Rovergauge questions
Discussion
I'm still getting to grips with Rovergauge and would like to know if what I'm seeing is 'normal' and nothing to worry about.
Recently, I hooked up Rovergauge to my 4L Chimaera to help track down an overfuelling issue where the short term lambdas were all over to the left, constantly trying to reduce the fuel supply to the injectors. I tracked this down to a perished vacuum hose between my fuel regulator and the plenum near the stepper motor. The short term lambda reduced right down to -20% to -30% on a warm engine. Long term lambdas always sat a zero - not sure why. All looked OK to me and the car ran fine.
After a few weeks I thought I'd see if anything had changed with the Rovergauge readings and to continue to get some experience using the software. This time I noticed that the long term lambdas were at -100% with the short term still around -20% to -30%. This was with a warmed engine after a 20 min drive. See below:
I then switched off the ignition and disconnected the ECU to reset it. Afterwards, the long term lambdas were back sitting at zero and the short terms were averaging around the -50% to -60% now. I also noticed the occasional time where the short term lambda readings disappeared for a few secs and then came back. Anything to worry about? Final thing I've noticed is that the Rovergauge engine temp doesn't follow my dash gauge. The PC readings rise faster than the dash gauge and are about 20 degrees higher after about 10 mins. After a decent road run, say 20 mins, both PC and dash are about the same (within 10 degrees). Anything unusual with that?
The car still drives fine but I was wondering if the lambdas show a -50% or more negative value is the car overfuelling? Very rarely do they pop across to the positive side and I've checked that by logging a short run.
I'd appreciate your thoughts.
Recently, I hooked up Rovergauge to my 4L Chimaera to help track down an overfuelling issue where the short term lambdas were all over to the left, constantly trying to reduce the fuel supply to the injectors. I tracked this down to a perished vacuum hose between my fuel regulator and the plenum near the stepper motor. The short term lambda reduced right down to -20% to -30% on a warm engine. Long term lambdas always sat a zero - not sure why. All looked OK to me and the car ran fine.
After a few weeks I thought I'd see if anything had changed with the Rovergauge readings and to continue to get some experience using the software. This time I noticed that the long term lambdas were at -100% with the short term still around -20% to -30%. This was with a warmed engine after a 20 min drive. See below:
I then switched off the ignition and disconnected the ECU to reset it. Afterwards, the long term lambdas were back sitting at zero and the short terms were averaging around the -50% to -60% now. I also noticed the occasional time where the short term lambda readings disappeared for a few secs and then came back. Anything to worry about? Final thing I've noticed is that the Rovergauge engine temp doesn't follow my dash gauge. The PC readings rise faster than the dash gauge and are about 20 degrees higher after about 10 mins. After a decent road run, say 20 mins, both PC and dash are about the same (within 10 degrees). Anything unusual with that?
The car still drives fine but I was wondering if the lambdas show a -50% or more negative value is the car overfuelling? Very rarely do they pop across to the positive side and I've checked that by logging a short run.
I'd appreciate your thoughts.
The reason for the shift in long term trim is it resets when you disconnect the ECU to zero. Then once the engine is nice and hot and at idle, the long term trim will slowly shift if the short term is either constantly adding or removing fuel until the short trim start to cycle around a mid point, at which point the long term trim stops moving. This process repeats each time the car is at idle when hot. If the long term trim is at max, then a sensor input is wrong, or the map is wrong.
The chip you show is on a MA scrambler board, but im surprised its not labeled, even just to persevere the data, as exposure to UV through the window wipes the chip. Mind you locked inside a dark ECU it should be OK. Always best to cover with black tape and then a label with the chip description.
The chip you show is on a MA scrambler board, but im surprised its not labeled, even just to persevere the data, as exposure to UV through the window wipes the chip. Mind you locked inside a dark ECU it should be OK. Always best to cover with black tape and then a label with the chip description.
Edited by blitzracing on Thursday 18th October 14:45
So after the reset, I might not be seeing a change in the long term trim simply because I'm not leaving it long enough at idle for changes to be seen. Would that be correct? After 10 mins at idle it has still been sitting at zero.
Since I took the picture of the ECU I have put some tape over the chip window, just to be safe.
Since I took the picture of the ECU I have put some tape over the chip window, just to be safe.
Dalamar said:
So after the reset, I might not be seeing a change in the long term trim simply because I'm not leaving it long enough at idle for changes to be seen. Would that be correct? After 10 mins at idle it has still been sitting at zero.
Since I took the picture of the ECU I have put some tape over the chip window, just to be safe.
The engine needs to be pretty hot as well- i think mid nineties, so if the long term trim not moving it may simply be too cold.Since I took the picture of the ECU I have put some tape over the chip window, just to be safe.
So, if I get the car nice and warm on a decent drive and find the following:
The long term trim is at zero or at least not maxed out
The short term trim is bouncing around on the negative side but not maxed out.
Then all is OK and I don't have any overfuelling issues. Does that sound about right? I haven't checked my MPG in a while but the car certainly 'smells' better after I fixed that perished hose plus the short term trims started to operate properly.
By the way, when I had that -100% long term trim state there where no fault codes listed.
