EGR questions

[woodsracer144]

ok so with a EGR What goes wrong with them that makes the car or truck not want run right? I had a teacher that has a VW passat TDI and it didnt like to start when it was really cold i fought with it for hours and then the end of the day it would finally want to start.

my sisters car is being the same way but its a 03 Kia spectra. Its only has about 98K but when it gets really super cold it doesnt like to start. It has enought cranking speed it just doesnt like to fire. I was thinking it was the EGR valve.


what does the egr really do. I knew a little about them when the 6.0 PSD first came out cause tehy were knowing for having problems with them but thing i got out of the diesels for a little while and now i cant remember anything about them...
any other thoughts?

[eastside 400]

well the most common problem with an EGR valve is that they get clogged up or stuck open, the carbon buildup can make the valve not seat properly which will let exhaust gas back into the intake when its not supposed to. large pieces of carbon can also break off and hold the valve open. You will usuaully get a really rough running engine when that happens. If the EGR is just broke and stuck close you will notice no problems besides a Check Engine Light. on diesels the carbon buildup is 10x worse, its gets clogged up very quick, that was the problem on the 6L, ford encourages techs to beat on the trucks when they are in the shop for service to help break up the carbon and let the turbo reach full boost since most drivers do not romp on the truck.

[CJM]

It has 0 do to with starting as it only opens when the car reaches a certain speed (usually cruising speed of 35+ mph). Its only related to emissions as well, what it does is recirculate the exhaust gases

What happens in the winter is people dont realize gasoline doesnt combust nearly as easily and also cheap gasoline doesnt ignite as well.

In order to start it, hold your foot to the pedal as you turn the key, it will hiccup a bit and finally turn over and be fine.

People also NEVER tune up thier cars

As for your teachers TDI-its a diesel and it needs to be plugged in when it gets cold, when it drops to the low 30's the fuel should have an additive put into it as it will gel and not flow, or it needs glow plugs.

I used to see people all the time when I was working as a mechanic/towing whose cars had issues starting. 5-10 cranks or so with my foot on the skinny pedal and 90% of them would crank over. The fuel just dont want to flow, or the injectors and engine arent getting the proper reading fromt he computer and the mass air flow sensor, people use cheap gas, people NEVER change fuel filters, etc, etc.

Try the method I mentioned with the skinny pedal-it works.

[chucked]

tell your sister to give the car a tiny bit of throttle next time she goes to start it when its cold and see if that helps.

[eastside 400]

you should not have to give a FI car any throttle to start it, gas "flows" the same cold or hot, its not like diesel. And the EGR can 100% effect starting if its malfunctioning. Yes it is an emissions device, but if it is stuck open then you will not create a vacuum and it could make starting a little harder. the tune-up on the car has a huge deal with starting, once you get it running, spray some salt water on the plug wires, cap and rotor if equipped, if it starts to sputter then you know that it is a problem. check the plugs to make sure they are terrible.

[CJM]

Nissan, Honda and GM cars generally need to have the throttle pushed from my experiences when it happens. it can happen to others but those are the common ones.

What happens when its cold is the car just doesnt get enough fuel or the mass air flow or similar sensor doesnt read right-thus not letting as much fuel in-or both.

It also happens when you let a car sit for awhile and then try to crank it-it bleeds off fuel pressure. My dads vette does this all the time, its hardly run and when it is you gotta push the throttle-the egr cant be clogged since its BRAND new, my F250 hasnt been started for over 4 months when I tried it-same deal, same thing goes for my friends old IDI diesel (no EGR).

So please, the egr isnt the culprit, nor related to any of this. If it was, more cars would have this issue as very few EGR units get replaced. Wanna know how its truly bad-your car smells like rotten eggs cause the egr is clogged or stuck open.

The issue is due to the cold, the mass air flow sensor (like I said before) isnt getting the right reading, the computer doesnt give you the right amount of fuel, while cranking you push the pedal and it allows more air (and depending on the car, more fuel).

