john5f

iTrader: (3)

Hope somebody can help this.

MY95 jdm wagon with TD05, Turbo back 3" decat, green panel filter, ported & wrapped headers running Major Sarcasm's ECU chip configured for the upgrades.

Before the engine is up to operating temperature the engine pulls all the way to the redline (only did this for test purposes). When warmed up it goes flat at 5,200 revs. Fitted new plugs, changed coilpacks and MAF but made no difference so took put it on a RR to get more info.

I had it on the rr on Friday and the afr had a small fluctuation start at about 4650 revs then suddenly dropped steeply from 10.2:1 to 13.9:1 at 5200 revs. Boost pressure was fine at 1.12 bar and holding.

Any ideas please?
Thanks

John

dabow

iTrader: (19)

was the chip mapped for the car, or a genairic map (spellings poor i know)

as when i had mine with the earlyer esl chip i got a lean read out.
mine was spiking quite bad too.

john5f

iTrader: (3)

The chip is a basic upgrade chip but mapped for the mods listed.
This thread has the details:
https://www.scoobynet.com/private-fo...to-1996-a.html

How does the fuel regulator work? I think it is by vacuum and is T'd to the boost guage which reads as expected. Is there a diaphragm and/or spring in it which could have broken down?

Thanks

dabow

iTrader: (19)

the fpr is ran via vacume but the boost gauge runs of the vacume from the inlet manifold
they do brake down easy over time, i put an uprated one on mine, set to 3bar
the standard ones are im sure 2.5bar, but unstableish from what i was told.

it is worth putting an after market one one.
fuel lab/turbosmart ect

john5f

iTrader: (3)

My boost guage has been plumbed in via a T to the fpr vacuum pipe so as the boost guage works OK you would expect there to be sufficient vacuum to operate the fpr.

It probably is a good idea then to fit an aftermarket one on anyway which I anticipate doing but is it likely that it fill fix the leaning problem?

Other alternative I guess is the fuel pump. It already had an aftermarket one of these when I got the car, but no markings on it so can't be sure exactly what it is.
Sufficient fuel being delivered before it reaches normal running temperature indicates to me? that the fuel pump is probably OK as the mixture is richer then.

Any other possibilities?

Tidgy

personaly i;d dump the generic chip and get it mapped properly.

did the dyno operator not give you any feedback on what was happening?

dabow

iTrader: (19)

not the best idea to have the vac hose plumbed to both, some of the models have something the vac hose goes to & out.

the vac hose for the boost gauge should be to the inlet manifold.
as the fpr only works once upto presure. may be thats your issue.

once its upto presure, the boost guage takes the presure
another thing, 95 cars only have a map sencer for 1.1bar, 16.5psi.
id replumb your set up mate, see if that makes a difference

john5f

iTrader: (3)

The chip has made a fantastic difference to performance and economy except for this so I'd really like to fix the problem if possible and keep the chip. It does come with high recommendations.
The dyno operator suggested trying a standard ECU. Problem there is just removing the chip wont work properly because of my upgrades (originally ECU is a standard wagon with TD04 turbo and standard exhaust) and I don't have access to a Z4 ECU.
He also suggested testing fuel pressure from the pump. He said that the fuel pump may be 2 stage but I don't think that is correct.
His main expertise is with Mazdas and, although he knows his way around Scoobies, he really didn't seem to have any definite ideas. He did suggest they could run full diagnostics to try to identify the problem area but that works out pretty expensive so I will only resort to that if I can't sort it myself.
Thanks

john5f

iTrader: (3)

Forgot to mention there are no error codes

Tidgy

if its made a big difference to economy i'd be asking why is that?

tbh sounds like you need to get it to a specialist who knows what there doing, it may be the fuel pump is on its way, or it may indeed be the map.

dabow

iTrader: (19)

first things first, disconect that gauge, to make the fpr set up right, then plumb the gauge to the inlet, to gauge the presure from that, this should also give a better reading.

then if no difference, as tidgy said. get the car to a rolling road who know scoobs, they may be able to shed some light to what could be happening
every car is different, so the map differs even if you had 2 exact cars
they would work, but scoobs are never the same 2 alike.

john5f

iTrader: (3)

I'll see where else I can plumb the Boost guage to. No free spaces so I'll need to T it from something. OE dump valve, canister, MAP sensor?
A later MAP sensor has a higher limit if I recall so that's a good idea as well.

