Hey Guys,
It appears I have a problem with the Engine Coolant Temperature Circuit Malfunctioning. I have used the search menu and could not find anything related to my experiences. So, here they are:

1. My Temp gauge reads between 40 and 90. When the AC is OFF it reads at 40 to 50. When the AC is on it reads between 80 to 90.

2. There is no oil in the expansion tank, and I'm not loosing any water.

3. I have no oil leaking, nor is there the milky look of the oil in the morning, while the engine is cold.

4. However, I have replaced the Engine Coolant Temp Sensor twice within a year because of the P0115 Code.

5. While driving, I'm noticing what seems to be a loss of acceleration when I'm making a right turn. I mash the gas and nothing for at least a second. It's as if there's air there or like something is clogged, or there is a vapor lock or something, I get no codes for that. I've only gotten the code for the Engine Coolant Temp Circuit Malfunction.

Now, I intend to do the following, but I still want your input.

I'm going to replace all Spark Plugs and Ignition Coils, Air Filters (taking out those crappy K&N's), Fuel Filter, Water Pump and Thermostat, Engine Coolant, Cabin Filter, Oil Pressure Sensor, the Fan Clutch, Serpentine Belt, Change the Engine Oil, and finally the Engine Coolant Temp Sensor (again).

What are your comments and or suggestions? What is happening here?

 

Hi,

I wouldn't bother doing all the work you list (unless of course this is required anyway) since I don't believe it will address your issue.
e.g. Change Serpentine belt. What can this possibly have to do with the temp sensor / guage.

However I'm interested why you have changed the sensor twice and what impact this had on the CEL/DTC?

In addition you quote:.... Temp gauge reads between 40 and 90. When the AC is OFF it reads at 40 to 50. When the AC is on it reads between 80 to 90.

,,,,so if you turn the AC OFF again the temp drops? If so Quickly? .....Immediately, in seconds, in minutes?

My thoughts.

Chances that the same sensor has gone bad more than once...very loooong. Subject to your response to the above question I suspect that you may have a CAN issue.

If the temp changes the moment you turn the AC ON/OFF then there is interaction on the CAN that shouldn't be occurring. The water temp is an input to the AC ECU as well as the engine ECU and other ECU's like the A1 Instrument pack.

If the temp moves slowly from one temp range to the other when the AC is switched ON/OFF then it feels more like something mechanical but can't figure out how something mechanical other than a REAL change in water temp could occur. If the water temp is changing then I would expect the water temp to be higher with the AC on, not lower!

So I'm reasonably certain you have a CAN interaction issue. Are the pins on the sensor connector clean and have no corrosion on them. A spec of salt and water and all sorts of strange things occur.

I await your answer. Good luck.

Stuart.

 

Personally sounds like HG lead / Ignition Coils with a faulty connection which gives you the intermittent problem on a corner as the "lean" is applied to those parts.

Will be interested to know what it was when you do sort it though so please let us know.

 

Stuart,
As you related, I'm mixing symptoms. My issue is engine performance related. My apologies for mixing apples and oranges.

The cooling system has absolutely nothing to do with what I'm experiencing. It's engine related, completely. When under accerleration the shifting seems to be delayed. The real issue is...if feels like the power is delayed. It feels like it's got a stopped up nose. In fact, that's exactly what it feels like. I get a lot of engine REV, but the power and acceleration do not match. That's what's going on. However, I get no Check Engine light for that. In fact, I don't even get it for the Malfunction of the Engine Coolant Temp Circuit anymore.

Recently, I changed the ball-joints, the sway-bar bushings, and the swaybar links. what a difference...geeeez. I changed all of the spark plugs, and replaced the coils paks on cylinders 1, 2, 5, and 7, as they are the oldest. I've taken out those darn K&N Filters and put Stock back in, engine purrrs. I changed the fuel filter as well, but I'm still left with that stopped up nose feeling.

My thoughts are MAF, 02Sensor,or CAT related right now.

 

I'm confused now since you have now introduced MORE symptoms. You didn't respond regarding the temp gauge questions I raised. So is this an entirely different and new problem?

"If the car feels as though its got a blocked nose" I need to understand your symptoms in more detail to offer any advice since you also state the engine Purrrrrs!

Are you saying the car doesn't change gear at the correct points?
Are you saying that the engine is smooth but doesn't seem to have any "omph" (kick).....or what?

Heres an idea to move you forward until I get some additional detail.

Firstly does the CEL come on when you turn the ignition on and then go out? If not then the CEL may be misfunctioning. If indeed it does go out after initial "bulb" check then this SUGGESTS that there is nothing wrong and if you access the OBD codes there SHOULD not be any. Please CONFIRM.

