FU-Q

i recently was driving to work and i didn't notice intil about halfway there that i had the power of a 4 cyl. when i got there i poped the hood and my digital egr valve is melting! i let it cool down and drove it home the longer i drove it the weaker it seamed, but i could still floor it with no power loss (i know i shouldend have floored it, but i figured it would help explain the problem).
when i got home my hard emissions hose from my intake to my emissions can was melted in one spot so i replaced it with that blue rubber hose that you get from pepboys. i replaced the digital egr valve with a new one.
It started to run fine until i gave it some throttle it made a sound like i have some kind of air leak and a slight exaust smell, yes the bolts are tight. i pulled it apart and saw alittle water in the platnum, it didn't smell like gas (the brand new one came factory sealed with the platnum).
I noticed my rpm gauge was not functioning (ive been having a problem with the relay so i jiggled it a little and it works) so i jiggled it and gave it some throttle at that moment the engine died and black smoke from behind the egr valve. how could i have made my problem worse???

P.S. sorry for the long post.

FU-Q

i forgot to mention that i have no trouble codes...

FU-Q

i just had another thought,
i noticed after trying to start it my fuel pump continued to run for about 20 sec. at the same time a muffled hissing sound from around the egr.
i just got done doing a fuel pump change a week ago, iv'e spent over 1g on this baby in the past year all mostly reguler maintenance but always at the wrong time, it's got 75,000 mi. i really don't want to get annother car like everybodys telling me to, i can't see myself driving anything else...

RB83L69

I'm not completely sure what "digital EGR valve" is; but it sounds to me like you have massive backl pressure in your exhaust, probably from the catalyst in yout catalytic converter breaking up.

Vader

With a digital EGR, you must be talking about something other than a ThirdGen. IIAC, all these cars got a vacuum servo/duty cycled solenoid system, except maybe the TTAs.

The fuel pump running was probably due to the oil pressure built up from cranking. The auxilliary oil pressure switch will maintain power to the fuel pump until the residual oil pressure drops below 4 PSIG (closes at 7, opens at 4). the hissing sound was likely the excess fuel volume being relieved through the regulator and returning to the tank. All very normal, except that they generally can't be heard when the engine is running.

Vader

...And the only reason they would be telling you to get another car is because they WANT your current one...

Nixon1

Late Third Gen V6's got digital EGR..earlier ones, and the V8's, got the vacuum EGR's. Vacuums are big and funny looking..the digital EGR should have no vacuum lines running to it, has 3 'clusters' arranged in a triangular type of pattern, and has a flat clip on the top with wires running out.

Vader

Well, I guess I didn't assume correctly, after all. I know that the Buicks were getting beetter ECMs and digital EGRs right around that time, but I guess I haven't seen enough of the Chevy V-6s to notice that. Thanks for the info. I'll have to check the "project" car more closely.

Nixon1

No problem... All of the 3.1 liter engines got the digital, and a few of the 2.8's got it as well...I'm just not 100% positive on the years. And all I really know about is Chevy V6's Vader...I'm always on the V6 board here. Hell, it's what I own...mine's a 91 3.1 with a Digital EGR, so I knew that one right off the bat. Vacuum EGR's are cheaper but harder to replace..digitals are the opposite....

FU-Q

yes, i had to disconect the exuast pipe at the cat for the fuel pump and after words it rattles like crazy at idle.
so is the backpressure what caused the origanal egr to melt?

RB83L69

Yes, it's possible. If the exhaust is clogged up, an enormous amount of pressure wil build up in it, and the weakest thing will get blown out.... might be the EGR valve, could be one of the AIR check valves, etc.

FU-Q

well my egr is brand new and nomatter how much i tighten the bolts i still see hissing exaust coming from both gaskets on the egr plus bubbles i pull it apart and see watery resedue in the platnum (this shouldent be here???) i thinking about returning my new egr for a cat and put on the melted egr since it seams to be working the same, but i wanna make sure that will be it.

Nixon1

Water coming from the EGR valve?? I can't imagine water should be coming anywhere from that system...you aren't burning off any rad. fluid in the cylinders are you?? Check for white smoke and sweet sort of smell in the exhaust...and check the rad. fluid level too..start it up cold with the cap open and wait for it to start circulating when the t-stat kicks on and blah, the water level should rise up close to the top. Now..you're running open exhaust in front of the cat?? Hmm...that would make MY car run like holy hell, but you've got a V8 so I'm not sure... Still though...I can't see how water would get into the EGR system........

