poor idle and high revs

[sammy]

Hi everyone,
Apologies if my questions are dumb or if I missed something obvious in the Tuning guide.
I’m in the middle if re-reading it but get my head fully around it
Before I ask the questions, here is the background.

Background
The car is a 2ltr 1979 Alfa Romeo Sedan
The motor is a little tired, but ran and idled ok on Carburettors
I’ve converted to Independent Throttle Bodies, MSII with V2.891
I used a Map file from another person I got a while back with the same type of engine and conversion. (i.e. exactly the same ITB, Injectors, Fuel Pump, EDIS4 tec)
I made sure I did my build the same as his to minimise any problems as I knew his MSII setup worked fine at the time.

The other day I started up the car for the first time with his bin settings.
Although it starts easily, it idles very poorly – Its very lumpy and revs far too high at idle. (1700revs) I tried adjusting the throttle stop until there is no more adjustment left, but still NBG.

One of the most confusing bits is that the AFR meter is showing around 13.0 , which isn’t that bad , so it doesn’t seem to be too lean or too rich so why is it so rough and idling so high.

I’m going to start fiddling with the cell values in the VE and see what happens, but I’m a little worried that I don’t fully understand what’s happing and I’m worried about deviating too much from the original map that worked fine for him.

Questions1)
Is my following understanding correct?
Each cell in the VE table represents an estimate of the amount of air going into the cylinder expressed as a percentage of the overall cylinder capacity
For example, in my map I have a 2ltr engine estimating that 35% of the air will be going in at 1000 when the MAP is reading 50KPA

and is this correct?
The MSII uses the VE cells to calculate the amount of fuel (i.e. injector open time) to allow into the engine to facilitate the required AFR which is indicated in the corresponding cells in the AFR table?

I've attached the log file and msi file

[sammy]

sorry Folks I just realised I accidenlty uploaded 2 log files .
The second file was supposed to be the uploaded MSI file. Please ignore the second one. i will upload the MSI when I get howm from work. Meanwhile the first Log file is correct
Sam

[trakkies]

Idle speed is controlled by the airflow as well as fuel. Sounds like you have a leak somewhere if shutting the throttles fully (and any bypass system for cold start fast idle) doesn't stop the engine.

[sammy]

Hi Trackies
Thanks for your help .... (yet again ... )

Vacuum Leak
The though did cross my mind, I checked all the vacuum yesterday hoses but I can’t really see an issue.

I built a vacuum plenum with all the throttle bodies plumbed up into it and the MAP sensor hose comes off it and goes to the MSII.

As a test, I tried pulling the MAP hose off the plenum and immediately I noticed the revs drop, but it still idled poorly.

I’m not sure how best to check other then visually and by holding my hands around things to feel for suction.

My next approach will be to remove the Plenum and plumb up all the vacuum hoses together to remove the plenum from the equation.

The old Alfas’ have a Manifold that bolts to the head and the Throttle bodies bolt onto the Manifold.
As part of the build I needed a new Manifold gasket, I couldn’t get one so I made one up using .8mm Gasket paper. Maybe Its leaking, so If the above doesn’t show anything then I will remove the Manifold and see if the gasket is leaking. I think It’s unlikely to be leaking as I used sealant on each sides of the gasket – but I guess I need to eliminate that from the equation too.

VE Changes
Meanwhile I played around with the VE table tonight (before I saw your post).
I tried lowering the values and things just got worse, I think it was pinging, at least there were ‘chuffing’ noises and some small flames coming through the TB ends.

I’m so close ... after all the work over the last year or so I’m feeling pretty down that I can't get it to idle.

