Guest bastaad525 Posted August 14, 2003 Share Posted August 14, 2003 I've begun to notice a kind of weird trend, well actually it may be perfectly normal I dunno? I notice that during the daytimes, which lately have been in the 100 degree range where I live, the turbo will max out at around 9-9.5 psi, which was the target I was aiming for. But when I go for a ride at night, when it's more like high 70's-low 80's temps, w/o adjusting anything, the boost will get up to almost 10.5psi... so I'll adjust it back down to 9ish, and of course the next day now I'm maxing out at about 8. What gives?? I got my first 'kill' tonite in a stop light race, only raced up to 50 anyways... I really find I can't pull up to the high mph's (or high RPMS... see next paragraph) I used to in a street race... a sign that I'm 'growing up' maybe? And anyways I didn't need to pull any higher for the guy to know he was had. So I raced this guy in a relatively new BMW 540i, and by 50mph I had a car on him Those cars are supposed to be pretty quick. Not like the M5's though but still... I'm happy In other news... my stumble is still there!!!! Happened once tonite driving around... now I'm really stumped. Have corrected ignition timing, cam timing, TPS setting, fixed the busted 6th injector, cleaned all connections like 5x, hunted down and fixed all vacuum leaks, replaced the ECU, replaced fuel filter, checked and regapped plugs... I give... at least it doesn't do it very often now. Was the first time in like 3-4 days. Next I'll try replacing the fuel pump and wiring to it, and FPR I guess. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted August 14, 2003 Share Posted August 14, 2003 mine stumbled twice and died while driving it today. It happend when I pressed in the clutch, idle dropped to 500 and fluttered then died. Whenever I would start the car, the engine would run fine, timing is great and everything, but after it warmed up the timing would change and the idle sounded different. I plugged in my TPS and kinda adjusted it and the idle and timing went to normal. Unplugged it and the engine idled funny again. I guess the TPS doesn't have any effect until the engine reaches operating temps. Even after adjusting the TPS, the snap crackle and pop when I let off the gas is still there, and it died twice like I mentioned above. is that the same kind of stumble you are talking about bastaad or is it the 4500 RPM stumble again? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 14, 2003 Share Posted August 14, 2003 The little stumble at 4500 rpm never went away... sometimes it's almost inperceptible, to the point where I wonder if it's just the tach acting weird at that rpm, and not the engine at all. What happened last night was a really bad hiccup, the same one I've been getting since I got the car back, that doesn't seem to happen at any particular RPM. Last night it happened when I was taking off from a light, I wasn't really watching the rpm's but right about when I was going to shift into second, the car jerked really badly and coughed. It happens mostly when I'm driving the car hard, going WOT, sometimes it happens right after a shift, sometimes it happens when just moseying along at idle and then suddenly giving it some throttle and it will sputter. Oh about the TPS, I believe you're right, it only comes into effect after the car warms up, and from what I know, disconnecting it puts it back into closed loop mode, which is the mode it runs in when it's not fully warmed up, which also as far as I know, makes it run w/o using the signal from some of the sensors such as the 02, to affect mixture, and can result in an overal rich mixture. Not sure how it would affect you szlash, but again, I had a Z-only place adjust my TPS, and it didn't fix my stumble, nor did it get rid of that poppoppop when I'm slowing down Quote Link to comment Share on other sites More sharing options...
fl327 Posted August 14, 2003 Share Posted August 14, 2003 boost going up a psi or so is common in the higher gears. freeways speeds and a quick stomp is putting a lot of load on the turbo, turbos like load. listen to your motor when it does that, most of the time its fine, but sometimes Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 15, 2003 Share Posted August 15, 2003 fl327 it seems your'e the only person who wants to reply to my posts anymore am I asking too many questions or what? The boost isn't only higher on the freeway, it's just higher in general. On the way to work this afternoon, I got on it in 3rd... really hot out, it settled at around 9psi. Then when I got off tonite at 9pm, did the same thing, WOT in 3rd, and it goes up almost to 10. And by the way you didn't finish your post Quote Link to comment Share on other sites More sharing options...
yo2001 Posted August 15, 2003 Share Posted August 15, 2003 ambient temp does effect the boost. Also, barometer. I would replied but I've been moving. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 15, 2003 Share Posted August 15, 2003 kewl Yo2001... moving up or moving down (in size)? Me and my g/f are dying to get out of our way too small apartment. I promised it's the next thing on the list after I got my car done... sure enough two days after I had gotten my car back she shows up with like three books with rental listings Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted August 15, 2003 Share Posted August 15, 2003 ahh sine we are on Trubo boost topic here is a little one for you now i have the l20et, simple mods, exhaust pod, and thats about it. the turbo is running stock boost, with the overboost safety vavle welded closed. so it should be running 6psi, "notate should" if i give her a hard run say thru 2 gears boost will drop back to 1/2 (stock gauge) and then goes like a N/a. Im suspecting the wastegate is a little bit on the stuffed side of things, ect. since you can do a 6k clutch drop and it wont spin she will bog, not build boost, and the take off. boost will build full, "sometimes" then back off. enough that you can feel it and watch it on the guage. I know its hard to really explain, but its pulling boost back like you wouldnt beleive. is it possible that timing can do this, ect? any insites would be greatfull, thanks nick Quote Link to comment Share on other sites More sharing options...
