Grande Punto Help reading the graph on MES

[robertzd]

Hy,

The problem I’m having with my grande punto 1.4 8V is while I drive in any gear and suddenly release gas pedal I get instant decrease of rpm (feels like kick when engine mount is bad).

Engine is not decreasing speed softly like it should I think.

All three engine mounts are installed new, clutch is new, Spark plugs, air filter. MAP cleaned.
The car idle run smoothly, acceleration is good, no other problems while driving , only that let’s say kick down when suddenly releasing gas pedal.

So I manage to connect car to MES but I cant thell what is bad.

I suspect Throttle angle position is strange when i release gas pedal. There is some spike.

Should it go straight down like, rpm, and gas pedal position?
Also graph throotle angle and gas pedal position. My throotle angle go only up to 83,3 % , but i can only catch it short time because it's responding only couple seconds when i give contact with key.

Any help or advice is appreciated , thanks

 

[portland_bill]

I've not got experience with teh 1.4 8v, but the 1.2 8v 60hp in the Panda is not smooth at very low speeds, and can be difficult to drive very slowly, like in slow traffic or around a car park. The same people who programmed that, could have been responsible for yours too.

A lot may depend on how quickly you release the accelerator. The computer measures accelrator position, its movement, and how quickly it moves. A quick release will stop injecting fuel, making the engine into an air pump, giving the maximum engine 'braking'. it also saves fuel. The engine does not need any fuel at that time, as the car is pushing the engine.
When the engine speed drops to a threshold, fuel will be injected again to prevent stalling.
The graphs of accelerator postion and throttle valve position match well, so it appears that the accelerator rheostat tracks are fine.

Have you only recently got the vehicle?
Has it 'always' done this? It could just be a characteristic, not a fault.
Or has it only recently changed behaviour?

Hopefully other 1.4 8v owners will add their experience.

 

[robertzd]

Thanks for repply “ Portland_bill”.

You have right there, it’s not smooth on low speeds, traffic jams. On low rpm’s.

I own the car for five years but my wife is driving it. I drive bravo 198.

As I remember it was doing that always, but didn’t pay some attention on that.

So recently when it was on clutch replacement and other stuff I mention I notice that behavior is different from other cars I drive. Then I start suspecting maybe is something wrong.

It could be it’s just made like that, hope that someone with same car will say it’s experience.

 

[The Panda Nut]

Our 169 is getting on a bit now and moving towards 90K miles so knocking around 150000km. The MAP sensor gets oily quite quickly. Cleaning this and the inside of the inlet manifold makes quite a noticable difference in its smooth running. It was awful for a while but with the MAP clean it drives OK. I just clean the inside of the manifild through the top after removing the throttle body. Might be worth a try?

 

[robertzd]

Hy "The Panda Nut"
I did clean MAP sensor and throttle valve. The valve was so much dirty. See picture.

But even with so much dirty valve he was ok on idle. Did not stall, vary rpm or something like that.

After cleaning it is a bit better, it’s noticeable. Kinda faster response on gas pedal. But that problem (if’s it’s problem) when fast removing foot from gas while driving is same with dirty or clean throttle.

I have done learn function of throttle after cleaning it.

 

[GrandePunto PL]

1. So your "clutch is new". How about the release fork/lever and plastic bushings? New also? Most common mistake is leaving those parts worn while swapping the clutch. It will wear the bearing prematurely. Plus, there are other mistakes during clutch swap possible. WHO did the clutch? You or "professional mechanics"?

2. All 8V engines = valve clearance (shims). Also common thing to neglect (clueless people do timing belts and forget about this).

3. Ignition system: what about old coil pack? Plugs is not enough (not always).

4. Engine/gearbox mounts are all new (3 or 4 of them, depends how you count it), but maybe installed wrong.
Or there is a worn part somewhere else (suspension, track control arm, stabilizer, struts - very common failure point: struts, bearings, springs).

5. There is no "problem" at all. Just because this car drives differently after some service was done, doesn't mean it's a "fault".

 

[robertzd]

Thanks for reply Grande Punto PL.

Clutch is completely new together with the booth hydraulic pistons and it was replaced by the professional mechanic, he advice to do complete because he say after replacing only clutch kit some of cylinders know to malfunction after short time.

Timing belt is also replaced by mechanic 60 thousand km ago. Now punto has 160 thousand.



What do you mean with coil packs? There is ignition coil. One pice that controls all spark plugs. I didn’t replace cables or that main ignition coil. It’s not cheap and don’t have any proof coil or cables are defective.



