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MS new build questions. help!


mikeh501

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@Bowie69 I think Mike has far bigger problems to sort with his vacuum leaks etc. before anything like that matters.

Likewise @mikeh501 I'd suggest there's no point putting a gas analyser on it or even trying to MOT it until you can solve the basic issues and then get the tune at least somewhere sensible.

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Without a restrictor, it is a 6mm barb straight into the plenum.... Quite a bit of air flows through that, from air filter, to rocker cover, through crankcase, out the other rocker cover breather straight into the plenum.

If nothing else, just block any barbs on the plenum base off for the moment, unless you actually need it to run.

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thanks guys. the plan is to block up the 6mm barb on the RHS just past the TB, and apply some more rtv on the PWM boss (problem is that boss is flat and carbon plenum has a slight curve to it) as these are the two which can definately see/feel. Do another vacumn check and see what it looks like and go from there. wont be bothering with o2/mot etc until this is done and we have done some further tuning. no point tuning it until we have air leaks sorted, but it is progress all the same.

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  • 2 weeks later...

Just a quick update for you chaps given youve been so much help. Didnt manage to get anything done engine wise on the build last week, and had to start dismantling the body ready for paintshop this week - so it looks outwardly like its gone backwards lol 🤪

Hopefully it will come back looking amazing in its bronze green paint 😁

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  • 4 weeks later...

Evening all. So quite a bit of progress. I think the engine problems are solved - thats a big statement! The air leak was the cause of the rich running by the looks of it and it now idles nicely, revs and generally behaves. Not given it a road test yet but it certainly seems much happier. Air was leaking both around the boss and the barb. Im now seeing MAP down into the 30s and at idle up around late 50s. Still a bit high perhaps. 

Couple of new questions.....

* Once the engine is warm the PWM is still open (I know this because I can squeeze the air pipe and it whistles and almost stalls. Should it close completely? The tune is using closed loop, is this why? I might change to open loop and properly set the idle screw on the TB?

* its minor but the idle tends to hunt is this the norm and dont worry or can it be tuned out. I think closed loop is chasing 900rpm...

Heres a pic of the very nearly finished article. chuffed.

20210515_165337206_iOS.jpeg

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Well done! Your map readings at idle and idle are perfect. 

As for questions.... 

Yes, idle valve will be open as you are in closed loop, it is trying to hit a value, and needs to be able to close more than it is at the moment to bring the idle down once really hot. 

Jumping idle and closed loop - this is exactly why I have binned using closed loop, there is just so many variables that affect it(timing, valve position, damping and fuel all affect it), I could never nail it down sufficiently so I was happy with it. I use the valve as warm up only, and compensate for engine loads like ac, hrw and engine fans, by putting a hole in the ignition map at idle, around 6 degrees, at lower than your ideal idle speed stick the timing up, which then picks the idle up again. Also make sure where you idle cells are they are almost exactly the same, as different fuel alone can make it hunt - this last part is relevant even if in closed loop. 

Looking very tidy on the outside too ;)

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As Bowie says - I gave up fiddling with closed loop and just used it at fixed values for warmup and left it, works fine and you can stabilise idle by sloping the fuel / ignition maps slightly around the idle point anyway.

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Tried moving to open loop this morning and after a bit of fiddling with the idle screw it was idling rock steady. Is there a process to map the idle? as I found myself weakening off the map at idle which increased the revs , then close the idle screw, then go back to the map weakening again. Got it idling at about 800 with the map as weak as I could - i.e. much more and it wouldnt hold idle steady and be almost stalling. I need to try another cold start to ensure I havent messed up proper warmup enrichment.

Another question now im fairly happy with the idle and pickup.... My air:fuel ratio is still showing around 15-17:1 typically when idling, and even as I weakened off the mix it didnt change much. Doesnt really change much as I give it a rev either. I just dont trust what its telling me after all the trouble ive had previously. It still smells a little rich so im thinking it is rich - absolutely nothing like it was before and no black stuff coming out of the exhaust either.

How can I diagnose this? is there a cheap tailpipe o2 sensor? could it be broken given all the poor running its endured? or covered in black soot maybe?

