Mapping Issue or 3rd party ECU?

[Monsterlime]

Ok, so this is a slight follow up to my post last year about my odd idle issues.

The car is running rich, it has been remapped and chipped, but is still running rich. It has a John Eales 218 cam and a Clive F Y Pipe - that is extent of the modifications.

I was not there when it was mapped, but it has had that white wire loop removed, which I believe makes it ignore the lambda sensors (because some cats have been removed)?

The other week, as I was taking her for a service, she was cutting out every time I pulled up at traffic lights etc. However, when I actually got there, it stopped and my mechanic couldn't reproduce it (this is somewhat annoying) and she hadn't done it prior to this for a few months. After the service, she hasn't done it, but on start up when warm the idle does drop really low before picking up again (this was happening before the service). The stepper motor was removed and all cleaned up, plugs changed (the old ones were black although the contacts themselves looked ok) etc.

My mechanic has run it through the Rover Gauge, we have changed the stepper, checked for air leaks all round the plenum and can find nothing wrong. It has also been suggested this might be because I don't use it enough, so am remedying that and will see how it goes but I have a feeling the issues will come back.

Is this a mapping issue? Can this be "fixed" with a better map on the Lucas ECU or would I just be better off putting in a 3rd party one? While I have been wavering on ownership, when I drive her and she works, it is superb and I have no desire to sell.

I have been considering some more extensive modifications - trumpets, larger afm, and maybe even a supercharger at some stage and I know a replacement ECU would bring out all of the potential of that but really, I'd just like it run right to begin with (and get a bit better fuel economy ).

[blitzracing]

If you are running green tune, you set the idle mixture with the adjustment on the side of the AFM- but who mapped it? Any mapper I know of would have set this correctly to get the idle mixture correct. You dont need to run the green tune (non cat map) just because you dont have cats, the white tune (catalysts map)is fine as you dont loose any power and the mixture control is more accurate with lambda probes- but which map did you have changed?. The idle wont be stable if the mixture is too rich, but it may just be a case of winding the CO trim on the side of the AFM to lean it off.

[Monsterlime]

It was mapped at Austec in Essex, but I haven't really been given much info on what was actually done. I know for definite that the lambda probes have been disabled/bypassed etc, so I would say it is likely using the green tune.

I was told that they had a LOT of problems getting it to idle correctly, and it only did so once they bypassed the lambda's.

Is there somewhere you would recommend me getting it remapped?

Thanks!

[blitzracing]

If you still have the lambda probes inplace and connected, id try going back to the white tune resistor, even if just as a test. You will need to let the car idle for at least 2.5 mins over 90'C engine temp to let let the mixture set it self as should and see how it idles. If you dont have the probes still then try winding the idle mixture screw on the side of the AFM- one way will make the engine run rich, like its on choke- the other will make the idle become lumpy as it leans off. You want to make it run lean, then back it off just far enough to get a smooth idle, and no more. Otherwise Jools at Kits and classics can map for around £250.

http://www.kitsandclassics.co.uk/engine-ecu/

[Monsterlime]

Superb, thanks. I believe the probes are still there, just the resistor was removed (which I do still have). I assume I should be disconnecting the battery/reconnecting it if I put the resistor back on?

[davep]

Monsterlime said:

Superb, thanks. I believe the probes are still there, just the resistor was removed (which I do still have). I assume I should be disconnecting the battery/reconnecting it if I put the resistor back on?

Assuming you haven't got a NAS 14CUX unit fitted, if the ECU doesn't see a tune resistor the software will run in limp home fuel map mode. Try connecting the White tune resistor and running with fuel map 5.

[Monsterlime]

Ok, so just to confirm, this is the tune resistor -



And would it be these instructions to change the fuel map - http://www.pistonheads.com/GASSING/topic.asp?h=0&a... ?

Not exactly straightforwards, but will try. Am tempted to get it just properly mapped by a pro, since I am definitely an amateur!

Of course, I've made everything worse tonight by leaning on the roof in slightly the wrong way while washing it, and busted the stitching on both rows at the top. Only about 4 inches worth, but its pretty bad. I knew I needed a new roof soon anyways, but now I REALLY need a new roof.

What to do first..

[davep]

Monsterlime in your first post you said the car has had a new 14CUX chip, which was then fuel mapped. As part of that mapping session the tune resistor was removed so it could be that the mapper has accessed the code in some way and reprogrammed it to disregard the tune resistor and use one fuel map only (as in NAS versions), probably Fuel Map 5. Before reconnecting a tune resistor you first need to determine what map the car is using, your mechanic that has RoverGauge will be able to tell you. If it was me I'd also contact the mapper who originally installed the new chip and ask the same question and then inform him that the fuelling is still pants. Then get your roof fixed.

[TV8]

Was it mapped in Essex or Crawley? The Crawley place wanted to remap my old car when it had a faulty AFM.

See if you can get a standard chip and try that. If you are relying on garages, give Dan Taylor a call and leave the car with him. He has a bunch of spares and will get to the bottom of why the car isn't running properly.

[blitzracing]

davep said:

Monsterlime said:

Superb, thanks. I believe the probes are still there, just the resistor was removed (which I do still have). I assume I should be disconnecting the battery/reconnecting it if I put the resistor back on?

