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irregular idle and tapping noise. i'm sick of fixing this car.

1246 Views 5 Replies 3 Participants Last post by  PhoenixSheriden
1991 ranger motor

so a couple days ago while i was out the mustang just up and died while idleing, rpms dropped to 400 and it quit. he started right back up. after that, he got worse; wanted to idle really low at about 600, i had to do the two foot thing to keep the rpms up at 800 because i didnt want it to die again. as i'm going home it seemed like it was making less power than normal, not a huge difference but enough that i noticed. i started him up and he hasnt died at idle since, but the rpms will start out high going up to 1500 for about 20-30 sec, then dropping and staying in the 600-800 range. and then i hear a tapping comming from the engine. it seems like its in the head or throttlebody, but i cant pinpoint its exact location. it tapps more as the engine rpms go up, at least it does while parked with me pulling the throttle by hand, its too noisy while driving for me to tell if it taps or not. pulled the hose from the fuel pressure regulator, and it did smell mildly of fuel. it has plenty of clean oil in it, and the dummy gauge in the dash reads about 2/3rds.

i checked timing and the cam and crank marks line up 100% perfect. air filter is clean. i just regapped the plugs and they were only a little bit off and they looked completely perfect. the head is new with less than 2k on it. i sprayed the maf with maf cleaner and it didnt change anything. engine off and engine running gave the same two codes; 172 (o2 sensor says running lean) and 332 (insufficient egr flow), i also got a 116 for the ect, but i replaced it a couple weeks ago.

about a year and a half ago i took out the pcv and capped off the crankcase hose and the egr. it was supposed to be temporary, but i sorta forgot about it. i'm gonna try and clean the iac, but i'm having trouble getting the bolts to let go without stripping the heads. i'm gonna try changing the fuel filter too. the icm and coil packs are less than 2 months old, and the plug wires are only 2 years old. i'm gonna test the pressure reg and the iac and adjust the stop screw.

whats got me confused is how any of these possibilities for the idle not behaving could be making my tapping noise :confused::headscratch:? any ideas?
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Maybe rounded off a cam, maybe a spring broke. Do a leakdown test and compression ratio. I hear you about the car quiting. I just got to putting the c-4 back in mine. Front seal went out. This is second time since had trans in car. Maurice
i'm still gonna test some things, but i think i might have gotten a REALLY bad tank of gas. i usually get my gas at costco and a couple hours ago when i got up i see on the front page of the paper that BP gas stations put out bad gas to multiple gas stations here in northwest indiana, and costco was one of the affected stations.
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i finally had time today to go out and work on my mustang. i tried to run a compression test, but dads crappy tester wasnt working. i wasnt thrilled that i'd gotten everything set up only to not be able to do the test, so i put it back together with the intention of just letting the shop figure it out.

but heres where it gets interesting. when i went to take the plug out of #1 on the exhaust side i found that the metal insert in the boot wire came out of the boot and stayed stuck on the plug. i have some spare plug wires, so i put one of those on the #1 exhaust, and i also put a used wire on #3 because the boot was loose while on the plug. i fire the mustang up just to make sure that it would start again, and the tapping noise changed! its quieter and irregular, whereas before it was loud and fast and constant.

i still am not sure, but i think its comming from #4 cylinder. today or tomorrow i'm gonna monkey with the wires more and see what happens. but could my problem be as simple as bad wires? i've just never heard of or seen bad wires do this.
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are you sure the sound is tapping and not ignition wires shorting to head they sound more like ticking then tapping. if it is a tapping you may have a lifter or cam follower whatever you want to call them not staying pumped up also the early ranger motors did have cam lobe issues
apparently fordzilla nailed it and the noise was ticking. i went out and got all new plug wires and put them on and no more tapping/ticking noise! took the stang for a short ride (started raining, mustang+slick roads= :nono: ) and he was fine!
i'm both happy and a little sad that it wasnt something worse, because if it was worse it woulda given me an excuse to go turbo. soon my pretty...soon you shall know the gift of turbo.
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