Soduh1 Posted May 10, 2013 Share Posted May 10, 2013 i have an issue with my fuel injected z. i just got an exhaust installed but before that the car ran fine. now my car will idle fine but as soon as the throttle is pressed the engine stumbles. dosent die but if u hold down the throttle the car will stumble for 2 or 3 seconds the rev up. any ideas? could this be a backpressure issue? Quote Link to comment Share on other sites More sharing options...
Domzs Posted May 10, 2013 Share Posted May 10, 2013 If the car ran fine before the new exh. system then you need to check the new exh. system . Poss. that something was left in there ( pipe or muffler ) or came loose/apart . Quote Link to comment Share on other sites More sharing options...
Leon Posted May 10, 2013 Share Posted May 10, 2013 My bet is on an electrical connector getting damaged, destroyed, or left disconnected during the exhaust install. Did you have a header put in? That's a more involved job than just replacing the exhaust pipe and something could've easily been left off or knocked loose. Quote Link to comment Share on other sites More sharing options...
9rider Posted May 17, 2013 Share Posted May 17, 2013 Back pressure ?? My Z is doing the same right now but I have low FP 32 PSI need to check out before the exhaust. Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted May 24, 2013 Share Posted May 24, 2013 It's probably a vacuum leak. Check the hoses. The Idle is fine so it's probably not any back pressure. It's stumbling on throttle because the vacuum isn't enough to pull the advancement. It catching up after 2-3 seconds goes right along with this diagnosis. Take a look for cracked hoses, or any disconnected barbs. These engines are old, the rubber doesn't last forever. Fortunately rubber is cheap to replace. Quote Link to comment Share on other sites More sharing options...
9rider Posted May 24, 2013 Share Posted May 24, 2013 Check TPS. How about take out your oil filler cap and see if the engine stall. Brake vacuum ? Advancing vacuum? Replace all the vacuum hose if you can, cost you around most $20. Quote Link to comment Share on other sites More sharing options...
Soduh1 Posted May 24, 2013 Author Share Posted May 24, 2013 ok so its defenetly not a back pressure issue nor a fuel issue... i found that when we remove the vacumm hose from the air ressure regulator the motor dosnt stall out but as soon as you disconect the vacuum house from the valve cover it stalls out after 2-3 seconds. also not sure if this is an issue or not but with the key in the on positioin if the flap in the maf is moved the injectors dump gas with no noticeable pulse. any advice is helpful and appreciated Quote Link to comment Share on other sites More sharing options...
Domzs Posted May 25, 2013 Share Posted May 25, 2013 First , which part of the exhaust sytem did you replace ? If you remove PCV hose from the valve cover it will stall because of unmetered air flow . Quote Link to comment Share on other sites More sharing options...
9rider Posted May 31, 2013 Share Posted May 31, 2013 key in the on positioin if the flap in the maf is moved the injectors dump gas with no noticeable pulse. I think it is normal since my car did the same when I troubleshoot my FI system. Or we may have 2 car with abnormal problem Quote Link to comment Share on other sites More sharing options...
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