Thanks

john5f

iTrader: (3)

Thanks for that guys, I'll lose the boost guage for testing and see if that makes a difference

dabow

iTrader: (19)

plumb the boost gauge to the inlet.
theres 3 out lets on the top, just plug a t peice to say the midle one.
regards the map sencer, there easy to do

i infact have a second one some where. the wiring is also easy to do, there 1.7bar map sencers.
and will work on your standard set up to.

john5f

iTrader: (3)

Changed the plumbing and warming up to test now. Will feedback results asap
Thanks again

dabow

iTrader: (19)

it may not solve your issue, but if its set up right...

who knows mate
good luck

john5f

iTrader: (3)

Quick update.

I plumbed the fpr vacuum hose direct and 'T'd the boost guage to the MAP sensor pipe.

On a test run the problem was still there so back to fpr or fuel pump faulty or maybe even the coolant temperature sensor I guess. Can't think of any other options apart from the ECU.
I have also just spoken with Major Sarcasm. He told me the oe MAP sensor is used by the chip and works fine with it. He is convinced that the chip is not causing the problem and is being very helpful and investigating too.

At least I now have the boost guage fitted to the right place.

Any other suggestions welcome.

Thanks again for advice. When I do have the problem sorted I will post the results.

Splitpin

It can't be the coolant temp sensor as cold run can only cause the mixture to be enriched, not leaned off. Unless something strange has been done to the underlying tables in the custom map.

It is unlikely to be the FPR given that the lean spot comes on so suddenly at a consistent engine speed. For the same reason it's unlikely to be the injectors or pump either. If it was any of those you would normally expect the leaning to occur much more gradually rather than spike down all of a sudden.

One plausible explanation for such a sudden (and apparently consistent) drop could be an error in the main ECU fuel map.

Incidentally, that 10.2:1 "normal" AFR sounds much richer than ideal for the amount of boost you're running. If this is a generic map that has been supplied by someone who hasn't had direct contact with your car, as per Tidgy's post I can only suggest you allow someone with the experience to do so to check things out.

dabow

iTrader: (19)

i wouldnt say its the chip.
but sounds like it spikes due to fuel

if it was throught the range, then maf comes to mind, but just a spike

do you have the read out of this spike, on say a graft
my car was spiking quite bad on a map i had, runing rich
some cars do frequently spike, but drivability has always been fine

if it spikes at the same point all the time, it could easy be the map printed on the chip/s
the only really way for you mate, is to book the car to a rolling road that specialises in subarus.

harvey

iTrader: (48)

10.2 AFR = Very rich.
13.9 AFR @1.1 bar = long past piston nipping teritory.
As boost pressure increases and revs rise, it is possible for the fuel pump to "fall over".
You don't know what fuel pump you have but you need a Walbro GS341 often referred to as 225 lph Walbro. When/if replacing the fuel pump look carefully at the rubber pipe from the top of the fuel pump connecting to the flared steel pipe which forms part of the fuel pump carrier assembly. These rubber pipes can collapse internally.
It is very unlikely the FPR will cause a sudden pressure drop but a second hand one or even borrowing one from someone locally will eliminate the FPR.
I have a second hand Walbro as described above which I know is in good working order that you can have for £30 plus postage and I will include an OE FPR FOC.
At that point you can eliminate both fuel pump which is a possible cause and FPR which is very unlikely.
It may well have done so far but it may also be the cause of you needing a new engine.
AFRs as described above will nip a piston in the bore no problem.
If I were a betting man I would guess the problem is with your chip and the easiest way to prove that is to eliminate the fuel pump and FPR.
Alternatively you can fit an OE ECU simply for the purpose of carefully taking the car to or past the existing problem area. If the AFR does not drop off suddenly at 5200 rpm then obviously no matter how highly recommended this chip might be that is the source of your problem.
You would be better to look at something like an ESL board or second hand Apexi IMHO.

dabow

iTrader: (19)

shouldnt afr's site around 11.0 and drop when you lay off the throttle.
sure its something like that.

this is why i asked if he has a read out, post it up

john5f

iTrader: (3)

Here is the afr map



Does this help?

john5f

iTrader: (3)

Just read the posts properly.

