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Old 11th February 2011, 15:18   #1
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Talking FIP Flop

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Originally Posted by Samurai View Post
Here is something I forgot to mention about Sunday. I usually fill up diesel after 250kms of travelling since the fuel gauge nowhere near accurate. It only gives me a very approximate indication.

After driving mostly around 50kmph all the way to Chikmagalur, I decided to top up the diesel tank as usual.

The petrol bunk kid fills up 14 litres of diesel and then stops.

Me: Why did you stop?
He: It is full.
Me: What do you mean? It can't be full so fast...
He: No, it is full.

I am stunned, I just pay and continue. After a while I jump out and check, he is right, it is full.

The distance covered since the last fill-up in Bangalore is almost 250Kms. And I am not going by the Jeep speedometer. I do know the physical distance.

That means I got 17.85kmpl for this drive!!!

I know it is outrageous. I usually get 11-12kmpl, when I mostly drive between 70-80kmph gunning the engine most of the time.

However, the first time I drove this Jeep, that is when I drove it from Bangalore to Manipal, I got something similar. At that time, I occasionally touched 70-80kmph, but mostly drove at 50-60kmph. At that I used the Jeep speedometer, which is at least 10% inflated.



But, I am not able explain the FE this time. All I can say is I couldn't gun the engine thanks to the wandering wheels. So, what does this mean? If one drives the XDP engined Jeep at 40-50kmph in 4th gear most of the time, one can get phenomenal mileage? I can tell you it is absolutely no fun...

Hi Samurai,

As Santhosh stated, my explorer used to give over 16kmpl milege on diesel, but that was when the engine was sealed condition.

After the recent overhaul (already clocked over 25000kms), the engine became super smooth. One needs to drive my jeep to believe the word super smooth with the peugeot. However the negative parts worked on my FE, yes the previuos gave me 16+ and I have records of reaching even 18kmpl.

When I was driving from chennai to aavalakonda, I found my FE has been reduced to 10kmpl, but remember I have explaned reaching hosur in 4 hours 15minutes from my home in chennai including 35kms of city traffic drive. This is one more reason for low FE on the last drive (over 320kms chennai to hosur).

However during the OTR, I have received feedback from Spike about smell of unburnt fuel in the exhaust. Yes, he was right in saying that as the smoke was also heavy. Both Spike and Mr.UBS explained me that we could control the fuel supply to the engine on the pump. But excessive fuel increases the power, at time people do that to get more power as explained by Mr.UBS.

So the next day to OTR I went to Hosur and asked Santhosh's mechanic to attend my excessive unburnt fuel issue on the pump and demanded him to adjust the screw. It was a magic he did before my eyes, he unscrewed a small screw on the back of the fuel injection pump and the smoke started reducing and the while returning to chennai pickup of my jeep reduced compare to my trip to hosur.

There is one more thing I noticed after reducing the fuel supply, that is bit of overheating. I was in 80-85deg.cel. while coming to bangalore, with the same kind of speed the return trip showed 90-95deg.cel. (remember i was pressing accelarator to the platform).

Now the final information, as of now my Jeep gives me 13-14kmpl, still it is lower that my old numbers.
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Old 11th February 2011, 15:29   #2
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Siva, sorry i couldnt be with you the other sunday morning after the OTR... If i would have been there I would have suggested 'not' to let any person touch the pump. Yes, it did give a semi-desired effect, but the FIP is best left to the bosch guys. Get it recaliberated. I am sensing the overheating is due to running a very lean FIP!! PS - Get a compression test done too. It is worth the 30-40$ investment. You can stop driving the engine before it blows away completely.
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Old 11th February 2011, 16:07   #3
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Wait, now that I think about it, I hadn't checked my FE since the engine overhaul, FIP and injector calibration. Avalakonda was the first OTR after all the work.
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Old 11th February 2011, 17:06   #4
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Originally Posted by trammway View Post

However during the OTR, I have received feedback from Spike about smell of unburnt fuel in the exhaust. Yes, he was right in saying that as the smoke was also heavy. Both Spike and Mr.UBS explained me that we could control the fuel supply to the engine on the pump. But excessive fuel increases the power, at time people do that to get more power as explained by Mr.UBS.

