ScrapMaker

Hey guys, I was driving down I-35 the other day and there was a stalled vehicle, so we all had to stop fairly quick.. nothing Porshe-esque, but much faster than normal... a startling kind of stop.

Anyways, as I was holding the pedal, after about 2 seconds of full breaking, the check engine light came on and I thought it was a brake pressure sensor of some kind, but later I checked and it was EGR.

Now I've gotten the EGR a couple of times now, and it always happens just driving along the highway at low speeds and low RPMs, I'm cool with that, and I have to replace the part... but why would it happen when I heavily brake, which I'm guessing takes a lot of the car's vacuum away?

There might be something else wrong besides the EGR, which is why I'm looking into this... I'd hate to replace the EGR (which is only two years old,) for $175 if it's something else.

I also seem to have a slight vacuum leak which may or may not be affecting my HVAC controls, but I am not sure if there is any correlation between the two. Maybe someone with a bit more expertise can chime in and help me out?

Thanks,

Steven

MrDude_1

between this and your HVAC problem, id start by checking and replacing all of the accessory vacuum lines...

ScrapMaker

So the vacuum leak could cause an EGR code? By pushing the brakes I created a low-vacuum condition that somehow triggered it? I wasn't sure if they were related in any way. I though that the EGR valve ONLY shoved exhaust gases back into the cylinders to burn up excess gasoline and whatnot.

MrDude_1

the EGR valve is triggered by vacuum.. the engine supplies the vacuum, and a computer controled silinoid valve opens or closes depending on if it wants the EGR on or not.

ScrapMaker

Thanks, that makes more sense. I think my actual EGR valve is fine then, and I really just have to go through and fix all the vacuum leaks...

the big problem is I think you have to remove the driver's-side fender to get to that plastic orb, and I think there is another cylindrical canister on the passenger side if I remember correctly... man I wish I had done this a year ago when I had my fenders and front clip off... damn that was stupid...

oh well...

dan_o_89_rs

i had trouble with an egr code. it ended up being the actual valve. but when diagnosing it, i was told that a vaccum leak (even not on the egr) can cause that to pop up. as well as the map sensor code.

i wouldnt think u need to pull the fender to get to that "orb of power". it does hold vaccum, i think it has to do with cruise control.

i would just check lines. making sure there are no obvious breaks.

ScrapMaker

heh, my cruise control went out around the same time I starting having all these problems with my HVAC controls... I guess it pretty much has to be a system-wide vacuum leak.

can someone give me a reference to what kind of vacuum I should be able to read with a mity-vac, and where I should tap into to test?

dan_o_89_rs

not sure man. ill do some searching later.

crapper_mekanic

the old fashioned way was with some ether.... (starting fluid)

ScrapMaker

I wondered how safe that would be, since there could be electrical connections and such. I have heard that before though, and I may attempt it pretty soon.

Derek The Great

why would you use starting fluid to check for misc. vacuume leaks? all u need is something that will foam or bubble up when exposed to the air leak. i only used starting fluid to check for leaks that involved idle problems and such...

ScrapMaker

so you suggest just putting soapy water on the vacuum lines?

Derek The Great

well, something you can spray on, because you will be there all day with soapy water, you could just put water in a bottle and spray it or use windex. i wouldnt want to use starting fluid on every line because i kno not every line leads to combustion...

crapper_mekanic

I said it was old fashioned, there is also your ear, a mechanic's stethoscope, and looking for old, chafed, or rotted hoses. Plus, ether will evaporate when used properly and in small amounts. This is a vacuum leak, right?

ScrapMaker

I know it is, but I can't find it..

what I could use is if maybe one of you guys could test your vacuum so I could compare it...

Derek The Great

could also be that that little delco remy thing that regulate? vaucuum to the egr valve has taken a dump. its a little black retangle lookin thing at the rear of your passenger side valve cover close to the distributer, i have an lo3 so it probally is differnt from your set up but im sure the part is there though.

ScrapMaker

it's entirely possible, but since my HVAC system starting acting up, as well as my cruise control COMPLETELY going out all at the same time... I think it's a system-wide vacuum leak...

anyone know what kind of vacuum I should be getting around idle?

crapper_mekanic

I'll be under the hood tomorrow night if things are slow at work, and I'll put a gauge on the motor for you. Probably somewhere around -20 in..

ScrapMaker

20??? wow, last time I checked, (months ago,) I think I had roughly 9!

I might have a severe vacuum leak

thanks, I appreciate it!