Guest bastaad525 Posted December 25, 2003 Share Posted December 25, 2003 I'm at a loss as to your problem bastaad...everything has been covered I believe. Chase You and me both.... Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted December 25, 2003 Share Posted December 25, 2003 you guys might be on to something with the tuning part. I drive around in my 260 turbo, and play with my Tec2 programable ecu, and I can change the afr in any rpm while driving, and it does make a differnce. I can lean it out and make it start burning my eyes in no time (don't remember if it was leaning out or richening it up that caused the smell) but that goes to show that the tuning can and will affect exhaust smell. just sumthin to think on.... good luck.. joel Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 25, 2003 Share Posted December 25, 2003 you know I'd always have thought that being too rich makes the smell stronger, however, when i was at the dyno I did a little experiment. I usually drive on the street with my 02 sensor disconnected, and I wanted to see exactly why the car feels better this way, so I tried connecting and disconnecting it while doing runs. The run with the 02 connected confirmed what I thought was the case, the car runs noticeably leaner with the 02 connected. Now, knowing that, I've several times tried seeing how this effects the exhaust smell, and contrary to what I thought, the exhaust smell is noticeably stronger with the 02 connected, hence it smells worse the leaner it is.... doesn't make sense but that's what I've observed. Quote Link to comment Share on other sites More sharing options...
Metallicar Posted December 26, 2003 Share Posted December 26, 2003 After High School in N.J., I worked my ass off and I bought my first new car, a 1975 280Z. I was a real find as it was a left over in the dealers lot after the 76 models came out, but not yet in stock. The reason it was probably there, it was a California car with a cat. I smelled the exhaust then as I do now (in my newer car, a 77). Right from the lot, it smelled. It would smell with the windows down or partially down, especially strong during deceleration. Under warranty, the dealer had the service shop go through the entire car and check all of the seals, gaskets, and hoses. But they knew from all of the 240’s and 260’s, that Nissan still had a problem. Learn to live with it was all I could do. Last year I restored a 1980 Jeep CJ-5. After all of the time and energy I put into the beast, I went for a ride. Gezz, did it stink! Since it had a soft top, there was no way to tighten up the rear. So I did extend the tail pipe so it extended past the rear bumper, I started at about 4†past, which looked stupid as hell. It did fix the problem, though. I took a sawzall and trimmed the pipe one half inch and took it for a ride, still okay…. Okay so I kept at it and I finally ended up cutting too much off. So in the end the extension ended being 2†past the rear bumper. The truth is, I did part ways with the 75 in 1982, traded up to a new ZX (the 75 had bad cancer, but was a great runner, over 300K miles when I traded it). The ZX was a good ride too. It did not smell at all. Okay so when the ZX was due to retire as my daily driver, I moved away from Nissan, because I got snobbish. I did not like the 300ZX offerings, way too much mush. I like the feel of the road at the seat of my pants. Anyway, I am back in the game with a ‘77’. I bought it from the original owner, low miles but needs paint and body seals and gaskets. It has been a work in progress for me, now a year. Just in primer at this point. I expect that once the body is finished, I will still have the smell in spite of new rubber goods. So I think that all I can do; is try what I learned with the Jeep. At this point I am guessing that I will have a problem, based on my past experience with the 75. Now, it took you guys to point out to me that those holes in the rear valance may have some purpose in resolving the fume problem. That did not occur to me. Also the 77& 78 have the sheet metal filler just above the bumper. I was planning on installing a Euro bumper and trimming that ugly thing off. Shit, I am not sure what to do now. I guess I am going to have to experiment. Sorry for the long post. I hope someone can get something useful out of this. Added info: I just looked at some pics of my 75, it too had the slots in the rear valance. So now what? Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted December 27, 2003 Share Posted December 27, 2003 Yeah that raises another question, as to fl327's setup, since he says that he doesn't get the fume stink in his Zcar with a turbo setup, but did with the V8 setup. That would make sense, since it all seems to be related to the exhaust velocity (or lack thereof). Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 27, 2003 Share Posted December 27, 2003 I never had exhaust smell in the car in the two N/A 280zx's I've owned. I find that odd too, considering the shape is very similar to the 240-280z. One solution I had thought of (which I thought was my own original idea until I stumbled on some pics of some guys who have done it) was to run side pipes, like the in the Shelby 427 Cobra's (which I am a big fan of) or early dodge vipers. I almost paid to have this done, however... I was hesitant because though it made sense how this may cut down on smell while moving, since exhaust is now ejected into the air stream, I thought the smell sitting at a light would be much worse since it would just waft up to the windows... it wasn't a trade I was willing to make. Metallicar - so they stink even with the cat in place?? I was certain that a cat would be all I needed to get rid of the problem... Anyone else with a cat equipped Z that can comment on if the smell is still a problem or not? Quote Link to comment Share on other sites More sharing options...