There is one more thing I noticed after reducing the fuel supply, that is bit of overheating. I was in 80-85deg.cel. while coming to bangalore, with the same kind of speed the return trip showed 90-95deg.cel. (remember i was pressing accelarator to the platform).
IMHO ,

1) avoid reducing diesel quantity/supply as it leads to under power = results in overheat

2) set the FE pump on little 'Advanced' side , scribe a mark & move it 1.5 mm at a time . check results after every adjustment

3) super smoothness + unburnt smell + black smoke ( does it have a lot of smoke before the engine heats up ?) point towards the retard timing

Sorry for this OT on Samurai's thread ( will post reasoning if allowed )

Sudarshan
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Old 11th February 2011, 17:36   #5
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Sure, go ahead. It is not really off-topic.
Thanks

1) in engines where the FE pump is driven via a gear, a lag creeps in as the gears wear . So to counter the sort of 'little Late' function, the advancement of pump helps ( particularly in older engines or set of old gears ) In 2112 cc peugeot , timing gears are hardly changed even if all other components are renewed . people change the bush of the idler gear .

2) diesel Quantity is set for optimum as well as for all possible conditions/loads , so any deviation other than the prescribed will show some odd results .IMHO its better left to the Authorised service guy , he has all the tools ,gauges and charts

3) I also suspect the dynamic advance gone wrong ,here one needs external adjustments to counter that effect to bring it under some control

4) IMHO the current diesel ( more efficient/higher cetane ? ) will need a slight advanced timing ,experts can tell more .

5) the nozzle pressure needs to be attended here if smoking/super smoothness is experienced , I think its 120 bars in older peugeot

Sudarshan
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Old 11th February 2011, 17:38   #6
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It was a magic he did before my eyes, he unscrewed a small screw on the back of the fuel injection pump and the smoke started reducing and the while returning to chennai pickup of my jeep reduced compare to my trip to hosur.

There is one more thing I noticed after reducing the fuel supply, that is bit of overheating. I was in 80-85deg.cel. while coming to bangalore, with the same kind of speed the return trip showed 90-95deg.cel. (remember i was pressing accelarator to the platform).

Now the final information, as of now my Jeep gives me 13-14kmpl, still it is lower that my old numbers.
Dont let any body touch your FIP. Its a delicate darling and needs the attention of knowledgeable folks!


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Originally Posted by Sudarshan View Post
IMHO ,

1) avoid reducing diesel quantity/supply as it leads to under power = results in overheat

2) set the FE pump on little 'Advanced' side , scribe a mark & move it 1.5 mm at a time . check results after every adjustment

3) super smoothness + unburnt smell + black smoke ( does it have a lot of smoke before the engine heats up ?) point towards the retard timing
IMO, the timing should be correct - Not advance nor retard..but i;ve seen guys play around 5 to 15 degrees..
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Old 11th February 2011, 18:38   #7
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Originally Posted by svsantosh View Post
If i would have been there I would have suggested 'not' to let any person touch the pump. Yes, it did give a semi-desired effect, but the FIP is best left to the bosch guys.
Quote:
Originally Posted by Sudarshan View Post
2) diesel Quantity is set for optimum as well as for all possible conditions/loads , so any deviation other than the prescribed will show some odd results .IMHO its better left to the Authorised service guy , he has all the tools ,gauges and charts
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Dont let any body touch your FIP. Its a delicate darling and needs the attention of knowledgeable folks!
So this is why my highly skilled mechanic promptly traveled to Mangalore with my FIP and injectors to a BOSCH authorised center for calibration. I was wondering why he didn't try it himself.
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Old 11th February 2011, 19:01   #8
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So this is why my highly skilled mechanic promptly traveled to Mangalore with my FIP and injectors to a BOSCH authorised center for calibration. I was wondering why he didn't try it himself.
Slightly OT But nevertheless:

Once a pump is touched, the effectiveness of the pump is tested [feedback] on a machine specifically designed for that.

On the machine, a lot of factors can be tested and the various internals of the pump can be replaced. AFAIK, there are no serviceable parts inside.

Most of our local guys do NOT go to the authorized service centre because the charges are high!

And a quarter turn does temporary wonders
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Old 11th February 2011, 20:54   #9
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Hi,
What exactly is 'running lean' in a diesel?

