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Discussion Starter · #21 ·
If the CTS is truly working correctly, then an air leak or low fuel pressure are possibilities. But I disagree about the fuel filter. A dirty fuel filter acts similarly to a resistor in series with an electrical load: When supplying current to a very small light bulb, the resistor may be insignificant. But use a large bulb instead, the Voltage may be lowered significantly by the same resistor.
In the case of your starting issue, consider that the lowest demand for fuel flow is at cranking RPM, while the highest demand for fuel flow is at full-throttle, max RPM. So a filter clogged enough to prevent the engine from starting, would be too clogged for driving.
Hi ylwagon,
Does air leak and/or low fuel pressure affect only first time engine start in the cold morning? I am asking because my car works fine after having a hard start once in the morning.
 

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I did not see it mentioned, out of curiousity ,how many miles are on the engine/car, and when was the last timing service done on the engine ?
 

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Discussion Starter · #23 ·
I did not see it mentioned, out of curiousity ,how many miles are on the engine/car, and when was the last timing service done on the engine ?
Hi cchief22,

My car is old(2003 passat wagon v6) but the mileage is relatively low of 60,600 miles. I am not sure what you mean by timing service but the timing belt in the engine was replaced about two years ago. My mechanic told me normally the timing belt needs to be replaced when the mileage reaches 70,000 miles or 80 months whichever is earlier.

Please let me know if there is any specific engine service you are referring to.

Thanks.

bigevent.
 

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Discussion Starter · #24 · (Edited)
Hi all,

I want to share with you that, today, I was able to start the engine on the second try. For future reference, I want to leave what happened the last couple of days.

11/19 (Friday) First day of the Cold Engine start issue. I was able to start the engine in 5 minutes. After the difficult start, it was fine the whole day. FYI, it was a lot colder two weeks ago but I did not have any issue with the Cold Engine Start.
11/20(Saturday) It was difficult to start the engine in the morning. The battery was replaced hoping that it would be okay the next day. It was fine to start the engine the whole day after replacing the battery.
11/21(Sunday) New battery did not help. It was difficult to start the engine in the morning. It was fine the whole day afterward.
11/22(Monday) It was difficult to start the engine in the morning. It was fine the whole day afterward. I went to see my mechanic and mentioned that CTS might be an issue. But he told me that CTS works fine and told me the fuel filter might be an issue. He suggested that the next day morning, turn on the key without cranking five times before cranking the engine.
11/23(Tuesday) Turning on the key without cranking did not work. It was difficult to start the engine in the morning. It was fine the whole day afterward.
11/24(Wednesday) I went to see my mechanic and he replaced the fuel filter anyway since I did not change it for a long time if not I have never changed. I mentioned low fuel pressure and air leak but he was not motivated to fix it, probably since it was right before Thanksgiving day.
11/25(Thursday) It was difficult to start the engine in the morning after replacing the fuel filter. It was fine the whole day afterward. I drove 200 miles to see my family in Maryland.
11/26(Friday) I filled the gas tank full from Wawa station and I was surprised that the expected miles the car can drive were a lot more than usual. When I fill my gas tank full at Sunoco in my neighborhood, the expected miles I can drive is about 280 -300 miles. This time, it showed 385 miles and I suspected it might be from the long distant trip the day before which is more mileage efficient than driving in the city. Or I thought the gas from Wawa station is better than the one from Sunoco. Or the new fuel filter might work better than the old one. One thing I did before I made another 200-mile trip back to New York, I cleaned the engine air filter and vacuumed the inside of the air filter housing area.
11/27(Today) I was able to start the engine on the second try on another cold morning. I am not sure if this is just a miracle of the day or if that can happen again tomorrow morning.

I will keep you updated.
 

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your car is far from "old" , I like to think of it as mature ! only 60k ! just broken in. I have a couple of thoughts but first I would put in a new coolant sensor, they can act funky with the age given. What oil was/is being put in the car ? I see 5W40 however ,synthetic or conventional ?, As I said CTS first ,inexpensive to at least eleiminate this from the failure equation.
 

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As a caveat to my previous post when was the last oil change ? Also the mileage shown and actual mileage that happens can vary greatly depending on circumstances. The reason for slow/delayed start after fuel filter replacement is air in the line. Personally two other suspects I will throw out not necessarily for your thoughts but rather for the other contributors, with the low mileage and age, check valve at fuel pump comes to mind as well as fuel pump relay. Relay is inexpensive and easy to eliminate from the failure equation, I am not one to throw money at an issue but when weighing time versus cost , I sometime defer to just replacing. What is nagging at me is the oil pressure possibly to a CCT (valve timing) collapse, you might not get a code and am not sure if cam sensor plays any part in start-up (I doubt). Out on a limb on that one.
 

