misfire and bad idle-very detailed description (long)

[91darkdsm]

ok so ive searched for countless hours and cant find any resolved issues or any quite the same as mine. mods listed in profile. ive been batteling a misfire and rough idle for a while when the car is warm, runs great when cold. it misfires consitently at idle and driving, the car does not stutter or bog when driving and pulls hard to the redline, things ive done are, swapped coil packs with known good ones, changed wires twice and am currently runnung msd 8.5mm, i replaced plugs three times this week with ngk bpr6es, then tried bpr7es, currently running bpr8es, and ive tried gapping all three at all different sizes with no luck, base timing is set at 5 btdc with plug grounded, when i unground it it jumps to like 14-18 btdc, ive checked cam timing and everything is in time to the t, bs, oil pump, cams, i cant feel the mifire during hard pulls but can tell its there during steady cruising, i also have a bad idle when its warm, i have adjusted it best i can and with all accessories off it idles around 1000 rpm, reason its a lil high is i believe either my altenator is weak or isc motor is bad,reason i say this is when u turn the headlights on, it idles a lil rougher, heat on and it drops significantly, and if i run my lights, heat and rear defroster it drops to like 3-400 rpm and sits there and idles real rough, ive done 3 blt"s and since have changed im gasket, tb gasket, injector o-rings, biss o-ring, and im holding good at 20 psi on the test, after making runs and pulling my plugs the ground strap is white looking and seems lean to me, but the threads around the top of blug are black and sootie maybe running lean up top and rich down low? tried adjusting my maft but no luck, im running 12 psi on stock fuel system which i thought was ok? i dont have a wb yet and and cant make any logs and heres why, i got the car and it had complete emissions delete, everything is out, now i figured id be throwing a cel for the emissons delete and really thought id be throwing one for the way its missing but nope, never throws a cel. The cel comes on with ignition as it should but ive never thrown a code(or tripped the light) now i went to log using data logger and i find the previous owner-or somebody cut the obd port out.. so i have to get to a jy and cut one out and rewire into mine. i have not pulled my ecu and will be doing so today to check for leaks or burns. the misfire is more annoying than anything and is a steady puh puh puh out exsaust and so bad sometimes it sounds like a subaru but never hesitates, or bogs under acceleration. i also pulled plug wires one at a time and and every one made a difference in the way the car ran but i did notice when i pulled a wire u could see the spark arking off the coil packs and did this with each wire pull. is that normal? i think ive covered everything and any help is greatly appreciated. ive learned alot from this forum and rarely ever make a thread as i find my answers from search. just not this time. sorry fo long post i just wanted to be very detailed so theres no guessing. keep in mind i dont beat the hell out of my car but i do drive it hard sometimes but thats why we build them. thanks for your time and patience with this long post. also need to check power transistor and ill be doing a compression test today and posting those up. besides isc, power transistor, altenator, ecu and everything els i listed what could it be, im stumped. car does not smoke and is never low on oil when doing change.

 

[doayamaha]

Sounds like the same thing my 94 was doing what mine ended up being was the o2 sensor one if the wires looked a little burned with a pin whole in the wire casing and I was reading no voltage from the o2 found this out with my friends logger switched to a wideband and simulated narrow band into ecu problem solved

 

[91darkdsm]

well i ran a dry compression test and it didnt look good, numbers were
4=110
3=100
2=90
1=65
what i dont get is the car doesent smoke, doesent use oil, its always still full at oil change time, it runs like a raped ape, i pull 20hg vacum at idle and around 24 at deceleration. maybe i did something wrong? i pulled the mpi fuse, screwed the tester in and cranked it at wot till it didnt move anymore, once i warm up a little ill pour a cap of oil down the plug hole and do it again and see if there about the same numbers. could it be bad valves, maybe sticking open? internals are stock with 108,825 miles. head supposedly only has about 10k on it. new timing belt about 14k miles ago. any info is appreciated. ok so i went and drove the car and did another dry test follewd by wet test, results are.......dry test
4=110
3=90
2=88
1=65
wet test
4=120
3=90
2=90
1=80
so im guessin bad valves and rings maybe any opinions?

 

[navyvr4]

do a leakdown test

 

[zanderson]

I had a similar problem with my second gen talon, part of the problem was the head gasket was starting to go. I read that would cause idle problems and could explain your compression. Also have you checked your MAF sensor? I don't think a wet test will tell you anything about the valves, but it is usually a sign of bad rings if comresion goes up.