pa312d Posted March 26, 2012 Share Posted March 26, 2012 i got a 78 Z Ive adjusted the TPS sensor and the timing is at 10* as my book states, but i got this intake pop that wont go away i am new to the z's. i try and rev the motor and as it slowly trys to pick up rpm's there is an intake pop thats keeping the motor from gaining rpm's. an it also is popping through the exhaust. ive done seafoam 2 times and figured it was just dirty injectors but apparently bot... any help would be much appreciated. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 26, 2012 Share Posted March 26, 2012 What's the fuel pressure? When was the last time it ran right? What's the history of the engine and parts? Several possible causes, some simple and some expensive, but confirming the basics is a good idea before getting carried away. Quote Link to comment Share on other sites More sharing options...
reliablejunkie Posted March 27, 2012 Share Posted March 27, 2012 the intake popping sounds like a lean running mixture but popping out the exhaust too could make it something else like the Air Mass Flow sensor. As NewZed states above we will need to know more about the engine etc. Quote Link to comment Share on other sites More sharing options...
pa312d Posted March 27, 2012 Author Share Posted March 27, 2012 What's the fuel pressure? When was the last time it ran right? What's the history of the engine and parts? Several possible causes, some simple and some expensive, but confirming the basics is a good idea before getting carried away. not sure what the fuel pressure is yet havent had time to test that. when i first got it ran right then i pulled the motor to repaint it and after that tstarted this. the lady that had it before me let it sit outside for 12+years and i pued around 4 gallons of oil water mix from the motor because it did have a cracked head. Quote Link to comment Share on other sites More sharing options...
JSM Posted March 27, 2012 Share Posted March 27, 2012 In my 78 that was under similar conditions had a very rusty tank. Fuel pressure was good at idle but above that nothing and then popIng like your describing. Sitting that long I would be surprised if the tank is rust free. Also change your fuel filter or check it at a minimum. Quote Link to comment Share on other sites More sharing options...
pa312d Posted March 27, 2012 Author Share Posted March 27, 2012 the intake popping sounds like a lean running mixture but popping out the exhaust too could make it something else like the Air Mass Flow sensor. As NewZed states above we will need to know more about the engine etc. is there any very reliable way to tune up the AFM i can turn that screw next to the dashpot and nothing seemingly happens... and i heard that the spring inside can get worn down and weak and i dont wanna play with that if i gotta. Quote Link to comment Share on other sites More sharing options...
Vonlam43 Posted April 27, 2012 Share Posted April 27, 2012 here you go i hope this helps out it did me quite a bit. http://atlanticz.ca/zclub/techtips/afm/calibration/index.html Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 27, 2012 Share Posted April 27, 2012 The screw next to the dashpot is the idle adjustment screw. It lets air past the throttle blade. If you can tune it with no effect, it is either so far out that the screw is not in the air flow path anymore or you have another path past the throttle blade, like a vacuum leak or the AAR is stuck open. Crank it all the way in, and if nothing happens check for those two problems. I wouldn't mess with the AFM until you get full control over air to the intake manifold. You'll just make a big mess, and end up going to carbs or trying Megasquirt. Popping back through the intake is also a fair sign of lean, which could also be a vacuum leak or plugged injectors or low fuel pressure... Quote Link to comment Share on other sites More sharing options...
B. Whisky Posted May 7, 2012 Share Posted May 7, 2012 Hi. I recently resolved this same issue on my zxt. For a while I could only stop the popping under applied throttle by enriching the fuel mix so much that u could light the tailpipe on fire when cold (no idle speed controls). Maybe two weeks ago, I referred to the fsm i had printed out last year, and started testing sensors at the ecu harness, starting with the tps, which immediately showed me an open circuit between the ecu and that sensor. Moving the tps around revealed the break to be at the sensor, as the multimeter would beep intermittently, and upon further inspection i discovered one of the two wires had broken right at the pin inside the boot. I spliced in a plug from a spare n/a harness and leaned out the afm, and it drove perfect for a whole lap around the shop, then the problem came back, albeit less severely. Turns out the tps itself had a broken piece of plastic inside that kept it tied to throttle position. Threw on the tps from the n/a harness and haven't had an issue since. Hope this helps. Quote Link to comment Share on other sites More sharing options...
B. Whisky Posted May 7, 2012 Share Posted May 7, 2012 I would leave the afm until you've established that the ecu is reading critical sensors properly. J/s Quote Link to comment Share on other sites More sharing options...
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