High MAP reading

StewartIngram · 15th May 2023, 18:50

OK this gets a little involved, but bear with me?
I have a DIY converted (not factory fit) LPG system, which has been used on 3 identical KV6 2.5 cars. Since fitting to this car (and possibly on the previous one - not sure) I've had a problem with the engine light coming on, always with the same (related?) readings.
Basically around cyl6 misfire, low fuel bank 2, sometimes bank 1 as well, lambda sensor occasionally not operating correctly.
The fault only seems to happen when I use a bit of throttle, say to overtake, and reach around 2700 rpm. If I ease off quickly when it flashes, it goes out, otherwise when it stays on I get the fault codes; I can't remember the exact codes without checking again.
It is fine on petrol. I have done quite extensive testing to pin it down, but not with urgency as it more of an annoyance than a fault but I'd like it fixed.
Having established petrol is ok, that actually eliminates quite a few things. Common to petrol is the ignition (plugs etc), I have checked all that as ok. (I have many spares so have been able to swap part around during diagnosis.)
I am also aware that ignition faults sometimes show up earlier on gas than on petrol.
I have done the correct calibration of the lpg ecu as per the KING (lpg) instructions a few times. I've even drained the gas tank, and removed the pick-up pipe in case it was twisted and had a partial blockage. Al the mods to run on lpg have been done exactly the same on all 3 cars, and I have meticulously checked all pipes for cracks etc that would cause an air leak.
Yesterday, I had another go, with the downloaded TinleyTech helpful instructions in front of me.
I again checked the ecu setup, & recalibrated it. I then suddenly noticed that the help page mentioned the MAP pressure is stated as "should be usually 0.2 - 0.4 bar at idle" . Is this correct? Mine was reading (using the KING software on the laptop (from memory) about 2.4 bar! Tinley then go on to say "Outside this range implicates pipework again. Fix it".
I found no faults with the pipework, which I assume to be the small bore vacuum pipes (most of which is added by me).
Only thing I can think of are the filters within the cam covers. Would this be right?

75driver · 15th May 2023, 20:30

Quote:

Originally Posted by StewartIngram

I again checked the ecu setup, & recalibrated it. I then suddenly noticed that the help page mentioned the MAP pressure is stated as "should be usually 0.2 - 0.4 bar at idle" . Is this correct? Mine was reading (using the KING software on the laptop (from memory) about 2.4 bar! Tinley then go on to say "Outside this range implicates pipework again. Fix it".
I found no faults with the pipework, which I assume to be the small bore vacuum pipes (most of which is added by me).
Only thing I can think of are the filters within the cam covers. Would this be right?

I might be barking up the wrong tree here, but is the discrepancy anything to do with units of measurement?
MAP is manifold absolute pressure, ie gauge pressure plus atmospheric pressure.
Atmospheric pressure is 1.01325 bar.
For the sake of arithmetic let’s call it 1.0 bar.
So a MAP pressure of 0.2 - 0.4 bar actually infers a vacuum (0.8 - 0.6 bar gauge below atmospheric pressure).
Could it be that the help page is actually referring to a gauge pressure of 0.2 - 0.4 bar, which would be an absolute pressure of 1.2 - 1.4 bar?
So, KING reading could either be 1 bar or 2 bar too high, depending on unit of measurements of help page.
Then again, what do I know, as I drive a dizzle.🙄, but it wouldn’t be the first time that 2 bodies expressing units of measurement differently has caused confusion.🥵

Sent from my iPhone using Tapatalk

StewartIngram · 16th May 2023, 07:19

I must admit I don't know the answer to that!
However, TinleyTech are highly respected, they sold me a lot of parts and inspected the fit. I dealt with them a lot and have respect for them. I ould think their 'help' is written around the software, the figure they quote is I'm sure in the same vein as the reading I took on screen from the KING software. I would like to know though!

StewartIngram · 20th May 2023, 10:56

Any other thoughts on this high MAP reading?

xsport · 23rd May 2023, 19:32

hi stewart. Have you changed the map pressure module that you fitted originally ? It may well be that it is either not receiving (due to bad vacuum pressure ,if the vac pipe is compromised by leaks or in any other way ) or the plug in connection supply or plug itself is not good. If all that checks out ok , dont assume it is giving correct readings after all these years, and could be faulty. For a not too high cost i would replace that part from tinley. The adaptations from a petrol driven ECM on to your LPG ECU piggy back are never good and are a compromise at best. This makes the map sensor you fitted even more important and i cannot help but feel , a new one would not go amiss. This is where i would start and then start looking again at your mapping fuel trims in live running against petrol trims. keep us informed ...

xsport · 23rd May 2023, 19:55

I had a problem with my original setup with the mapping. I have never used the Automap apart from the first time set up. They are miles out and cannot apply to each vehicle types and their needs, but probably enough to keep it running for calibrating further. You need to reset your mapping , especially around 2000 + rpm to see if you are over or under fueling. (as im sure you know how) The banks would have to be miles out of tune to be out, provided you do not have a manifold leak . Check your o2 sensors as well for correct function , again in live mapping you should see them working. keep us up to date stewart if you find your problem.

