Newbie to megasquirt, thankyous and problems!

[rusty_wingnut]

First off as a complete megasquirt novice and going on two weeks worth of reading Nige's original build thread, I took the plunge, fitted a 3.9 V8 to my 90, and bought one of Nige's kits.

It hasn't been all plain sailing, not becuase of Nige's kit but because of me, so big thanks to Nige and Fridge who not only asnwered a shed load of daft questions and wasted hours helping me, even rushing around to repair the ECU after I let some smoke out. Cheers guys. A minor thanks to my mate Jon, who gave me some excellent excuses to lose my licence by lending me his Impreza while I got the 90 working!

I feel it is time to fly Nige's megasquirt nest and reveal myself as a public squirter, and as a result have a couple of questions for the floor.

1) I have just been for MOT and have had some big problems with missing and a very hot lhs cat. I think I may have qured this by making my plug leads properly! I have managed to remove the Ford plug connecters and fit them to new leads and the new coil connectors supplied by Nige. I do however wish to know where to find the "REQ FUEL" value in Megatune so I can turn her down a bit as she is very rich.

2) How on earth do you give the ECU control to modify values as it sees fit? I am not talking full control but the ability to change something a bit.

These are all things Nige showed me but being a plum I have managed to forget and don't want to screw up another ECU!

Cheers

[FridgeFreezer]

REQ_FUEL is in the Constants page:

It's important to understand that this moves *everything* up or down, it is the starting value for all the calculations so if you are only running rich at certain points it's better to tweak it in the fuel map. For initial setup or trying to get things in the ballpark, you can tweak it by a fair bit (+/-20% at a time) to see what works and then work on the fuel map for finer tuning. The auto-tune feature is not bad for getting a workable fuel map but it won't get the idle zone right.

The way to allow MS "closed-loop" control is to go into EGO settings (Exhaust Gas Oxygen - the Lambda sensor value), it should look something like this:

This does of course assume your lambda sensor is working and your exhaust is gas-tight (air getting in will throw the readings and hence the results).

[rusty_wingnut]

Cheers FF!

I now have stumbled on another problem that has me stumped big time. The Lambda is wired in and reading when the vehicle is running. I took the vehicle for test and it failed I adjusted the REQ FUEL to get the hydrocarbons test, but the O2 reading in the exhaust is to high. So I took the 90 home and checked a couple of joints, found a couple of minor leaks that were cured by nipping the flanges up properly. The exhaust is now 100% air tight and with no noticeable blows. SO I took the truck back to the test centre only to be told the reading is the same :(

At this point a typical MOT inspector/expert came over and gave me a right earful on how it wasn't running on all 8, I've fitted new plugs and leads since the first test and all 8 sparks are there and present. I found what I thought was a dodgy injector where number 8 plug was lightly wet but not as coloured as all the others, so replaced that injector. My system is wired so that two injectors are powered by the same wire and earthed as a pair, so if one plug was different there should be a second if it was a wiring fault

Frankly I am stumped, and it's getting depressing I have got some video of the truck running. The exhaust is the standard 3.9 Y pipe with cats, into 300tdi mid box and a simple straight pipe after.

If anyone has any ideas I would love to hear them, I found the reading on AF ratio gauge inmegatune a bit weird as well, sitting around 15 after a blast, and then opening the throttle it spins around to maximum and goes red :S

I've done a compression test and have 165 within plus or minu 10% on every cylinder.

Help

[Dave W]

Did they try the fast idle test rather than a static idle test ?

The fast idle test allows the lambda correction to work if you have it configured and is usually easier to pass although you should be able to pass both. EGO correction at low engine speeds isn't very effective so you wouldn't normally have it enabled below about 1200 rpm.

What age is the engine and vehicle, are you sure they're testing it as the correct age ?

I've had testers test my vehicles as a cat equipped vehicle, for example, when the vehicle doesn't have them fitted and doesn't require cats.

Reducing the req fuel setting for emissions is really a BAD thing to do. You're adjusting fuelling throughout the range when you only need to adjust the areas around the idle. It sounds like you've weakened out the mixture to far to try and get the HC right that you're fuel map is now completely screwed. You should never touch the req fuel setting once you have an engine running properly throughout it's range.

I'd concentrate on getting the mixture right at idle using your lambda sensor. If the MOT station are friendly I'd also run a comparison between their probe and your lambda sensor. If your lambda sensor shows a good mix and their probe shows it as very weak then maybe you have a duff lambda sensor. Usually though lambda sensors tend to start reading leaner as they age rather than richer so there is a tendency to overfuel to compensate.

