Fuel Economy Issues, Help me find the issue?
 

So, Ive decided that after reading about every thread that I can find that may be somewhat relative. I cant seem to find the issue with my MS. Long story short is that I'm getting terrible gas mileage. 20-21 mpg almost exclusively highway driving, stock na 1.6 engine w/ :brain: MS1. :noob:

Firstly, my AFR targets are decent, not great, but they certainly should be better than 20 mpg. at least it feels that way.

Next, I know my mat and coolant related air density tables are all sorts of fubared, problem is that I don't know where to find the mat table after countless times trying to find it. and coolant air density shouldn't have that much effect.

All of this leads me to believe my spark map is not the greatest.
To my knowledge, it is the diypnp base map that is provided.

what do you guys think that I am missing. I'm trying to learn MS as a whole, but to be honest, As a Hands on guy this is really hard to learn without seeing it right in front of my face...

Needs lots more ve tuning, the spark table is fine. Much of your ve table is untuned.

For reference, my setup gets 28-33mpg average depending on how hard I am on it but I have a bigger motor that revs 4k rpm at 120kph (75mph).

If you are just cruising around are you actually seeing mid 15's AFR? Or is it richer or bouncing? You could go .5-1 leaner blow 70kpa if you don't have a cat, but even with your current map I'd expect better mileage unless you're just constantly flogging on it.

It will fluctuate a lot, If i pussy foot it on the highway i can manage 15.3-15.5, but the second a hill comes up it will bounce back down to 14-13 afr and constantly bounce between those values depending on the situation. some instances, it will not hit 15 afr at all and pretty much stay at 14.7

Did you use the DIY 460cc base map?
Maybe you still have your AEs on the stock map levels?
In tuner studio:
Basic Settings
Acceleration Enrichment wizard

I had these still on the 240cc map when I switched injectors, even after tuning the VE table with VEAL my mileage still sucked.
It became better once the AE table was tuned (reduced my AE by 25% at least).

^ I hadnt touched that. I'm reducing them now by 25% and will see what that does for me.

Heres the new AE table, I know tps enrich is off, my tps is being fixed today and should be back on soon.

Your VE table is miserable. Where is the linear progression? Why are you squirting more fuel and low idle than cruise?

I'm going to tune a shit ton over the next couple of days. Work on smoothing it out alot, ect.
Hustler, Where do you see more fuel at idle than cruise? Some of the high kpa areas at idle rpms I havent managed to touch yet, going to get them soon. Normal Idle kpa's though the fuel is fine, idling around 14.6

I am having a similar problem... 15-18mpg here, so keeping tabs on this thread!

Which wbo2 do you have? Have you calibrated it recently? Does it match the output in TS? Have you bothered to read your spark plugs? Did you read the tuning section of the mega manual? http://www.msextra.com/doc/ms1extra/...ing_Manual.htm

You probably will get 20mpg (or worse) if you are driving wot everywhere with those afr targets and base ae settings.

I average 25-30 and that includes flogging the car a few times.

LC-1 calibrated about 2.5 months ago. I also rewired everything on it because it was showing 1afr off between TS and my gauge, It seemed almost perfect back then, but it feels like its not quite correct now.

I just moved back home where my tools are, So I will be looking at the spark plugs tomorrow am. I have read the tuning section, but I am rereading it now.

Would it be wise to disable AE for the time being? til I get this all sorted out? I'm not driving wot everywhere, mostly highway driving.
This last tank seems like its gotten around 21-22 mpg, almost exclusively highway driving, tuning most of it, and flogging a little bit to get a wider range of cells during tuning.

Hmmm, so upon reading more into the tuning I realized something, the suggested values for kpa for cruising are 30-60 kpa, My car cruises at 70 mph at 80 kpa... I'm going to check my idle kpa as a start, but is there anything else that would explain why my cruise is so high just to maintain a constant speed?

You're not boosted are you? Turbo adding a little pressure bringing it closer to atmospheric?

How many rpms at 70?

N/A

approx 4k.

The only reason for me being at that high of a kpa is because any lower kpa and the car wont stay at a constant speed...

I would check what the MAP reading is before starting the car. (Static) Very well could be the MAP sensor has an offset. not a problem for running the car, but needs to be known or you will be tuning in the wrong area. Otherwise the 80kpa at cruise is an indication of notably out of tune. Also would suggest to verify the actual timing.

If your static kpa checks out around 90-100 then check your idle vacuum kpa. Factory spec for the 1.6 is >450 torr or >60 kpa. If it is lower then you have an intake leak. Did you select the correct map sensor in megatune/TS? Where is the map signal sourced from? is it pinched anywhere?

If you have time you could swap the stock ecu and injectors back in to isolate the problem.

Once you get the map signal sorted then I suggest starting your tune over with better afr targets

Static map is 99.0 kpa, Idling warmed up is low 40's kpa. Did you mean less than 60 kpa, or more than 60? more doesnt really make sense, and unless i dont understand it, should be indicative of a leak.