If this is a true statement (and also taking into account your strange temp gauge problem) I wonder if the car IS overheating because one of your cats has broken up and blocked the exhaust system. The engine management system would have trouble working this one out. It would certainly lead to reduced power and overheating although to actually ":block" the exhaust takes some doing. Have you been experiencing a rattle from the cats or somewhere under the car for a period of time?.

When the engine is cold, preferably on a cold morning, start the car and observe the exhaust pipe(S) hidden behind the rear bumper. Do both emit a similar amount of steam when cold? Also taking care not to burn your hand does the pressure in each pipe seem similar?

Unlikely that it is the MAF since you state that the CEL is not indicating a fault. The MAF should illuminate the CEL if there is a fuelling or circuit fault + store a code.

Is your lack of power OBVIOUS or is it just that there doesn't seem to be as muchpower as some point in the past that you think you remember You could of course do a ROUGH and QUICK 0-60 mph acceleration test (subject to usual safety precautions) and advise what you get 5, 10, 15, 20 secs?

Stuart

 

Stuart,

By no means do I wish to create confusion, so I'll be as careful as I can to explain my experiences so that others may receive proper advice relative to these symptoms.

1. The Engine Coolant Temp Circuit Malfunction (P0115) Code that I received must have been a glitch or something, because I'm no longer receiving that same code. However, I do believe that I have a lazy water pump and/or thermostat. I will change them both to rule out either. I've already purchased them, just have not installed them as of yet. Not really ready to tackle the job, maybe in a week or so.

2. When I turn the key to ON, yes the CEL illuminates and then goes out. Once the vehicle is started the CEL does not come back on. So, No, it's not tossing any codes.

3. It purrrs because it was time for the plugs and filters to be changed. That's just the bottomline. I changed the coils that I've referenced because I hadn't done it. But I did take out the K&N Filters and returned to Stock Filters, and that was the noticeable difference.

4. Now, here's what I'm experiencing, that there be no confusion.

When I'm casually driving, taking it easy, the vehicle shifts normally. When it reaches 2,000 rpms there is a vibration. However, as the vehicle continues to pick up speed it rises above the vibration to where it's non-existent until cruising speed is reached, and then there is a rythmic humming underneath me.

When I jump on the accelerator from a dead start, the vehicle suffers. It's as if the vehicle doesn't know what to do! No, it doesn't jump into gear like it would if it was a Transmission Slip...no, I know what that feels like. But it's like being lost between space and time, almost like a vapor-lock. It will accelerate, but will struggle to do so. I'll get a lot of RPM's, but the speed is not proportionate. There is no omph (no kick) as you've described.

I've changed the CATS in '05. Well, I changed the defective ones which include the Right-Front & Rear, and the Left Rear. The Left-Front at that time could not be changed because there was no evidence of damage. However, I'm thinking now that it may be the problem. Also, I didn't change out the resonator and muffler. And I'm wondering whether these could also be contributing factors?

I'll check the exhaust flow and get back to you.

David

 

Hi David,

1. The Engine Coolant Temp Circuit Malfunction (P0115) Code that I received must have been a glitch or something, because I'm no longer receiving that same code. However, I do believe that I have a lazy water pump and/or thermostat. I will change them both to rule out either. I've already purchased them, just have not installed them as of yet. Not really ready to tackle the job, maybe in a week or so.

No response still to my question re whether temp changes quickly or slowly when turning the AC on....or is the gauge frunctioning OK once again.
If so this may still be an indicator towards your loss of power issue.
Incidentally with a good scanner you could read the temp data stream and determine whether its the data or the gauge that was causing the problem.

2. When I turn the key to ON, yes the CEL illuminates and then goes out. Once the vehicle is started the CEL does not come back on. So, No, it's not tossing any codes.

Good. However there can be stored codes without the CEL illuminating. All depends on severity of the issue. .

3. It purrrs because it was time for the plugs and filters to be changed. That's just the bottomline. I changed the coils that I've referenced because I hadn't done it. But I did take out the K&N Filters and returned to Stock Filters, and that was the noticeable difference.

Good. Changing the coils seems a little drastic unless something was wrong!

4. Now, here's what I'm experiencing, that there be no confusion.
When I'm casually driving, taking it easy, the vehicle shifts normally. When it reaches 2,000 rpms there is a vibration. However, as the vehicle continues to pick up speed it rises above the vibration to where it's non-existent until cruising speed is reached, and then there is a rythmic humming underneath me.

I understand. But is this issue always at 2000 rpm or at the equivalent road speed? What I am asking is in which gear or in every gear at 2000rpm?

