Reset your ECU and pitch the lambda probe. Then your ECU won´t be able to re-adjust again - I think this is the only solution...
I had this problem, too. Then I changed to a programmable ECU.
Juergen

joe - paul has also mentioned to me about the 6th injector option when i couldnt find enough fuel for my car.

luckily turned out to be simply a corrupt novitec, running lean the whole rev range so i didnt investigate it any further.

paul was saying that it is enough to give the car that extra bit of fuel to make it safe, but thats all it would do.

i can see begbie's concern and lets face it, it is a shortcut to sorting out a fuelling issue and i certainly wouldnt consider it whilst there are other options.

Yep true enough, it must be soo annoying to be on the cusp of the fuelling of the 20vt injectors.

Joe

Good morning,

About std injectors and high fuel pressure, I had my car in RR last spring with std injectors and app. 3.8 bar fuel pressure. I could "only" receive 340 bhp with A/F 14.5, so it was really lean run . With that chip, how it has been programmed, the safe bhp limit would have been near 320 bhp. So I think it depends on base chip, what can you achieve with higher fuel pressure.

Extra injector, my friend build in this summer four (4) Turbo Uno injectors into his Coupe with TO4 turbo, he added also four relays, which are functioning according to the pressure. One relay or solenoid for each injector, then he adjusted the system so that first injector open in 1 bar, second in 1.2 bar and third in 1.4 bar. Fouth injector was for reserve, depending of AF readings. They are working very well, you can see it directly from AF meter, when they opens.

Yesterday I raised my fuel pressure up to 3.6 bar and my feeling is that I went to the wrong way. No problems with idling, but when accelerating with full throttle, I feel it much heavier, like I have extra 500 lb in my car. So back to lower fuel pressure.

- Jari -

Hi Jari ,... I think you ought to be able to adjust your fuel pressure from within your car

bet a day doesnt go by, that your fuelling doesnt change

I've heard of using Saab cold start injectors, boost activated above 1.2bar before, similar to your friends setup.

Joe

rs500 came equipped with 8 injectors (although not connected). Large injectors have poor control at low speed i.e. small pulse width, leading to poor idle and poor fuel mixing. 2 stage injection is the pro way, large injectors are a simple way.

rich

Just had a chat to Claudio at Perfect Touch about the latest unichip. He says as a general rule they can control injectors 50% larger than the standard items using them, so moving up to 16vt jobbies from 20vt ones should be fine.

They have them in stock and ready to go. The bad news is that they are more expensive than the older model at £395 fitted, and then mapping at £110 / hour.

that's good Simon isnt it

Nigel, you should be able to get a good £100 for your Unichip s/h

Joe

Why is running a higher fuel pressure any different from fitting bigger injectors? I'd have throught the ECU would have been equally confused as for a certain injection period more fuel will be injected giving the same problems as fitting larger injectors

John

I'll buy yor old unichip off you Nigel

It's my next move anyway.

Damn.. you read my mind Jimbo...

hehee,.. yep lets sell Nigel's unichip ,before he even knows about it!!

right £100 for starters

I've now taken to twice-daily resetting of the ECU Its the only way to keep close to PTS's correct mapping

I need to contact Dastek to see if they fancy doing me a discount on the new-fangled kit - perhaps they'll use me as a subsidised guinea pig

Anyone got details of who to speak to and a contact number?

surely paul can offer a good deal in PX against the newer unichip?

after all its only 6 months old, and he fitted it.

perhaps do a deal with paul and jimbo to cut costs down, but then again you cant be sure that the new unichip will solve your problem.

fergie has details of a guy at dastek he used to speak with.

I tell you again...Reset your ECU and pitch the lambda probe!
I had this problem for 1 whole year - you map a new chip... functioning wonderful...but after some driving with normal load your ECU will learn, that you are too rich and will adapt!
Thus we programmed ~30 chips - eyery time with the same result. I got richer and richer with my chips... very lean at low revs and very very rich at high revs...
Thus I had some problems at the beginning after installing the chip - because it was too richt at high revs... but after some time the ECU tried to adapt... but could not adapt enough - the chip now almost was satisfying... nevertheless this was no good solution.
Meanwhile I think that you can avoid this problem by pitching lambda probe... then you don´t have the closed loop any more...
I would try it
juergen

juergen - sorry, but we're losing something in the translation here - what do you mean by "pitching the lambda probe" - do you mean get rid of it?

Surely this would result in all sorts of awful running at lower revs - the whole idea of the lambda is to allow the ECU to hunt for stoich - without it, the ECU will just deliver what it THINKS the engine wants, not what it really needs.

