Guest szlash280z Posted August 13, 2003 Share Posted August 13, 2003 whenever I let off the throttle all the way no matter how fast I was going, my exhaust will sound all poppy and crappy. If I put my foot on the gas just ever so slightly while trying to slow down, the sound will stop. And if I press in the clutch the noise stops but the RPM drops to 500 and then limply springs back to normal. I just have the DP and nothing after that. Could this be because of a mal adjusted TPS? I never adjusted it. is a poppy exhaust because of a rich condition or a lean condition? The car has great power, and it pulls all the way past 5K with no problems the car has an 83 Stock ECCS system and no EGR. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 13, 2003 Share Posted August 13, 2003 It's running rich on deceleration. TPS adjustment could be the problem... Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted August 13, 2003 Share Posted August 13, 2003 cool! thats a good thing in a way! at least it's not running lean! Thanks drax! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 13, 2003 Share Posted August 13, 2003 mine does this too. I'm used to hearing it on cars that dont have full exhausts. My N/A motor did this too. My TPS has been properly adjusted, and it still does it. You hear a lot of musclecars and even harleys do this too. I wouldn't worry about it, but that's just me. Quote Link to comment Share on other sites More sharing options...
Guest Simon Posted August 13, 2003 Share Posted August 13, 2003 There are quite a few aftermarket computers which by default will cut the fuel completly on deceleration like that. not sure if the stock can do it. Sim Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted August 13, 2003 Share Posted August 13, 2003 Everything I have read says the computer cuts the fuel entirely on deceleration. But that was on N/A cars, I don't know if its the same for the turbo or not. so you still hear it even with your muffler bastaad? it's embarrassing to me. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 13, 2003 Share Posted August 13, 2003 yep I still hear it. Why would it be embarrasing? It's that musclecar sound man I really dont think there's a way to get rid of it though. Well if you put full exhaust with either cat and muffler, pre muffler and muffler, or glasspack/resonator and muffler (resonators are bad for turbos though) it will probably cut it down to where you dont hear it anymore, or only very little. The other option, and this is how I drive, though not because the sound bothers me, is to decel in neutral. I started doing this when I first got the 240z and had massive problems with exhaust fumes in the car whenever I decelled. So I just got in the habit of whenever I needed to slow down, put it in neutral and let it idle and just coast down with the brakes, which would minimize or elliminate the excess exhaust. It's harder on the brakes, for sure, but so what they're easy and cheap to replace anyways. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted August 13, 2003 Share Posted August 13, 2003 hmm, I will try the neutral thing. I kinda got used to the engine braking in the NA though. now that you mention that technique, I always had a lot more exhaust smell in the cab with the NA and that might have been the cause. why are resonators bad for turbos? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 13, 2003 Share Posted August 13, 2003 well i dont know about ALL resonators, but the type with baffles inside are very restrictive from what I hear, just like regular mufflers with baffles are. You want anything in your exhaust line to have a straight thru configuration, like glasspacks and performance mufflers, that you can actually hold up and see thru to the other side. It wouldn't kill your car or anythign to run a resonator, but it will slow down the turbo response. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted August 13, 2003 Share Posted August 13, 2003 when I went to the exhaust shop, they only had ricer mufflers. I expressed my dissatisfaction with that and he came up with some alternatives. he had what he called a resonator or glasspack (can't remember) it was straight thru and only had small hooks (like a cheese grater) and maintained a visible 3" ID the entire length. he said it cuts the noise down by 1/3rd, is something like that bad for a system? your signature says you just have a glaspack? how is that working for you? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 14, 2003 Share Posted August 14, 2003 yep just a glasspack... I can't say if or how much it is affecting performance, but you can see straight thru the thing, and it's only about 12 inches long, I dont think it would hurt much. It's not too loud, sounds good at idle... doesn't really have what most would consider a 'nice' sound when I get on it though... really just sounds like whoooooooooosh rushing air coming out of the tailpipe. I guess I dont really like the sound when I'm flooring it... no biggie as soon as $$$ permits I need to redo the whole damn thing anyways in mandrel 3" and get a real muffler that has a nice sound. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 14, 2003 Share Posted August 14, 2003 I've always been told that the "cheese grater" glasspacks seriously reduce flow. Reason is that all of those little hooks cause the exhaust to tumble and slow down. Its sounds logical, so I've always avoided those like the plague. I'd stick with a straight thru that has holes, not the cheese grater. Jon Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 14, 2003 Share Posted August 14, 2003 Just another thought - you wouldn't want a port that looked like the surface of a cheese grater at all. More non-scientific proof that these things are not helping flow. Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 15, 2003 Share Posted August 15, 2003 szlash, I found an article tonite that might help to put you a bit more at ease about your burbling exhaust, as far as, what it's doing being something typical or not. It's regarding the mufflerless exhaust system on the Dodge SRT4 neon: "The SRT-4 has no mufflers, which helps make up for the compromised exhaust routing (dual exhaust from an inline four engine). That's right, there's a turbo, a catalytic converter, and two resonators in the exhaust system, but no actual mufflers. Again, the engineers insist that this will make it to production (test car was a pre production test model). We'll be impressed if it does, as the SRT-4 sounds as pissed as it acts. Burbling and popping under engine braking and spitting backfires under hard acceleration gives us some doubts about the production readiness of the exhaust system, but we absolutely love it" So it's just that you dont have any muffler... again, my built up N/A engine, which also had only a glasspack, would also burble like this on decel if the car was in gear... I think it would go for any mufflerless car. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted August 15, 2003 Share Posted August 15, 2003 hmmm... it just sounds broken to me! I always made fun of ricers when their cars did that... I need to check my plugs for condition, and I know my wires are deadlined (arcs jumped out when I tested them at night!) hopefully new wires will help?... Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted August 15, 2003 Share Posted August 15, 2003 It seems broken to me too, and here is my experience, albeit with the Z31 turbo ECU. My first ECU swap was an '87 Z31 turbo. I wired it in and it all worked well enough, but I had a bit of popping on throttle lift, just like you. It would get pretty bad on engine braking downhill, but not explosive, just pop-pop-pop-pop-pop.... I didn't have any driveability problems with it, either on the street or the dragstrip. Then I turned it loose on a local road course, and I'd get into it for a few laps, hard braking, hard acceleration, you know. After a bit, it would start stumbling, then if I stayed in it, I would lose engine power completely. If I just coasted in gear with the throttle open, it would eventually catch and run again, but only if I took it easy. I checked the plugs: 1, 2, 3 were great, and 4, 5, 6 would be soaked with fuel; it was flooding with all the throttle lifting I was doing. I tried everything, and the problem on the road course was always there, for two years. I never fixed it until I swapped in another ECU, this year, I got an '86 Z31 turbo ECU. It doesn't have the pop-pop-pop at all, and it kicks butt around the road course. My guess is the ECU has a bad injector driver that will not allow it to shut off in a reasonable time. Like I said,the only problem I ever had was with multiple throttle lifts and very hard driving. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 16, 2003 Share Posted August 16, 2003 Sleeper - but were you running a full exhaust w/muffler? When I finally added a muffler to my N/A, I couldn't hear the popping anymore. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 26, 2003 Share Posted September 26, 2003 Not a dead thread yet... Pop pop pop on decel is what I get in my new swap. I have 2.5" SS. DP and all the way back with a 2.5" "See-Through" Maganaflow at the tail. It smells rich after engine braking. I confirmed the TPS working. I drove it with and without the switch with almost no noticeable change. I am almost convinced that an FI Z with a free flowing exhaust will decel rich no matter what engine is in it. My N/A did it and now my 83 Turbo (factory setup) is doing it. I know the N/A was supposed to do fuel cut above a certain rev and then resume fuel below a certain rev but it alway smelled rich anyhow. My 83 Motor has all new injectors and all sensors, wiring, timing all check out good. It still goes put-put-pop-put when decelerating and is stinky. It seems so common among the "swappers" that I am beginning to accept it. I may try to rig up a switch to turn off the injectors or ECU manually during decel to see what happens. Dave Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted September 26, 2003 Share Posted September 26, 2003 heheh yeah it does seem more common than not. I did have my tps tested and adjusted by a Z-only shop, and I still get the pop-pop-pop on decel even ever installing my full exhaust. It doesn't affect driveability really, but yeah if I decel in gear that is when the smell in the cabin is at it's worst... so I always put it in neutral when I'm coming to a red light or whatever. Why is it that 90% of turbo swaps have problems with running rich? There HAS to be a reason for that.... Anyways that's why I'm hoping to be switching over to a Megasquirt real soon.... Quote Link to comment Share on other sites More sharing options...
Guest Smooth Operator Posted September 26, 2003 Share Posted September 26, 2003 My friend's Blazer does that really loud on decelleration. Just started after he got his new muffler on. Quote Link to comment Share on other sites More sharing options...
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