Whats causing my tubby to run lean ????

[Munnsy]

been to rolling road today but found the ecu was running the car very lean up to 4000 rpm then fueled accordingly assd it should after this point.
aparently according to ryan this is typical blitz ecu behaviour and so he told me to have a look inside the ecu, this is what i found

















is the top board supposed to only be half a board in length of the ecu casing?? Not really sure what im looking for any advice would be great


i really cant see anything unusual though??
The board when opening the ecu is attatched to the main boared with big white bands, but really not sure how to tell
anyone got any pics of the inside of a standard rev3 turbo ecu? otherwise the problem lies elswhere
tell me what you think

[Caribbean_Blue]

Dave put your AFR graph up to to show problem. May help.

[Munnsy]

yeah sorry reece should have thought of that myself







sorry were the best i could get them, basically as far as i can understand, the graph shows its running very lean up to 4000 rpm then resumes normal fueling,
Ryan and charlie both said blitz ecus do this all the time.
Now what im after really is how to determine if i have another board in the ecu and if it is blitz or similar.

Does the original ecu only have one board where mine has 2???

if someone could please just unscrew the 4 screws on there ecu to compare would really really appreciate

cheers

[steve b]

I've not seen a normal rev3 AFR chart but i doubt it looks like that.

Basically on transition between vacuum and positive boost it should be hitting around the mid / high 13's, 14:1's ok which is what it looks like, hard to tell. Where does it go into positiave boost rpm wise? If its about 4000rpm all cool.

Heres a rough AFR map I made for my Eunos so only goes to 1.2 bar :-



The look of your AFR graph it looks like they are just keep it 14:1 as late as possible then jump to "in boost" fueling, it'll help spool by getting things hot.

I guess as long as EGT isn't too high and it doesn't knock who cares made good power.

[Munnsy]

to be honest with you steve i really am out of my depth, i cant really understand the graphs, and im just relaying what ryna and charlie said to me today.
They basically told me to lay off the boost as its running unhealthily lean,
he mentioned open and closed loops too which totally lost me.lol
All i can really relate to is the blitz ecu or similar, they are renown for doing what mine has done, hence i need to know
1. is mine blitz??
2 if not then what other factors do i need to check??
o2 sensors and the like??
thanks for the input bud

[steve b]

Well if Ryan thinks its unhealty lean I guess it is getting into boost while its still at 14:1 which is a bit poo.

Do you have a graph with boost on it? Where boost hits zero psi or atmospheric pressure, see what revs its doing. Then look at your AFR chart, see where it starts to dive, what revs is it doing. As long as the revs when boost goes positive is the same as or after the point where the AFR's dive it shouldn't cause damage.

It looks too rich at the top end as well actually, is it about 10.2:1 ? Make most power @ 12:1 but its safer to be at about 11.5, anyway I thought its normal for MR2's to be overly rich in boost, thats why ECU replacements are so popular, lean them out at the top to gain power. Thought the Blitz/ Mines Ecu's did the leaning at the top so maybe it isn't a modified ECU.

Confusing

I guess it is a problem, I'd don't know about the stock ECU but i'd have thought at wide open throttle it'd go open loop, closed loop s only for cruise with a stock narrowband lambda sensor so i doubt its that.

[Munnsy]

yeah i do have a graph,
it peaks at 3750 rpm approx, but is boostin well before this.
I see more clearly now you have expained it little simpler
So if my ecu is stock which im pretty sure it is, have you any idea how to cure this???
dave

[steve b]

yeah i do have a graph,
it peaks at 3750 rpm approx, but is boostin well before this.
I see more clearly now you have expained it little simpler
So if my ecu is stock which im pretty sure it is, have you any idea how to cure this???
dave

Boosting well before this it is an issue then

Afraid I can't help, but doubt its an open / closed loop thing, see my edited post above.

[toxo]

Just to clarify, that is definately a standard ECU. This is a pic of the inside of my 3S-GTE ECU, which is also totally standard (albeit from a Celica):

http://theshado.ws/images/imoc/P021008_15.24.JPG (haven't put it in [img] tags as its massive but I'm not resizing it)

From memory most of the jap ECU's from TOMs, Mines, Blitz etc stick add on boards onto the standard ECU, but they change the casing as the add on boards don't fit inside the standard box.

