Honda D Series Forum banner

1 - 17 of 17 Posts

·
Registered
92 Civic Hatch
Joined
·
1,757 Posts
Discussion Starter #1
OK....

Spark plugs gapped to .025
Stock Y8 distributor and coil
Compression is good 128-135 psi across all 4 (75mm vitaras)
650cc precision injectors, E85, 70psi Fuel Pressure on Walbro 255lph


http://www.d-series.org/forums/forced-induction/144992-coolant-purging-through-radiator-cap.html
^^^^ Link to coolant issue thread for back ground on that issue

So I retorqued my head up to 75 ft lbs. and slapped a new radiator cap on, along with retarding the timing on my distributor.

I took the civic out and did a pull to see if I will push coolant straight out the rad. cap anymore, it seemed fine, and pulled strong off of wastegate pressure. Tried to up the boost to 14 lbs, it pulled fine, and then broke up right before I let off the gas.

It then proceeded to cut out, similar to blowing out the spark, and missfire after about 8-9lbs of boost.

It will also missfire when I try and accelerate from a stop, until i get higher in the RPMS ( around 3-4k, doesnt seem RPM specific) then it will smooth out.
I am watching my gauges and nothing seems out of the ordinary, A/F seems good, Oil psi is good.

It drives fine when its smooth, but it seems coming off of vacuum into light load, or above 9lbs boost, it likes to missfire....
Right off of start up though it will drive fine and pull strong for a couple pulls, then it just progressively gets worse.

No weird colors of smoke

Ideas? Think it could be the coil going kaput, and when it heats up isnt giving off enough voltage? Need to down gap plugs some more?

Im just getting worn out from fighting this freakin car...:uh::uh::uh:
 

·
Registered
See above...
Joined
·
13,322 Posts
I had the same gap on my plugs, and didn't have a single issue. Perhaps time to try a new dizzy.

LP or HP Walbro? 70psi seems a heck of alot...but I'm not your tuner, so what do I know. With my HP in-tank Walbro 255 and 1000cc injectors I had 58 psi at idle.

GL bro!
 

·
Registered
Joined
·
1,187 Posts
try advancing the timing just a little bit. not a whole lot, but just a little bit... my buddy had a problem similar to this on his old ls/v set up when his distributor wasnt tight enough and it kept retarding itself slowly to the point that he eventually couldnt even rev over 4500 because it would just break up.
 

·
Registered
92 Civic Hatch
Joined
·
1,757 Posts
Discussion Starter #6
more info on the engine build and what software are you tuning with?
Jdm d15b bottom end with 75mm vitaras and fj rods, kms block guard
Y8 head, crower stg 2 turbo cam, bisi valve springs, port n polish
650cc precision inj, 255 HP walbro,
omni 4 bar map sensor
Tuned on crome for e85

how old are the plugs?
,
Plugs have approx 4k miles, same plugs used on dyno
When I pulled the plugs there was no weird discoloration, or fouling
At base of ceramic it was turning kind of dark yellow-ish


Thanks for the responses so far guys!
 

·
my name says Guest, but Im really a MEMBER
Joined
·
10,488 Posts
why are you retarding the dizzy instead of though your tuning software???


yeah, and 70psi seems like a lot since you have 680cc injectors. you should be able to run stock pressure and get all your fuel needs through the injectors.
 

·
Registered
same
Joined
·
1,624 Posts
your compression is low, rings are bad most likely....

you should be hitting 175-180 with that setup.


either way, gap the plugs down until the problem goes away, shouldnt take any less than .015...
 

·
Registered
92 Civic Hatch
Joined
·
1,757 Posts
Discussion Starter #9
your compression is low, rings are bad most likely....

you should be hitting 175-180 with that setup.


either way, gap the plugs down until the problem goes away, shouldnt take any less than .015...

Ive always wondered this my self, I just figured it was because i had the vitaras that the numbers were so low...hmmm....

I could understand gapping the plugs down for the boost missfire, but what I dont get is why would it do it under part throttle as well?
 

·
Registered
Joined
·
1,187 Posts
advance the distributor a little bit from where you retarded it to.....
 

·
Registered
same
Joined
·
1,624 Posts
didnt read your original post correctly sorry.

i'll tell you this much, when you have head lift and you eat coolant the gasket see's extreme heat and its burnt. you might not think its leaking anymore but once it lifts the head you need a new gasket.

i had the exact same issue with missing after a pull, it fully blew the head gasket the next day at 18psi. you are burning coolant causing it to miss.

if you are pulling the head again i'd go ahead and pull the pan and pop the pistons out and take a look at them, aswell as replace the rings. you can verify the rings are bad by doing a wet compression test... make sure you do the test on a warm engine though or everyone will jump your crap about it... i have low compression when cold on one cylinder, when warm all are good wet/dry....
 

·
Registered
92 Civic Hatch
Joined
·
1,757 Posts
Discussion Starter #13
same plugs you dynod with while getting tuned?i honestly would change the plugs even tho they aint got many miles on them...
when I pull the head again, Im going to slap a new set in

advance the distributor a little bit from where you retarded it to.....
Im going to put it back to stock once the head gets pulled, didnt make a difference unfortunately

didnt read your original post correctly sorry.

i'll tell you this much, when you have head lift and you eat coolant the gasket see's extreme heat and its burnt. you might not think its leaking anymore but once it lifts the head you need a new gasket.

i had the exact same issue with missing after a pull, it fully blew the head gasket the next day at 18psi. you are burning coolant causing it to miss.

if you are pulling the head again i'd go ahead and pull the pan and pop the pistons out and take a look at them, aswell as replace the rings. you can verify the rings are bad by doing a wet compression test... make sure you do the test on a warm engine though or everyone will jump your crap about it... i have low compression when cold on one cylinder, when warm all are good wet/dry....

I was kind of suspecting this, Im gunna find a good machine shop this week, and when I get back home again, Ill pull the head and get it milled flat, new HG, and Ill consider the rings. Im not sure on the rings though, cause im not burning oil, my vacuum is good, and compression is even. Ill probably pop a few pistons out though and check to see what i can see

Thanks for the continued input!
 

·
Registered
92 Civic Hatch
Joined
·
1,757 Posts
Discussion Starter #17
do a dry and wet compression test on a warm engine, then tell me your rings arent bad...

or you have standard length rods....
Yeah Im going to re-do the comp test when i get back home (im in Kansas right now, going home on the weekends)

when I did it, I believe it was on a cold motor, and I didnt disconnect the charge piping from the TB when I did it :pinch:

I will report back with results when its done.

I am planning on pulling the whole motor/trans when i rebuild the trans and put my LSD in, and am going to send out the STOCK D15b head to have new seats put in it, new Valve guides, and am going to throw that back on, using stock timing gear and cam, to eliminate confusing timing problems as well.

Seems a LOT of guys have problems with head lift with the Y8 Head, so i think Im just going to sell it, the AEM Cam gear and my crower cam I have in it.
 
1 - 17 of 17 Posts
Top