it gets too hot, so if it says 7 CO, you can be pretty sure it's at least 7 CO.

John, you cheapskate LOL. Go get one, or make yer own

 

Interesting thread!
I have a MY2000 with PPP and next mods are Magnex d/p, PE exhaust manifold (equal length) fitted the same time with my knocklink sensor and SPA dual boost/EGT gauge (for safety).
A friend with the above setup but with HKS ex.manifold (not equal) hasn't overboost, lean mixture or det problems (R.Road tested and measured), so I am just curius if anybody with similar mods has any thoughts!
Is the manifold the reason for more lean mixture (leaner with just the d/p)?
As my friend told me after the d/p the ex.manifold corrected any overboost etc (less boost - why?), and is pretty good for the EGT of his car.
Your opinions please!
JIM

 

I have a sneaking suspicion that with PPP your boost will be all over the place if you do a lot of breathing mods

How about a boost controller?

I can tell you now that you could fit a Dawes and forget the manifold and probably get similar results and not need a fuel computer and save yourself an absolute packet. If you get a manifold you COULD lean it out too much and have naff boost and fuelling.

However I am running about 9% CO at 18 PSI from 2400 to 5300RPM on MY00 PPP with Magnex downpipe and a Dawes, so I would probably have some room for leaning it out a bit.

 

Thanks for your quick answer.
According to Stephen's car witch is more or less the same modified http://www.steve.ukmail.org/car/ it seems that there isn't lean mixture problem (more than 10% CO), but bear in mind:
Different ECU (His is OEM while mine is PPP = more boost)
Different exhaust (His is complete PE while mine is PPP = STI centre section, WR backbox = more restrictive)
Different car witch is more important and different climate conditions (although this time we have less than -5 Celsius degree!).
Must I use the OEM centre section just for sure?
JIM

 

I think there were questions as to whether Steve's car WAS lean at certain points following his manifold. RB5SCOTT had to put a fuel computer on his 01 to sort it out after his manifold or headers I believe. It may be OK, but you risk being lean and not being able to do anything about it unless you buy more trickery. I think there are cheaper ways to get the same power personally. Can't recommend which exhaust bits to use - you need to know the fuelling and advance on your car and take it from there. If you have to put restrictions back in to cure lean spots I think it has become a bit pointless?

 

So, is the Select Monitor a safe way to monitoring the mixture after all the above mods?
At least the knocklink, EGT sensor is a indication of lean and/or det, or must I buy a AFR controller?

 

"So, is the Select Monitor a safe way to monitoring the mixture after all the above mods?"

No but it will tell you injector duty cycle, ignition advance. You need a separate AFR meter or a RR exhaust gas analyzer.

"At least the knocklink, EGT sensor is a indication of lean and/or det, or must I buy a AFR controller?"

Knocklink and EGT are different ways of telling you the result of lean fuelling or knock which is a single common pathway from a number of undesirable engine characteristics - eg. temperature, advance, fuelling, pressure.

You only need a fuel computer if your fuelling is off.

 

I've just spotted this thread and will post some comment but will do that tomorrow. I think that there is certainly some misinformation flying around, a knock sensor is just that, a sensor, its the gizmo on the other end that makes the difference whether its a Knocklink or an ecu. Just to say that the Knocklink is adjustable for sensitivity as engines are not all the same in terms of basic "noise" generation, the ecu is programmed to filter out the normal background but in my experience that can vary enormously. Any way just off to bed so more tomorrow.