opti problem or not??

limige

limige

Club Member
hey guys, i rebuilt my engine the other year, barely drove the car last year because i needed tires. been driving it some this year but still not alot, need an exhaust, the car is too loud with a single 3" pipe out the back....

anyway, here's the basics of the car 94zm6
stock rotating assembly, new bearings/rings
heavily p/p stock heads
heavily worked intake, stock tb and intake so far
combo motorsports double roller timing set, hardened teeth
electric wp
edelbrock headers and straghtpipe
230/236 comp cam
promag 1.6's stock lifters hardened pushrods
aeromotive fuel system, sumped tank sy/ty injectors running at 60psi
some tuning done from borrowed programs

so car always ran fine, needs a dynotune other than that its good until lately

the problem
i noticed the other week it picked up a stuble from 5000-5500, figured maybe opti was acting up.
after i refilled the tank i checked it again, still there.
drove about 20 minutes away, checked it today it did it again, alittle worst. then it did it at around 2500-3000 easing along in third gear.. did our business and on our way home it did it again around 2500, started coasting with clutch in due to a stop coming up and it stalled, popped the clutch and it fired up and ran alittle before backfiring twice and stalling again.

stopped and tried to restart, it backfired again. waiting tried again, this time it fired, spit and sputter then died. that's all it does now, spit, spudder die.

so did my opti crap out or is it something else?
it acts like the timing chain skipped a tooth, but it's practically brand new. i don't think i've put more than 10k on it since the rebuild. if that.
could it be the maf?

most importantly how can i test these things to rule it out?

thanks, sorry for the long post.

mike
 
Hmm hows the fuel pressure ?

Also could be opti trouble

Sean


limige said:
hey guys, i rebuilt my engine the other year, barely drove the car last year because i needed tires. been driving it some this year but still not alot, need an exhaust, the car is too loud with a single 3" pipe out the back....

anyway, here's the basics of the car 94zm6
stock rotating assembly, new bearings/rings
heavily p/p stock heads
heavily worked intake, stock tb and intake so far
combo motorsports double roller timing set, hardened teeth
electric wp
edelbrock headers and straghtpipe
230/236 comp cam
promag 1.6's stock lifters hardened pushrods
aeromotive fuel system, sumped tank sy/ty injectors running at 60psi
some tuning done from borrowed programs

so car always ran fine, needs a dynotune other than that its good until lately

the problem
i noticed the other week it picked up a stuble from 5000-5500, figured maybe opti was acting up.
after i refilled the tank i checked it again, still there.
drove about 20 minutes away, checked it today it did it again, alittle worst. then it did it at around 2500-3000 easing along in third gear.. did our business and on our way home it did it again around 2500, started coasting with clutch in due to a stop coming up and it stalled, popped the clutch and it fired up and ran alittle before backfiring twice and stalling again.

stopped and tried to restart, it backfired again. waiting tried again, this time it fired, spit and sputter then died. that's all it does now, spit, spudder die.

so did my opti crap out or is it something else?
it acts like the timing chain skipped a tooth, but it's practically brand new. i don't think i've put more than 10k on it since the rebuild. if that.
could it be the maf?

most importantly how can i test these things to rule it out?

thanks, sorry for the long post.

mike
Click to expand...
 
60 is where i want it, i'm running sy/ty injectors which run about 30-32# at what is it 42 psi, anyhow, they are a pintile design injector and will atomize better at higher pressures. being a 32# injector is shy for my hp goals, bumping up the pressure is a way of making the most of what i can, they only cost me $50 for 12.


so anyway, checked the codes, nothing came up, reflashed the program and there is no change, it fires less now that i reflashed it.

the opti is the only logical choice i can come up with...unless anyone has any better thoughts..
 
I'm definitely no expert, but I have read a thousand threads on the LT1 since I got one and almost always problems with these motors can be traced back to the opti. I'd check out that thread posted above first as you most likely have a non-vented opti(94?) and I believe those are more expensive than the vented ones but that's probably it. From what I've read, they usually die slowly, picking up more problems then totally crapping out. Good luck.

:)
 
Sounds just like my buddies car. Both times his opti went his car started stumbling at different RPM ranges. The shitty part is the 2nd time it went was like 50 miles after we did a cam swap. So he had to tear it all back apart to swap the opti
 
i would definately say the opti is an option. make sure grounds are good and maf is good ...check for breaks in the wiring to the coil and to the maf. i guess if it was i i would check these small things before tearin down for an opti replace....i know the opti doesn't have the best reputation but i have never had a problem with them but i've always had the vented version.....
 
update, finally tore it down last week.
the damn rotor had a screw fall out and the other one broke!
that would explain it! got a new accel cap/rotor for $77 drilled out the broken screw and put it back together with the rotor screws lock tited. now she runs great! no more stumble, took it out to muskegon without a hitch, i think the mpg picked up too! found a wire rubbing on the back of the idler pulley.

i think i'm gonna take the car to sean later for tuning, after i finish my tb and get a cold air kit on it. i may hitup ubly soon to see what it doing.
 
lol, i considered that, but it only cost me $77 for the cap and rotor and a few bucks for water pump gaskets, much cheaper than a change over.
 
i went to the local carquest and had him order it, list was 135 and he gave it to me for 77, hey i'm not complaining, i thought i was gonna have to pay summit 110 plus handling and shipping charges!!

they're cap and rotor kits from standard were 190 or something, i told him to pull up a price on the accel and i was very pleased, he had it next day too!
 
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