As for the AFR going red when you use the throttle, that is possibly normal, it depends which way it's going. You'd normally expect your acceleration enrichment to give a rich mixture as you open the throttle which should settle to normal once the throttle position is stable.

[rusty_wingnut]

Should of stated the 90 is 1996, and the 3.9 came from a 1996 Discovery, with Cats - so the downpipes and Y piece were fitted, and linked into the rest of the diesel system.

The test was performed at 2000rpm.

The AFR gauge spins clockwise reading anything upto the maximum of 28, that would be a lean mixture, would it not? I will change the REQ FUEL back to 20 to match Nige's original map. Then turn on EGO correction and see what happens.

Only onething did cross my mind this morning and that was the fuel pressure regulator - the only part of the fuel system I haven't changed.

[rusty_wingnut]

So I changed back to Nige's settings and turned the EGO correction up to 70% control. It found a good idle and didn't hunt about as much. After another start the right hand cat was glowing hot, hinting at a missfire, all sparks are present though. I'm at a bit of loss as it doesn't miss and then sometimes it does.

[rusty_wingnut]

Gents I am at a loss with this and don't know what is wrong with it. I will pay handsomely for someone to take a look if anyone is interested?

[Bowie69]

Well I'd start by ringing Nige, he's hardly a million miles away from you.

TBH though, from the questions you are asking, you really really need to go and read the Megamanual, in specific the bits about tuning and lambda.

[CwazyWabbit]

Bowie69 I bow to your superior knowledge on this subject, would bad setup on megasquirt lead to a misfire on just the one cylinder? or would that more likely be caused by a faulty plug/lead/coil pack? If it is not down to megasquirt then I would try swapping stuff from one set of 4 cylinders to the other and see if the problem moves, some things break down under load even though they appear fine when visually tested.

[Dave W]

70% is way too much for EGO control, On a properly mapped engine 10% is more than enough, 70% will leave your mixture all over the place as the "swings" either side of 14.7 will be huge and take too long to recover from.

If you're fuelling is going too lean when you open the throttle then either your map is too lean or you don't have the acceleration enrichment set up properly. Concentrate on getting your fuelling tuned in first then when it's running at or around 14.7 AFR throughout the rpm range increase the acceleration enrichment slightly to overcome any hesitation when you hit the throttle.

If you have a misfire then that needs sorting first, have you tried changing out a coil pack ?

[Bowie69]

Bowie69 I bow to your superior knowledge on this subject, would bad setup on megasquirt lead to a misfire on just the one cylinder?

If it fouls an already slightly iffy plug, then yes, especially as the plug leads were initally fitted to the wrong plugs.

My point is, even if it is all wired up correctly, but then you start setting things like the EGO to 70% and using the REQ_FUEL to tune the engine (NOT what it is designed for), you could well end up with another set of fouled plugs and be scratching your head all over again, and cost yourself another set of plugs.

Other things to check now:

• Given there was a problem with a hot cat, this could have melted if it got really hot, and is now blocking the exhaust.
  
• I know the compression figures are OK, but burnt oil will screw around with AFR readings
  
• Clearly you have fuel going in to the hot cat side, the only other thing it needs is a properly timed spark, can you say for sure it is properly timed on all 4 cylinders?
  
• Have you checked the timing with a timing light? Retarded timing will give the same hot cat symptoms.
  
• Acceleration enrichment kicks in when you hit the throttle, so if this is not worling the AFR will spin round weak, but then should stabilise as you hold an engine speed.
  
• Yes, 28 on the AFR gauge is a very weak mixture, 28 parts air to 1 part fuel, where as stoic is 14.7 parts air to one part fuel.
  
• If you have a spare coil pack, then as suggested above swap it out, if not, go and find one, the last few I bought were about £10-12 delivered off ebay, complete with leads.
  
• Consider changing the plugs for a new set, but if it doesn't fix the problem, consider swapping the old ones back in unbtil you get it sorted.
  

[rusty_wingnut]

Poor Nige, I've hassled the bloke to the point where he should be telling me to do one.

I'll try your list Bowie, having ordered a coil pack. The timing gun has been on it and it looked fine firing at around 6* BTDC, but I will check again

[Bowie69]

As you mentioned as well, the fuel pressure reg could be faulty, or a weak fuel pump, only supplying neough fuel for idle. Which fuel pump are you using?

