ananimator Posted July 28, 2004 Share Posted July 28, 2004 Hello all, This is my first post. I didn't have any luck searching for my problem. I have a '70 240 that has an '83 turbo engine and 5 speed. It starts up great and runs fine as long as I don't nail the pedal. It runs and drives smooth and even has good pickup as long as you I ease the throttle. As soon as nail it, the power drops, it coughs and sputters. Sounds like blow off and maybe backfire? The computer has been swapped, the air flow meter has been swapped and the idling fuel pressure is good. Next my mechanic is going to test the fuel pressure while driving. Has anyone gone through this? Any suggestions? Thanks very much. Bill '70ZXT '71ZX Quote Link to comment Share on other sites More sharing options...
datsunlover Posted July 28, 2004 Share Posted July 28, 2004 Have you checked the tps? could be out of adjustment or have a short in it at/close to the full throttle position... or maybe a leak/hole in one of the rubber hoses/piping in or out if the AFM? Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted July 28, 2004 Share Posted July 28, 2004 Do the famous ECU connector cleaning. Whenever that happened to me I would disconnect the and clean the ECU connectors and the AFM connector with electrical contact cleaner. It would always work. Could also be a small leak somewhere. Quote Link to comment Share on other sites More sharing options...
ananimator Posted July 30, 2004 Author Share Posted July 30, 2004 Hi again, Well I temporarily got the car back so my mechanic can fix an exhaust problem on my ‘72. So far he has done the following to my ‘70 turbo: Removed, cleaned and replaced the spark plugs. Checked the timing index marks and set timing. Checked the fuel pressure, both idling and driving . 45lbs. when driving. Checked the throttle positioning switch and adjustment. Swapped the ECM with a known good part. Swapped a new AFM to test. Did a smoke test of intake system. Only found one small leak in a crankcase hose. Replaced. Has suggested testing the injectors for flow, changing the crank angle sensor or installing a new wiring harness as the only things left. He tells me the only harness available is for an ‘82(mine is an ‘83), will cost about $500 and is only 60% sure that is the problem. I cleaned the ECM contacts again today. It actually runs a little worse. I wanted to clan the contacts on the TPS and the AFM but could not figure out how to get the connectors off. What is the trick? When driving, if you slowly depress the throttle, it runs smoothly, but if you depress too quickly, it pop and loses power. Could there be something with the distributor that is causing this problem? I would hate to spend big bucks to replace the wiring harness if that does not fix the problem. Any other suggestions? Also would like to know if there is a turbo expert in the San Diego area. Thanks very much, Bill 8) ‘70ZXT ‘71ZX Quote Link to comment Share on other sites More sharing options...
v8dats Posted July 31, 2004 Share Posted July 31, 2004 i agree with datsunluver i think it might be the tps i had a similar problem with my old 260zt.went to the junkyard and grabbed one replaced it and fixed it right away Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted July 31, 2004 Share Posted July 31, 2004 I have been going through a similar problem, and have done much of the same in trying to get my car running. I've had it start to run great about two times on me after doing some work around the engine, but really for no good known reason. The car seems fine when not under high load at higher rpms. It's like I can use about half of my throttle pedal, and really seems like the car only has as much power as a stock L24 engine. When it's running correctly I have a hard time picking my head up off of the seat, and have traction problems. I know for a fact that my distributor is not in the best of shape, you turn it and it feels like something broke off into the bushings. The vibration of this alone could probably make the sensing go bad. The fact that it times out good at idle, and then under load it acts like the timing is way off kind of makes me suspect a problem, but it's hard to tell if the problem is timing or fuel related. Anyways, I feel your pain. I've been going through this stuff for some time, lots of people saying it sounds like the tps, but if it were only that easy then it would have been fixed so long ago. Keep us updated. If I get mine running well I'll let you know. Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted August 21, 2004 Share Posted August 21, 2004 Turned out that the little key or cog that aligns the crank pulley was missing on my engine, and the crank pulley was not aligned properly. To sum it up my timing was messed up because of this by a lot I bet. Anyways, fixed it up, timed it correctly and am now running 12psi with good pull through the band. Best of luck figuring out your running problems. Quote Link to comment Share on other sites More sharing options...
Guest jinsei888 Posted October 21, 2006 Share Posted October 21, 2006 When I had this same problem with a previous turbo car, I ended up swapping out spark plug wires, spark plugs, cap and rotor....then suddenly it was fixed...I dunno if it was because I had 10 year old parts and swapped with new better ones, or if something was simply loose... Check your connections, and consider getting some new wires, plugs, and cap and rotor if you haven't changed them in some time Quote Link to comment Share on other sites More sharing options...
GHtokyo Posted October 30, 2006 Share Posted October 30, 2006 Wow that is strange, I thought that key to align the crank pully was right on the crankshaft. It must have been ground off, or broke off. Wierd! Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 30, 2006 Share Posted October 30, 2006 How old was this thread? YIKES! Quote Link to comment Share on other sites More sharing options...
Guest jinsei888 Posted October 31, 2006 Share Posted October 31, 2006 lol, sorry cygnus, I'm still a newb when searching and reposting haha Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted November 1, 2006 Share Posted November 1, 2006 I think you need a better mechanic. If you are paying someone to do all this you need to get better help. Unless you are speaking metaphorically in the third person of yourself as the mechanic. Quote Link to comment Share on other sites More sharing options...
SonOfZZZap Posted November 1, 2006 Share Posted November 1, 2006 Well, sounds like an air metering problem. Either throttle position sensor or your MAF meter. Either way when you hit WOT and want go fast power, something is saying "TOO MUCH AIR!" and killing it. The backfire is from you gunning it and the fuel not burning because of your current problem. so when the exhaust pulls air back in and you got extra fuel and heat with compression in exhaust ="BOOM!". I wish you luck. -Jared Quote Link to comment Share on other sites More sharing options...
alexideways Posted November 2, 2006 Share Posted November 2, 2006 Guys! this the original question was asked in 2004. Quote Link to comment Share on other sites More sharing options...
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