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Old 05-12-2011, 10:48 PM   #1
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Default 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/ MS1.

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...
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Old 05-12-2011, 11:09 PM   #2
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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).
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Old 05-12-2011, 11:14 PM   #3
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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.
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Old 05-13-2011, 12:05 AM   #4
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It will fluctuate a lot, If i ***** 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
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Old 05-13-2011, 01:49 AM   #5
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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).
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Old 05-13-2011, 08:50 AM   #6
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^ 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.
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Old 05-13-2011, 11:48 AM   #7
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Your VE table is miserable. Where is the linear progression? Why are you squirting more fuel and low idle than cruise?
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Old 05-15-2011, 08:42 PM   #8
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I'm going to tune a **** 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
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Old 05-15-2011, 09:38 PM   #9
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I am having a similar problem... 15-18mpg here, so keeping tabs on this thread!
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Old 05-16-2011, 07:57 PM   #10
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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.
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Old 05-16-2011, 10:52 PM   #11
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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.
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Old 05-16-2011, 11:15 PM   #12
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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?
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Old 05-17-2011, 07:34 AM   #13
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You're not boosted are you? Turbo adding a little pressure bringing it closer to atmospheric?

How many rpms at 70?
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Old 05-17-2011, 10:06 AM   #14
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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...
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Old 05-17-2011, 11:46 AM   #15
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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.
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Old 05-17-2011, 03:19 PM   #16
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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
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Old 05-17-2011, 06:31 PM   #17
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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.
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80kpa at cruise is an indication of notably out of tune
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.
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Old 05-17-2011, 06:43 PM   #18
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Hmm maybe I converted to kpa wrong lol.
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Old 05-17-2011, 07:14 PM   #19
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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.
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Old 05-17-2011, 09:30 PM   #20
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^ 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.
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