1994 400HC Fuel map confusion.
Discussion
I have had occasional idle issues and so finally fired up the Rovergauge I bought last year. My car is a 1994 400HC, so has lambdas/ CATs , but when I look at the Rovergauge it shows I have Fuel Map 2, and Tune 2967.
Rovergauge also has the lambda trim type greyed out which suggests to me it can't communicate with them?
Google and the usual RV8 sites suggest that R2967 is indeed a 400cat ecu tune, but Map 2 seems to turn up as a non cat map, supported by what I see wrt the lambdas being greyed out.
At warm idle I have idle bypass reading of 9%, is this too low?
MAF reading direct 31%
Throttle corrected 0%
Hopefully someone can make sense of this and offer me some guidance on whether I have an issue here or not.
Cheers
Iain.
Rovergauge also has the lambda trim type greyed out which suggests to me it can't communicate with them?
Google and the usual RV8 sites suggest that R2967 is indeed a 400cat ecu tune, but Map 2 seems to turn up as a non cat map, supported by what I see wrt the lambdas being greyed out.
At warm idle I have idle bypass reading of 9%, is this too low?
MAF reading direct 31%
Throttle corrected 0%
Hopefully someone can make sense of this and offer me some guidance on whether I have an issue here or not.
Cheers
Iain.
legacy4cam said:
Thanks for replying Steve.
There is a tune resistor, more confusion though, its white wires but resistance measures 460ohms rather than 3900 I see quoted online for a White tune.
How do I know if the Ecu can see it.... or is that a daft laddie question....
Iain.
You have the answers there.There is a tune resistor, more confusion though, its white wires but resistance measures 460ohms rather than 3900 I see quoted online for a White tune.
How do I know if the Ecu can see it.... or is that a daft laddie question....
Iain.
470ohm is green tune for map 2. Rovergauge is saying map 2 so the ECU is seeing the resistor.
Get or make yourself a white tune and go from there.
Steve
Quick google suggest £30 for a new one....
Making one...is it as simple as cutting off my existing one and soldering and insulating a new one to the existing connector. I assume Marlins for the resistor is okay, and am I asking for something specific, I read that the existing are 1/2 watt, but mention on a 1 watt being compatible and easier to use.
Thanks for the help Steve.
Making one...is it as simple as cutting off my existing one and soldering and insulating a new one to the existing connector. I assume Marlins for the resistor is okay, and am I asking for something specific, I read that the existing are 1/2 watt, but mention on a 1 watt being compatible and easier to use.
Thanks for the help Steve.
legacy4cam said:
Tvr parts have a "blue" which they advertise as for all CAT equipped cars. Doesn't seem to be any off the shelf 3900ohm resistors, but I'll keep looking.
Should running the car with no resistor force the ecu to run the cat map?
No tune resistor = Limp Home Map, Map 0, which is indeed a CAT map (closed loop).Should running the car with no resistor force the ecu to run the cat map?
http://www.maplin.co.uk/p/metal-film-06w-39k-ohm-r...
Mark/Blitz, cheers for response, does the one above look suitable?
From the first post do you agree my car appears to have the wrong map in place, and should I be concerned/have the opportunity to improve significantly the engine efficiency with something new from the work done by others to apply more modern maps.
Grateful for the help, great to have a forum to canvass opinion and help from.
Iain
Mark/Blitz, cheers for response, does the one above look suitable?
From the first post do you agree my car appears to have the wrong map in place, and should I be concerned/have the opportunity to improve significantly the engine efficiency with something new from the work done by others to apply more modern maps.
Grateful for the help, great to have a forum to canvass opinion and help from.
Iain
Umm- a 1994 engine should be running white tune anyway. The green tune does not cycle the catalyst properly and the emissions are higher, but its better for MPG and less shunting at low speed. Once you go back to white tune the lambda probes will need to work to get the fuelling correct, but RoverGauge will show you the fuel trim levels moving if alls well. You must reset the ECU by unplugging / replugging it after a resistor change, then get the car hot, and let it idle for 2.5 mins- this will allow the ECU to re-learn its fuel settings. If you dont do this the car may shunt badly as the fuel trim levels may be wrong. That resistor will do fine.