Nixon1

Wait..you've got a digital EGR...so..what engine do you have? A 2.8 or a 3.1 V6 then? I assumed it was a V8 cause I rarely see V6 posts outside of the V6 board...

FU-Q

i don't know what happen to my sig...
ya its a v6 3.1. no, im not running open exhaust in front of the cat (but i don't see why it would make the car run any worse.) all the times i start it up its cold, im afraid to let it run for too long to get it up to tempeture. the antifreeze i use is the ****ty red gm stuff, the water i see in the exaust is clear (don't smell like gas eather). any other ideas...

Hrock

I would replace the Cat.. known cat failure causes
severely retarded ignition timing
Water/coolant leakage to the combustion chamber
Methlehydrate in large dosage or Alcohol based fuel additives.
Physical Damage...

Your cat suffered one these and now is developing Back Pressure.
a DEGR operates Via a stepper driven motor system and probably is working fine ... You might have a Warped Intake PLenum..

sounds like your problem scenario was like this....

Cat got damaged and PLugged Up.. Back pressure developed and your ECM over compensated with more fuel. Your Exhaust manifolds got really hot and your EGR system with it.. Conducting the heat upward to your EGR servo and possibly causing it to warp.. ( most times its hard for this to happen with Cast iron products for EGR systems but not impossible if its an aluminum)


So anyway there you go. You probably have a secondary affect of coolant leakage from the Extreme temperatures.. So Track everything before you buy anything

FU-Q

i do have a pretty good dent in it.
thanks for the info, its very heplful. i'll check it out...

FU-Q

im still waiting for my cat converter, but i disconnected the old cat (a little stream of water came out of the pipes while doing so) and started her up. it acted the same way, what is the next thing i should check?

Hrock

Your Cat obviously is not the Cause so you have a Special Case..

I would say that the whistle your hearing is the High level Air it is sucking into the intake chamber from the IDLE AIR CONTROL VALVE ( its the left hand module protruding from your throttle body with about 4 wires on it.. Your computer will do this if the following occurs...

INITIAL STARTUP
-Cranks for as much as 15 seconds before Firing up..
-While Started initially Stalling on you immediately or stumbling
around leading to a stall..

Stalling after touching the pedal..
Pressing the Pedal down very slowly and it stumbles but will idle up .

You see Exhaust is a burnt product and will no longer burn as usual. Your EGR offers a reduction in emisions Via Collecting your exhaust and feeding it into the intake in small quantities and then adding more AIR from the IAC , Because your computer thinks your car is not delivering the proper amount of air it retards the injection pulse and increases the Air (IAC valve) however it only goes so far...


So in this instance I think you might want to take the D-EGR off Make sure its closed and verify that ( Even grab your old one and Close it manually) ( May Have to Break the Plastic off)

Then run your car for now with it closed perminently ( UNPLUGGED) I imagine your Wiring hardness to the EGR is Melted and you may have Computer OutPut Failure.. If so Chance that you have wrecked the new EGR valve...

Get a metal Plate ( tin ) cut and drill it and mount it to the Exhaust input side of the valve body and plug the whole perminently.. All you want is to close the EGR somehow and Know that no Gas or exhaust are making it into your car..

Hrock

I most gaurantee it that you have an INTAKE Gasket failure and your getting Water from your heads into the EGR port which comes from the INTAKE and goes to the EGR... Then it will fill up with water and Hydraulic the EGR open Via Excessive temperature and Steam through adding Water to your exhaust and you should be able to see that coming from your tail pipe..

Very noticable amount of white smoke and Sweet Maple Syrup smell from the exhaust...

Is that the case... Well you need to by a complete Intake Manifold kit ( probably 35 or so dollars) and rip away... That kit comes with all the stuff for your Fuel injectors and PLenum.. It does not include Fuel line Seals..

alrighty then.. Give me a hollar ..

FU-Q

ok, i'll try that and post the results. thanks

FU-Q

ive been thinking and i came to the conclusion that i gonna stop putting money into this 6 cyl and drop a 350 in it instead.
ive put over 1,000 in the past year in it (no real big problems but reguler maintance **** fuel pump, alt, water pump, ...) seams like every three months or so im catching a ride to work. i don't think an engine change can stop problems from popping-up but i would have a better reason to fix it.

Nixon1

Hey, whatever floats your boat... I wish I had a 350..besides the fact that I can barely keep gas in the car NOW...if I had a 350, I wouldn't be able to take it anywhere!