(Probably Silly) question about CRD MAP sensor

[seafish]

I pulled the Bosch MAP sensor on my CRD to clean today and while it was only lightly coated with soot and oil that I easily cleaned, I noticed that the actual probe is LOOSE...

In other words, I can gently wiggle the probe left and right with a dental pick even though the the plastic center baffle, which is located right next to it, is rigid.

Pics below -- NOTE that for some reason the wiggly probe has a yellow hashmark on it that did not cleanup. You can also see that probe itself is crooked inside the cage housing it.

So my (probably silly) question is --

Is it normal for the probe to lightly and loosely wiggle from side to side??

And also a simple followup request, if someone has a link to a resistance reading or test for the MAP sensor, I could also use that to check if its in working condition.

 

[Billwill]

I have the 2002 2.5L Export CRD with a fixed-vane Turbo....they only made the 2.5L for that one year for the Export market!

Both on this Forum and numerous other KJ Forums I have visited over the years there is a BIG warning not to touch the MAP Sensor at all....only flush it out with some alcohol to clean the carbon off!

So 22 years later with 200,000 Kms on the clock the Map is still working fine!

Looking at your MAP Sensor I would suggest you get a new one!

 

[KJowner]

You will know if the MAP isn't working, if its not you won't have any power, the ECU uses it to calculate fuelling relative to boost.

 

[seafish]

Both on this Forum and numerous other KJ Forums I have visited over the years there is a BIG warning not to touch the MAP Sensor at all....only flush it out with some alcohol to clean the carbon off!

Hard for me to believe that the MAP sensor can be THAT "don't even touch it" sensitive given that its bolted to the top of a shaking, oil eating, fire spewing beast of a motor... but what do I know?

That said, I am a fairly coordinated and thoughtful mechanic and did use MAF fluid to spray and clean the sensor. Only after I saw minor movement of the probe as I cleaned it with the spray can, did I use a dental pick (and not my favorite vise-grips ) to gently "probe the probe" upon doing which I confirmed small but actual "wiggly piggly" movement. If I broke it by doing what I did, then it was already broken. None of this paragraph is to suggest that I havent broken some things as I attempt to fix them!!!


Unfortunately without specs, I wont be able to test said sensor until the rest of the front of the engine and jeep go back together after the TB, turbo and GP service that I am on the downhill side of completing. In the meantime. MAP is now clean and reinstalled on top of the monster.

In fact, I got her test started yesterday...AFTER some of the various and most important parts were properly bolted back to the block, but BEFORE putting the front timing cover, as well as the rest of many other various important parts, back on. And despite pre-lubing the new turbo, I still needed to check actual oil flow through the turbo supply line, as well as check and adjust final tension on the new timing belt.

Since, for reasons still unknown, cranking the starter with the crankshaft sensor unplugged for many multiple 10 second intervals did NOT show me any oil flow at the loose banjo bolt on top of the turbo, I decided to actually fire her up while keeping the turbo shaft from spinning. In a rare display of common sense, I used needle nose vise-grips on the shaft nut zip tied to viscous heater instead of using my fingers to keep the turbo from spinning up even at idle .

And so with the crankshaft sensor plugged back in, and the oil supply line still loosened on the turbo, I had my excellent daughter turn the key and, within moments of start up, I witnessed a veritable gusher of oil flow to the turbo, which resulted in a sharp yell of excitement from me, so excellent daughter immediately shut her down, after which I properly tightened the banjo bolt on the the turbo oil supply line, reset the timing belt tensioner to mark ... and called it a day!!!

Thanks again for the advice on the MAP sensor...I'll wait to see how she runs down the road, and more importantly UP the hills, after full front end reassembly and will simply buy a new Bosch sensor from IDP if needed.

 

[KJowner]

I think this is the datasheet for our sensors.

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[seafish]

^^^
THANK YOU...dam...it's even got the pinout diagram on it.

Now all I got to do is brave the rain, pull the sensor, walk it back up to the house, set some water up to boil on the stovetop with a thermometer, locate the DVM (the hardest part ), calibrate the leads, and finally chart the MAP sensor while trying not to burn the DVM leads on the open flame.

In my slightly weakened state, even saying all that makes me kinda tired...prolly gonna wait just to see how she runs after I get her done. But MUCH appreciate the chart!!!

