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Cold Start Problem On 3.6, Low Idle And Dies (Video)


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Since the past week or so I have a problem starting the car when cold.

It only happens on the first morning start. The idle get lower and lower and the engine dies. If I try to restart the car immediately after it usually fail. either no start at all, or same low idle and die. If I push the gas when the idle is 'normal' the engine dies right away. Whne I wait let's say 15 to 20 minutes, then I the car usually restart, and if I don't touch the gas, and let it warm, after that I can rev it and it will run all day and restart all day without any trouble.

To cut it short here is a video of the problem

http://www.youtube.com/watch?v=2JYgWEzqRnE

I already cleaned the Throttle body. Not yet the MAF.

Anybody experienced that kind of problem ?

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I would start by cleaning the throttle body and butterfly valve on the intake.

BTW... the MAF has little or nothing to do with idle.

I already did clean the MAF and the butterfly valve, they were quite greasy and sticky. But the problem is still there each morning. What is weird is that after that first start then the car runs perfect all day !

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I'll check it out again and may be try another cleanup but last time I did it, two days ago :) it was pretty clean...

do you know what are the normal value for TRA, FRA and air flow (over the MAF)... could this help me understand if the idle is having problem coming form somewhere ? I do have the durametric but no idea where to look :(

Before:

452484d1276808113-tough-start-and-low-idle-rpm-caught-on-video-img_5206.jpg

452522d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5252.jpg

452523d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5253.jpg

AFTER CLEANING:

452524d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5254.jpg

PLENUM BEFORE:

452525d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5257.jpg

452526d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5258.jpg

PLENUM AFTER:

452527d1276814229-tough-start-and-low-idle-rpm-caught-on-video-img_5260.jpg

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I'll check it out again and may be try another cleanup but last time I did it, two days ago :) it was pretty clean...

do you know what are the normal value for TRA, FRA and air flow (over the MAF)... could this help me understand if the idle is having problem coming form somewhere ? I do have the durametric but no idea where to look :(

Before:

452484d1276808113-tough-start-and-low-idle-rpm-caught-on-video-img_5206.jpg

452522d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5252.jpg

452523d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5253.jpg

AFTER CLEANING:

452524d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5254.jpg

PLENUM BEFORE:

452525d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5257.jpg

452526d1276814027-tough-start-and-low-idle-rpm-caught-on-video-img_5258.jpg

PLENUM AFTER:

452527d1276814229-tough-start-and-low-idle-rpm-caught-on-video-img_5260.jpg

Your 2003 has three mixture correction ranges, rkat (close to idle), frau (mid range) and frao (upper range), tra was used on earleir dme versions. mine run at about 0.5 for rkat and 1.0 for frau and frao.

in addition to the throttle butterfly sticking, etc., you might want to look at one of the temperature sensors that could be reading high and telling the dme that the engine is warm. Sounds like you need more air and fuel when starting in the morning.

hope this helps.

p.s. just a hunch, check for vacuum leaks like at the oil filler cap.

Edited by george996
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I check for vacuum leak and when I pull the oil filler cap, the idle goes down and I can ear a suction but the cap is easy to pull by hand. I head that when there is a leak the oil filler cap can be hard to pull by hand, right ?

where are the temperature sensor you are talking about ;) ?

For info I cleaned up the MAF and Throttle again this weekend and even went as far as removing the plenum, a pain to put back. But at least now everything is cleaned up. I even put my hand in the intake to clean there, but it was not too dirty.

On the other hand, the 'thing/bridge' behind the plenum which links both air intake, was pretty oily but I could not remove that one. I tried to clean as much as possible but no way to remove it without pulling the intake I think.

The important part is that once the car has gone through the first morning problem. If I let it sit for 30 minutes and then go back to it for a start. It always starts like nothing happened before. And I would do nothing during that wait time. no temperature change or anything. That is the weirdest thing !

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here are my FRA values...

the engine was at idle and fully warmed up

I see my RKAT values are half of yours... does it mean anything special ?

what are the values to check the fuel pump effectiveness ?

Phil

all the values look good, well within allowable range. I would not worry about the fuel pump since if the fuel pressure or capacity were incorrect it would be seen in the mixture adaptation values that we just looked at.

use durametric to check the engine temperature sensors before you start in the morning. Check water temp, oil temp and intake air temp.

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ok so today again it won't start in the morning.

I removed the vaccum line plugged on top of the throttle body and spray some carb cleaner and it would start right away..for a second or two.

I assume the fuel do not reach the engine in the moring for some unknown reason... I bet some air valvle somewhere doesn't work

I heard problem with the tank breather valve...does anybody know how to check this out ?

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  • 1 year later...

sorry for not replying here earlier, I had a long discussion on rennlist about it

The answer was super simple, it was simply a bad tank of gas. I noticed that the station I had filled up a few days earlier went out of service a few days later certainly after detecting a problem in their tanks.

Anyways after putting some gas additive (techron) and refueling at a good station the problem was gone

The dealer told me the source of problem is water falling at the bottom of the gas tank. When the car sits for a while, the water goes at the bottom of the tank, right on top of the fuel pump, so when you start there is enough good gas in the line to start the car but when the water comes up then the engine all together in a concentrated form, then engine stalls.

The bad thing for me is that I had my car filled up complettly so it took me time to run off some gas and filled up at another station. I could not find a way to drain the gas easily, tube in the filler hole won't work.

Good luck with your issue, I hope it is as easy as mine. BTW this is now 1 year after the problem occured and it never happened again so I am pretty sure of my solution ;)

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