Okay, picked up a 3900ohm resistor from Maplins, soldered into the plug and as the gurus suggested, I now have an ecu running map 5, lambda so can watch trimming at idle. Not had time to do much more but will use it for work tomorrow.
Might be wishful thinking, but car seemed to be less rich when idling in garage , last night I had burning eyes from the fumes....
One question for blitz or Steve, there is a bit of an offset between the 2 lambdas,I'll monitor to see if they continue in that state once it's done a few miles.
I'll try the heat shield as well, and the inlet hose looks rough, anyone come up with a budget alternate to the usual suspect for replacement.
Might be wishful thinking, but car seemed to be less rich when idling in garage , last night I had burning eyes from the fumes....
One question for blitz or Steve, there is a bit of an offset between the 2 lambdas,I'll monitor to see if they continue in that state once it's done a few miles.
I'll try the heat shield as well, and the inlet hose looks rough, anyone come up with a budget alternate to the usual suspect for replacement.
legacy4cam said:
......One question for blitz or Steve, there is a bit of an offset between the 2 lambdas,I'll monitor to see if they continue in that state once it's done a few miles. ..........
Yes there will be an offset.The throttle body being on one side of the plenum means the air flow is not equal bank to bank.Also the Lambda sensors can lose performance over time and normally get 'lazy' rather than fail. In your case if the lambdas have not been in use for some time I would just be thankful they are working at all.
Steve
Update - I fitted the resistor , map now shows as Map 5 , and car run okay for the 60 miles I did with the laptop on the passenger seat, bit of low speed shunting, and occasional high idle at rest for a period of a few seconds.
I suspect that I may need to check / set base idle and CO/AFM from basic start up again, as the car has has lambdas and an AFM in the period immediately before I got the car, so it may never have been correct since whatever caused the car to be fitted with a 480 ohm resistor, which on inspection looks like another home made affair ....
However, yesterday (Rovergauge left at home) the car got into a real kangaroo mode, cut out and wouldn't restart , wouldn't clear until I did a ECU reset so didn't catch the codes or Rovergauge data...
What does the ECU reset instantly that would have caused such poor running and failure to start...if I know that it may narrow down my fault area somewhat.
I intend to go back to the start , and check for air leaks, test again the Stepper motor ( wiring faults to these???) as my original symptom was poor idle and shunting that I did not experience previously.
I believe it's my own fault since I advertised it for sale, I may rename it Herbie! 5000miles lst yr and never missed a beat despite the wrong map....hope I have done the right thing getting it back to the right one...sometimes ignorance is bliss!
Iain.
I suspect that I may need to check / set base idle and CO/AFM from basic start up again, as the car has has lambdas and an AFM in the period immediately before I got the car, so it may never have been correct since whatever caused the car to be fitted with a 480 ohm resistor, which on inspection looks like another home made affair ....
However, yesterday (Rovergauge left at home) the car got into a real kangaroo mode, cut out and wouldn't restart , wouldn't clear until I did a ECU reset so didn't catch the codes or Rovergauge data...
What does the ECU reset instantly that would have caused such poor running and failure to start...if I know that it may narrow down my fault area somewhat.
I intend to go back to the start , and check for air leaks, test again the Stepper motor ( wiring faults to these???) as my original symptom was poor idle and shunting that I did not experience previously.
I believe it's my own fault since I advertised it for sale, I may rename it Herbie! 5000miles lst yr and never missed a beat despite the wrong map....hope I have done the right thing getting it back to the right one...sometimes ignorance is bliss!
Iain.
Its important to let the long term trim settle or it may Kangaroo- so plug rover gauge in, and watch the long term trim slowly move at idle on a hot engine- if you do an ecu reset it will start at zero and slowly move over about 2.5 mins. If you watch the short term as well- it may start cycling but either positive or negative, but as the long term trim sets it should start to cycling around the mid point, so it will swing plus and minus.You don't need to set the CO trim at all on the white map, as the long term trim is in place of the CO trim on the side of the AFM, and automatic. General problem with shunting is the lambda map is quite lean- ie 14.7 :1 AFR, and this can make the car shunt if everything else is not spot on. As a work around if you switch to green map, and set the CO trim to run a bit rich- say 13.5:1, the engine will be much smoother, but its bad for the catalyst and the environment, but this maybe whats been done by the previous owner to get around the shunting. In term of poor idle, don't always blame the ECU side of things, it could be something as simple as a bad plug extender.
