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Old 01-01-2020   #1
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Panda 100HP Coolant Sensor Measured Value

Hi Guys

Getting a really lean mixture.

Symptoms:
RPM Hesitation especially across high RPM
0-100 in 13/14 seconds
Overall sluggish

Checks done:
Removing plugs shows a very white burn (indicating lean)
TPS & Potentiometers (Voltage Looks good on both and Throttlebody coheres with pedal)
Upstream and Downstream Sensors (Upstream fluctuates around 1.46 to 1.78 volts playing with the throttle, downstream doesn't move at 1.46 volts)
Compression Check (14 to 14.5 bar across all cylinders)
Fuel pump (The fuel screen is clear of any dirt) Will get around to doing a pressure check)
Temp sensor (was included in the new thermostat housing, car warms up failry quick and sits just slightly above the middle mark HOWEVER doing a diagnostic check on that range showed 135.7 degrees Celsius at that mark so I'm suspecting it might be the incorrect calibrated sensor)

Suspecting:
Map sensor
Coolant Temp sensor
Fuel Pump
Fuel Pressure Regulator

Notes:
No Codes thrown from ECU

Thank you
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Old 02-01-2020   #2
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Re: Panda 100HP Coolant Sensor Measured Value

what does the ambient temperature read before you start the engine ?


Should read within a degree of what Google says it is at your location
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Old 02-01-2020   #3
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Re: Panda 100HP Coolant Sensor Measured Value

if its the same as the 1.1 and 1.2 there's only one coolant sensor and as the gauge reads okay it will be near enough
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Last edited by koalar; 02-01-2020 at 01:55.
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Old 02-01-2020   #4
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Re: Panda 100HP Coolant Sensor Measured Value

looks like there's something wrong with the figures from the scanner ?
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Old 02-01-2020   #5
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Re: Panda 100HP Coolant Sensor Measured Value

A mat grey plugs is normal on my cars on supermarket petrol


gone are the days of carbs and leaded petrol which gave a nice brown colour.
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Old 02-01-2020   #6
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Re: Panda 100HP Coolant Sensor Measured Value

Quote Originally Posted by koalar View Post
gone are the days of carbs and leaded petrol which gave a nice brown colour.
That "nice" brown colour was lead deposits on the plug. The same stuff settled on the exhaust valve seats.
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Old 08-01-2020   #7
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Re: Panda 100HP Coolant Sensor Measured Value

Sorry for the late reply. Festive season and birthdays had me pretty occupied. #capricorns_makes_my_wallet_go_on_a_diet .

Ambient temp is fairly accurate (additionally I donít see any hiccups with cold starts)

From what I can tell the 1.4 has only one sensor too, right on the thermostat housing. I cannot recall the color of the one that came off but I know that the replacement was a different color. This is why I took a temp reading.

Iím also starting to think that the reader might be at fault because the temp is through the roof, even if I convert to degrees Fahrenheit it doesnít look accurate. Also O2 sensor upstream should fluctuate between .4 and .8 and mine is between 1.4 and 1.8v. Why the extra volt? All I can think is that the reader might be adding the ambient and the water temp together? Also adds 1 volt to the O2? I donít know, it is a very reputable brand this side and the software is up to date. It was a pretty expensive reader and we use it for the workshop everyday all day. Can anybody recommend a reader that can stream live date with a quick response and offer scoped readings?

At first glance the plug looked fine but when I had a closer look and compared with ngkís pics it is quite clear that its lean. Itís burning white as in a4 page white.

As always thanks for all the help guys
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Old 08-01-2020   #8
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Re: Panda 100HP Coolant Sensor Measured Value

Just replaced my (100HP) thermostat and the sensor was brown (opening temp 88 degrees) My son's Tjet MiTo uses a fysically same thermostat (ordered at the same time) with a green sensor (opening temperature 80 degrees).
So although I could switch them out, the MiTo thermostat would open too soon anbd leave the engine too cold. Dial in the dash would still be in the middle though as long as the enginetemp stays between 80 and 100 degrees.

gr J
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Old 08-01-2020   #9
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Re: Panda 100HP Coolant Sensor Measured Value

0-100 kph or mph ?
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Old 09-01-2020   #10
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The new sensor is green. I do recall the old one being brown.

I found the negative terminal on the battery corroding insanely fast. Occasional power steering failure with red light on dash. No difficulty starting or other bad battery problems but think this could be a sign of battery failure or perhaps alternator undercharging. Diagnostics and multimeter shows 14 - 14.2v during idle and rev up. So my money is on the battery.

Side note. Disconnecting the map sensor and taking for a drive. No improvement in performance however did fix the rpm hanging after gear change. Now itís more like our other 100hp. Instant drop when putting the clutch in

It was 14 seconds for the 0-100km/h time. Should be around 9 seconds?
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Old 09-01-2020   #11
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Re: Panda 100HP Coolant Sensor Measured Value

I think you have a thermostat wioth opening temp 80 degrees which leaves your engine too cold even if the dash says it's good.

gr J
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Old 09-01-2020   #12
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Re: Panda 100HP Coolant Sensor Measured Value

I think I might still have the old one. Iíll have a look thank you for the advice.

I came across two things just now. Double checking the map sensor, wiggling it slightly as the car is idling, a huge amount of vacuum was sleeping through. Inspecting it closely it was not seeping through the sensor o ring but instead the intake manifold separated on the corner. It doesnít leak on idle but applying literally just a touch of pressure cause a leak that sends the rpm sky rocketing.

Second thing I noticed was that I place my hand on the exhaust thereís almost no pressure, on the other 100hp I can only hold my hand there for a second or two until it pops off with pressure. Side note the faulty hesitating 100HP has 14 to 15 bar compression per cylinder.

Iím wondering if the cat isnít blocked because of the slight hiss on high rpm and also both catalytic converter killer situations occurred over lengthy periods on the car. Blown head gasket, over fueling and excessive oil burn
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Old 09-01-2020   #13
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Re: Panda 100HP Coolant Sensor Measured Value

Just came across something and I think Iím right on the money. I donít know how I came about doing this but left foot braking and trying to accelerate I noticed the ecu cuts the throttle and slowly eases it back again. The hesitation I feel whilst driving is identical to that kind of throttle cut. I jumped on the inter webs and checked for previous brake switch problems and low and behold, numerous posts of guys with not only pandas having hiccups with brake switches. No fault codes, brake lights not staying on but hesitation/loss of power/power cutting out. Iím going to yank that plastic piece of crap out and see if it needs resetting as itís ratchet type or perhaps faulty connector or dry connection.

I really pray itís the problem because Iím at my wits end trying to find this problem.
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Old 09-01-2020   #14
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Re: Panda 100HP Coolant Sensor Measured Value

Quote Originally Posted by A3jeroen View Post
I think you have a thermostat wioth opening temp 80 degrees which leaves your engine too cold even if the dash says it's good.

gr J
shouldn't hurt acceleration just economy.
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Old 10-01-2020   #15
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Re: Panda 100HP Coolant Sensor Measured Value

My question is that if the engine ecu reads 135 degrees Celsius, will it try to shower the engine with fuel to attempt to cool it or will it further lean it out to restrict performance?

Judging by the super white burn on the plug Iím guessing itís the latter
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