[TheRecklessEngineer]

IIRC the AFR gauge won't work with a narrowband sensor - it'll give some indication of rich/lean, but won't tell you the AFR exactly.

I might be talking out of my bottom here though...

[Dave W]

IIRC the AFR gauge won't work with a narrowband sensor - it'll give some indication of rich/lean, but won't tell you the AFR exactly.

I might be talking out of my bottom here though...

You're kind of right although it does actually give you a "narrow band" around stoich where it does tell you the AFR it's just as it gets outside that "narrow band" in the middle it falls off a cliff edge simply indicating too rich or too lean. Some narrow band sensors are "narrower" than others too.

Which reminds me, thinking about the OP, you're not using the Land Rover lambda sensors are you ??? If you are that may be your problem as they don't work in the same way as "normal" narrow band lambda sensors, working off a completely different principle and voltage range to "normal" ones.

[rusty_wingnut]

I'm using lambdas supplied by Nige

The fuel pump is the standard 3.9 Disco one fitted into a 90 tank as per Nige's build.

The regulator is something I have a spare of and will try that as well.

[V8 Freak]

I'm no expert but there is a lot of good information in this thread.

Limit EGO correction to about 25% and only over 1500 RPM.

Check and change all the items in the suggestions above and clean the plugs properly.

Load a safe 3.9 map that someone else has used or that Nige supplied. Then run the engine... Let it warm up and then let Tunerstudio work it's magic tuning live while you wait. Don't be tempted to rev hard, just lift revs and hit some cells and see if TunerStudio wants to change them....

Go for a gentle drive (Is it road legal? I can't remember now..) and see if TunerStudio thinks your map is way off the mark or if it's just tweaking a few cells.

When my Hydrocarbons were a little high on MOT day, I lowered the fuelling in just two cells in the VE map and it passed with flying colours. (No cats on mine though!)

Let us know how you get on and post up the map you are using if you can. Shame I'm a little too far away to offer hands on assistance.

Neil

[Hybrid_From_Hell]

Right

I have been reading here, there is some good stuff as others have said, I have up to now

just been to manically busy to add much, but Have a few moments so here goes

This is sort of "Generic" info, but also to try to sort Mr Wingnut Out

Emmissions

The new your truck the cleaner the emmissions need to be, we ali know that, but, and this is

key - the newer / cleaner means you have to be far closer to perfectyion than say my old 4.5 race thingy in a 1985 emmisions

90, when you enter the world of "Cats" slightly out in a few places = fail.

So, what can cause things to be out

(I know Dave has done some of these)

PLUGS - if fouled tried or not gapped right spark can be poor or collapsing under load - Chnage Plugs

OIL - if you have been a cranking and a cranking or the oil is old and contaminated - peeps ignore this - but

fresh oil can help emissions

CATs - check for air leaks and where the lambda is fitted needs to be hot to work,

TIMING - essential if you timing is out from where it should be the effect on emmisions is HUGE. 1st check

with a dynamic strobe what you are actaully getting, then trim within Megadsquirt to get EXCATLY what Adnace you SHOULD have at the right RPM - PERIOD

Fuelling - another huge effect, and there are a number of things on fuelling to take account of

1. MSQ - My MSQs are "Safe Maps" that means the spark advance is backed off a bit and the fuel is upped for saftey, ie its better to run

less spark than too much and more furl than too weak, the net resul get you running MSQ its not as good as you can get - or I can give you -

but - YOU HAVE TO ENSURE everything like the timing is spot on before loading a high spark / lesser fuel MSq, or damage is easily a good possiblity

As Mr V8 says, ecven with my rich MSQ get either MLV or Tuner Studio to retune, it will defo lean it off and then soem, and this wil help emmissions,

but also you need the spark at the tickover to be what it should be and not what it is, if anyone is hapopy there settings (TDC) TRIGGER WHEEL etc are

spot on I can give better MSQS sparl tables etc, but on your head be it = few peeps have done seruious damage with a MSQ thats soft on spark and a tad rich

on fuelling - but peeps HAVE with MSQs where spark / timing is out and thus far far far to advanced and too weak / lean / detonation / pinking etc

But going back to the beginning the higher the MOT Target the closer you have to be on things

