i had misfires after a short race. after scanning, cylinders 5 and 7 were acting inappropriately. because of a similar issue in the past (where 2 and 7 were misfiring), i assumed the opti again. instead of replacing my third opti, i opted to go delteq. everything is installed flalwessly, but my symptoms persist. these symptoms include a rougher than normal idle, obvious skipping, and almost stalling (after revving).

i know that its a broad question, but any pointers? if the plugs were not up to par, would they cause an issue such as this? would a mechanical issue cause this, such as internals being screwed up (valvetrain, bottom end, etc.)

from here, i will scan again, checking O2's, fuel delivery, etc. and go from there. in the meantime, any tips are greatly appreciated.

thanks

jb

 

pull the plugs from those cylinders. Check the wires. If neither of these then move onto fuel and valves. A bent valve or improper torqued rocker will cause this code as well.

 

kinda cerious on what the problem is i got a buddy with a 96z that has same problem. He has intstalled deltech/longtubes/plugs/wires all at the same time the car runs better but still misses and pops/backfires and sometimes wants to stall.
jb

 

If your opti was screwed up and all you did was slap the deltech system on what makes you think it would run any different. It uses the optical part of the Opti still, so if that was what was wrong with the old one, you might want to buy a new one so you know you have a good optical pickup.

 

I not sure what you can buy a new Opti for, but you can buy just the optical part at the link below.......

http://www.impalasuperstore.com/nais...ts.asp?page=2#

It might be cheaper to go this route instead of buying a complete new optispark.

TOM B

 

well i am in the midst of compression testing as to eliminate mechanical causes. so far so good, but i still have 5 more to go tomorrow morning. pulled all plugs, 5 were blackened, 3 were normal. tomorrow afternoon i will be scanning to eliminate electronic causes.

i had to custom mount the delteq unit due to custom valve covers, and vortech ductwork. so i mounted it inverted from the stb on the driver side. i ran cyl 2468 up and bundled across the stb. they are brand new heat treated 9mm, should they be separated? i doubt so, however it could be something as stupid as that. and as far as the optical sensor, would i be able to diagnose this with a code or a test? i will keep that in mind though, and check it out if need be.

anyways, i will get back tomorrow night to update. thanks for the help everyone...

jb

 

ok then peoples, i think i found the cause of my misfire. the compression test told the story. cylinder number drew a zero reading compared to 160-200 lbs for the rest of the cylinders. upon pulling the valve cover, noticed the exhaust valve spring bound up and collapsed upon itself. the rocker is loose.

my knowledge base is limited to the valve covers in this area, but i am inclined to say bent valve? i am now preparing to remove the head, but i have never tackled this. any idea what to expect, such as piston damage, head damage, etc?

littleredz, maybe do a compression test? it surprised me, but it is what it is...

thanks again for the help people...

 

Dynomite,

How many miles on that motor and who built it?

Seems to be a failed valve spring.

Did you over rev it or something?

I have a very similar situation with my 355. I'm slapping a delteq on there hoping it will fix the problem. It lost like 40-50 percent of the power.
I noticed most of the plugs on the driver side were wet with gas, like they weren't firing, so I think the opti is toast. It's coming together tomorrow and i'm really excited about getting this car running again, been sitting in the garage for about 3 months now.

 

dynomite,

is the spring broken.. i have broken springs cause the valve to hang open just enough for the piston to make contact and bend it in the guide. if the spring is not broken, i would ask same as above.. was the motor over revved? is your cam timing correct.. skip a tooth possibly? pulling the heads is not too bad.. no walk in the park, but just takes some solid wrench time!

Chris

 

i would say that i overrevved it. on green, i didnt feather anything. mashed it thru 1st about 6k, and hit 2nd hard for a great afterlaunch. only about a 6 second race, nothing big. immediately after, i almost stalled, i had to goose it all the way home. on a small stretch of highway, i couldnt travel over 50mph, and had to do it in 6th gear to avoid bogging.

so intitially, i thought it was opti, as ive encountered similar issues in the past that ended up being the opti. scanned it and 2 cylinders were misfiring. converted to delteq. upon starting, problems persisted. and here we are today.

the motor was built by jpr in jersey. not a standup person in my opinion, but ive done my fair share of badmouthing him in the past. i consider myself lucky that my motor runs at least (considering some of the posts ive read on his work). the motor has about 3000 miles on it since upgrade. its held up well so far. i am sure that it was just the overrevving that did it. ive got pics, i would hafta send them to someone who can post them though.

the spring is not broken, just effed up pretty bad . bound in on itself, out of whack. i hope its not too bad. i am excited about pulling the head, as ive never tackled this type of project before. i just hope it ends with the valve and doesnt continue further south if you know what i mean. i gotta make georgia on memorial day!!

jb

 

dynomite,

Once the head is off the car, rotate the crank and if you have a dial indicator gauge or can borrow one, i would mic up the cylinders that had the bent valves.. in some instances severe mainly, but never hurts to check, the piston hitting the valve can damage the rings or piston and you won't see it until you put the repaired head back on the car and fire it up.. you will have massive crankcase pressure likely pushing oil out the dipstick hole.. I have had this happen twice now on radical solid roller setups and unfortunate missed shifts, and in one event, this was the case. If this has happened, as long as the cylinder mics out in spec, you can replace the rings or piston with the motor in the car, i would also replace the bearings of that cylinders components just to be on the safe side.. but again that is in an extreme case of P2V interference, with soem luck you just notched the piston slightly and bent the valve! Good luck with it!

Chris

 

all the cylinders tested within range on compression. so its just number 6 im tackling. ive just drained the engine of coolant, so the intakes coming off today.

a question, when im ready to remove the head. i need to remove the rockers to allow room to the bolts. do i just unscrew the nuts and pull the rockers off? is it that straightforward? and what of the head bolts themselves, should they be removed in a certain order?

again, ill learn quick, but i never tackled an issue like this before personally. im still excited...im gonna need the luck. thanks

jb

 

yes, you remove the rocker arm nuts, remove the rockers, remove the pushrods, remove the intake, remove header/manifold bolts, remove the head bolts by the rockers and on the rim below the header/manifold, remove coolant crossover in back, take out top bolts in acc bracket if doing that side, unplug and remove the coil AIR and EGR if you have it, coolant temp switch connector.......think I got the basics there.......everything is as simple as unbolting, it just all takes time........your biggest expense will be gaskets, and springs......................and however valuable your time is


Don't forget to drain your coolant before you pull the heads, you will need new head bolts, I've surfaced the heads, and I've thrown them on without surfacing them, no difference from my personal expierence.

 

thanks for the help. dr side is okay, cylinder number 6 is the culprit. again though, thanks. i will keep your advice in mind. will update...