The map sensor is correct, and signal is not pinched, goes from a T in the stock fpr line, through the firewall and strait into the ecu. Its also a very thick vaccum line to prevent pinching.

I'm going to my friends house weds evening, I can check timing there, as well as try out the stock ecu so long as I can find my injectors again.
I felt that was kinda a flag, only reason my afr targets are the way they are now is in an effort to have decent cruise afrs.

Hmm maybe I converted to kpa wrong lol.

Low 40's is not ok for a stock car - hell it's not ok for a built engine either. I would expect something between 27 and 31kPa.

^ that's probably my issue then, I'll take a look at it tomorrow when there is light out, have some fun with something explosive and see if I cant find a vacuum leak. :facepalm:

The more load the engine is under, the lower your kpa's should be. Remember, atmospheric air is 100kpa at sea level.

^^^ Umm i don't think that's correct.
At full throttle I see close to 100Kpa and at idle around the 20s-30s...
cruise high 50s-60s...

Is the engine at higher load at idle or wot?

ok, good to hear your MAP is in the ballpark. 40 kpa at idle is very low as said. I had a toasted oil burner 1.8 with 45% leakdown pull better than 35kpa. So something is up there. As several noted, your fuel map is also toast. Example -Appears you have added fuel to your cranking map location (800rpm/101kpa) to get it started. That needs flattened out and the fuel added to your cranking %.

But lets talk about your timing for just a moment since you asked about cruise mpg. It is my understanding that the factory 1.6 runs 34 degrees timing for WOT. yours is way slow comparison. Given that, your 101kpa line should not be lower than 30 above 3k rpm. Increasing as throttle is taken out. your map has you cruising at 29-30. (slow) 4k cruise should be better than 35 and closer to 40 for decent economy. So how about this for an experiment. (still check your timing) Lets put a little bubble in your table table at cruise. A small bubble so you can shift rpm up or down out of it if the engine doesn't like it and get it off the road to change it. won't be with this small change, but good practice. Set your 4k 84kpa, 75kpa and 55kpa cells all to 35 degrees. Go for a drive (datalog) and see if it improves your cruise kpa at 4k. Move in and out of that speed to see effect. This will give some indication of where you need to go. in the end should be nearer 40 degrees at light cruise.

There is quite a bit more as you also indicated other tables in question. My thought is to get you started with some small things to gain that MS knowledge you are looking for and the rest will become easier.

Sorry for the long post.\

MSQ?

Ah yes, I may have missed the relativity to throttle butterfly position there... My bad! At WOT, atmospheric pressure is available for the taking. Hence the 100kPa at WOT. Sorry for the bad information.

oh, one more thing. I see you are running MAPdot. That can cause a lot of induced Accel enrichment if the MAP is dancing. I have found TPSdot much more forgiving to the tune.

KPa is the load on the engine, the higher the number the higher the load period.

With a turbo you could in theory have 120kpa at part throttle yet an n/a car has 100kpa at WOT. Just because the turbo is at part throttle doesn't mean load is lower.

Not just in theory. You can easily reach 100% load at just 30% throttle on a turbo car (with a supercharger it is different due to the bypass valve). More than that and the boost kicks in. I have datalogs of a car doing 10psi on 70% throttle.

You know I don't know why I wrote 'theory' as I experienced it everytime I tuned my mates old Greddy'd MK1 :facepalm:

There is a lot of serious retardation in this thread; carefully choose what and who you listen to.
This is what a fuel table should look like:
http://i55.tinypic.com/1zwn485.jpg

Stop posting.

OP, I certainly agree with Hustler on the MAP. It need serious attention. You mentioned sounding lost with the MS. Learning MS and trying to tune can be overwhelming, which is why I suggested a small adjustment to what you have (running)to see cause and effect. Frankly though you could start over with a basemap and be much better off.

Understood - thanks for clarifying, chaps.

Sounds like an awesome plan, I'm still going to take things step by step though. First thing is vacuum leak, I checked with the engine warm and idling with a can of brake cleaner. Nothing caused the car to rev up, But I have an itching feeling that it has to do with the Thermostat part of the idle valve. So my next step is to pull that off and see whats up with it,

My friend with the timing light ended up being busy, So I havent had the chance to check timing, But I'm going to do so as soon as I find someone that I can borrow one from. After that, then I will start messing with timing like you suggested.

I'll also take a msq in the morning while I drive to work. DERP, I was thinking log for some reason, msq shoud be attached now.

As for cranking % that was an untuned area from when I scaled out the boosted cells. Its been mostly tuned out now, And I'm about to hand pull out the rest as soon as I finish typing this.

So my order of attack is to:

1. Turn off map dot and get tps working again asap. until then no accel enrich.

2. find that damn vacuum leak/ see if it is in fact leaking, if so, make a new afr target table and rework my fuel table. if not rework afr targets anyways and move to 3.

3. check base timing

4. test small area with more timing advance

5.???