Thanks for your help
Sam

[Matt Cramer]

We have some tips on idle tuning that may help; check them out here:

http://www.DIYAutoTune.com/tech_article ... uning.html

[Bluehaze]

Gday Sammy

I'm relatively new to this caper myself, so you more experienced Mser's forgive me if Im off the mark.
Im not particularly familiar with the hardware on anything as exotic as the Alfa, (I'm more into the domestic stuff) However, looking at your log a couple of things:

Your MAP looks really jumpy, and in some spots it's creating an accel enrich situation. Maybe smoothing out your Map feedback as well as dis-abling AE as far as MapDot goes, anyhow. You obviously have a decent cam in that thing. Your PW is tracking the lumps in your MAP, maybe flatten out the table in the MAP plane.

Your TPS looks a bit weird, how's that set up? I find it difficult to believe that opening the throttle 1% can get such an increase in revs.

How's your coolant sensor and IAT sensor traveling? I know Its been cold around here lately, but your motor isn't getting over 15 degrees, so you've also got WUE throwing another unknown into the mix.

I'm also curious about your battery voltage, It starts around 10v then suddenly goes up to 13.something and stays there. No connection to mis-behaviour, but might indicate an electrical problem (Like a dodgy earth-can cause some crazy stuff)
It may well be that your settings are close to pretty good, but if the ECU is getting dodgy info, then you'll get a dodgy result.

[trakkies]

I'd still first find out why the idle speed can't be reduced to zero, as it were. This means air is getting past the throttles in some way. Best to get these basics sorted first before tuning as otherwise you'll be chasing your tail.

[sammy]

Trakkies
I still haven’t ruled out a leaky manifold gasket causing a rough idle. I’m getting a new one and I’ll try it this coming weekend.
Meanwhile I took some of Bluehazes’ suggestions and did notice an improvement - but not a total fix.

Bluehaze ,
Although I ran my car with MSII managing EDIS4 ignition for about a year, its only in the last week that I put the injectors on and started Fuel Tuning, so I’m not an experience MSer tuner at all.

The real experts on this site are Trakkies and Mat Cramer (maybe some others too)
My biggest fear is that these blokes will find another hobby and leave the forums before I get this car going – then I'll really be stuffed

Your suggestion about AE got me thinking.
I checked my settings and found the ‘Low RPM’ was set to 1000.
So I assume it was trying to enrich at 1000 RPM?
I change this to 2500RPM and I also changed the Map Ave lag from 60 to 50 and the RPM from 80 to 50.
While I was at it I also made some other changes , can’t remember them all, but they seemed like a good idea at the time.

Anyway the result is that its now idling at 900rpm with no surging !
However its still idling very rough – I need to work on this now - maybe theres still a leaky gasket issue?

my setup is not typical standard Alfa, its too much to explain here.
I’m in Melbourne also, so if you want to catch up and talk MSII, I can explain my set up & hardware over a beer or coffee etc. …

PM me if you like.


There is another Megasquirer in Melb that I know of, maybe we should set up a Megasquirt Melbourne Beer club where we can catch up over a beer and share Megasquirt ideas and experience

BTW following are some other items you mentioned with my comments following

maybe flatten out the table in the MAP plane.?

Not sure what you mean by this? I attached are a couple of the latest log files if it helps

Your TPS looks a bit weird, how's that set up? I find it difficult to believe that opening the throttle 1% can get such an increase in revs.

I have 4 Independent Throttle Bodies, They are almost too large for the car and I expect that they will result is a sharp increase in revs with small movements, but for a 1% movement I wouldnt expect that much increase, I’ll have to look at this closer.

How's your coolant sensor and IAT sensor traveling? I know Its been cold around here lately, but your motor isn't getting over 15 degrees, so you've also got WUE throwing another unknown into the mix.

I’m very low on coolant. The manifold has coolant running through it and when I removed it most was drained. I didn’t run the car that long and I plan to get some tomorrow, I suspect the coolant didn’t get up to the top of the heater hose where the sensor is.