Assuming you haven't got a NAS 14CUX unit fitted, if the ECU doesn't see a tune resistor the software will run in limp home fuel map mode. Try connecting the White tune resistor and running with fuel map 5.

^^^ This big time. In Limp home mode car will run pretty poorly- and leaving the tune resistor out strikes me that someone did not know what they where doing. It terms of ECU reset, you can disconnect the battery, or just unplug the ECU for a short period- a few seconds will do. Dont forget to let it re-trim afterwards- the initial fuelling may be some way out on a reset ECU.

[Monsterlime]

Ok, so, I plugged my Rover Gauge in tonight when I got home, and this is what it displayed -



From what has been said, I assume that this is rather wrong? Unless 1 suddenly means 5 in TVR land (wouldn't exactly be a surprise )!

[davep]

Monsterlime said:

Ok, so, I plugged my Rover Gauge in tonight when I got home, and this is what it displayed -



From what has been said, I assume that this is rather wrong? Unless 1 suddenly means 5 in TVR land (wouldn't exactly be a surprise )!

You are running with the map for Australia and the rest of the world (180 Ohms), Fuel Map 1, which is hard to understand as there is no tune resistor connected to your ECU. Fuel Map 1 is an open loop map (non-cat) and would probably explain the over-fuelling as you've come from a R2967 TVR Cat tune using Fuel Map 5. Here's the various tune resistor details:


180 Ohms Red No cat - Australia and "the rest of the world."
470 Ohms Green No cat - UK and European vehicles without catalytic converters
910 Ohms Yellow No cat - Saudi vehicles (without catalytic converters)
1800 Ohms Blue Cat - Saudi vehicles (with catalytic converters)
3900 Ohms White Cat - TVR, USA and European vehicles with catalytic converters

When the car was mapped Fuel Map 1 was selected (must be coded in the software as each time I've pulled the tune resistor the limp home map is selected) and the non-cat fuel map tuned to suit your car. So perhaps the first thing to check is if adjustments in the MAF CO Trim level make a difference. The procedure for this is on Blitz's website.

Edited by davep on Tuesday 24th February 18:01

[blitzracing]

Taking two steps backwards- I dont know why the car would have need re chipping in the first place- the modifications would not appear to be that big and far as I can see the cam is pretty mild. I reckon the TVR map should be just fine for this, so Id pop the white tune resistor back in and give it a go. At least this way the ECU will correct the idle mixture automatically. Rover Gauge should show you the fuel trims after a while- as as long as the long term trim is not sitting at 100% you have a good basis to start with.

[Sardonicus]

blitzracing said:

Taking two steps backwards- I dont know why the car would have need re chipping in the first place- the modifications would not appear to be that big and far as I can see the cam is pretty mild. I reckon the TVR map should be just fine for this, so Id pop the white tune resistor back in and give it a go. At least this way the ECU will correct the idle mixture automatically. Rover Gauge should show you the fuel trims after a while- as as long as the long term trim is not sitting at 100% you have a good basis to start with.

What Blitz said

[Monsterlime]

Thanks all!

I'll look at putting the resistor back in (glad I have a butane powered soldering iron), and if that doesn't improve things, I will take the car up to Kits and Classics.

I'm pretty sure the reason it was fiddled with initially was due to the fact it wasn't idling properly after the new cam and Y pipe were fitted, however I believe part of that was tracked down to a failing ignition amp. It was the early part of last year this started, so my memory might be faulty!

[PH430]

Maybe you have a temp sensor for the ECU thats not giving the write note. Or you have air in your Cooling system. I had that problem running rich at low revs when cold. On idle it was running like a pig.

[Monsterlime]

I did check for air etc, and couldn't find anything. I would also expect that to happen all the time? It only cuts out when hot, not cold, and had not done it until Monday night, when I moved it about on the drive, since the service.

So, I went to put the tune resistor back when I got home, but I found this -



What is it? The dial thing is wired into where the tune resistor goes. Is it a work of genius, and will allow me to alter the resistance on the fly, or is it something else entirely?

[blitzracing]

theres nothing to stop you putting a variable resistor in there (cant see if thats what it is though) , and then changing the map as you wish- but you would need to use a test meter to get the correct resistance value before powering up the ECU- you also need to do an ECU reset if you do change the resistance, or it throws a fault code. If it is a variable resistor you could try setting it to 3.9 k ohms to go back to map 5. At least that accounts for the very odd selection of map 1.

[Monsterlime]

Hmm, thanks. My electrical testing abilities are limited so I just want to confirm - can I test the resistance while it is still attached to the car? Or should I disconnect it, set it, and then reattach? Or just disconnect the ECU and the battery?

Would better pics help?

Could it be something else?

Thanks!

Edit - After a quick Google, it definitely looks like a variable resistor. On a bigger version of the pic, I can see 3 wires coming out of it, which indicates it is a variable potentiometer, so I assume only 2 are actually connected, although I'd need to remove the tape to confirm.

Edited by Monsterlime on Wednesday 25th February 19:37

[davep]

It looks like the same type of variable pot that's used in the wiper speed circuit! Having a variable resistor in the ECU's tune resistor circuit is not a good idea, a switched resistor array would be a better solution.