How can engine mounts be installed wrong? That part I did myself. I’m electric engineer and know plenty stuf to do myself. On 1.4 8V there is 2 side mounts and gearbox one (under engine) is assembled of two part. All are new one and, you cant miss anything. Every bolt goes in its place. You cant bolt anything wrong.

I think there is nothing else worn out. At least I cant hear it or feel it while driving and mechanic didn’t report me while he was servicing car. But maybe he didn’t notice it.

The car driver better after all this is replaced, cleaned.

The thing that is strange to me is that RPM.

For instance try driving 60km/h steady foot on gas, and suddenly remove foot of gas. How does RPM acts?

On bravo, and my company vehicle rpm just stay still and slowly start decreasing.

And on punto you feel that little jump, you see it on graph.

 

[GrandePunto PL]

Do you understand English? The message was: Your car is not maintained properly, fully. You do one thing, but skip on another.

1. Clutch. Do you have brand new lever/fork and it's plastic bushings? If not, your clutch swap job was NOT "professional".
Example link: https://www.ebay.co.uk/itm/276071679305

2. Timing belt should be done with valve clearance check (there is a Guide on forum). It is additional 10-15 minutes while you are there during timing belt job (which requires removing valve cover if the job was top notch Pro like you claim).

3. I said coil pack. Without "s" (not "packs"), don't paraphrase my posts. Yes I know there is one module. I did spark plugs Guide years ago on this forum.

4. "Simple" jobs can be done improperly. It happens. Check the suspension and the mounts once again.

Maybe I will try to grab similar MES data log as yours. Tomorrow. Mine is not jerking at all. "Engine braking" is smooth.
By the way. Check this Polish forum, it is loaded with details (no need to translate, pictures are enough): http://fiatpunto.com.pl/forum37.html

 

[portland_bill]

Do you understand English?
Your car is not maintained properly, fully. You do one thing, but skip on another.
1. Clutch. Do you have brand new lever/fork and it's plastic bushings? If not, your clutch swap job was NOT "professional".
Example link: https://www.ebay.co.uk/itm/276071679305
2. Timing belt should be done with valve clearance check (there is a Guide on forum). It is additional 10-15 minutes while you are there during timing belt job (which requires removing valve cover).
3. I said coil pack. Without "s" (not "packs"), don't paraphrase my posts. Yes I know there is one module. I did spark plugs Guide years ago on this forum.
4. "Simple" jobs can be done improperly. It happens. Check the suspension and the mounts once again.

Maybe I will try to grap similar MES data log as yours. Tomorrow. Mine is not jerking at all. "Engine braking" is smooth.

@GrandePunto PL Why the vitriol. Be nice.

 

[GrandePunto PL]

He will not listen. He knows better. Being "nice" doesn't work.
This is a technical forum, not social media (I don't need "likes" and not looking for "friends" here).
His car lacks maintenance (it's all over the place, not systematic). It will get better, so no worries.

 

[robertzd]

GrandePunto PL thanks for you reply but you don’t need to be rude. English is not my mother language, but I understand it. Not some technical terms but I google then. And from previous post I didn’t realize you’re pointing for bad maintenance.

• Clutch . Mechanic didn’t tell me he replaced that part (fork and bushing) so probably he didn’t.
• Timing belt. I have no idea does mechanic check valve clearance when replacing timing belt.
• Coil pack. You’re right there. No S, that’s my bad. Sory. And that’s nice tutorial you made for spark plugs. Thumbs up.
• I agree with that. There is a saying who is working he is mistaking. It’s normal.

I disagree with you that I don’t listen. You obviously have a loot of knowledge about cars. Maybe you’re a professional mechanic. At my place the mechanics are not so professional. Their goal is to replace thing as fast they can. They wont even bother to find out is something really wrong with the car when he only little kick revs when releasing gas pedal. You know what they say.

It’s old car. It’s normal to do so.

And i don’t want to pay mechanic so he could say, maybe is, MAP, maybe are spark cables, coil pack, throttle valve and so on. I could be that kind of mechanic. It’s cheaper at least.

Car don’t have any code error so it’s hard to relate to something. That’s why I’l listen to advice any of members. I want to test and find out as many of data to compare with.