Splitpin, as you say, of course it can't be the coolant temp sensor, that was a thought I had before the rr run, I just hadn't got it out of my mind (senility creeping in again)

Also, when not up to temperature, there is no sign of hesitation beyond 5,200 rpm (only for testing purposes) which probably points towards the fuel pump being capable of pushing enough fuel out. I guess it's possible that when the pump has warmed up it could become faulty.

Harvey, I read your post on another thread about the fuel pipe on the pump and checked that today. I will probably take you up on your Walbro offer in any event as I prefer to deal with known quantities. Should I email/pm/phone you tomorrow?

I am awaiting feedback on the chip from MS.

It would also be nice to find someone locally willing to lend a Z4 ECU to try.

Maybe the above chart will give additional clues.

Thanks again guys, all this info from you knowledgeable people is really appreciated.

dabow

iTrader: (19)

the last time i seen a reading like that, the presure hose came of the fuel reg
not saying its that.

the charts im used to seeing, the afr reading is in the lower part of the graft
except area 52, theres are like that

to be honist mate, try and contact simon (jgm/jollygreenmonster)
area 52, scoobyclinic or any of the other tuners on here, they will know what parts meen what on that graft

your afrs are high & does look frantic.
pm'ed jgm to have a butches
jgm always helped me with mine

john5f

iTrader: (3)

Thanks for that

Whatever happened to setting points, turning the dissie to adjust timing, plugs, tappets, carb jetting & mixture adjustments? There's only the plugs left that aren't controlled by the system. Those were the days (or maybe not!!!)

john5f

iTrader: (3)

Interesting chart isn't it? and a bit scary.

I don't know if Splitpin or Harvey have seen the graph yet but theirs and jgm's comments would be interesting.

saiklon

In my opinion the spike at 5250 is too big and sudden to be caused by an FPR or fuel pump. Those would cause a gradual leaning out. There must be an issue with the fuel map on the chip.

harvey

iTrader: (48)

As I have already said, you are in piston nipping territory.
All your graph has done is add to my belief that you have a duff ECU or chip. From the AFR plot I can tell you that a defective pump or FPR does not behave like that.
Think about what you are saying. The fuel pump does not suddenly become defective around 5200 rpm and then recover to a certain extent.
You do not need a Z4 ECU to prove the existing ECU is defective. Any UK ECU 93-96 will allow you to run the car on a trial basis just to get a fuel plot to show there is no spike at 5200 rpm. At that point you have proven conclusively the issue is down to the ECU currently in use.
Your fuel plot shows the ECU controlling AFRs to start with but there is then a major glitch.
Chips are not the way to tune a Subaru. Do yourself a favour and get a mappable ECU as already said above. New Simtek on your car is £940 fitted and mapped or you can get a second hand Apexi or ESL fitted and mapped, probably for around £500. A blown engine will probably cost you more than both of these options.
Until you try a different ECU there is no point in more hot air on here and wild theories.
You can contact me via email per my profile if you wish.

john5f

iTrader: (3)

Thanks Harvey.

Seems pretty conclusive that it is the ECU then. I just need to get hold of a standard one to confirm it.

The ways of finding information are by reading and asking questions and on here there is obviously a lot of expertise and experienced people willing to help. It is all much appreciated.

It's probably worth my while fitting a known fuel pump anyway so I will be in contact to take you up on your kind offer.

Out of interest, is there documentation anywhere which explains maps and mapping in some detail as I would like to get an understand of it?

Thanks again for all the help and advice.

John

saiklon

The map is the most likely problem, not the ECU. You can turn your ECU back to standard by reconnecting resistor J1 which is disconnected when the ECU is chipped.

This page shows a picture of that resistor: http://www.alcyone.org.uk/ssm/ecumod.html