fl327 Posted August 15, 2003 Share Posted August 15, 2003 L20et, ive heard of those. If it is like the L28et in terms of stock efi, the timing wont effect boost unless you are having trouble reaching high rpm as well. I really dont think it is the timing. It is not uncommon for the WGA on these cars to be faulty, some older zxt cars dont make much boost at all because it sticks open, also, are you running an aftermarket or stock guage? Maybe some holes in the weld? The stock guage sucks, It will tell you that you are making 7psi if you rev it at idle. I always pull the pov off the car once im ready to make boost changes, Is it possible that it is leaking boost pressure at higher gears due a leak that occurs at high load situations?? Im not sure temp has anything to do with, but I also dont boost that hard when its over 85 degrees or so outside, Im chicken I guess. Does it run good cruising? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 16, 2003 Share Posted August 16, 2003 the POV is removed, and I'm running an autometer boost gauge. It definately seems to be temp related though because it's always one way in the daytime and one way at night. I dont think there's any kind of leak there. In the daytimes It will always peg like 9-9.5 psi, in 3rd or 4th gear holding it at WOT. At night it will will always peg and stay at 10-10.5. I will get different boost levels in 1st and 2nd but I think this is normal, so I always test in 3rd and 4th. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted August 16, 2003 Share Posted August 16, 2003 I had temperature related boost issues with my MBC from MSA. It is a bleeder type with a pressure relief valve. It has a spring inside that seemed to lose tension with heat, as my boost would actually rise with increasing under-hood temperatures. Not what I would call an ideal setup. So I broke down and found a deal on a Greedy Profec B and it rocks. Boost is solid, and tunable to reduce or eliminate spiking and creeping. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 16, 2003 Share Posted August 16, 2003 I think you have a vacuum leak bastaad and at night since its darker, the air is heavier (more pigment than daytime air) so it clogs up the leak for you. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 16, 2003 Share Posted August 16, 2003 man I have checked everything like 50,000 times, for leaks... I keep thinking it would make perfect sense if I did have one still, it would explain a lot, but there are none to be found. Sleeper, yeah I thought about that too, it was actually after you told me your experience with the MSA MBC that I decided to build my own grainger one, since everyone seems to love those. It's a great MBC by the way especially for part throttle boosting.... And anywho my problem is actually the opposite, boost gets lower in the heat and higher in cooler weather. But Drax hits on a good possibility, about air density. Could I just be getting less boost because the air is that much less dense in the 100 deg + weather? By the way I read a review of that Profec B in Sport Compact Car, man that thing does rock, and it's one of the cheaper programmable electronic units... I think it had the fastest, best boost response out of 7 units they tried, or maybe second best, but functionality wise it was just great. If I ever do upgrade from my Grainger this would be the unit I would buy. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted August 16, 2003 Share Posted August 16, 2003 If you have the ball and spring type controller, temperature affects them as well. And the way it's built will cause boost to drop with temperature, that's the point I was trying to make. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 16, 2003 Share Posted August 16, 2003 I get it now... it's because the MSA and grainger kinda work in the opposite way, if the spring looses tension from heat in the MSA, it opens wider, bleeds more air, and raises boost, if the spring in the grainger looses tension, it lets the air by sooner = less boost... kewl well then at least it's somewhat to be expected and nothing to really worry about... I'll just be a tad bit slower in the daytime but ah well isnt' everyone slower in the heat anyways? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted August 16, 2003 Share Posted August 16, 2003 I get it now... it's because the MSA and grainger kinda work in the opposite way' date=' if the spring looses tension from heat in the MSA, it opens wider, bleeds more air, and raises boost, if the spring in the grainger looses tension, it lets the air by sooner = less boost... kewl well then at least it's somewhat to be expected and nothing to really worry about... I'll just be a tad bit slower in the daytime but ah well isnt' everyone slower in the heat anyways?[/quote'] Exactly - it works the right way. Mine was making me nervous. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 16, 2003 Share Posted August 16, 2003 Sleeper how much did you get your Profec B for? The more I read on some of the stuff it does the more I want one... plus at first I thought I'd be fine w/o a dial in the cabin, but I see more and more how nice it would be to have one. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 17, 2003 Share Posted August 17, 2003 Hmm... I thought I'd get a comment on my previous post. I guess its funnier in my mind. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 17, 2003 Share Posted August 17, 2003 you know... I was gonna make a comment but I didn't know if I was just taking it the wrong way or if you were really being serious or what... pigment in the air clogging my vacuum leaks... so were you poking fun at me or what? Let me in on the punchline Quote Link to comment Share on other sites More sharing options...
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