xsport · 23rd May 2023, 20:37

map pressure 0.1 bar . reducer 1.15 bar these are my kv6 bigas settings (which i believe is the same bigas /king system) You could start by resetting your evaporator/reducer settings to the same as mine above and see what happens and remap. 160 up to 2000rpm then over this figure 180 with 2.0 injector size. see how it goes.

xsport · 23rd May 2023, 21:03

75DRIVER . I think you may have a valid point here. I do not take much notice of these guidelines as they are not specific to any particular engine. After all , this system could be used on a 6 or 8 cylinder, straight or V6 or indeed a 4 cylinder ,with or without a turbo !! It does not set a tune mapping that can or will be specific to a KV6 , so its one size fits all. I think the figures that you projected could well be correct. ..

StewartIngram · 24th May 2023, 07:13

Some good ideas there, thanks.
Firstly, no criticism of anyone, just clarifying my setup. Bought new and installed in 2007, swapped out to replacement cars 3 times no problems. It was checked by Tinley at first install, minor tuning done at that time, nothing more than tinkering with it as he was happy. All the vac pipes seem perfect, no apparent leaks. I'm more than satisfied with it over the years.
I have a box of spares, some noew, some used (but believed ok) so I am able to swap items easily. Hopefully later today I shall have a look at the pressure module, I have a couple of those. I will keep you informed.
I did ask about the cam cover filters and pinholes being blocked; what difference would they make? They are on my roundtuit list, but just wondering.

xsport · 24th May 2023, 10:56

hi stewart. I would have thought that the cam cover filters if blocked to that degree would be an issue on petrol as well. tinley at one time included a map for individual cars to download and send via email. They would probably have known the basic multiplyer numbers for your map anyway, as the KV6 was a popular engine. The filters i think are a side issue not to be bothered with yet. whilst under fueling or over fueling seems the more likely issue. If the vehicle ticks over fine and runs ok until asked for more fuel then most issues are fine. Normally under fueling will throw the eml light and the vehicle will revert back to petrol on the bigas system, if a sudden heavy demand for fuel is demanded . This could be at 2 - 3000 k revs. over fueling at those rpm will cause the engine to sound like a badly running V8 YANK and wont rev freely once up to 2500 -3000 k and suffocates. Its interesting to note that cylinder 6 is probably near your MAP sensor nozzle. In live readings you can see the cylinder numbers live operate and see if there is any issue. I dont think your issues go beyond fueling ,as all other parameters seem working ok , but one never knows ! Take a close look at cylinder 6 nozzle feed pipe to check pipe connection and condition. It is strange that number 6 cylinder has been mentioned rather than just the left or right bank .Just the weather for tinkering !! ..

15th May 2023, 18:50	#1
StewartIngram Gets stuck in Rover 75 Connoisseur 2.5 V6 auto Join Date: Jan 2008 Location: Chatteris, Cambridgeshire Posts: 917 Thanks: 320 Thanked 159 Times in 127 Posts	High MAP reading OK this gets a little involved, but bear with me? I have a DIY converted (not factory fit) LPG system, which has been used on 3 identical KV6 2.5 cars. Since fitting to this car (and possibly on the previous one - not sure) I've had a problem with the engine light coming on, always with the same (related?) readings. Basically around cyl6 misfire, low fuel bank 2, sometimes bank 1 as well, lambda sensor occasionally not operating correctly. The fault only seems to happen when I use a bit of throttle, say to overtake, and reach around 2700 rpm. If I ease off quickly when it flashes, it goes out, otherwise when it stays on I get the fault codes; I can't remember the exact codes without checking again. It is fine on petrol. I have done quite extensive testing to pin it down, but not with urgency as it more of an annoyance than a fault but I'd like it fixed. Having established petrol is ok, that actually eliminates quite a few things. Common to petrol is the ignition (plugs etc), I have checked all that as ok. (I have many spares so have been able to swap part around during diagnosis.) I am also aware that ignition faults sometimes show up earlier on gas than on petrol. I have done the correct calibration of the lpg ecu as per the KING (lpg) instructions a few times. I've even drained the gas tank, and removed the pick-up pipe in case it was twisted and had a partial blockage. Al the mods to run on lpg have been done exactly the same on all 3 cars, and I have meticulously checked all pipes for cracks etc that would cause an air leak. Yesterday, I had another go, with the downloaded TinleyTech helpful instructions in front of me. I again checked the ecu setup, & recalibrated it. I then suddenly noticed that the help page mentioned the MAP pressure is stated as *"should be usually 0.2 - 0.4 bar at idle"* . Is this correct? Mine was reading (using the KING software on the laptop (from memory) about 2.4 bar! Tinley then go on to say *"Outside this range implicates pipework again. Fix it"*. I found no faults with the pipework, which I assume to be the small bore vacuum pipes (most of which is added by me). Only thing I can think of are the filters within the cam covers. Would this be right?

