ok guys, here's the deal. my '86 buick, which has the 2.5L Iron Duke, has a bad miss on the #3 cylinder. it's pretty bad under load, but at higher RPM's it seems to be bad, then smooth out for a moment, then start missing again. we've varified that it does have spark, but just in case we replaced the plugs (all four) wires (all four) and coil packs (both of them). so it IS sparking. however, after each replacement of the plugs (gone through about four sets now) within 5 to 10 minutes of running, the #3 plug has a nasty black carbon buildup on it.
next stop would usually be fueling... but it's a TBI engine, which means if the other cylinders are working, this one should be, too. so, with two down, we moved to compression... which is what we were stuck on for a while. dont have the stuff to do a compression check... and havent gotten around to just stickin my finger on the hole and seeing if there's any seepage as you turn the crank. so for a while we were worried that we were gonna have to rip apart the engine... at which point we'd just sell the car.
so we noticed the other day that at higher rpm's, it seemed like it sometimes clears up for a second, then goes right back to missing, so the idea pops into my head... could it be a lifter? what do you think? im hoping it's the lifter... much easier to replace.
also, if it is the lifter, i was going through the autozone site to check lifter and pushrod part #'s, and crossreferencing them, and found out that the part #'s are the same for the 2.5 Iron Duke as my 3.8L engine in my GTP... well, i just happen to have extra lifters and pushrods. could someone double check that for me?
TIA
Andy
it's not how fast you go, it's how you get there that counts.
ZZP XP cam, 1.6 rockers, 105# springs, speedbuilt FWI, 3.3" modular pulley, TOG headers,
3" exhaust, flomatched injectors
'97 GTP 14.06@100.6mph pre cam w/ 3.5" pulley, I/E
I checked the part numbers and I got that your lifters are the same part number, but the pushrods are not. As for the problem, you got me, sorry.
thanks for double checkin for me. i'd rather get new rods than lifters, they cost less.
so no one can help me with the actual problem?
Andy
it's not how fast you go, it's how you get there that counts.
ZZP XP cam, 1.6 rockers, 105# springs, speedbuilt FWI, 3.3" modular pulley, TOG headers,
3" exhaust, flomatched injectors
'97 GTP 14.06@100.6mph pre cam w/ 3.5" pulley, I/E