I'm away for weekend, so will get back to it on Tuesday.
When I first set it to the white map , the long term trim seemed to set up to odd bank at -45 and even to -25 after idling for 10 mins or so at full temp, fans cutting in and out.
For info, no plug extenders, just a set of leads straight onto plugs (!) Not given any bother, and no arcing witnessed under bonnet in darkness (not scientific I grant you ) . I will revisit these also, and look at whether extenders might be a wise purchase.
As always ta for advice....time is my enemy at the moment, but I don't know if there is anyone local to central Scotland who would actually do the basics and not simply throw parts and (my) money at the problem...
Cheers, Iain.
When I first set it to the white map , the long term trim seemed to set up to odd bank at -45 and even to -25 after idling for 10 mins or so at full temp, fans cutting in and out.
For info, no plug extenders, just a set of leads straight onto plugs (!) Not given any bother, and no arcing witnessed under bonnet in darkness (not scientific I grant you ) . I will revisit these also, and look at whether extenders might be a wise purchase.
As always ta for advice....time is my enemy at the moment, but I don't know if there is anyone local to central Scotland who would actually do the basics and not simply throw parts and (my) money at the problem...
Cheers, Iain.
legacy4cam said:
However, yesterday (Rovergauge left at home) the car got into a real kangaroo mode, cut out and wouldn't restart , wouldn't clear until I did a ECU reset so didn't catch the codes or Rovergauge data...
What does the ECU reset instantly that would have caused such poor running and failure to start...if I know that it may narrow down my fault area somewhat.
Iain.
If the car does it again, check for fault codes 02 and 03 (RAM Fail, battery or ECU disconnected and Incorrect checksum value).What does the ECU reset instantly that would have caused such poor running and failure to start...if I know that it may narrow down my fault area somewhat.
Iain.
Your ECU has 19 bytes of internal RAM that is battery-backed, normally this means the values held there are not cleared with ignition off or upon the normal ECU code reset. The 'always On' supply for this RAM backup is removed when the ECU connector is disconnected and the operating values and fault codes are reset.
To verify that the values held in the battery-backed area of RAM are valid a check(sum) is done during start up and shut down. If the result of the check is not as expected the ECU assumes the battery-backed RAM data has been corrupted or is unreliable, and fault code 03 is set. Upon the next code reset and with fault code 03 set, the internal RAM is reinitialized, and if the check routine is then successful, fault code 03 is cleared, if not the unreliable RAM data condition continues.
As to the cause, if there's no fault code 02 (usually dodgy ECU connector) also being set, the ECU's internal RAM or its associated circuits are suspect so try another ECU unit.
The contents of the battery-backed RAM and values held there can be viewed in the later versions of RoverGauge (0.9.2) by selecting Options/Battery-backed RAM ..., the values are shown in hexadecimal. Finally, simply resetting the ECU does not in itself cure any fault conditions it only clears the battery-backed operating values (which the ECU then has to re-learn from zero) and fault codes (which will eventually return if the fault has not been resolved).
Mmmm,
Got some of that ....my car has a master battery isolator, which doubled as ECU reset in this instance, so I guess that clears the RAM also.
If the ECU is suspect, what is the best source of a reliable replacement, and is there differences between the TVR ECU's and the Land Rover parent unit which you read the part number from on the labels..
Does anyone do bench testing of the units that I could send mine to for checking?
As an aside, is it usual to have "400 HC" written in magic marker on the ECU , or is that an indicator that my car may already have had an ECU change and someone writes this onto a used ebay special and marks price up accordingly...
Got some of that ....my car has a master battery isolator, which doubled as ECU reset in this instance, so I guess that clears the RAM also.
If the ECU is suspect, what is the best source of a reliable replacement, and is there differences between the TVR ECU's and the Land Rover parent unit which you read the part number from on the labels..
Does anyone do bench testing of the units that I could send mine to for checking?
As an aside, is it usual to have "400 HC" written in magic marker on the ECU , or is that an indicator that my car may already have had an ECU change and someone writes this onto a used ebay special and marks price up accordingly...
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