 

[KJowner]

^^^
THANK YOU...dam...it's even got the pinout diagram on it.

Now all I got to do is brave the rain, pull the sensor, walk it back up to the house, set some water up to boil on the stovetop with a thermometer, locate the DVM (the hardest part ), calibrate the leads, and finally chart the MAP sensor while trying not to burn the DVM leads on the open flame.

In my slightly weakened state, even saying all that makes me kinda tired...prolly gonna wait just to see how she runs after I get her done. But MUCH appreciate the chart!!!

No problem, however the bit you really need to see is the pressure transducer, the temperature is handy to check but it's only the offset for manifold air temperature.
On my old beast the transducer only drives the fuel but on your modern one its controlling the VNT too.

 

[seafish]

the bit you really need to see is the pressure transducer, the temperature is handy to check but it's only the offset for manifold air temperature.

Shows you what I know...are you saying that charting the resistance at various actual temps will NOT test the pressure transducer as well??

I would have thunk that checking resistance between pins 1 and 2 at various charted temps would test the pressure transducer for proper functioning, but now you've got me thinking that I dont know what Im talking about, which is MUCH more likely to be true!!

Is there a link to an actual MAP sensor testing procedure that Im missing ??

if not, Ill just see how she drives, and if she throws any DTCs, after getting her back together.
Like others have said, I can always just buy a new MAP sensor if mine seems to be acting up

 

[KJowner]

There are 2 sensors in the package, temperature as you say is easy enough to test on pins 1 & 2, pressure would be a lot more involved and require a test rig with a pump or well regulate air supply. A good scan tool can read it on the car though.
To be honest I'd just take it round the block, if it's not working it'll be totally gutless.

 

[seafish]

To be honest I'd just take it round the block, if it's not working it'll be totally gutless

I totally agree with this statement

 

[seafish]

Instead of starting another silly question thread about yet another sensor, I will try to ask it here, since searching didn't yield the needed answers.

I am in the process of swapping out the coolant thermostat housing with the modded one I bought fromRobert on LostJeeps. I removed the sensor from the housing, and I would like to test it before reinstalling it on the new housing just became it is a PIA to get to on the BACK of the housing. so d just as soon swap now instead of being forced to later, IF it is going out of spec.

My questions are --

1) Anyone here, like (@KJowner), have a temperature/resistance chart for the coolant temp sensor ??

2) Does the oem coolant temp sensor have a 200k lifespan?

Below are pics of the thermocouple in question and also one of me tapping out the lower/inner thermostat mounting bolt hole that was not only hard to access but also very tight to remove...had to back it in and out and in and out and in and out and ... before she finally came free.

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[KJowner]

Sorry I haven't got anything on that sensor, they are very common and fitted to loads of cars and trucks so shouldn't be hard to get if yours is dead.

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[iceaxe1967]

My 2006 map sensor was loose when I bought it used in 2014. I eventually replaced it and noticed a difference but mostly with no black smoke when accelerating on the freeway. Just replace it is my advice.

 

[WWDiesel]

I pulled the Bosch MAP sensor on my CRD to clean today and while it was only lightly coated with soot and oil that I easily cleaned, I noticed that the actual probe is LOOSE...

In other words, I can gently wiggle the probe left and right with a dental pick even though the the plastic center baffle, which is located right next to it, is rigid.

Pics below -- NOTE that for some reason the wiggly probe has a yellow hashmark on it that did not cleanup. You can also see that probe itself is crooked inside the cage housing it.

So my (probably silly) question is --

Is it normal for the probe to lightly and loosely wiggle from side to side??

And also a simple followup request, if someone has a link to a resistance reading or test for the MAP sensor, I could also use that to check if its in working condition.

It is possible to move the small temperature bulb from side to side, but it should not be "loose".
Best to just replace the sensor with the GM Bosch MAP sensor; much less expensive than the OEM one and works perfect.
GM PN: 55206797
New GM PN; 55568175

 

[seafish]

^^^ Thank you...that's exactly what I wanted to know.

 

[seafish]

Heres a picture of the Standard Motor Products coolant sensor #TS633 that I installed on the modified thermostat housing (with replaceable 95*C or 200*F Gates thermostat) before I put the housing back on the block today.

I got the sensor locally from Oreillys and was pleased to note that it says Made in Italy on the box as well as on the sensor itself.

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