16th May 2023, 07:19	#3
StewartIngram Gets stuck in Rover 75 Connoisseur 2.5 V6 auto Join Date: Jan 2008 Location: Chatteris, Cambridgeshire Posts: 917 Thanks: 320 Thanked 159 Times in 127 Posts	I must admit I don't know the answer to that! However, TinleyTech are highly respected, they sold me a lot of parts and inspected the fit. I dealt with them a lot and have respect for them. I ould think their 'help' is written around the software, the figure they quote is I'm sure in the same vein as the reading I took on screen from the KING software. I would like to know though!

20th May 2023, 10:56	#4
StewartIngram Gets stuck in Rover 75 Connoisseur 2.5 V6 auto Join Date: Jan 2008 Location: Chatteris, Cambridgeshire Posts: 917 Thanks: 320 Thanked 159 Times in 127 Posts	Any other thoughts on this high MAP reading?

23rd May 2023, 19:32	#5
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,738 Thanks: 358 Thanked 419 Times in 310 Posts	hi stewart. Have you changed the map pressure module that you fitted originally ? It may well be that it is either not receiving (due to bad vacuum pressure ,if the vac pipe is compromised by leaks or in any other way ) or the plug in connection supply or plug itself is not good. If all that checks out ok , dont assume it is giving correct readings after all these years, and could be faulty. For a not too high cost i would replace that part from tinley. The adaptations from a petrol driven ECM on to your LPG ECU piggy back are never good and are a compromise at best. This makes the map sensor you fitted even more important and i cannot help but feel , a new one would not go amiss. This is where i would start and then start looking again at your mapping fuel trims in live running against petrol trims. keep us informed ...

23rd May 2023, 19:55	#6
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,738 Thanks: 358 Thanked 419 Times in 310 Posts	I had a problem with my original setup with the mapping. I have never used the Automap apart from the first time set up. They are miles out and cannot apply to each vehicle types and their needs, but probably enough to keep it running for calibrating further. You need to reset your mapping , especially around 2000 + rpm to see if you are over or under fueling. (as im sure you know how) The banks would have to be miles out of tune to be out, provided you do not have a manifold leak . Check your o2 sensors as well for correct function , again in live mapping you should see them working. keep us up to date stewart if you find your problem.

23rd May 2023, 20:37	#7
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,738 Thanks: 358 Thanked 419 Times in 310 Posts	map pressure 0.1 bar . reducer 1.15 bar these are my kv6 bigas settings (which i believe is the same bigas /king system) You could start by resetting your evaporator/reducer settings to the same as mine above and see what happens and remap. 160 up to 2000rpm then over this figure 180 with 2.0 injector size. see how it goes.

23rd May 2023, 21:03	#8
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,738 Thanks: 358 Thanked 419 Times in 310 Posts	75DRIVER . I think you may have a valid point here. I do not take much notice of these guidelines as they are not specific to any particular engine. After all , this system could be used on a 6 or 8 cylinder, straight or V6 or indeed a 4 cylinder ,with or without a turbo !! It does not set a tune mapping that can or will be specific to a KV6 , so its one size fits all. I think the figures that you projected could well be correct. ..

24th May 2023, 07:13	#9
StewartIngram Gets stuck in Rover 75 Connoisseur 2.5 V6 auto Join Date: Jan 2008 Location: Chatteris, Cambridgeshire Posts: 917 Thanks: 320 Thanked 159 Times in 127 Posts	Some good ideas there, thanks. Firstly, no criticism of anyone, just clarifying my setup. Bought new and installed in 2007, swapped out to replacement cars 3 times no problems. It was checked by Tinley at first install, minor tuning done at that time, nothing more than tinkering with it as he was happy. All the vac pipes seem perfect, no apparent leaks. I'm more than satisfied with it over the years. I have a box of spares, some noew, some used (but believed ok) so I am able to swap items easily. Hopefully later today I shall have a look at the pressure module, I have a couple of those. I will keep you informed. I did ask about the cam cover filters and pinholes being blocked; what difference would they make? They are on my roundtuit list, but just wondering.

24th May 2023, 10:56	#10
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,738 Thanks: 358 Thanked 419 Times in 310 Posts	hi stewart. I would have thought that the cam cover filters if blocked to that degree would be an issue on petrol as well. tinley at one time included a map for individual cars to download and send via email. They would probably have known the basic multiplyer numbers for your map anyway, as the KV6 was a popular engine. The filters i think are a side issue not to be bothered with yet. whilst under fueling or over fueling seems the more likely issue. If the vehicle ticks over fine and runs ok until asked for more fuel then most issues are fine. Normally under fueling will throw the eml light and the vehicle will revert back to petrol on the bigas system, if a sudden heavy demand for fuel is demanded . This could be at 2 - 3000 k revs. over fueling at those rpm will cause the engine to sound like a badly running V8 YANK and wont rev freely once up to 2500 -3000 k and suffocates. Its interesting to note that cylinder 6 is probably near your MAP sensor nozzle. In live readings you can see the cylinder numbers live operate and see if there is any issue. I dont think your issues go beyond fueling ,as all other parameters seem working ok , but one never knows ! Take a close look at cylinder 6 nozzle feed pipe to check pipe connection and condition. It is strange that number 6 cylinder has been mentioned rather than just the left or right bank .Just the weather for tinkering !! ..