Instructions to change fuel maps on 14CUX Griffith, Chimaera

As said you can seet the LT trim get added bit by bit with no genuine feedback until it hits 100% with RG. I never ran the test long enough to throw and error code, as it takes some time for the ECU to work out it has lost control of the mixture- several minutes of no lambda switch signal.

Well, having been at TVR Griff Own for 15 years it’s a delight to see so much work being done on the ECU, mine had the original 1992 Map. I’m no expert but have taken the plunge and purchased a cable from Mark and read all your contributions, thanks . Steve has been extremely helpful and after purchasing a programmer and some blank chips, I have a working and up-to-date ECU and Griff is now purring like a cat and fume free . I’ll be trialing the extended range RPM too. I may occasional ask a few questions that may seem quite simple to you experts but please bear with me while I come up to speed.

MPO it's good to see another Griffith pre-cat owner taking advantage of this thread and Steve's site, I'm assuming you've a pre-cat as you mentioned an original '92 tune (R2422?) being fitted to your car. What tune are you using now? Any questions, simple or otherwise, fire away, we're all in the same boat.

My apologies Jools, in addition to the above there is a decision branch in the Adjust Long Term Trim code that prevents long term adjustment if Engine Coolant Temperature is less than 87 degrees C in closed loop. So you are correct, long term trim values are calculated but not applied until ECT reaches 87 degrees or above, so yet more wasted processing effort.

It's quite usual to have load sites where you think they're not required .. though a many cylinder large capacity engine on management could easily run down to very low speeds (sub 500rpm easily) so you have to account for someone using those revs I suppose (eg pulling a tree stump out with a land rover ..). Also you might have a situation whereby your transmission is stuck in a high gear and you are forced to drive in rpm bands you wouldn't normally go into. On a production engine install there's all sorts of scenarios that in 99 percent of driving you'd never encounter, but have to be accounted for.
I do wonder why they're quite so closely stacked bearing in mind the limited number of rpm sites the lucas has, and it's perfectly reasonable to assume that on our higher revving engines we might rob peter to pay paul and move the lower rpm sites up a bit to make better use of what we have. You have to be a aware of fuel dropping out of the airstream at low engine speeds so maybe the developers decided it was better to have greater resolution at very low revs and let the higher rev stuff take care of itself.
The engine needs fuelling from the end of the cranking stages to full engine running mode too so some degree of fuelling control is still required at low revs to take care of that also. Whether quite so much control is required is open for debate.
But until anyone comes up with a definite reason to start moving them all I would suggest that things work OK as they are so don't go messing too much. It's an interesting question that I've casually wondered about myself but never given it too much thought, if you see what I mean.

Absolutely WOW! Well done to you all!
What a read this whole thread has been and taking about a full day from post 1 to finish.
I am really pleased to have found people that have dedicated their free time to put some much development into something that could easily be replaced by something newer and more programmable as I was about to do.
Maybe in the wrong area for the vehicle but completely relevant to the ECU.
With all the information and guidance I think I might dabble with the ECU and see what improvements I can now do.

I currently have an Australian delivered 93 Discovery running the 3.5 V8 v-belt and 14CUX and was wanting to play with the ECU and was even looking at going the MS route but armed with so much information I am reconsidering.
I have only just given the top end a complete refresh after making some poor decisions and buying a badly rebuilt 3.9 that was used as parts for the 3.5. And hopefully after tonight I should have it running again after the distributor decided to fall apart internally then being butchered by myself.

I also loved to hear that the RG program has been updated so much in such a small amount of time. I think I was still using version 0.5.0 as I didn't expect so many updates. I built the cable myself after sourcing the parts locally.

Now with all this lets see what I can break!

Regards, Kieran

Kieran

I'm delighted to hear that this project could help save another 14CUX and should you have any questions please do not hesitate to ask how ever big or small.
I have to confess I agree with jjohnson23 that a number of us would really appreciate a copy of your prom as we are yet to see a 3.5L 14CUX. You may already know you can save the prom image via RoverGauge's file menu option "Save PROM image". Please let me know if you don't mind and I'll send you a private message with my email address.
Cheers
Steve

Welcome Kieran. Your screenshot shows that you have an auto box on your D1, that's a first for this thread. If you have the time and the inclination could you do a test drive with data logging On and perhaps share the resulting log file in your dropbox account. Also I have the disassembled listing file for your tune where you can 'read' the code rather than looking at the binary version, if you're interested let me know how to upload it to your dropbox or perhaps I can get SteveSprint to put it up on his website.

From what you say the D1 would have/do run with open loop tunes (Fuel Maps 1, 2 or 3), putting cats on and not changing to a closed loop tune (Fuel Maps 4 or 5) would mean the vehicle running like a dog.

Kieran,thanks for giving us access to your prom image.
I`m going to make a straight copy over the next week or so and give it a go in my car.
The maf scalar is quite different to the 3.9 engines so it should make for some interesting reading of the log file afterwards.
Steve sprint,I will let you know how much of the table is used compared to the 3.9 tunes if you wish.

Guys, a quick method for doing file compares to identify differences in the data variables, scalers, etc., between two tunes is to use the Windiff.exe utility. This is especially useful on .lst files, for example:



The above shows the Fuel Map 1 area for R2832 (red) and a TVR R2967 (yellow).