280Zen Posted December 29, 2003 Share Posted December 29, 2003 Funny that this has been brought up. My 83 NA is starting to blow smoke, I know I need to redo the rings and Valve seals but the fumes in the car are getting worse each week it seems. I know now that the weather has turned cooler my car seems to run rich most of the time. I think my Cold start and thermotime might be bad, I'm also thinking I may need to replace the 02 sensor. but keep up the ideas, I need to do something before I pass out going down the road Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 1, 2004 Share Posted January 1, 2004 Well I got new front and rear oil seals put in and also installed a new oil pan gasket, so there's no more oil leaking from the engine, but I'm still getting way more fumes in the car than I was about a month ago... so I'm really at a loss as to what may have caused the sudden return of the fumes. For quite a while I drove the car and had no smell at all or sometimes very little, even with the windows open... the smell started at about the same time as the oil leak from the front so I just assumed this had something to do with it. So I'm back to square one. I checked all the exhaust manifold bolts and found them all to be tight. All my seals are still in good shape (many have been recently replaced). No one ever confirmed for me if adding a catalytic converter would help with the fumes or not... Also, for people who have gone from a straight tip to a tip that points down, did you notice any improvement? I may try this at the same time as installing the converter. Quote Link to comment Share on other sites More sharing options...
Bob_H Posted January 1, 2004 Share Posted January 1, 2004 A couple of thoughts. First, the hole in the later 280z cars rear lower valence. In the early Z's, airflow would build up behind that panel under the car, and on many you will notice the center of that lower panel bows out a little. They put those "vents" in that lower valence to help relieve some of that built up pressure. And in my experiementing, which is backed up by Metalicar, extending the exhaust tip helps significantly. It is a very turbulent area of the body behind the hatch, and if the exhaust is dumping into that area, it will just stick in that area. In the previously linked post, it was covered fairly well about the discussion about the airflow flowing up along the C pillar to the window area - but who really knows if that is the case. No real answer for you, but the one I have seen work every time is to get a downward facing tip, i.e. it goes down at about a 45 degree angle, putting the exhaust into the high energy air leaving the bottom of the car. Or at least have a squared off tip vice a 45 degree cut that goes up,(which most of us have because it looks best). -Bob Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 1, 2004 Share Posted January 1, 2004 My tip points down no difference. Someone suggested putting a 90° bend pointing outward( toward the wheel) I have not tried this asa of yet. Your fumes wont have anything to do with an oil leak. Burning oil stinks but nothing like exhaust. Rufus Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 1, 2004 Share Posted January 1, 2004 I tried putting a tip that pointed down and away, towards the rear driver side wheel, extended enough to just clear the rear quarter panel/fender, and it did NOT help at all if anything I swear it made the fumes worse. Not to mention it looked crap. Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 1, 2004 Share Posted January 1, 2004 I have been trying not to think about it to be honest. My car is in pieces... I am getting ready to do all kinds of mods...If after I spend all kinds of dough... it still reaks... I will NOT be happy!!! Quote Link to comment Share on other sites More sharing options...
Moridin Posted January 1, 2004 Share Posted January 1, 2004 A cat should help quite a bit actually from what it sounds like. You will sacrifice little to no performance (maybe a few HP at most) by using a good aftermarket high flow piece. My friend has a turbo Volvo, and with the test pipe in (instead of the cat), the thing stinks. He doesn't smell it inside, because the car is aerodynamicly different then the Z. With the cat in, I can barely smell anything when I'm behind him, and its quieter too. EDIT: Oh...and the tune may also affect something. Too rich and you have too many carbon type emissions. Too lean and your NOx levels go through the roof. I believe a cat will clean up the rich end. Not sure about NOx levels. Quote Link to comment Share on other sites More sharing options...