EGO Correction, - no WAY should 70% be there - its a Fine tune for things like the difference between a stinking hot day and an ice cold one - and 5-10%

is the max, and all changes are lost on start up / switching off etrc, if you are at 70% not only is this wrong and mad but gives a 0 solid VE Table, gawd knows whats going to be going on

pping EGO correction is NOT a solution to a key prob

AFR guage is not it is a Narrow band reading of a voltage converted to "A Sort" of AFR extrapolation, its OK but don't read too much into it When you "Boot" the engine AE will kick in so the AFR extrap will jump - its not accuarte or even meant to be more a guide things are a working generally

On the subject of Tunning think of Fuel Required as HOW BIG a Carb you might wnat to try, think of the VE table as the needles fitted and MLV or TS as

getting "That old guy" to make your coughy motor that has the right bits on it but runs like **** to run right.

There are not shortcuts to getting things right the otrdfer is

Check all cyls are firing

Set Tickover Correctyly and butterfly clearance and without PWMs etc

Check fuel pressure and return etc

Make sure all engine mechanical parts are OK - throttle cable, camshaft, lambda positioing etc etc

Check install is 100% Correct - no leaks bodges or near enoughs

Check the basics components are perfect - PLUGS INJECTORS Air filer, OIL, TIMNING etc etc etc

Check the Tickover / Timing dynamically vs what MT says you have, trim to 0 - ZERO not near enough

TUNE VE table via Tuner studio,

Make sure spark advance and table is as good as can be

Maybe bring in PWM and PWM control to help tickover,

Look at the cells the tickover is living in - record the numbers and go get it tested,

change the cells for VE and also for spark to help O2 and HCs not change the carb from a twin dellorte to a 4 barell

READ the A-Z Thread - SEP around tuning and also print off and completely read the Megamanual for Extra as well

Get the basicas 100% right, tune, spark, and record the numbers, then fine tune one thing at a time and see what needed.

I am still happy to help, I am a call away but you need to methodically work through step by step, a non cat is easy a cat takes more work as

I have said befopre everything needs to be more close to MOT standards, most of my MSQs are racer based - so thats performance only a **** the MOT

I know many peeps who have a MOT MSQ and a Road MSQ and a Rce MSQ and select accordingly - it will behave like 3 x different engines.

Hope this lot helps

Make sure the test being done is done to the right levels

[rusty_wingnut]

Thinking about this today I have remembered something else that I thought was a bit odd. On the bottom of Megatune with the engine running the F.Idle box flicks off and on and not all the green lights (circles things) appear to be on.....

[FridgeFreezer]

Just to add my 2p's worth, the AFR gauge is not accurate except when it reads 14.7:1, beyond that all you can say is that you are richer or leaner than that point, this is the response of the O2 sensor:

If you have a misfire, leaky injector, air leak, etc. then it will be throwing the answers out - oil, unburnt fuel or unexpected air will confuse the O2 sensor and potentially foul it up. Sort "hardware" problems out before you worry about tuning.

If the F.Idle box is flicking on & off then potentially your engine is either running too cool, there's a problem with the coolant sensor input, or your warmup enrichment settings are incorrect.

If you AFR/EGO reading is bouncing off the top of the red bit other than under hard acceleration then you are too rich, that won't help and fouling plugs or lambda sensors will again throw your readings off and lead you down the wrong alley.

Posting a data log of your engine running is also very helpful rather than describing various symptoms.

[Bowie69]

Posting a data log of your engine running is also very helpful rather than describing various symptoms.

I agree strongly ^^^^ Even a screen shot would be handy, with the engine up to temp.

[Hybrid_From_Hell]

Dave

Slow down, breathe in and get logical structural and step by step(able)

Poking at this that and the other will prob make things worse

Its a CAT MOT Standard test pass you are after, things have to be pretty spot on in all areas, so

work through the basics 1st trusting absolutwely nothing, then see how things are and report back

Nige

[rusty_wingnut]

Right, I went back through some basics like trigger wheel, coil wiring and leaks etc - nothing untoward was found so fired it up and put on the logging feature in megatune, providing you helpful chaps with this lovely log file, the coolant rises nicely, but the rpm and MAT are a bit allover the place.

The coil I ordered from Mondeo parts arrived and turns out to be a more modern type with different fittings for the leads - so haven't be able to try that.

I have swapped the FP regulator as well, she doesn't seem any different.

[rusty_wingnut]

forgot the file though it appears I can't upload it, is there a format for this?

[Bowie69]

Here it is:

http://www.thebowate...stysdatalog.zip

Sorry, no chance to look at it, just on a call out.