Guest jjohart Posted March 7, 2004 Share Posted March 7, 2004 Hi again, in addition to heat soak like condition in prev. post, I have come to the conclusion that when my local mechanic redid the exhaust gasket 2 weeks ago (the original aftermarket one snapped as they sealed it, or something like that, so they told me!), it stopped the exhaust leak through ventilation and clicky engine sound, but, upon driving the car in sub 40 degree weather since, I have found it becomes buzzy like a low flying airplane underhood, the shifter vibrates like a dentist's drill and the exhaust develops a dual tone, like a two note chord on electric guitar with fuzzbox! That said, I am guessing that this is the exhaust gasket "flexing" or hitting something it doesn't when it's warmer out!?! Is that possible...it's just my simple observation, but this is yet again one tough problem to present at time of service appointments (I took it back this week, they had it X 4 days and I even drove it 2 hours to try to provoke it but it was 50F out and naturally it never even hinted of the condition!). Would it really take 5 hours to re-do, which is what they made noise about having to do it at their cost the second time to get it right!! My gut says they shoulda got it right the first time, and I'm tempted to take it over to Nissan (they said they used a Nissan gasket the 2nd time), but I can see this is going to the point of costing me plenty and not having an easy time of finding a fix....any comments appreciated, particularly as to the possibility that said gaskets really do flex or rub on something in different operating conditions, i.e weather temp changes?!?! Thanks in advance! John Quote Link to comment Share on other sites More sharing options...
zxgts-4 Posted March 7, 2004 Share Posted March 7, 2004 H John as this is long distance diagnosis its definitely not the same as being there when you can work through things systematicly. In theory the intercooler could make any airflow meter or air temp meter, (both in the one unit), problems worse. Check that flap moves freely, particularly when cold. Heat problems of the type you describe would correspond to vapour lock but would be unusual in that ambient temp unless engine was running hotter than usual. ie bad thermostat. But could be affecting ignition module in distributer but you would expect other running probems. If youve had mechanics near exhaust sytem check that exhaust gas sensor wire hasn't been knocked off. You dont say whether the high speed vibration is when car is moving or stationary, if stationary it will probably relate to engine tune, if moving it could be a drive line item. Early Z expert may not be the answer for tune advice as ECCS is on ZXT is more like Z31 system. Good general Fuel injection expert should be able to trace most problems and name and explain reason for any component replacement. Odd one out of left field if car has been sitting awhile or has old exhaust system, check for loose baffles in mufflers which can cause intermitant blockages and overheating. Now that youve done injectors the only other thing that may dribble fuel into manifold is the start valve. The simplest way to check whether you have lean or rich mixture stumble at startup is have someone stand behind vehicle when you start it, if it puffs black sooty till it runs clear then you have fuel getting into manifold if not then vapour lock, low fuel pressure or ignition problem would be more likely. Personally I would consider ECU problems at the end after checking everything else, it analyses data from sensors to make a decision which is where the problems are more times than not. Thanks for feedback and posting in correct forum. Thats all I can think of for the moment, good luck Neil Quote Link to comment Share on other sites More sharing options...
zxgts-4 Posted March 7, 2004 Share Posted March 7, 2004 Further info on possible vapour lock issue, the shop manual says to check fuel tank vent lines and the fuel tank vent valve, which is located under rear of car adjacent fuel pump. Remove from vehicle. It has three connections 2 out of its sides, one to fuel tank, one to charcoal canister the third out of the base, if you suck on this air should not come out, if you blow into it gently air should not flow, if you blow forcefully the diaphram should lift and air should flow freely. If not it should be replaced. Something I might just check on mine because I've been getting fuel tank pressure buildup and the odd problem like yours, of initial engine rough idle that clears, during this summer when ambient has been +30C. Further to under bonnet buzzing and flat exhaust sound, could that be a Turbo wastegate control issue. Something you can ask mechanic while their looking at it, not an area where I have any expertise. Further to Exhaust gasket question, if both flange faces are flat and bolts are done up correctly there shouldn't be any further problem. But if engine isn't running properly and vibrating a lot this could be working the joint loose again. Thats all for this morning. Good luck Neil. Quote Link to comment Share on other sites More sharing options...
Guest jjohart Posted March 9, 2004 Share Posted March 9, 2004 Thanks for all the late summer tips..it is snow and raincicles from here near Boston, MA, USA, but the car definitely heats up enough underhood to verify what I've thought all the long...SOMETHING under the bonnet, as you say, is being heated by normal operating temperatures to become malfunctioning on restarts, B/C when I experimented driving around, leaving the hood up while parked/shut off, the restart was astoundingly NORMAL, whilst the same routine, bonnet down, produces all of the stalling, sputtering and poor delivery until air is pushed under bonnet, i.e, venting whatever isn't happy, be it fuel rail or god knows what else! SO, I'm leaving it at a New Hampshire dealer to see if they can isolate the stock componentry which is amis, hopefully without their blaming it squarely on the intercooler. That said, if there's no hope without a fuel regulator or some other compensentory device, then it's off to the local racing stockist/installer! BTW, to Melbourne, AUS...is the children's morning show "Brum" filmed on location in Melbourne? I've been to Syd and Cairns, but never got to the "Boston" of Vic! Cheers John Quote Link to comment Share on other sites More sharing options...
Guest jjohart Posted March 9, 2004 Share Posted March 9, 2004 No, I'm afraid it wasn't the exhaust gasket, though the awful sounds showed up about a day after said work was done. This time, it turned out to be a bolt affixing the harmonic balancer to the driveshaft crank, or something like that. Had this come completely off, it might have required a new motor after likely damages ensued!! Needless to say, the bolt required a few turns, but what my mechanic left me scratching my head about is the issue of pressure needed for that bolt to come loose/reaffix. Apparently the tool they used measures torque in something called around here as "Newton units", which may or may not be reference to Sir Issac, but on my 280ZXT, it took only 100 N.U to make the bolt turn, as I understand it. The mechanic told me that certain German marque prestige vehicles are so tightly connected that it takes a certain amount of leverage to move them, like a long pipe held by one person in the right positioning, and another person to kick it full force multiple blows to get it even to move!! I don't understand why that bolt came loose at all, but being that this is now a 21 year old car, so long as it STAYS in place hereafter, all's right with the world now!! Cheers John Quote Link to comment Share on other sites More sharing options...
zxgts-4 Posted March 10, 2004 Share Posted March 10, 2004 Hi John glad to hear you are once again at peace with your 280ZXT, sorry but Im not big on childrens programs so I cant answer your question regards Brum. As to loose crank bolt, it is probably just one of those things that happen and Newton/Metres is the metric equivelant of Torque measurement, US is probably more used to Foot/Pounds. Anyway cheers Neil Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.