Metallicar Posted January 1, 2004 Share Posted January 1, 2004 Just looking around I found this: http://www.mcsrr.org/pressreleases/nhtsa01p.html It seems the exhaust problem is not limited to the Z car. I thought I would browse the web to see what solutions owners of other vehicles have done. Quote Link to comment Share on other sites More sharing options...
Bob_H Posted January 1, 2004 Share Posted January 1, 2004 I tried putting a tip that pointed down and away, towards the rear driver side wheel, extended enough to just clear the rear quarter panel/fender, and it did NOT help at all if anything I swear it made the fumes worse. Not to mention it looked crap. Part of my suggestion to turn the tip down also includes ensuring it is far enough away from the car to be in that energized airflow. If you stop the exhaust tip at the rear valance, you are assured of having problems as that is a very stagnant area of airflow around the car. So a tip pointed down that still doesn't clear the end of the bumper will likely still have a problem. I wasn't clear about that in my first post. Sorry. -Bob Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 2, 2004 Share Posted January 2, 2004 Well... soon I will be installing a full new exhaust, I will go ahead and put a cat in there... I think it will help. It's been a while, but I do sorta remember having my 280zx, which was built up, fully rebuilt engine, running on stock EFI, high flow exhaust, and I did have a cat in there (had to to pass smog) and I dont ever remember having an issue with fumes, either in, or standing behind, the car. And by the way I found out that the recent increase in smell is definately being caused by oil, I got a good look at the underside of the downpipe and there was splatter all over it. What sux is I just paid a grip of money to have the front and rear main seal and the oil pan gasket replaced, got the car back and now it's leaking worse than it was before (?!?!?!?!?!) the seals are fine but the oil pan is just pouring... 1/2 a quart of oil lost in 30 mi. of driving, it's getting all over the crossmember and blowing onto DP from there. When I opened the hood when I got to work after picking the car up, all this smoke came wafting outta the engine bay... man I'm pissed. Quote Link to comment Share on other sites More sharing options...
BillZ260 Posted January 5, 2004 Share Posted January 5, 2004 I may have come across why there can be an ubundnce of fuel and or exhaust fumes in these early z's. This weekend I finished welding in the cover where my spare tire was. A buddy of mine was touching up some of my work from underneath the car when I notice that you could see a reflection of the blue light very easily in the hatch area, while he was welding on the UNDER SIDE of the car. Closer inspection lead me to realize that the "C" channel that supports the rear strut towers are not sealed. If you reach your fingers around the the inside of the "C", you can reach down under neath the car? Also there was light coming around the outside edges of the "C" as well. If there was any exhaust or fuel leak under neath the car, I would assume that it would easily be pulled into the car by way of these holes. And when you windows are down, it should be even worse correct? Did anyone else realixze this? I was very suprized by this. I will find a pic and show you what I mean. Here is a crude pic, had to borrow it from someone on this site and draw on it. Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 5, 2004 Share Posted January 5, 2004 I've never had my strut trim off to see these chanelles (sp?) It sounds like it would be very possible for fumes to get in there. Although I don't have any exaust leaks, I do have a short tip ending just past the car. So if fumes got pulled under, they could shoout up those cha...(Square Stock!) and get in the cabin...Definately something to consider. Thanks!! Rufus Quote Link to comment Share on other sites More sharing options...
Phantom Posted January 5, 2004 Share Posted January 5, 2004 Have had a bad problem with exhaust fumes for years - especially upon exiting the interstate (slowing down) with the windows rolled down. With the windows up and the AC or vent on it was never a problem. Interestingly enough, since the LS1 has been installed the problem has gone away. Haven't quite figured that one out yet but I'm not getting gassed any more. I've got a new set of rear hatch seals that I'm going to install anyway but right now - no problem. Quote Link to comment Share on other sites More sharing options...
twoeightythreez Posted January 7, 2007 Share Posted January 7, 2007 I filled those holes with expanding foam, replaced the hatch seal, (actually I replaced all the weatherstripping), filled the hatch with foam, and then sealed the trim panel to the hatch. I have no exhaust smell problems anymore (now I can smell the intake mixture that wafts thru the firewall when the BOV vents, it's quite a bit more pleasant than exhaust anyway) I also have boost leaks, I had the IC piping made yesterday but I believe it's leaking around the TB (My ghetto IC piping held boost, this stuff does not...odd) Quote Link to comment Share on other sites More sharing options...
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