rotten eggs exhaust??

[wyk3d]

Finished my rebuild a few months ago and have been breaking it in. The engine now has around 800miles on it but im still getting the rotten eggs smell out the exhaust. The cat is brand new and is a TH cat for the 3"DP. Is the car just out of tune or something?? What causes this besides a plugged cat??

Dan

 

[Swt_86]

Think that "rotten eggs" smell is from running way too rich. Do you have a scan tool? I'd get to the bottom of that problem b4 you ruin the new cat. Just my .02

 

[JFH]

Try a different brand of gas the next tankful. When I had my 84 for a daily drive it would stink switched to Sunoco and the smell went away.

John

 

[wyk3d]

hard to believe its TOO rich...the car runs really well, no bogging or stuttering from a take off. Spool is nice as well. Ill check tomorrow on some numbers. Is there anything else that may cause this besides a too rich condition? Could the wrong chip make the car do this?? I havent upgraded my chip since the rebuild.

Dan

 

[TurboDave]

Originally posted by wyk3d
hard to believe its TOO rich...the car runs really well, no bogging or stuttering from a take off. Spool is nice as well. Ill check tomorrow on some numbers. Is there anything else that may cause this besides a too rich condition? Could the wrong chip make the car do this?? I havent upgraded my chip since the rebuild.

Dan

Unless you've changed injectors, you shouldn't have to worry about the chip being too far off. The smell is likely only noticeable during closed loop operation (around town). You need to get a scan tool on there, and see how things are "really" running.

 

[dsa87gn]

Do you notice the smell after nailing it ? I was getting the same smell when I was playing around and thought my cat was getting plugged. I pulled it off and it was ok. After a normal leisurely drive I didn't get any smell.

I also agree with JFH, different gas sometimes gives different odors..

 

[wyk3d]

Alright.....scantool info is as follows in park at idle(~800rpm):

iac - 19
tps - .42
BLM - 140
lv8 - 42
o2 cross - 5-14
maf - 7gm/s
spark adv 33*
int - 124-131

in gear at idle (~750-800)
IAC - 30
tps .44
BLM 138
Int - 128-131
lv8 - 48
spark adv 36
maf 9gm/s

I took if for a few wide open blasts and i peaked around 900 on my o2s. That was with FP at 40. I lowered FP to 38 1/2 and still peaked around 900. For some reason my boost seems to have dropped off. I recall it being around 16 now my guage is reading 12. Should i add more boost to lean it out. I have no knock with it to the floor. Do my numbers look bad??

Dan

 

[charlloots]

Originally posted by wyk3d
Alright.....scantool info is as follows in park at idle(~800rpm):

iac - 19
tps - .42
BLM - 140
lv8 - 42
o2 cross - 5-14
maf - 7gm/s
spark adv 33*
int - 124-131

in gear at idle (~750-800)
IAC - 30
tps .44
BLM 138
Int - 128-131
lv8 - 48
spark adv 36
maf 9gm/s

I took if for a few wide open blasts and i peaked around 900 on my o2s. That was with FP at 40. I lowered FP to 38 1/2 and still peaked around 900. For some reason my boost seems to have dropped off. I recall it being around 16 now my guage is reading 12. Should i add more boost to lean it out. I have no knock with it to the floor. Do my numbers look bad??

Dan

hey dan your o2 are way high you need to bring them down to 750 - 770 at wot . keep bringing your fuel pres down 2 psi at a time until your down where you need to be . WAY TO RICH.

 

[wyk3d]

750-780 ive heard is a bit too lean for the street. Im aware its too rich. I guess ill try raising boost as i already tried lowering FP and it didnt do the trick.

Dan

 

[ThikStik]

That was one of the first complaints from the public when cats started appearing in 1975. Unfortunately I cant remember anything else the article said.
It is cat related for sure so maybe call the maker. Hey , this IS what a test pipe is for , right?
GL

 

[gofstbuick]

The cat is not the cure all, fix all. It can only process so much HC,CO and NOx. The rotten egg smell is sulfur dioxide, a partial catalyst event between changing HC and CO to CO2 and H2O. Your engine is either running too rich, or you may have some false air in front of the O2 sensor. At idle, the O2 sensor should be switching. Can you create enough of a vacuum leak to temporarily drive the O2 numbers down? If not, your O2 may be biased rich, then change your O2 sensor. If you can, then your engine is probably running rich and look for a rich problem. Try that first, and tell us what happens.

 

[Dan Thompson]

Do you have an exhaust leak BEFORE the O2 sensor like bad DS header or crossover pipe?

 

[wyk3d]

we checked and double checked for a vac leak som ewhere. Sprayed all kinds of things around anything that had vac to it and no RPM change (Did this recently to try and find a whistle near the intake when i tap the throttle)The car has one of the smoothest idles ive seen and setting the tps/iac is a snap. From everything ive read if i have a leak on the crossover or ds header i would have driveability problems. I dont have any of that. The car runs really strong and idles smooth. Its just this damn smell and an apparent rich condition. What else can i do to lean the car out besides cranking the boost. For some reason i recall setting it at 16(mind could be slipping) but now its around 13 or so my vac guage says.

Dan

 

[gofstbuick]

So, if you create a vacuum leak, can you drive the O2 readings (on your scan tool) down? How old is your O2 sensor? Have you been running leaded fuel with your current O2 sensor? Maybe your O2 sensor is bad.

 

[wyk3d]

The age of the sensor is unknown. Id guess 3 or 4 years. The car has never seen anything above or below 93octane. Havent tried to create a vac it was a bit rainy today to mess with it. Did get a chance to check a few things that have been bothering me and found that my boost gauge was off a few lbs and had a tiny tiny leak where it connects to the gauge. Fixed the leak and things are well again with the gauge, would explain why i suddenly lost boost. Would put boost around 14-15#'s with no knock. Tomorrow weather permitting ill see if the O2 is good and if so im going to add a few #s and see if the richness goes away without introducing knock.

 

[blackbuick87]

I would change the O2 and be sure to reset the ECM. Excessively high O2 is usually a sign of a bad sensor

 

[wyk3d]

created the vac leak and the o2s went to the floor bottoming out around 30 and staying there. Turned up the boost 1# to 14lbs im getting knock and the car is still running in the 850, fp is at 38static. What else is left for me besides a chip upgrade?

Dan

 

[gofstbuick]

87 GN, TE-51, 009's, JL Chip, ATR in-tank Super Pump, Dynomax Race Magnums, Hooker 2 1/2 Xhaust

Is that JL chip for 009s? If so, then another source of fuel (creating a rich condition from O2 readings) could come from your EVAP cannister. It may be purging at idle. Pull the vacuum hose going to the purge solenoid (and plug the line), then see if the O2 numbers drop.

I'll be leaving work soon (1615 PST), so I may not be able to respond after that time, but I'm sure there are many capable members to help you. I'll try and look this weekend though

 

[wyk3d]

dont have an evap canister. It was off the car when i purchased it. All i have there is a vac line with a plastic cap that looks like a vent. And yes the chip was burned with the 009s and the 51 turbo at PTE before i did the rebuild.

Dan

 

[gofstbuick]

I'm running out of ideas. Sorry. Will think about it over the weekend.