I'm also curious about your battery voltage, It starts around 10v then suddenly goes up to 13.something and stays there. No connection to mis-behaviour, but might indicate an electrical problem (Like a dodgy earth-can cause some crazy stuff)

The battery was new , but I drained it while mucking around trying to get it started. I put a Charger on it long enough to start the engine. I have an 85Amp Alternator so I guess there was enough current once it started

[sammy]

sorry , I forgot the attachments in the previous post
Sam

[trakkies]

Thanks for the compliment Sammy, but I'm not to be even mentioned in the same breath as Matt on matters MS. I simply try to pass on my limited experience - as others have done for me. However I do have quite a bit of practice playing with old cars of many types, and some problems seen here ain't MS specific.

[sammy]

Ok folks

Just to confuse things further, here is tonight’s installment …. Your thoughts would be much appreciated.

The car idles - but its still really rough.

I tried a number of things, I testing each injector, injector leads and plugs, replaced spark plugs and leads etc … but it was No Bloody Good.

Meanwhile the AFR was always hovering around 13 to 14 so I didn’t think it was a mixture issue.

At idle the VE table had 30% in the cell and I was reluctant to change this value as I was happy with the AFR figures, but it did it anyway. I started dropping it a bit at a time and once I got to around 20 it started to idle better.
I took it down to 18 and it wasn’t too bad at all, still a little bit lumpy but almost aceptable.

However, when I checked the AFR, it was showing 16+ and the gauge was flashing RED..

So now I’m confused (nothing new) because it seems the car wants 18% in the VE but this will cause a lean condition.

I’m guessing one option could be to richen it up again and advance the timing to allow it to burn longer.

Do you think this would improve the idle ?

I initally set ignition advance to 10 for idle as this is what the car had when it was on carbies and it ran fine, I thought EFI wouldn’t have changed that at all.

Anyway , unless someone has any other suggestions ,I give it a go tomorrow night
Sam

[Bluehaze]

Hi Sammy
Looks like your'e making progress, which can't be a bad thing.
Apart from the battery voltage sitting low- second log shows it sitting stubbornly a around 10 volts- how much faith do you have in your WB sensor? It looks (according to the log) like it runs reasonably, but of course this is no substitute for being there.
Without leaving the Idle phase, why not pretend you don't have an O2 sensor, and just adjust your mixture down like you said, until it sounds right, you should find a point where the MAP bottoms out and further leaning out will create misses. I know with my 202, any sustained running at 16 at idle and it misses like all get out!
I'm not sure how reliable your O2 sensor/meter is, but maybe you need to cast a skeptical eye at that. Perhaps even dis-able and remove it and sub it for a NB one and just run it to a (digital) voltmeter. At least you will know where the switch-over point is in your Idle fuelling.
Another thing worth checking is your plugs and exhaust; before WB or even NB sensors our ears, eyes and noses worked pretty well..

[Matt Cramer]

The prime rule of tuning is to do what works. If the engine likes to idle lean, it likes to idle lean - or, as Bluehaze pointed out, the wideband may be having issues.

[sammy]

Yes folks that makes sense ... but.....

Everywhere I look I see warnings and disclaimers about running lean and melting pistons,
so I’m a little nervous about it.

Also the WB was installed in the car for almost a year while It still ran on Carburettors and it seemed to be working ok Up to a week ago It showed the car idling well between 11 to 13 AFR . So even if the readings are incorrect, I would think it would be consistently incorrect keep showing the same values when I have the ITB installed.
i.e. It should still show it idling well at 11 to 13 AFR?.

Never the less, it does make sense to go with what the car wants …… so I’ll try that over the week end and see how I go.

thanks
sam

[Matt Cramer]

It's possible you may have developed an exhaust leak - or the sensor may need recalibrating.

[sammy]

At this stage I'm thinking anything is possible (although I can’t detect an exhaust leak anywhere).

As far as it running better with lower VE values – I think I was just kidding myself … Yes its better, but still worse than what I had with the carbies.

I may not be describing the problem properly, … but it’s not just a rough idle, it’s like missing or running on 3 cylinders, it’s an uneven idle.

I know there’s a logical explanation but it isn’t obvious to me at the moment.

I can’t rule out the coincidence of something unrelated to the MS going wrong.