When I jump on the accelerator from a dead start, the vehicle suffers. It's as if the vehicle doesn't know what to do! No, it doesn't jump into gear like it would if it was a Transmission Slip...no, I know what that feels like. But it's like being lost between space and time, almost like a vapor-lock.
Hesitation. Yes?

It will accelerate, but will struggle to do so. I'll get a lot of RPM's, but the speed is not proportionate. There is no omph (no kick) as you've described.
Lots of revs and no speed = slip. However you state that it is not slip. Once again what gear are you in when you have lots of revs and no speed.
What are the rough accel times please.

I've changed the CATS in '05. Well, I changed the defective ones which include the Right-Front & Rear, and the Left Rear. The Left-Front at that time could not be changed because there was no evidence of damage. However, I'm thinking now that it may be the problem. Also, I didn't change out the resonator and muffler. And I'm wondering whether these could also be contributing factors?
A defective front cat can wreck the engine (particle ingestion) but mine are going strong after 110k miles although the rear ones let go (rattle) much earlier.

Your symptoms seem to suggest transmission slip so is the trans fluid level correct. What colour is the oil. What is the vehicle / transmission history?
This proposal is reinforced by the 2000 rev vibration and heterodyne (pulsing hum/vibration). Something (quite possible the torque converter) is rythmically coming into and out of vibration due to a balance issue which may indicate some form of internal problem.
I'm afraid I have never encountered a failed TC previously so this is relatively low on any list of possibilities.
Are the transmission "doughnut" couplings in good order. If not then this could be causing the heterodyne and reduce the possibility that it is the TC.

I'll check the exhaust flow and get back to you.
I don't think this will show anything up since you would have had a bad rattle prior to the remaining cat monolith becoming jammed, but its nice to remove it as a possibility. You've also had new cats.

A final point. If there really are no codes (and OBD covers trans as well as engine) then your problem would appear to be mechanical rather than electrical.
My current feeling is that you have slip in either the TC (hence the OOB) or gear brake bands.

 

Stuart,

With regard to the following, I'm attempting to describe these symptoms as illustratively as possible. Having said that,

No response still to my question re whether temp changes quickly or slowly when turning the AC on....or is the gauge frunctioning OK once again.
If so this may still be an indicator towards your loss of power issue.
Incidentally with a good scanner you could read the temp data stream and determine whether its the data or the gauge that was causing the problem.

Reply. Yes, the temperature does change rather quickly. Not immediate, but relatively quick.


Good. However there can be stored codes without the CEL illuminating. All depends on severity of the issue. .

Reply. Yes, I do understand that depending upon how many times the CEL tripped, codes would become part of the permanent memory until the issue is resolved and the code erased or reset.


Good. Changing the coils seems a little drastic unless something was wrong!

Reply. That's just it, with no codes...I just wanted them changed. Process of elimination.


I understand. But is this issue always at 2000 rpm or at the equivalent road speed? What I am asking is in which gear or in every gear at 2000rpm?

Reply. No, not necessarily, which further confuses me, because I can be in Park and rev the engine, and once it reaches the 2000 rpm mark, I start to get the vibration. It's just consistent when driving, however, when driving the experience occurs at about 2000 rpm's while making the transition to 3rd gear.


Hesitation. Yes?

Reply. You say, Hesitation. I don't call it a hesitation, because it's not hesitatating. It's simply as if there is no fuel pressure, and the gas pedal feels like mush, or just feels weak.


Lots of revs and no speed = slip. However you state that it is not slip. Once again what gear are you in when you have lots of revs and no speed.
What are the rough accel times please.

Reply. The reason I'm having problems with your analogy on this item is because the vehicle is not jerking. It doesn't pop into gear. I know what it feels like to slip. The experience occurs when you do a transmission service and forget to replace the filter, or the filter slip off into the pan. You get one heck of slip. That's not the experience here. It feels more like what occurs in some vehicles when the 02 sensor is not working.


A defective front cat can wreck the engine (particle ingestion) but mine are going strong after 110k miles although the rear ones let go (rattle) much earlier.

Reply. This is my chief concern, right here!


Your symptoms seem to suggest transmission slip so is the trans fluid level correct. What colour is the oil. What is the vehicle / transmission history?
This proposal is reinforced by the 2000 rev vibration and heterodyne (pulsing hum/vibration). Something (quite possible the torque converter) is rythmically coming into and out of vibration due to a balance issue which may indicate some form of internal problem.
I'm afraid I have never encountered a failed TC previously so this is relatively low on any list of possibilities.
Are the transmission "doughnut" couplings in good order. If not then this could be causing the heterodyne and reduce the possibility that it is the TC.