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If it *smells* rich and reads lean, then you could have a cylinder not firing, as you get one cylinders worth of unburnt fuel out the exhaust which just vaporises - our nose then says this rich. 

The misfiring cylinder also dumps a cylinder worth of oxygen down the exhaust as well, which tells the O2 sensor it is weak.... 

I would pull the plugs just to make sure they all look happy :)

 

Rover V8s like to to idle about 13.5:1, so if your readings are right, then they are too lean. 

Widebands are a couple of hundred pounds now, but wont solve a misfire for you unfortunately, certainly a handy tool though. 

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15 hours ago, mikeh501 said:

Tried moving to open loop this morning and after a bit of fiddling with the idle screw it was idling rock steady. Is there a process to map the idle? as I found myself weakening off the map at idle which increased the revs , then close the idle screw, then go back to the map weakening again. Got it idling at about 800 with the map as weak as I could - i.e. much more and it wouldnt hold idle steady and be almost stalling. I need to try another cold start to ensure I havent messed up proper warmup enrichment.

Another question now im fairly happy with the idle and pickup.... My air:fuel ratio is still showing around 15-17:1 typically when idling, and even as I weakened off the mix it didnt change much. Doesnt really change much as I give it a rev either. I just dont trust what its telling me after all the trouble ive had previously. It still smells a little rich so im thinking it is rich - absolutely nothing like it was before and no black stuff coming out of the exhaust either.

How can I diagnose this? is there a cheap tailpipe o2 sensor? could it be broken given all the poor running its endured? or covered in black soot maybe?

The process is pretty much as you described - turn the idle screw down until it's about right and then dial the map in if it needs it.

Also, enrichments like warmup / cold start are the last things you do after you've got it running right under "normal" conditions, otherwise every change you make affects something you've just tuned.

Why are you aiming so lean? Rover V8's like to idle a tad rich and 15-17 is too lean for much other than light-load cruising.

Also - if you're not using a wideband O2 sensor the AFR numbers mean nothing, a narrowband sensor simply switches from low voltage (<0.5v) to high voltage (>0.5v) at 14.7:1, you can't infer anything else from the output of those sensors and it annoys me that TunerStudio etc. insist on showing an AFR gauge when it's completely wrong.

O2 sensors get thrown off by exhaust leaks and misfires letting air or unburnt fuel down the exhaust so trust your nose - if it smells rich, it's rich, the sensor could be picking up an air leak or be coated in unburnt fuel and mis-reading lean.

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On 4/9/2021 at 10:39 AM, FridgeFreezer said:

Bowie - do you mean restriction(s) in the engine breather pipes into the plenum? I think it depends on setup doesn't it?

Some motors have a restrictor in the bottom of the drivers side breather spigot in the rocker cover, some (later?) ones do not, and seem to just rely on the plastic spiral oil separator to act as a restriction. If there's too much restriction (ie. the spiral wotsit is full of gunk) then the engine will blow oil out of the front cover at high sustained revs (guess how I found this out!). 

There's a few threads about using a PCV instead of the separator as a better solution.  

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6 hours ago, FridgeFreezer said:

The process is pretty much as you described - turn the idle screw down until it's about right and then dial the map in if it needs it.

Also, enrichments like warmup / cold start are the last things you do after you've got it running right under "normal" conditions, otherwise every change you make affects something you've just tuned.

Why are you aiming so lean? Rover V8's like to idle a tad rich and 15-17 is too lean for much other than light-load cruising.

Also - if you're not using a wideband O2 sensor the AFR numbers mean nothing, a narrowband sensor simply switches from low voltage (<0.5v) to high voltage (>0.5v) at 14.7:1, you can't infer anything else from the output of those sensors and it annoys me that TunerStudio etc. insist on showing an AFR gauge when it's completely wrong.

O2 sensors get thrown off by exhaust leaks and misfires letting air or unburnt fuel down the exhaust so trust your nose - if it smells rich, it's rich, the sensor could be picking up an air leak or be coated in unburnt fuel and mis-reading lean.