I going to reinstall the Carburettors sometime over the next 3 or 4 days

If it does not idle properly with those then I know it’s not the MS or a config fault.

On the other hand if it does idle well, it may be hard to go back to the MS .

[sammy]

hi everyone, sorry for to the late update.

the problem i was having wascaused by a numebr of things ...

1) my spark plugs were only 6 months old so the last thig I check were the pklugs. well.... one was stuffed !
2) Overly rich mixture. I think the mixture was so rich that it wasnt burning all the fuel
I read somewhere where this actually results in more oxygen which fools the WB (and hence VE analyzer) into enriching , making a bad situation worse.
so I switched off VE Alayzer and manuall corrected the VE bins .

If now Idles so much better - so thanks to you all for your help

ISam

BTW I still have other problems but I've started another thread for that

[sammy]

Hi everyone,

I'm running 4 Independant Throttle bodies, MSII and 2.86 of the code.

I have 3 questions I'm hoping someone can help me with.

1) with Acc Enrichment : the Tuning Manaul suggests starting the TPSdot threshold at 1.0 and to try to keep it below 2.0, while the tunerstudio mentions the TPSdot threshold %/Sec should be around 15
what am I missing with this? can someone explain how this works ? I tried reading about it but the more I read the more my head spins.

2) I have my car idling ok, but often when I blip the throttle i get a really lean condition.
I know I will have to use Alfa-N blending but in the short term I just want to dirve the car on SD for a while.

I have attached a log file to show what i mean.
At 30.99 seconds you will notice that it goes very lean for no reason.
Can anyione shed some light on this? I cant seem to work out why this is happening

3) As you can see from the Log, at idle the kPa is around 65 -70 and under accel it drops to 30 or less. Is this what people expect to see with ITB and SD?

I'm greatfull for any help, ideas or thoughts
Sam

[Matt Cramer]

Hi everyone,

I'm running 4 Independant Throttle bodies, MSII and 2.86 of the code.

I have 3 questions I'm hoping someone can help me with.

1) with Acc Enrichment : the Tuning Manaul suggests starting the TPSdot threshold at 1.0 and to try to keep it below 2.0, while the tunerstudio mentions the TPSdot threshold %/Sec should be around 15
what am I missing with this? can someone explain how this works ? I tried reading about it but the more I read the more my head spins.

Seems like you have an outdated bit of documentation. Current code uses a percent throttle opening per second; 15% / sec is a fairly low value. You may need it higher depending on the level of TPS noise.

2) I have my car idling ok, but often when I blip the throttle i get a really lean condition.
I know I will have to use Alfa-N blending but in the short term I just want to dirve the car on SD for a while.

Probably the acceleration enrichment needs tuning. Also, please post a current MSQ.

[sammy]

Hi Matt

thanks for your help

I uploaded the MSQ file.

When I enter all the relevant parameter and generate the VE table the bins are way too high at idle (~30) so I found by dropping them to around ~20 the car will idle ok.
I set the Acceleration Enrichment off by setting the upper and lower RPM thresholds to same value. (1000).
I then tried some pulls up and down the road with VE analyser on.
I’m not 100% sure what I should expect the bins to look like i.e. should the scale evenly ? etc. …)
I tried a pull in 4th gear from ~1400 RPM up to ~3500.
I tried a few more pulls in other gears.

Each time I was very gentle with the throttle. If I pushed just a touch more it would go Very Lean and cough and splutter and almost give up.

I turned VEAnalyzer off and tried normal driving – but it was No Bloody Good.

I tried putting Acceleration Enrichment back on but still NBG

If I blip the throttle at idle a few times it just bogs down rich - but on the road I cant even accelarate much without enriching.

I'm not sure about the TPS noise. It airly stable with only the occasional 1% shift according to the logs.

As far as Accel Tuning – I'm sure you are right - It may have something to do with it, but I would have thought I should still get some level of drivabiklity without it?
Sam