Reply. The transmission was replaced at 130k. I have 218k on it now.

I don't think this will show anything up since you would have had a bad rattle prior to the remaining cat monolith becoming jammed, but its nice to remove it as a possibility. You've also had new cats.


Reply. Your right! I didn't show anything. Nonetheless, I will have it checked.

A final point. If there really are no codes (and OBD covers trans as well as engine) then your problem would appear to be mechanical rather than electrical.
My current feeling is that you have slip in either the TC (hence the OOB) or gear brake bands.


Reply. I'm told by two Mercedes Benz mechanics that, there could possibly be afew things to consider: 1.) The MAF has set values by which to function, so as to compensate for some malfunction or shortcoming. 2.) The same for the02 Sensors, and may simply need to be replaced. 3.) The CAT could be clogged or damaged. 4.) The drive-shaft needs replacing. 5.) The Flex Discs are fine, however, the U-Joints maybe bad, and the something to do with the propeller shaft in the transmission and driveshaft (can't explain exactly), along with the Center Support Bearing.

However, I will check the Transmission Fluid and get a service anyway.

I hope this gives you a little moreinformation to consider as well. Your thoughts, ideas, and/or suggestions are solicited and appreciated.

David

 

Hi Dave,
You're doing fine. Its not your words just that new bits of data keep being added to the problem.
Sorry if I sound a bit demanding. Its just my nature or the fact that I am a Brit.

The latest revelation is the fact that the car has had a new trans AND the fact that the car has now done 220k miles!

Was the trans rebuilt or replaced? New or used? Was the TC changed or is that original?

If the vibration is present in Park at 2000 revs I believe it increases the odds on it being the TC (or engine).

Although axle, driveshafts and UJ's may be contributory I don't see how they can have anything to do with the vibration if it is present in Park and stationary!

You also seem to equate slip with jerk into transmission.
The TC is a fluid coupling. If for example there was no auto trans fluid in it you would get 100% slip = no drive. With the exception of lockup in top gear the TC always slips. the issue is whether it is slipping more than it should. The TC is a bit like a turbine with vanes that create and react to the high pressure "jets" of oil in the unit. I fear that a vane may have become detached. Snatching into gear in my view (I think this is what you have experienced previously, is totally different.)

As I stated previously I don't believe your problem is electrical (and this includes the MAF and O2 sensors) since there are no codes stored.

If emmissions are threathened the engine ECU instructs the EMS Engine Management System to use set values known as "Limp Home" which will allow the engine (and trans) to work but with limited performance. This situation is signalled by strange lack of gear shifting, very limited performance and CEL. I do not think this is your problem.

It is quite difficult to check the integrity of the front cats since the monolith is not usually visible. Of course you can check that they don't rattle once removed. The front cats don't usually rattle in situ because gravity keeps the monolith roughly in place since they are mounted near to vertical. However the rear cats are mounted horizontally and road bumps etc cause these to rattle especially when cold if faulty.

Look forward to your reply re history of TC.

Stuart.

 

Took my automobile to my Benz Mechanic. He confirmed that there was nothing "electrical" going on with my vehicle. Whatever is going on is "mechanical." The onlyquestion is, "what?" This, BTW, was on Friday past.

Today, I was just curious enough to plug-in my OBDII Scanner, and I now get a code P0170 "Fuel Trim Malfunction (Bank no.1)." However, it has not tripped the CEL.

Well, to update you, this is what I've found. A search of the above listed Code via this forum revealed asimilar history describing what I've been experiencing all along. I have been trying to explain it, but it is difficult to understand, and even more difficult to accurately describe. Especiallyfrom a fella who hovers over his automobile to ensure that all systems are "go!" This is very frustrating!

So, I went online to oneof theParts Stores and was getting ready to order a new MAF, and a Fuel Pressure Regulator (this is not cheap stuff!).I found out that the MAF can be cleaned! I've order 2 cans of the CRC MAF Sensor Cleaner to trybefore I replace it. However, I don't believe it's the problem, but I'm going to clean it anyway. As I was looking at the top of the engine is when I thought about replacing the Fuel Pressure Regulator, but then something struck me as strange! I was somehow drawn to the hose (that squiggly one) that goes from the Valve Coverinto the Intake Manifold.Notonly is it flimsy as all hec, but it was eaten up! The whole underside and lenght of the hose is just deteriorated!The front side or top side of it, near the MAF has abig hole in it, as if something has eatenit! I'm almost positive that this is the source of my problem, and why I've been experiencing the Limp Mode situation.

Additionally, I'm going to repace the Motor and Transmission Mounts. I'll update you further, once I clean the MAF, and replace this hose.

David