The long term trim is at zero or at least not maxed out
The short term trim is bouncing around on the negative side but not maxed out.
Then all is OK and I don't have any overfuelling issues. Does that sound about right? I haven't checked my MPG in a while but the car certainly 'smells' better after I fixed that perished hose plus the short term trims started to operate properly.
By the way, when I had that -100% long term trim state there where no fault codes listed.
Some final bits and pieces on this topic from me...
Replaced the ignition coil this weekend and re-crimped the connections to the power amplifier too. It was the last thing in the ignition circuit that I wanted to change this year as I'd already changed plugs, leads, cap and rotor. I disconnected the battery as I was messing around with the electrics so the ECU had another reboot.
The car started up fine and no real noticeable difference with the new coil which was a Bosch 0221122392. The original look ancient and had a broken cap where the connectors are so I thought I'd get it sorted.
Anyway, with Rovergauge attached for the warm up and once warm the short term trims were bouncing around zero and even went to the positive side which I'd never really seen before. The long term lambdas were at zero for a long time but after a laptop crash and restart went almost both hard over on the negative. Still no fault codes.
Notice now my maximum rev limit has changed from 5400 to 6800 as in the previous uploads! No idea why. Any thoughts?
Finally, I thought I'd see how she drove (the most important thing) and to test the mpg before I took her off the road at the end of the month. She drives great, happy in 4th at 30 mph, and no shunting at all. The run I did was from my local petrol station (filled right up), 5 miles to the motorway with the usual 5pm town traffic, around 20 miles on the motorway up and down, then the 5 miles back to fill up again. All in all 33 miles measured on the odometer and by GPS and to fill back up to the second click, 4.2L rounded up. That's 35 mpg! I admit I was tip toeing around on the motorway going the same speed as the trucks as I thought the town driving was going to kill the mpg but what a surprise. The last time I'd measured the mpg was when I first drove her home after buying last year. That was 23 mpg from Belfast to Manchester.
Sorting out the ignition items has really made a difference this year, from lots of shunting even when warm to a smooth 30 mph in 4th with a great mpg.
Replaced the ignition coil this weekend and re-crimped the connections to the power amplifier too. It was the last thing in the ignition circuit that I wanted to change this year as I'd already changed plugs, leads, cap and rotor. I disconnected the battery as I was messing around with the electrics so the ECU had another reboot.
The car started up fine and no real noticeable difference with the new coil which was a Bosch 0221122392. The original look ancient and had a broken cap where the connectors are so I thought I'd get it sorted.
Anyway, with Rovergauge attached for the warm up and once warm the short term trims were bouncing around zero and even went to the positive side which I'd never really seen before. The long term lambdas were at zero for a long time but after a laptop crash and restart went almost both hard over on the negative. Still no fault codes.
Notice now my maximum rev limit has changed from 5400 to 6800 as in the previous uploads! No idea why. Any thoughts?
Finally, I thought I'd see how she drove (the most important thing) and to test the mpg before I took her off the road at the end of the month. She drives great, happy in 4th at 30 mph, and no shunting at all. The run I did was from my local petrol station (filled right up), 5 miles to the motorway with the usual 5pm town traffic, around 20 miles on the motorway up and down, then the 5 miles back to fill up again. All in all 33 miles measured on the odometer and by GPS and to fill back up to the second click, 4.2L rounded up. That's 35 mpg! I admit I was tip toeing around on the motorway going the same speed as the trucks as I thought the town driving was going to kill the mpg but what a surprise. The last time I'd measured the mpg was when I first drove her home after buying last year. That was 23 mpg from Belfast to Manchester.
Sorting out the ignition items has really made a difference this year, from lots of shunting even when warm to a smooth 30 mph in 4th with a great mpg.
You are not the first person to comment on the shift in RPM limit but I have no idea why it is not consistent. Your long term trim is still very high, its basically saying the engine is running too rich, so its removing fuel to get it somewhere near correct. The RV8's do run better a bit richer than the 14.7:1 AFR the lambda setting tries to hold, but as the fuel map is unknown, it may not be ideal, so the fuel trim is making up for it. TBH, id be trying a stock TVR chip in there and see if the trim gets better.
Thanks again. I'll program one of those chips using Stevesprint's info at http://www.remap-14cux.uk/ over the winter. It will be interesting to see if there is a difference like you say.
By the way, is this the correct PROM to try?
http://www.remap-14cux.uk/bins/R3652_400.bin
My car is the 1995 Chimaera 4L.
http://www.remap-14cux.uk/bins/R3652_400.bin
My car is the 1995 Chimaera 4L.
I’ve bought myself a spare ECU recently as I know mine has had water in it in the past so I saw one from a 450 Chimaera (2000) advertised on the internet and decided to go for it.
I was looking to put that Steve Sprint chip in it but before I do that I was hoping to give the ECU a quick fire up to make sure all is working beforehand. I realise the fuel map won’t be correct but could you please let me know if this would be ok to do?
I was looking to put that Steve Sprint chip in it but before I do that I was hoping to give the ECU a quick fire up to make sure all is working beforehand. I realise the fuel map won’t be correct but could you please let me know if this would be ok to do?
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