 

[GrandePunto PL]

Your first picture doesn't make sense. When you accelerate, the throttle moves faster than the pedal...it moves first (maybe it's a bug in the software - translation error or mixed parameters).
Second is corrupted too (throttle is following the pedal at the beginning, then it's a flat line).
It doesn't mean that accelerator pedal and/or throttle body is faulty, but it is possible. Among other things (timing, clutch, valve lash, VVT, exhaust restriction or leak etc.).

Note, that CAN data frame refresh rate is about 10x longer than single ignition event in the cylinder. You may never catch a problem, if it's in the cylinder, valves, ignition etc. Or it's very difficult. Real diagnostics is done with oscilloscope, exhaust gas analyzer and so on. Not "computers", erasing fault codes ("errors").

But. I did two aggressive test drives. "Pedal to the metal", idle, then 100% gas to the floor and releasing to 0%. Car behaves well, it is smooth all the time. There are additional data, like spark advance, camshaft positions etc. You should do similar test, grab more parameters.

 

[robertzd]

GrandePunto PL thanks for your effort and data.

(When you accelerate, the throttle moves faster than the pedal). You mean on this situation?

Picture under, I magnify the spot. I add parallel line, it looks they raise at same time?

(Second is corrupted too). I’l record a new one. I find out later that I record it wrong. Max throttle angle on picture recorded was 83,8 degree. It was strange to me also so I did tray again and it goes to 100%. Throttle reacts only couple seconds after I add contact with key and I press record of graph too late. So i didn’t record it to the end. I'l record new.

Is there some other way to read excel data?

I make excell graph of the data you send. Ratio (don’t know to explain), is big. RPM is high and all other data are small on graph. I zoomed in max I can. And it’s clearly that you throttle is following pedal position much better (linear).
Maybe it’s because difference of MES graph, and excel , I’l try to export my data and make excel graph of them.


This is one picture from other day, car is parked, rpm holding about 2300 and releasing gas pedal. RPM, Throttle position, 2 potentiometers inside (if i'm right?) and gas pedal position.

Also throttle don’t follow pedal nice.

I get youre point that process in engine is much faster than MES and maybe wont be able to catch problem.

But at least I can compare to something when someone reply back with it’s situation.

Once again thanks

 

[s130]

I'll chip in here with two items.

1) Sampling rates for any system have to be at least twice as fast as any expected change (Nyquist - Shannon Sampling Theorem.

MES can only sample from 20/min to 300/min - MAX - this equates to 5/second. The more plots you have the harder it is for MES to capture the data. I see your rate is MAX and scale X20. The MES screen plot refresh is about once per second so plotting the raw CSV data is probably going to give better results.

2) BACKLASH in Gearbox - Flywheel (DMF) - Driveshafts

If there is any float in the drive chain then till the float is taken up then RPM will drop quickly and then be followed by a kick and then subsequent slower fall rate.

You have had the engine mounts done so I would be checking the gearbox/differential and CV joints. One easy way to do this is to jack up one front wheel and then put the car in gear. Now you can rock the wheel forwards and backwards and note the amount of movement and for any excessive clonking/banging noises. Do this for all gears including reverse. NOTE! There will always be some movement and noise and what is excessive or not is another matter

 

[robertzd]

GrandePunto PL i find out i can add your data to MES , so forget about question about Exell graph , it looks stupid now .


s130 thanks for your comment. I understand that gap on drivetrain can cause kick.
Couple weeks ago I was checking underneath the engine. Was suspecting did some brake caliper stuck maybe (it didn’t).

I check booth driveshafts. Twisting it, puling in-out like youtube videos instruct. The tripod joint don’t have play inside cup. But when car is on jack in gear it can move. Complete shaft. As you say it’s supposed to do so, but don’t know how much is allowed, and also I didn’t try in all gears, only 1th. (will try out all)

I lifted my bravo, it has less move , and on official car, caddy it has same play even more i think. But it’s only visual, cant measure it. Will try maybe put some mark on wheel and on fender, so try to measure movement ?

I'l try to find some video, i think i made it.

 

[s130]

To me that video looks "typically" normal. It is very difficult (as I mentioned in my original post) to actually define a normal / abnormal movement. All vehicles can/do differ so nothing is absolutely definitive.

I guess the plus point is that you have checked the drive train backlash. Compare both sides and then compare with your other cars. If all the same or similar at least you have created a reference for future use.

Not sure what else to add.

 

[robertzd]

S130 thanks for reply.

I’ll try to compare booth driveshafts for play (diference beetwen them) when I manage.

I have one question. Today I was comparing my graphs to GrandePunto PL.

And I find that my throttle angle has peak up when it’s on a way down. I make two circle on picture, what I mean.