I was doing the idle adjustment just because id moved from closed to open loop really. As soon as I changed it the idle was about 1250rpm and wanted to bring it down. Good question on why am I trying to lean it off... 2 things really, it smells a bit rich and lumpy still so thought i needed to tbh, and I was looking at the AFR and noting it really wasnt changing at all, so Im not sure what im supposed to do? does everyone just use their nose and ears to dial it in?

@Bowie - Ive used a infrared thermometer on the exhaust manifolds and they are all pretty much the same so i dont think its missing much if at all. Its had new plugs in it too, although once its done a few miles ill whip them out again to check.

I guess im a bit worried about it getting past its MOT when I book it in as its a 1994 vehicle its supposed to have cats and id assume a level of o2/HC it cant be more than. Just want to know it will pass before I go.

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8 minutes ago, mikeh501 said:

I guess im a bit worried about it getting past its MOT when I book it in as its a 1994 vehicle its supposed to have cats and id assume a level of o2/HC it cant be more than. Just want to know it will pass before I go.

Lean does not equal low emissions - and if it came with cats it will probably need them to pass an MOT as it's very hard to get anywhere near without them;

airfuel.jpg

 

Narrowband O2 sensors can tell you if it's rich or lean - the closer it is to 1v the richer it is and the closer it is to 0v the leaner it is, but they CANNOT tell you an AFR number other than the fact they switch past 0.5v at 14.7:1.

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Gotcha, still leaves how I can really judge whats happening if i cant trust the sensor.... Quick Q... in tuner studio there is a front/rear O2 voltage metric which I assume is the one to look for. In megalog HDim reviewing a log I took yesterday when it was idling nicely and cant find those metrics in the log.There is one called 'O2' but the reading is about 0.05 and 0.1 which would obviously be very lean given as you say it runs from 0.0>1.0

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Great if running on all 8, half the battle!

If the lambda reading isn't changing, there's a possibility it is dead or fouled, if the latter, removal and heating to cherry red with a blow lamp should get it working again, if it rattles when you remove it, maybe not 😛

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Guys, just been out to it. starts on the key like a beaut. i just had a look at some of the values in tuner studio and im confused.

Ive been staring at the air:fuel ratio metric which as you can see is about 17... i turned on those other ones just. what is air:fuel ratio 2? that ones reads more like it. Also see the O2 voltages which I assume correspond to the air:fuel ratio metrics.

Why is there 2 of each? I only have 1 sensor fitted! Have I been looking at the wrong one all the time?

2.PNG

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It's probably worth posting a copy of your .msq file - then we can see what's going on.

In terms of the gauges, you can set those up however you want, even if the hardware behind the gauge doesn't exist, or to have them set 'wrong' so that the ecu gets a duff reading...

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Any chance of a copy of the .ini file as well - TunerStudio throws a wobbly and doesn't want to import it :(

Think it's maincontroller.ini inside the ProjectCFG folder in the TS project..

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Yes it's confusing unfortunately and I don't know why they do it like that - MS *can* have 2x O2 sensors so they put the gauges in for them *if* they were wired up but for most people they're not used and will display some random value of whatever's connected to the spare pin of the CPU - usually nothing so it's just floating around 0v-ish. The old Megatune software didn't have this nonsense in it, it wasn't as full featured but it also wasn't so easy to confuse yourself.

And no I can't remember if it's front or rear that's the correct one :ph34r:

To say it again - with a narrowband O2 sensor the AFR gauge is basically made-up numbers, O2 sensor voltage is the only one that will tell you the truth because all you can tell with an NBO2 sensor is the voltage it's generating, and as we've already said that can be affected by leaks / misfires etc.

Also worth pointing out again - trust your ears, eyes, nose, and seat of pants - you never had all these gauges with carbs and yet people managed to tune them up, if it sounds like it's running badly IT IS, if it smells like it's running rich IT IS - just because there's some numbers on the laptop screen that doesn't always mean they're right. Sensors can lie or be damaged or not even connected, and the ECU does not "know" anything, it's a very basic device.

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