boatbum Posted October 27, 2002 Share Posted October 27, 2002 78 280z with stock engine. It had been sitting for a few years and I just got it running last week for my Velo Rossa project. The muffler is off but the "pre-muffler" is still on. Anyway - I fires right up and idles great and sounds fine but when you give it gas - it it goes as high as about 1800 - 2000 rpms and hesitates. I did the usual to get it running, drained oil and gas and put oil in spark plug holes before turning it by hand. Drained and purged old gas and ran new gas through lines before hooking the fuel line back to the fuel rail. I am not a mechanic and would like some insight as to where to start looking. BTW - compression is fine. Thanks for any input. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 27, 2002 Share Posted October 27, 2002 TEO....the old Zs suffer from setting. Take the gas cap off to see if any of the gas tank vent lines are plugged. The car will idle normally but not rev if the gas tank is not vented. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 27, 2002 Share Posted October 27, 2002 You could have a shorted idle switch on the TPS - it may have corroded while sitting. The ECU will not fuel for any load if the idle contact is closed. Quote Link to comment Share on other sites More sharing options...
RPMS Posted October 28, 2002 Share Posted October 28, 2002 This may sound crazy, but check your distributor to make sure the mechanical and vacuum advances and everything else in there is working. I had very similar problems in my car, acting like it had a rev limiter put on it at 2,500 rpm. It didn't clear up until I replaced the distributor with one from another car. Probably not the issue, but worth checking. Quote Link to comment Share on other sites More sharing options...
boatbum Posted October 28, 2002 Author Share Posted October 28, 2002 Thanks for the starting points. I did some searching for Distributors and TPS and found a ton of stuff. I will play with it again next week and see what comes out. Thanks! Teo Quote Link to comment Share on other sites More sharing options...
boatbum Posted October 30, 2002 Author Share Posted October 30, 2002 Myron, This totally floors me - I don't even have the air filter connected. I took it off when I tore off the front end and I will try to get over the car tomorrow before I jet out of town because I won't be able to sleep until I test this. I did test the gas cap idea and the TPS looked ok. Thanks a million, Teo Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 30, 2002 Share Posted October 30, 2002 That totally amazes me!! I find it hard to believe, but then again my Toyota truck with a 22RE and a flapper would run like crap with a K&N filter in it, runs great now that I went back to paper element. Quote Link to comment Share on other sites More sharing options...
MYRON Posted October 31, 2002 Share Posted October 31, 2002 This may sound even crazier than the previous post. I had a 78 that I stuck the motor and tranny in from an 82 model. After doing so, I had a bout 4 wires that I coudlnt figure out what they were for. the car would do exactly like you say: start,idle fine, rev to 2k then hesitate real bad... My dads solution was to have me switch the ENTIRE wiring harness from the 82 and graft it into my 78... I did it(like a dummy)!! I went to start the car and I got the same problem... I spent 3 days leaning over the car trying to figure out the problem.... then my buddy came over and we were both leaning over the car scratching our heads.. I am trying to rev the car past its 2K "barrier"... My buddy held his hand over the air cleaner inlet and BAM it ran like a top. He want choking the car completely, just restricting the airflow. Turns out it didnt have a filter in it. When I installed a filter I never had another problem. I guess the airflow meter needs a little restriction for it to work properly. Just plain weird!!! Myron Quote Link to comment Share on other sites More sharing options...
boatbum Posted October 31, 2002 Author Share Posted October 31, 2002 Well, I tried to block the airflow a bit and that actually improved a bit but still no go. It is stuck at about 1500 without anything and with my hand over it I get about 2K. Will keep at it Thanks for all the help so far. BTW - this motor is a candidate for a refreshening anyway but I would like to see what is going on before I tear into it... Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted November 2, 2002 Share Posted November 2, 2002 Ive heard of this prob. several times, half of the time its the air flow meter not functioning properly. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted November 3, 2002 Share Posted November 3, 2002 i have a similar problem but mine is at 4k same car 78 280z. mine has a CAI intake on it... could this be a problem maker? also bigbore throttle body and brand new afm Quote Link to comment Share on other sites More sharing options...
Guest MHarpham Posted May 2, 2006 Share Posted May 2, 2006 I am also having a simular problem in my 78 280z. Seems pretty common. gonna try some stuff mentioned. hollar if you find something that works. Mattharpham@hotmail.com 1978 280z 2+2 Quote Link to comment Share on other sites More sharing options...
Guest MHarpham Posted May 13, 2006 Share Posted May 13, 2006 My problem turned Out to be my AFM. The Spring tension screw had come loose. I had to adjust the tension on the gear in it several times. Always tighter before it would rev under load. Quote Link to comment Share on other sites More sharing options...
racerx260 Posted May 21, 2006 Share Posted May 21, 2006 It can be something as simple as the fuel filter.It gets clogged and will not pass enough fuel to wind out the motor.I haven't had it do it that low mine usually stopped reving at about 4000 ,but with it sitting it could have gummed up bad. Quote Link to comment Share on other sites More sharing options...
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