Guest jjohart Posted February 6, 2004 Share Posted February 6, 2004 I am at wits end with my newly I/C'd 280ZXT. I have posted sev. X, and gotten many helpful, if technically hopeful answers, which I have printed and steered my local mechanic's way, everything from leaky injectors, running rich, vapor lock, intake area fan not working, etc. All of these, plus the Z shop manual for diagnostic testing of a car that "starts rough/poor idle" will be looked at next MON by the mechanic. Alas, I don't know of a really good tech in the New England region for dealing with a lot of the more technically advanced suggestions, so it's the local "Natick Auto Clinic" for now{sidebar-suggestions for good mechanics in N.E/NY appreciated for this car..closest I've found is MD!)... Anyway, sometimes the simplest solution is the best, so since I'm the DRIVER (experiencing Z-sympathy to all those who mod their cars with I/C's and never have a problem), I would like to know if anyone would give a rat's arse if I suggested that the extra plumbing, intercooler of unknown efficiency (used NPR, with some bent vanes) might somehow exasperate the engine bay componentry getting hotter!?!?!?! Once again, the situation starts WHEN I drive the car 5-10miles, set the turbo timer for 2-3 mins b4 shutdown, wait 5-10 and RESTART IS KAPUT=stalls, 2-6 sec. crank time, sputtering, VERY limited throttle response (my "cure" is to step on the gas, til the revs rise with a very poor sounding engine (nothing like the cold drives!) into 2-3,000rpms X 30 secs, or more, at which point it eventually settles back to a normal idle/though still poor throttle response, as if the car had lost 10-40bhp, at least until I drive it in motion for a min!! Maybe a question would be..is it possible that the car is hampered in dispelling heat by the extra plumbing? Do intake lines, long piping to I/C and "cold air filters" have less efficiency than shorter stock lengths when a car is sitting warm idling? Does it have any effect on lessening the car's ability to lessen heat when the car is shut off after said warm idling? My first guess is no, I've never felt a stock or cold air filter or intake plumbing get warmer when the car was shut down and I popped the hood to clean the filter. My last 328ic had a "cold air filter" by Turner/Conforti, and I did notice less power before I silicone glued and insulated the cheap plastic "heat shield"..in fact, I could put my hand on a chrome trim ring around the IFG element, and it was plenty hot...so that scenario seems of some note at least in heat intrusion impacting performance in motion. What I am getting at, but haven't tested, is that the I/C being added has exacerbated a heat soak condition, AFAICT. Would it prove anything if I was able to get the stall condition to occur as described above, but then if I popped the hood during the engine off period and then restarted and EVERYTHING WORKED PROPERLY?!!? Seems to me, that would only reinforce my admittedly novice hypothesis. I am not ruling ANYTHING else out, but it seems to me if engine air is being held back by mucho plumbing of little effect at idle/stopped/turbo timed to off and allowed to fester under the hood to much negative performance effect, then WHAT THE HELL DO I DO NOW!?!? Put in computer fans under the hood vents? Put some sort of additional fan into the intake plumbing? Lager beer in the coolant? I know a lot of people on the list live in parts south and west, so maybe the cold weather around here makes em' scoff. What I have noticed on this list is that a lot of experienced Hybrid Z owners are quick to avoid mentioning that it COULD be the impact of my mods on the car's design, rather than something wrong with the STOCK STUFF. I DID experience some of this poor restart issue shortly before the car went in, and I know it's the quick and dumb route to just go "its the damn mods, why did I listen to that site chat and spend 4 grand on engine mods when the thing re-idles like a jalopy now?! Would it prove some point of validity in my point, similarly, if I let it idle like an hour, at high and idle revs, then find driveability is exactly the same IF I DON'T DO THE SHUT-DOWN/WAIT AND SOAK? What about hood open, no turbo timer and restarts=no hesitation...what's it all about, Hybrid Z ?Seemed to me, in a ten minute trial of that, there was no impact on performance (engine fan running, perhaps). 8) , but again, if, by raising my hood every time I shut the car off for 10 mins during my daily driver runs, I"ve found a "solution", however laughable, WHAT'S the LIKELY CAUSE, if indeed it ain't the mod, and WHAT CAN I DO to keep it cooler under hood? The car was tuned, injectors cleaned, wires cap and rotor replaced, head gasket work completed (though they are going to redo the exhaust gasket, b/c I smell something (exhaust or coolant) in the ventilation/heat when I rev above 3,000 while driving! I just don't think there's much in my car's performance that is sub-par when this condition isn't active. My personal worst case solution is to simply live with it, only use the turbo timer for 15 secs (except on long runs) and put it all to myself to blame? Whatever, thanks for reading, most suggestions appreciated (other than to cut the hood in half or put on a stupid looking fibreglass duct!). John Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted February 6, 2004 Share Posted February 6, 2004 Intercooler piping has no effect. My engine compartment is so tight on the intake side. I have 2 2.5 inch intercooler lines, plus the 3 inch line for the maf, all mandrel bent. You have some other issue. Loose or bad connection, bad CAS, leaking injectors, clogged fuel filter. If you suspect the intercooler lines, bypass them, put the J pipe back in and see what happens. Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted February 6, 2004 Share Posted February 6, 2004 Sorry I don't know much about turbos...but I love the title of your post. Good Luck. Rufus Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted February 7, 2004 Share Posted February 7, 2004 Well I'll take a stab at your prob and give you a bit of background on the Z as well.. It might shed some light or give you an idea. Some of these ideas btw are my personal opinion/experience..so carry some salt in your pocket when reading this... 1st is this a 240Z? does it have the stock hood "ala" no hood vents? later model 280's have the vents to help reduce "heat soak" of the fuel rails after coming off the highway in summer and shutting the car off for a few minutes... (nissan factory fix) 2nd Do you have a stock clutch fan? is so..junk it... buy a high quality electric fan.. 3rd Wrap wrap wrap your fuel lines. 4th change your fuel filter.. if it was replaced last year.. change it again...one fill up with crappy dirty gas, and your new filter is junk... 5th check your timing...check your spark plugs... are they looking lean?..(ie clean... or tan...or black and sooty?) 6th check your thermostat. you should have approx 180 degrees... 7th do you have an air dam out front?.. bumpers?.. what is blocking your rad?...anything?...(not including i/c) I have an air dam with a aluminum belly pan under the engine bay...no probs with heat... I have a 260 bumper out front as well, and a huge i/c blocking my rad... I plan on using aluminum sheeting to help direct air at my i/c. I have a big hollow area infront of my i/c between it and the air dam... I plan on filling it in to reduce air turbulance infront of the i/c.. 8th is your fuel return working?...is it circulating hot fuel back to the tank?.. 9th just because you have a turbo timer doesn't mean you can go WOT down the street and then just park the car and let it idle....and hope it will stay cool...(it won't ) Yea not the be all end all, but its a start.... Good luck.. keep us posted... Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 7, 2004 Share Posted February 7, 2004 I would be tempted to say heat soak myself. My 75 does that after I stop and fill up for gas after driving for three hours at 80+ across the desert. If I keep going and keep air moving through the engine bay, all is fine. Have you driven the car with a fuel gauge (this will sound/look kinda stupid) taped on your windshield? I did this to determine that the fuel pressure was just jmping all around (bubbles in the rail) and stayed that way until the cool fuel worked it's way through the hot section of the rail, and pressure came up/stabilized. What I rigged for my long desert trips is a bypass so I can hold the fuel pump "on" for 15 or 20 seconds after a hot-soak episode. By pre-priming the fuel rail, my troubles went away all together. All it took was making sure the rail was up to full pressure and no bubbles were in the line before I cranked the car for initial fire. This may not be what you are experiencing, but the gauge will at least tell you what, if anything, your fuel system is doing when very hot. The I/C WILL add heat to the engine bay. If from nothing else restriction of flow over the radiator. A fan to circulate air after shutdown may help (like Nissan did). I run a 160 Chevy Thermostat in the car, and in general the car runs at 170 when fully hot which is close enough for stock ECU to turn off almost all of the cold enrichments. I still get 22mpg on my 75 while driving 80+ towing a small trailer, so it's not too rich! Good luck man, I know I didn't answer your questions directly, but thought this might help. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted February 7, 2004 Share Posted February 7, 2004 My guess would also be heat soak but do not dismiss a FP problem. The late-model hood vents are highly recommended. Consider hooking up a FP gauge so you see what is going on when you are cranking and sputtering. Quote Link to comment Share on other sites More sharing options...
Organdonor Posted February 8, 2004 Share Posted February 8, 2004 Is your o2 sensor hooked up. I had this problem after running on the freeway. I would shut it down and when I go back to start it (after comming out the store) I would have the same symptoms. I noticed my o2 had come unhooked, pluged it back in and no more problems. Quote Link to comment Share on other sites More sharing options...
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