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Discussion Starter · #27 ·
your car is far from "old" , I like to think of it as mature ! only 60k ! just broken in. I have a couple of thoughts but first I would put in a new coolant sensor, they can act funky with the age given. What oil was/is being put in the car ? I see 5W40 however ,synthetic or conventional ?, As I said CTS first ,inexpensive to at least eleiminate this from the failure equation.
Hi cchief22,

I changed the engine oil last June. I asked my mechanic to add 5W-40 and he used Mobile 1 Turbo Diesel Truck 5W-40. You can check my old post below.


Recently, I added two quarts to top up. It has been a known issue that my car needs oil topping up this much before it reaches 5,000 miles after changing engine oil. I still have 2,000 more miles to go before I am supposed to change my engine oil. I will plan on using a recommended oil below this time, not the Mobile 1 Turbo Diesel Truck 5W-40 that my mechanic used.


I will mention CTS replacement when I visit my mechanic next time, but he did not like that I keep mentioning CTS because he believes that CTS is working and my car will show engine light if CTS is not working.
 

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Discussion Starter · #28 · (Edited)
As a caveat to my previous post when was the last oil change ? Also the mileage shown and actual mileage that happens can vary greatly depending on circumstances. The reason for slow/delayed start after fuel filter replacement is air in the line. Personally two other suspects I will throw out not necessarily for your thoughts but rather for the other contributors, with the low mileage and age, check valve at fuel pump comes to mind as well as fuel pump relay. Relay is inexpensive and easy to eliminate from the failure equation, I am not one to throw money at an issue but when weighing time versus cost , I sometime defer to just replacing. What is nagging at me is the oil pressure possibly to a CCT (valve timing) collapse, you might not get a code and am not sure if cam sensor plays any part in start-up (I doubt). Out on a limb on that one.
Hi cchief22,

Yesterday, I told my mechanic that the fuel filter replacement did not help when I started the engine in the morning. But today I was able to start the engine on the second try. I am hoping the new engine filter helped the issue. I will keep an eye on it tomorrow if I can start the engine better. When I called my mechanic yesterday, he wanted to see the fuel injector if the problem continues after the fuel filter change. Is the fuel injector related to the fuel pump relay? I will mention the fuel pump relay when I speak with my mechanic again next week.

Thank you

bigevent
 

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You should check the oil level regularly, and NEVER allow it to go down more than 1 quart.

The kind of CTS fault that would cause your issue, would not set a fault light.
I believe your fault is as others have suggested, most likely a faulty CTS or could be an air leak.

The fuel filter or air filter were not the problem, and could not cause an issue like you have.
The injectors are not related to the fuel pump relay, and neither would cause your issue.
 

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I asked my mechanic to add 5W-40 and he used Mobile 1 Turbo Diesel Truck 5W-40. ...I will plan on using a recommended oil below this time, not the Mobile 1 Turbo Diesel Truck 5W-40 that my mechanic used...I will mention CTS replacement when I visit my mechanic next time, but he did not like that I keep mentioning CTS because he believes that CTS is working and my car will show engine light if CTS is not working.
I have an uneasy feeling about that mechanic of yours. Throwing your money at new parts (battery, fuel filter), using wrong engine oil, but won't change the inexpensive, potential cause of your starting problem. Do you know if he's checked fuel trims yet?

By the way, Tomvw mentioned that a faulty CTS can cause a starting problem, but won't set a fault light. That is because the sensor can fail in a way that gives a temperature signal which the engine computer accepts as legitimate, but is in fact completely wrong. Your sensor may be "stuck" sending a hot-coolant temperature signal, which results in too-little fuel to start the engine properly. I'll give your mechanic the benefit of doubt, that he checks the CTS reading while the engine is hot, and thinks the sensor is OK.
 

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I'm late to the party but after reading through this whole thread I'm suspect of the CTS as other pointed out.
I agree with ylwagon, that mechanic is costing you money. With all the history of a failed CTS in this forum that would be one of the first things I would replace.
The CTS runs about $15 for an aftermarket and about $30 for a Genuine.
Changing out the CTS only takes a few minutes.