6. Profit?

And heres my current ve table, it more closely represents yours hustler,
Not happy with it, but it seems to be running a little bit better for me until i get the timing and vacuum checked out.

Update time. I believe I found the issue, or at least part of the issue. On the thermostatic part of the idle valve, the bit that sticks off the im, the stupid rubber seal in there is broken between the two chambers. I closed it off as best I could for the time being and my warm idle kpa dropped to an avg of 36-37 kpa. so its better but I do believe that it is still causing a vacuum leak.

I also tested a small spot of timing advance and that seemed to help out a lot as well. I'm going to leave my spark map the way it is for now, until I can find a timing light to use and check my base timing.

I also added fuel back into the 80kpa area on my target tables, but only a little bit since I still am hitting that area for the time being. But I will gradually bring that back down to where it should be.

Cruising at 70 mph now sits around 65-75kpa, so it has certaintly improved.

Only Question I have now is, does anyone know a part number, or a name for the small seal thats shaped like (I) in the thermostatic part of the idle valve? Or should I just not worry about it at this point?

Sounds like great progress. Before you know it MS tuning will be old hat. Definitely finish up the vacuum leaks. Tuning to leaks is impossible. I dont have info on the seal, someone else might.

Link to Gasket

This one?
I just head to my local dealer for special parts like this as they don't really charge too much over what you get online but at least there's peace of mind I have the right part.

Good find on the gasket, your idle should be sitting closer to the 30s than the 40s except if a/c is on.

I just offer a little advice on changing timing and doing 70mph drives without verifying what your base timing is... Be careful!
I doorknocked down my street and borrowed a timing light to fix timing when mine broke. Ended up meeting like minded neighbours and fixed my issue.
Man even here in australia, where we pay twice of any other country for parts, timing lights can be had as cheap as $20 so I would grab that over the next tank of gas just for peace of mind.

Good luck :)

I agree with ampz. Driving a car without knowing timing is not wise. Atleast you arent boosted yet.. that shit would have exploded already.

Thanks!

Thats not the gasket, This >>Clicky clicky!
The gasket that would be there.

Yeah, idle is still upper 30s but its lower now. So im gonna fix that and it should land me where I want to be. no a/c so no worry there.
I'm gonna poke around and find a light, tired of trying to find someone i already know that isnt on vacation right now :facepalm:
On a good note, keeping the car in that small spot seems to really help things out, the engine sounds alot less strained, and so far the tank seems to be lasting a whole lot longer than usual. Its hard to say what right now, but certainly headed in the right direction! :bigtu:


Edit: ISC valve gasket?? maybe?

I still cants find this gasket o-ring type deal. but the good news is that my timing is back where it needs to be, so I feel a whole lot better messing with timing knowing that it is infact where Im telling it to be.

I'm also getting approx 28 mpg now. so Ive already increased my mileage by quite a good bit. the engine sounds a lot less stressed in every situation, which is a good step in the right direction as well

My next steps are to redo my afr targets, and mess with timing a little bit, hopefully with a det can, but we will see.

heres how my spark map looks currently, you can see where the bubble is,
Does anyone have any suggestions of approximately where spark should be? In the meantime I'm going to look at others spark tables to get an idea.

I made a spark table for Johnwag's car and can't post it since I'm at work...but it's floating around on here somehwere.

Searched with no luck. any idea on keywords or a thread name to where I could find it?

it wasnt in logical places like his build thread and such.

Hey, My 70 Cutlass was rear ended and totaled. So been a bit preoccupied. Here is a spark map thread with a few maps to take a look at. You might want to take your 85kpa down a couple of degrees now just to be safer. 34-35ish range.
https://www.miataturbo.net/megasquirt-18/spark-map-itt-i-beg-you-post-44713/
Keep in mind that since you are not yet boosted about any map posted will run for ya - with a word of caution, pinging is always possible so proceed with the usual caution. Any will get you around the block safely for sure. CRAIGO's on page four.

tuning tidbit. one of the reasons I had you set the "bubble" to one number was to have stable timing in that area. Chasing timing can suk. Timing does affect fuel needs.

Thanks Tim! I have to head to work right now, but I'll check it out when I get home. Sorry to hear about the cutlass, I hope that everything works out the best that it possibly can for ya! :bigtu:

Also, thanks for the tidbit, I had kinda figured that would be an issue when changing timing. It really didnt change as much as I was expecting it to.

She was a beauty. 3 years of work gone in 1/2 a second. My little boy cried...

Timing has a lot of room when running light load and does not show fuel changes as much. Remember to think in percentages to recognize how much you really changed fuel. Once you get the feel for it, bump that bubble area around a couple degrees to see your results. Generally move the whole bubble. You will find throttle/rpm areas that like to run and note those as you tweak. I will get blasted for this but the motor could run between 40-50 advance on low power settings for efficiency. But there is compromise needed on the MS. Timing will oscillate (chase) if timing jumps to abruptly.