Could be clogged injectors, weak or bad fuel pump, bad mass air flow sensor, a small clog in the fuel rail or lines, not enough fuel pressure, etc, etc. Or the car could just need a tune up.

Considering most only fix the car when it breaks-alot of stuff could be it.

The mechanic hath spoken..

[woodsracer144]

you can say what you want but i know the diesel in that TID wasnt jelled, and i know what was in it. I filled it up for her cause she was low the first time it happened. I replaced the fuel filter in it and put Diesel 911 in it. she too it to a local Vw hobbiest that just has a **** ton of Vw's and and i know she got the EGR replaced/ fixed... I know how to start a diesel also. I drive one every night at work. I cycle the glow plugs for about 6-7 times depending on how cold it is and it pops right off... other people cycle 2 times and wear the batt out turning it over.

I held it to the floor once when it was about 10 below and it fired up... I dont know if she doesnt understand that or what but i thought that since its EFI it should just run by its self with out the throttle to the floor in my mind. but idk.

[chucked]

When everything is working you shouldnt need to give it throttle, but since theres obviously something wrong Im asking to give it a tiny bit of throttle to rule out a few things. For example, if the idle control valve has a problem, NO air will go through it at idle, so, it wont idle without giving it throttle.

[CJM]

its a pos VW, what do you want lol?

and I highly doubt so many cars I serviced had bad IACV. Like I said, the car isnt allowing enough fuel in due to the air reading the MAF is giving, push the throttle and it allows more air.

[k4f5x0r]

2.8l 4 cyl CRD diesel engine in my jeep and it starts perfectly fine all winter running off of mobile diesel zero fuel additives and starting with glow plugs cycled for about 10 seconds.

Its recommended to plug it in when its below 10-15 degree's(F) but only to prevent starter and other engine wear, it will start when its that cold with just the glow plugs.

as for the EGR, it is the stupidest thing in the world, especially in diesels. As soon as i can afford to im getting a tune that reduces the use of the EGR to the bare minimum so i dont have to worry about it spitting useless crap into my motor.


Edit: also the car is regularly serviced. Glow plug#2 actually just went out this week and is getting replaced today.

[eastside 400]

and I highly doubt so many cars I serviced had bad IACV. Like I said, the car isnt allowing enough fuel in due to the air reading the MAF is giving, push the throttle and it allows more air.

so your saying that its not getting enough fuel due the MAF, so you should press the throttle to give then engine more air? that would make the already lean condition even worse. You would have some drivabilty problems if your MAF was so far off as to not let the car start, most cars will start without the MAF connected even, the ECU can use default values for when sensor problems occur, but since you seem to know that every car needs to have the throttle pressed for starting and the MAF is the cause then go ahead and give it throttle

[CJM]

Im sorry, this whole time I keep thinking MAF-which could be the culprit. After thinking about it awhile I remembered the IAT could be as well. The intake air temp sensor senses how cold it is and if it reads it wrong it will not send the proper amount of gas (usually to rich). I do stand a bit corrected-but both are possible causes. Maybe due to the cold weather the sensor gets an improper reading, maybe it freezes up..

But it cant be the idle air control valve-this controls the idle speed and not much else.

Why this happens when its cold out, im not sure. Alot of cases I have experienced the people said they put the car away fine and next day it wouldnt run. Maybe it was colder in the morning and it isnt reading right, maybe its a fault in the ECM-not sure. Like I said it most commonly seems to happen on the import cars (specially nissan and honda) than others. But after doing towing and wrenching for years almost all of the cars I had this happen to started and had no more issues, very few needed any work and in those cases it was the MAF and IAT.

When it cranks it keeps spraying fuel the entire time, open the throttle and it leans it out with more air and finally will catch when you get the right mixture. When everything is normal it cranks and fires almost immediately.

I hope that makes sense.

[woodsracer144]

alright one way or another giving it throttle will help it or should help it start.