Proper values

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Proper values

Postby cacperec » Sun Sep 16, 2018 12:05 am

hi, I've bought brand new Fiat Tipo with 1.6 MultiJet engine (120hp) in January 2018 , and since begining car is acting weird. Main issue is high fuel consumption - basicly it's 6.3 or 5.8 per tank. Car dealer said that everything is fine, but I've bought OBD interface and found some strange (in my opinion) values. It's very hard to find proper values in the internet, so maybe here someone could help me.

Here is what I got:
- on idle (840 rpm, engine started and warm) I've got 0.92 kPa on intake manifold absolute pressure sensor. Isn't it to high? It never goes below it, only get higher if accelerate
- Calculated Engine Load Value shows 30-36% on idle - if AC is on it goes up about 10%. I did compare it to Renault clio and it showed 20-22% on idle. Second strange thing is, it never reaches 100 (clio does) - mostly it stops at 85% when accelerate.
- Absolute pedal position D and E - they show very same value (what's difference between them btw?) - it's 19% if not touching pedal at all, never goes below it - shouldn't it be 0?

I can't find anyone who could verify this values. I've asked 4 mechanics, visited dyno (not sure if it's right word - I mean the place where they checked real engine power - btw it was 132hp which looks odd to me).

Thanks in advance

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Re: Proper values

Postby jtdpow » Sun Sep 16, 2018 11:03 am

i think all its fine,the absolute pressure show this value because its the atmospheric pressure,the other valies are fine because that values its write in the maps lije you see inthe diagnostic,the pedal value are fine too because pedal value are the same in all modes

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Re: Proper values

Postby cacperec » Sun Sep 16, 2018 12:34 pm

so what barometric sensor is for then? Someone replied my question on other forum and said MAP sensor should show 0.45 at idle (becouse of vacuum), and barometric preasure when engine is off or accelerating.In my case it shows 0.92 on idle, and 2.5 when accelerating. I'm getting totally different answers for very same question and getting more and more confused ....

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Re: Proper values

Postby jtdpow » Sun Sep 16, 2018 10:10 pm

i think your car has one map sensor and one barometric sensor....

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Re: Proper values

Postby jurebv » Sun Sep 16, 2018 11:49 pm

you mean 92kpa?

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Re: Proper values

Postby adriancl » Mon Sep 17, 2018 4:51 pm

jurebv wrote:you mean 92kpa?


For sure must be 92kPa, because 0,92kPa mean 0.0092bar, so I assume, diag tool is not good, or user write wrong values on his post.
About engine load, can't compare with other brand,is not relevant.
After Throttle flap, on idle must have values under atm pressure, because is vacuum created behind throttle flap.Anyway, look also on diag about throttle flap opening angle,must have between 5-9deg. at idle.

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Re: Proper values

Postby cacperec » Tue Sep 25, 2018 10:37 pm

of course I ment 92kpa - my mistake -sorry, got confused after using different programs.

First thing cleared after more research: diesel engine does not create vacuum like gasoline so Map sensor should show value close to barometric at idle. This creates another question: if there's no vacuum why is it lower then barometric?(100kPa in my case).

About throttle: in my case I've got 85% at idle (I assume it shows how much it's closed, not opened, right?), and 5% when driving.

My car acts weirdly most of the time and fuel consumption is too high in my opinion. Mostly it's constant no matter if driving slowly or speeding, which makes it even more odd.

What I see when it has a bad day (which is mostly) at idle and warm engine:
- MAF shows 6-8 g/s (looks too low, isn't it?)
- MAP shows 92-94 and changing between
- CEL (calculated engine load) shows 30-40% (no ac, no nothing on)
And avarage fuel consumption is 6,3 or 5,8 as I mentioned before. There were barely few times I got other values. Before 14000 km every single time it was 6.3 - no matter what. What's interesting , while driving it shows really low values like 3.8 or 4.6. I can drive like this for 40-50 km, and average consumption is not affected at all. So it looks like car "thinks" consumption is low, but it is not for real.


But from time to time car acts like it should:
- acceleration is much better
- fuel consumption lowers to 5.2 per tank even with highway speeds (120-130 km/h)
Idle values for that are:
- MAF shows 11 g/s
- MAP shows 90 kPa steady
- CEL is about 16-20% !

That makes me think the second situation is normal , and the car has some issue becouse mostly acting like in first example.

That is why I'm looking for proper values so I can compare and make dealer to fix it.

Other strange readings I have when driving:
- EGR error - many errors here, mostly below 0, reaches -50% , sometimes even -100%. From time to time gives positive value up to +50%

- I drive about 100 km per day, and every single day I can feel engine chokes (very smoothly, it accelerates and all) for a few sesonds - when it happens, instant fuel consumption shows 10l/100km and throttle is closing for this very time. It happens several times a day.

So any clue, suggestion or tip is welcome.

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Re: Proper values

Postby jurebv » Wed Sep 26, 2018 10:41 am

MAP should be a bit lower because of the intake system resistance, the rest looks pretty normal to me... throttle position is not opened completely on idle to have lower emissions, can you post MAF readings per stroke? About performance change, it varries on how much air is inside cylinder which varrirs on air density which varries on temperature, elevation...

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Re: Proper values

Postby cacperec » Fri Sep 28, 2018 4:00 pm

Unfortunately there is not such unit as per stroke- only g/s or kg/h.

There is another mistery to solve: one of apps (eobd-facile) crashes from time to time. I've written to developer, they asked for some logs which I've provided them. They have found crash problem: ECU or ELM interface gives some unexpected data, here's sample:

0900
7E806490054620000

7E804410C1462
7E803410D34
7E80462220600
7E804411007A0
7E803410B0C
7E8034104C0
7E803410D35

Only first two rows (green one) are expected, rest of them not.

My ECU unfortunately does not provide LTFT or STFT values which would help me a lot in this case.

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Re: Proper values

Postby jurebv » Fri Sep 28, 2018 4:08 pm

G/s or kg/h dont mean anything without rpm to go with...post full log with rpm

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