at my witts end

[dpersico]

ok heres what i did so far. i had a coolant leak, broke down the top of the motor ie upper,lowern plenum, heads. visually inspected combustion chambers, valve spring height, guideseals, burnt or bent valves and block,andto my supriseeven after badly overheating all was in good shape. there was not even arim on the top of the cylenders.the car had 11800+ miles on it.(maby it was repowered at some time) so i proceeded to reassmble with all new gaskets and even replased the internal pipe that connects to the upper planum gasket to the mpa sensor. when i was putting it toghther i used some silicone....sparingly...to all gaskets and torked every thing down to specs ans sequaqnce according to alldata. i let everything cure. replaced plugs n wires, air filter and changed the oil n filter. when i first started it up there was a little bit of expected smoke sinse i keeped everything oiled as to resist r4usting inh the cylenders lifter guides ect. then it ran excellent. about 2 weeks after it started to run like there was a vaccume leak. i changed the emission line that controlls the fuel regulator, and evap purge. and again it ran fine. i now keep throwing codes. p0300, p0304, p0122, n p0123 and the car seems to sputter upon excelleration when im already at hgy speeds. ocasionly it will feel very shaky at a stop. but never bogs down or stalls. so far i got rid of the p0171, but p0122 and p0300, p0304 keeps setting. and before the misfire codes set the mil flashes telling me that the converter could become damaged. the car is a 1998 monte z34 with a 3.8 motor. any ideas on what im missing? thanks dave

[nycemsmedic67]

btw i ment no disrespect with those posts, just mad at the car and my inability to resolve the issue. please forgive any disrespect.
dave

[maxwedge]

Any misfire can be caused by coils, wires, plugs, lean mixtrue, low fuel pressure, vacuum leaks, based on the 304 look at that cylinders secondary ign components. Check fuel pressure at the rail, make sure that injector connector is in properly. Look at the tps connections also for the 122 123 codes.

[nycemsmedic67]

ok heres what i done so far. 1 checked spark both from the coil to wires, and wires to plugs with a non induction timing light. no misses there light is at a steady flash at varying speeds, this says nothing about plugs tho. i saw no signs of arking, ie white deposits on wire boots. also tells nothing about comp. either. listined to injectors to hear pulsing........all sound the same. wires n connections good. ck fuel press @ fuel rail @ idle 40lbs steady which did increase while reving engine. checked fuel regulator to see if its pissing out gas, clean. when i replaced the emssion hose for the fuel reg, and evap the p0171 went away. checked tps..........dead spot about 1/2 throttle, didnt ck ckp sensor..........think i should? will do dry n wet comp test tommorow. put in 93 oct gass(why not, even tho the owners manuel stats 87 good). sprayed down engine, hoses map sensor/pvc area with brake cleaner with no change in idle quility. could i be floating a valve? but id get rough idle at higher rpms.no? now not only p0304, but also p0300. dont have a tech 2, but heres the freese frame data from my sears scanner
p0304
fuel cl
load 2.7%
ect 170 deg f
stft 6.2
ltft 16.4(never lower at idle but will go below 15 @2000rpm)
map 18 (vacuum gaugh at the brake booster when manually tested sts 14)
rpm 748
veh speed 0
spark adv 21 deg
iat 100
maf .629 lbs/min
tps 0%
O2 sensor b1 s1 .720
o2 b1 s2 .195

gm fsc dtcp0300
cl
load 3.5%
ect 114
stft 3.1
ltft 16.4
map 17.1
rpm 893
veh speed 0
maf .859
tps 0%

[oldblu65]

Dave , do you have two accounts on AF under different names or....?

[nycemsmedic67]

no....i appoligise for the dubble post, its even annoying me.... once again i appoligise.
Dave

[nycemsmedic67]

update ........while driving my "loving" wife around i rememberd how much i missed my 74 nova. then it came to mind hey how about the vacuum resovior. well i dont know if this was the only problem, but i switched it out and car ran almost as smooth as a babys but.......almost. i still have a shake, but stft and ltft both went down. ltft from 16.8 to 14. its a start.