[Munnsy]

great thanks bud, i did think it was standard but was told that over in japan alot of guys added another board in the stock casing to look original,
So next question then what on earth do i do the sort the fueling out?

[steve b]

I'm sure getting Ryan to pop a Link G4 in will sort it

[lockys96]

i just dont get it, people who buy blitz ecu's, they are mapped in japan for a said car or certain spec.

then a lot of people buy them as if they are gold dust and just slap onto there car.

id just get a link or power fc circa £500 and have that extra reliability

[Ryan.g]

Hi Dave

Got your E-mails but thought it would be better to post on here.

The ecu does look standard indead which is very strange as the afr curve almost copies the blitz curve which we saw on a celica gt4 a couple of months ago but yours doesn't seem as bad as the power curve is smoother.



The problem is that when it is at Full boost ie 1bar the fueling is still at 14:1 for a good few seconds which is causing it to knock as thats why the power run was aborted on 2 of the Runs. Inside the cabin you could hear it knocking just with the ear defenders. But it disappears after the ecu pulls the timing back.

I would suggest checking the error codes to ensure that all the sensors are fine espically the TPS sensor. See the BGB for this.

As you can see above in the image. The second fueling line is after i have mapped the car on a powerfc. Now it lost some mid range power due to the base timing orginally being set at 15 degrees which will add alot of power low down but it was knocking very badly as you can see on the curve where the ecu is pulling the timing. But with the fueing being correct after 4k it finally made alot more power and torque as is alot safer now.

Ryan

[jimGTS]

could running well advanced timing make it run lean?
instead of running 10btdc...

werth swapping in another fpr?
sorting the fuel pump out?

swapping out for another stock rev3 ecu?

[syrus_sw20]

could be the ig Timing if you are close to Hertfordshire pop down to Rob at TRRacing sure he will sort it out.

[Driftlimits Performance]

could be the ig Timing if you are close to Hertfordshire pop down to Rob at TRRacing sure he will sort it out

Dave would never 2 time me!

[syrus_sw20]

sorry skywalker did not mean to tread on anyones toes

[Kongaroo]

How are you measuring the AFR? Are you using tail sniffer in the exhaust pipe?

The reason I am asking is because your AFR curve would be considered roughly normal for a stock ECU if the first 4000 RPMs of it were about 1.5 AFR points richer across the whole segment.

It's quite common for a tail sniffer to read leaner than a wideband sensor installed in a downpipe throughout the lower RPM range. This is because at lower RPMs often not all the atmospheric air in the exhaust pipe is able to be displaced by the burnt gases coming from the engine so you get a leaner reading than you would get in the downpipe.

This is going to be even more true for a tubby because even the standard exhaust is pretty big compared to most other cars meaning there is more atospheric air to displace (I notice you have a Nur Spec ). Leaner readings could also occur if the tail sniffer is not quite far enough in or if there are holes in the exhaust

One other thing to consider is what gear you are using for the pull. It's hard to tell on your photo but it looks like full throttle was applied at about 2200RPM - was this 3rd or 4th gear? Bear in mind that you are never really going to be trying to do a full throttle overtake in 3rd or 4th starting at only 2200RPM because it would take forever to get anywhere (in other words it's unlikely you will ever see that AFR curve during normal driving anyway).

If you are indeed measuring AFR using a tail sniffer it might be worthwhile to make a logged comparison run with a wideband sensor in the downpipe because you car seems to be putting out a decent 302 BHP on that dyno run

Btw was it your ECU or the celica ECU that Ryan could hear the knocking on?

[Munnsy]

No it was my ecu he could hear the knocking in the cabin
As for afr he did use the prong up the exhaust ( tail sniffer) and it makes complete sense in what you are saying (even though i am a complete ameature to reading graphs etc and general modifications)
I am in the process of buying an power fc, and in the mean time i will look for error codes to rule out any sensors that may be playing a part.
As for ignition timing i have recently had a cambelt change done at 3s, is it a possability in this situation???
Also as for the pulls, i believe they were done in 3rd
any other help would be really great and i really do appreciate your help so far guys
dave

[jimGTS]

i would check timing yourself, just to be sure.