I have visions of bore-wash from over-rich mixture, or detonation from weak mixture

Also, I imagine the ECU would throw a permanent error code if the lambda was disconnected

Nigel, why not try phoning Dastek direct and chatting to the guys there? Presumably they have some experience having done a lot of work on Fergies car.

contact details

Disconnect it (connector near battery in a left-hand-car)... you won´t get a failure code (as I know, maybe ground it).
Then the engine will run according to the map of the chip - if it is well mapped you will have no problem regarding lower revs etc...

check them out for 2 if you want,I was waiting on the new unichip for my next step,Barbz` hybrid turbo,3" elbow,bigger injectors,work done on the manifold, and running methanol in my aquamist

I've run my car with the lamda disconnected Nigel - not for long, but it seemed to be OK. Worth a go!

I drove my car for about 70 miles with the lambda disconnected without problems.

The AFR gauge showed a constant stoich measurement (which is how I realised that it wasn't connected)

Also I might add that when my lambda went to heaven - I wasn't getting any error codes come up.

Chris

Quote:

---

Surely this would result in all sorts of awful running at lower revs - the whole idea of the lambda is to allow the ECU to hunt for stoich - without it, the ECU will just deliver what it THINKS the engine wants, not what it really needs.

---

it's just the same as your 70%+ throttle maps which also do not use the lambda sensor. As long as the ECU is mapped it will be fine (unless you change fuel grade of course). Most people running aftermarket ECUs do not use lambda sensors at all as their maps are already fine-tuned for their setup, and so there is no benefit in using the signal.

John

I always said I wouldn't try to cover new Coupe tuning ground - I was always happy to let the likes of JohnS, Barbz, Mavric etc do this for me. I don't generally have the time or money to keep trying new stuff out.

However, it looks like I might be the first to try a stock ECU and a Unichip without a lambda

John - do you run a lambda? Do you know if the likes of Barbz and Mavric run one?

I have a new problem - I think it might be related.

On VERY light throttle openings, the car is either eccaerating or decelerating, and the transition between the two is very jerk (its actually a PITA to drive)

So - I can be trundling along in say 3rd gear at 20mph, and the ECU will just decide to cut the fuel (my AFR meter drops off the scale) A couple of seconds later (when the car has slowed a bit), it cuts in again and the AFR meter shows eighht or nine LEDs. This will happen about once every five seconds

In 1st gear its even worse - trying to hold say 5mph, the car will accelerate / decelerate / accelerate / decelerate every one or two seconds, without moving the throttle pedal at all.

Any theories?

the lambda is not the problem....

disconnect the air flow meter and see if ur problems go away...i am willing to put money on this solution...

If ur problems go away then you need to fit a map sensor with the bigger injectors...I am looking into a custom map sensor and i will be trying 440cc injectors with this.

i have tried my car without the lambda sensor and without the afm plugged in and the ecu reverts to a base map...the lambda sensor will make very little difference anyway due to its accuracy compared to a wideband...

with the afm disconnected the ecu will give a constant map and therefore will nto keep varying it to compensate the fuel delivered by the bigger injectors.......

I don't run a lambda sensor at all for engine management. The one I have is purely for tuning/visual validation.

I think Mavric does run a wideband sensor.


John

I've experienced this as well, it seems tobe something to do with the ECU trying to set the long term fuel trim and short term fuel trim right. I tried testing it with the SAFC II and with the stock lambda, it didn't matter if I were to turn the correction value up to +50% or -50%, at idle, adjusting the SAFC II have no effect on the integrated lambda reading, but when you start moving, the lambda will constantly be changing, no matter how you adjust the SAFC II output.

The ECU expects to see an oscillating value of 0.2~0.7V (successful cross count value over 0.45V) to ensure that the car is fuelling right under normal, non-WOT conditions. Therefore, when we modify the injectors or use the SAFC-II or other computers to try to alter this signal, it will inevitably result in a incorrect normal condition (manifested by the integrated lambda value, with 0 being ideal, and a negative for rich conditions while a positive reading for lean conditions. Just remember that for Lambda=1 =14.7, so for a smaller lambda, it means rich conditions, vice versa).

Now, in order to fool the computer and yet achieve the ARF we desire, we need a wide band lambda, such as the LM-1 to send out an analogue signal which matches the expectation of the ECU (Stock value: 0.2~0.7V = 14.7 +/- 0.5, new value = 0.2~0.7V = 12.5 +/- 0.5). By allowing the analogue to mimic what the stock ECU sees, it will not try to interfere the new AFR that you have mapped the car to run at. Anyway, it's just a simple way of explaining it, more detailed version will be available when I've done the conversion next month. I hope that helps.