I understand play anywhere in drivetrain can cause rpm kick, but will it impact also throttle position?

Will it also cause throttle position increase when the rpm kick up?

I don’t know am I asking question clear.

GrandePunto PL. I have try again Throttle / pedal position graph, and it’s the same as before.

Throttle position (degrees) don’t go up to 100%, but also your’ s is 83,8 max position. I believe it is normal, it reaches max and then it’s a flat line (max position) while time passes.

 

[GrandePunto PL]

1. Car is a machine.
If there is a problem, you check things in order:
- mechanical (wear, "play", runout, alignment and so on, mechanical things, features, procedures),
- hydraulic/pneumatic (compression, pressures, PCV "breather" system, intake/exhaust leaks, oil delivery),
- electrical (power generation and delivery),
- electronics (wiring, sensors),
- software bugs (there are some in the ECU).
Basics. Then we step up our game, the disciplines can mix (mechanical problem inside electrical component and so on).

2. Throttle angle (degrees) does not reach more then 90 degrees probably, so don't expect number 100 per-cent. You're mixing units.

3. On my graph the engine rpm, correlates more with spark advance and camshaft position. The "dips" in rpm are there, but smaller than yours.
"Peaks/dips" in the throttle are not there. Check the throttle (if there is a play in the flap or sensor - potentiometer). Used throttles are cheap, you can swap one (although parts swapping is not "diagnostics").
Throttle Guide: https://www.fiatforum.com/guides/throttle-body-disassembly-porting-testing-1-4-8v.723/
Dips/blips in RPM can be caused by almost anything. If not mechanical (valve or drive train), it can be injectors or ignition system.

4. Many electrical parts work both ways, you can read what's going on inside by viewing the oscilloscope waveforms. Random example is a injector, you can see if the plunger/needle is moving or not (it's stuck).
Examples: https://www.google.com/search?q=injector+current+ramp&tbm=isch&source=lnms
Ignition system the same (secondary winding waveforms, you can see the combustion process or not - shorted sparkplug etc.).
So the throttle can do the same probably (the air flow moves the flap), but this is not normal condition (it's so bad that you can see this via OBD data).

My bets are still mechanical. Things that were done to the car recently (or neglected, ignored in the process): timing (+ valves, +VVT), clutch (done improperly), mounts. That area. Engine, gearbox (there is a natural wear inside) and how they are mounted.
Also, rule out the silly stupid things like completely clogged PCV system (small hose orifice): https://www.fiatforum.com/threads/breather-hose-replacement-1-2-1-4-8v.262269/post-4351952

PS
As for "throttle faster than gas pedal" it is a FES/MES nature unfortunately. We should ask the MES author, how the program scans the CAN lines, asks, grabs the data frames. Probably in specific order, just like it's presented in the program. So the battery voltage is a very first data you see. Then is a couple more and engine RPM. Then throttle angle. Accelerator pedal is further down the line. That's why the throttle moves before the driver blips the "gas" according to data logs. This is a bug which renders the whole software almost useless for real Diagnostics (which is done using oscilloscope anyway, ODB2 is just a rough guide).

 

[robertzd]

Thanks for answer GrandePunto PL

I have checked that PL forum that you mention above. There are many great tutorials and also it’s nice documented with pictures. I have see that one for throttle disassembly and cleaning also.

I have inspect again engine mounts and play in gearbox. I made some videos also.

I raise only left wheel in the air and run the car. You can see now what he does when the gas in released fast. You can feel all car shakes good when this happens. Probably this is what’s happening while driving also.

So next thing I did, I remove tire from that wheel which is in the air. I know tire has some weight, and that will cause more kick if there is play in gearbox.

Try to run again without tire and there is almost no kick anymore, not so big, it’s for sure 90 % less kick than with the tire. And there is no RPM kick . They drop easy linear.

With this I find out I'm thinking that problem is my gearbox. Maybe differential because the kick is present in any gear. (ok didn’t try reverse, I forgot).

Can you tell me your opinion on this? Am I on right way?


On one video I can hear some noise for gears inside gearbox also. During driving car on road there is no noise from gearbox, no vibration on steering wheel. Nothing that I can say, hmm that’s strange noise (or vibrations) what is that?

 

[GrandePunto PL]

Sounds like worn gearbox (differential probably). Engine noises are a bit "funny" too.
For now you can renew the oil (check what's in the old one, some metal chips, debris) plus some oil additive to silence it.
Or look for used (but better) one.