wolfman_dlc Posted July 23, 2011 Share Posted July 23, 2011 I have an 82 280zx turbo with usual minor modifications. Intercooler, Catless 3in ex, fuel log, egr and other vacuum equipment removed, K+N Filter, alum 3core rad/ 2 12in electric fans, gm ignition module/ accel super coil. Every thing else is mostly stock and running stock boost. When free reving the engine with pedal fully dropped It hits a wall at around 5-5500 rpm. But if I let off just a little it will jump up to around 6200 no prblem. The same under load. When driving about 50mph and punch it the car accels roughly sometimes frontfires and feels like im towing a semi. If I let off just a little, the car accels beautifully and full of power. I Searched for this and found some saying they hit walls at 4-5000 rpms but unsure if their prblms are related. I only have some wild guesses as to why this is happening. My best guess is the afm but have tested it and all is good, Fuel pressure is testing good when free reving, from what I understand the timing is not adjustable, could is be a pedal adjustment? I want to get this figured out before I start turning up the boost any! Any Ideas appreciated- Daniel Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted July 23, 2011 Share Posted July 23, 2011 I don't see how it could be an issue with the pedal or linkage. My guess would be an a/f issue. Perhaps bad injectors? Consistent fuel pressure doesn't necessarily mean you're getting consistent fuel into the cylinders. Quote Link to comment Share on other sites More sharing options...
wolfman_dlc Posted July 23, 2011 Author Share Posted July 23, 2011 Im starting to lean towards injectors myself. I seem to remember a surge in fuel pressure a wot like perhaps the injectors were at full flow but regulator was giving more pressure. If the injectors were at full flow at almost WOT, the increased air at wot would have caused it to go lean. I dont know the history on these injectors but will start looking for a higher flowing set especialy if I plan to turn the boost up anytime soon!! Thanks for the quick reply! any other suggestions welcome Daniel Quote Link to comment Share on other sites More sharing options...
Josh280z Posted July 23, 2011 Share Posted July 23, 2011 Just because you have good fuel pressure when free revving doesn't mean the fuel pump can keep up with the load of driving down the street. This happened to mean, I could run it up too 6K easy, free revving. When I'd put it in gear it would bog down and the engine would cough and sputter. All I'm saying is that it might be the fuel pump, don't rule it out just yet. Quote Link to comment Share on other sites More sharing options...
wolfman_dlc Posted July 23, 2011 Author Share Posted July 23, 2011 But thats just it, I had the same prblem when free reving and was watching the fuel pressure gauge. WOT free reving only got me to about 5500 max rpm. Let off just a little and it would jump up to the 6k+ rpm with good pressure the entire time. Im also leaning to my afm. Just tested according to the fsm and the first test specifies 280-400 ohms on first and second pin of afm. Im only getting 200 ohms. Fsm says to replace, can I just add a resistor in line to adjust or would that be a waist of time? Quote Link to comment Share on other sites More sharing options...
wolfman_dlc Posted July 23, 2011 Author Share Posted July 23, 2011 Update!! warning results may not be typical.... I spliced a 100 ohm resistor to wire connected to pin one of AFM. I started her up and she wouldnt idle. The AFM had been opened at some point before I bought her so my guess was she may have been adjusted enough to get her to run. I was correct!! As the car was idling irratically I moved the the "pointer" forward to richen the mixture. It died immediately, tried again only leaning her out and the idle smoothed and raised slightly. I dont yet have a wide band so I adjusted for best sound and rpm/vacuum. Jumped back in driver seat and she free reved at WOT to over 6500 rpm crisply. Now for the driving test!! 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.