Regards
Sutripta
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Old 11th February 2011, 21:46   #10
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Something like 81:1 instead of 80:1
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Old 11th February 2011, 21:56   #11
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What exactly is 'running lean' in a diesel?
Sorry Da, i didnt know the correct term. I meant to say the pump can be tuned to give more or less power/timing/idling, whatever. I mean to the highlight the lower spec setting. What is it called?
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Old 12th February 2011, 10:45   #12
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Hi,
What exactly is 'running lean' in a diesel?
The stoichiometric AFR is 14.7 : 1. i,e 14.7 parts air to 1 part fuel. Any higher quantity of air is leaner and a higher quantity of fuel is richer!!

Does it make sense?
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Old 12th February 2011, 13:57   #13
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Dear Trammway and all - there you go again! Now it's the FIP that I need to explain. The mechanical pump come in two configurations, in line and rotary. The "older" old generation vehicles used an inline pump and the "newer" old generation vehicles used a rotary pump (some of them still do). The fuel delivery quantity is controlled by changing the orientation of a helix inside the delivery module. What your technician did was change this orientation. This is not the correct thing to do as it is to be set by using a dial guage calibrated against a master sample which also denotes the crank angle at which fuel injection takes place. In common jargon, this is known as "advance" or "retard". If it is advanced, lots of smoke will come but power will marginally increase. This is what technicians do to give some more life to dead engines. If it is retarded, cooling system demand wil lincrease due to flame front travelling through a larger crank angle. Both are harmful to the engine and the environment. ECU controlled engines save all this hassle as nobody will mess around with them.

Best regards,

Behram Dhabhar

Last edited by Rehaan : 13th February 2011 at 17:47. Reason: Post edited. Will send you a PM regarding it.
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Old 12th February 2011, 14:56   #14
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The fuel delivery quantity is controlled by changing the orientation of a helix inside the delivery module. What your technician did was change this orientation. This is not the correct thing to do as it is to be set by using a dial guage calibrated against a master sample which also denotes the crank angle at which fuel injection takes place. In common jargon, this is known as "advance" or "retard". If it is advanced, lots of smoke will come but power will marginally increase. This is what technicians do to give some more life to dead engines. If it is retarded, cooling system demand wil lincrease due to flame front travelling through a larger crank angle. Both are harmful to the engine and the environment.
Sir, thanks for the great explanation.


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Originally Posted by DHABHAR.BEHRAM View Post
ECU controlled engines save all this hassle as nobody will mess around with them.
Sir, my apologies to you for the above misconception. It is easier to play around with these electronic ECU stuff nowadays than the older systems IMO.

All one needs is a piggyback ECU that fools the "electronic system" by sending wrong signals, thereby increasing the rail pressure and giving more power.

Infact, it would be nice if THAR could come in 2 modes - oops, we are way OT here

Last edited by Rehaan : 13th February 2011 at 17:47. Reason: Edited quoted post
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Old 12th February 2011, 15:30   #15
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Here is a schematic overview picture of VE pump aka rotary pump with mechanical governor.

FIP Flop-ve_pump.jpg

There are only two things that can be adjusted with this pump.

1) Delivery rate
2) start of delivery

Both are different entity. Delivery rate is adjusted in the governor device which will lead to lean or rich mixture and start of delivery is adjusted in the timing device which will advance or the retard the injection w.r.t TDC.
Advancing will cause less smoke but will increase the combustion noise. Advancing will increase the chamber pressure which will in turn cause over heating. retarding is quite safer compared to advancing, except it will increase more unburnt carbon particles and inefficient burning which will decrease F.E. and more soot is again a problem for engine and environment. Engine knocking is result of bad timing or a bad injector.
Adjusting the delivery rate, if its lean it will cause NOx emissions due to excess oxygen. The excess oxygen causes flame tip temperature in the combustion to reach the peak values where the excess Nitrogen in the combustion chamber reacts with the excess oxygen to produce unstable Nitrogen Oxides. This is also the reason for the increase in engine temperature.
Running rich will increase the unburnt carbon but will decrease the NOx. F.E will go down. will it increase the power? yes but its not the CLEAN DIESEL POWER.

the mechanical governor part is explained here with more details. Bosch VW Type INjection Pump Governor Operation
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