Not related to your issue but...
Why is that mechanic using Deisel oil on a gas engine? I could understand if you were on a road trip under emergency use only because that was the only oil available at the moment, but for him to just reach for it.
Meh I would seriously doubt his/her competence at that point.
 
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You should check the oil level regularly, and NEVER allow it to go down more than 1 quart.

The kind of CTS fault that would cause your issue, would not set a fault light.
I believe your fault is as others have suggested, most likely a faulty CTS or could be an air leak.

The fuel filter or air filter were not the problem, and could not cause an issue like you have.
The injectors are not related to the fuel pump relay, and neither would cause your issue.
Totally agree on the CTS and the OP should note to the mechanic that the CTS puts out two signals one to instrument panel which may be a good/clean signal,but the other signal which is to the ECU and might be bad, leading to issues. As a sidebar to the OP, these so called mechanics who put diesil oil in you car will definately not want to be told anything, lots of luck with them. As to relay, if you note when OP says he tries for "five" minutes... who knows at this point what is meant, as in his video he (OP) is on/off with ignition,on/off over and over, I have had this issue with my 1.8, fuel pump relay, points/contacts pitted.....I do think I have talked myself out of a possible relay issue as supposibly the problem has been consistent with the first/initial start, engine cold, then starting fine. And agree with AP on this one as to mechanic,almost better off finding another one who is not supposidly a VW/Audi foreign car mechanic, and will do what you request.
 

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Discussion Starter · #33 · (Edited)
Thank you all,

cchief22, what is OP? I am planning on visiting VW Dealer Service below. I will let them know to replace the CTS and hope the mechanic in the VW service will know better about this.

Please let me know any good mechanic I can try in NYC area.

Today, I had another rough engine start in the morning. The engine starts after a couple of cranking but it does not maintain and dies in a few seconds. I intentionally did not step on the accelerator. I am leaving the video below that I took today. I want to mention that the exhaust smell was bad after the engine finally started.


Thank you again and I will keep you updated.

bigevent
 

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You might mention this forums recommendation about the CTS, but the dealership should have technicians who can diagnose the problem correctly. It also might be a good idea to leave the car at the dealer overnight, so they can check it cold the next morning.
 

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Discussion Starter · #35 ·
You might mention this forums recommendation about the CTS, but the dealership should have technicians who can diagnose the problem correctly. It also might be a good idea to leave the car at the dealer overnight, so they can check it cold the next morning.
Thank you ylwagon,

I will mention this article and forum and recommendations about the CTS.

bigevent
 

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Thank you all,

cchief22, what is OP? I am planning on visiting VW Dealer Service below. I will let them know to replace the CTS and hope the mechanic in the VW service will know better about this.

Please let me know any good mechanic I can try in NYC area.

Today, I had another rough engine start in the morning. The engine starts after a couple of cranking but it does not maintain and dies in a few seconds. I intentionally did not step on the accelerator. I am leaving the video below that I took today. I want to mention that the exhaust smell was bad after the engine finally started.


Thank you again and I will keep you updated.

bigevent
Sorry Big Event "OP" Original Post (Poster) which would be you. For replies and discussion purposes regarding your initial post in this thread. And just for future reference your car is what is know as a DBW ,Drive By Wire, pumping the accelerator does nothing like old cars of the past ,it is all electronic.
 

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Discussion Starter · #37 ·
Sorry Big Event "OP" Original Post (Poster) which would be you. For replies and discussion purposes regarding your initial post in this thread. And just for future reference your car is what is know as a DBW ,Drive By Wire, pumping the accelerator does nothing like old cars of the past ,it is all electronic.
Thank you cchieff22. I learned a lot from you and many experienced contributors in this forum.

Bigevent
 

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When you had the similar issue, was it okay after you started the engine first time in the morning? I am trying to understand why my car works fine the whole day after the difficult start once in the morning.
Typical failure mode: The element of the sensor that informs the engine control computer is telling it the engine is hot. Last time, for me, higher than normal operating temp. So, the computer does not supply the extra fuel needed for starting. After you get it running and warm, the mixture is closer to correct. Most places, it's colder at night, so in the morning...
 

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Discussion Starter · #40 ·
I find the Duralast CTS in the attached image that fits on my 2003 Passat wagon V6 from autozone. It does not have a clamp and a seal so I will ask if I can purchase them separately. I am thinking about buying it myself and ask a mechanic near me to replace asap since many if you think that might be an issue. Please let me know if you have any recommendation for a specific model/brand of the CTS part.

Thanks.
bigevent
 

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