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View Full Version : 16-17psi/sputtering at top end



KillSwitchNY
03-12-2010, 12:22 AM
Ok, a few of you guys were shooting out ideas earlier in my post about my cam sensor touching the belt, but i wanted to make a new thread so i can get a list of things to check or change.

95 SC automatic.
Stock motor only mods are
NGK Platinum Plugs (stock gap)
255lph Forced induction pump
Mac Fenderwell intake
flowmaster mufflers
March 10% pulley
(cam sensor was reinstalled at the same time the pulley was done, do to pulling the timing cover)

First off, i know that doing a pulley and boosting 16-17psi is dangerous with stock cats/resonator... i am going to muffler shop tomorrow for custom exhaust estimate, doing mandrel tubes off manifold to magnaflow cats/resonator. Mandrel Exhaust Systems true dual pipes, and mufflers are undecided as of now.

Driving normal she drives fine, Boosts about 15psi at half throttle and on the verge of 17psi full throttle... but past 16 it starts to sputter and feels like a miss fire:confused: but stops as soon as i get off throttle. But there was 1 instance when i was full throttle/ full bost when it did not sputter.

do i need colder spark plugs? close the gap? fuel problem? any suggestions/ advice is welcome and appreciated. this car is so much quicker with the pulley and i really dont want to take it off if i dont have to :(

BLOWN38
03-12-2010, 12:36 AM
I would definatly close the gap. You may also be getting some valve float. When I had stock valve springs with 17 pounds of boost, when I hit 5k rpm it would feel like a rev limiter. I changed everything electrical, had tune adjusted for rev limit and nothing fixed it. Then one day I spoke with DD and he said it was prolly valve float cause the stock springs suck.

KillSwitchNY
03-12-2010, 12:40 AM
Exactly, it DID feel like a slight rev limiter. Did you change springs? If so did it cure the problem?
Hopefully the exhaust work will bring the psi down just enough. i really cant be tearing into the motor yet. But if i do i would just pull the heads, do MLS gaskets, machine the heads, new everything plus a cam. :confused: MY MUSTANG IS NEVER GONNA GET FINISHED:confused:

XxSlowpokexX
03-12-2010, 01:10 AM
You could be experiencing detonation, blowing out the spark, Perhaps hitting the rev limiter.

Lower the gap, make sure your not going anywhere past 5500rpm and use only high octane gas

Valve float does not feel any of the above

KillSwitchNY
03-12-2010, 01:38 AM
You could be experiencing detonation, blowing out the spark, Perhaps hitting the rev limiter.

Lower the gap, make sure your not going anywhere past 5500rpm and use only high octane gas

Valve float does not feel any of the above

Ok. Will close the gap... Its at .054 now any suggestions? And I'm not past 5500. I think the car shifts at more like 4900 -5000. Just drove the car. Noticed that between the sloppy 1-2 shift the boost peaks at like 19 for a second.... Scary

rzimmerl
03-12-2010, 08:14 AM
I think your running too much OD without an intercooler upgrade. Your more then likely slowing your self down with too high of inlet temps causing the engine to pull timing. Sounds like your getting detonation, switch to standard Autolite 103's (2 heat ranges colder then stock) and gap at .030.

David Neibert
03-12-2010, 11:33 AM
Change the resonator and rock on.

David

KillSwitchNY
03-12-2010, 09:36 PM
Check, Check and Check!
Went to Meineke this morning and spoke to my buddy over there about making custom down pipes to high flow cats/dual in dual out magnaflow Tru X Muffler to dual 2.5 pipes to Flowmaster super 44's ( i know i know, flowmaster is not the actual "master of flow", but i like the deeper tone) Still wondering about saving the cash and not putting any cats. DO NOT want the ricey "zing zing" sound though.

Bought NGK TR6 Plugs, copper core 1 step colder. Will gap at the RZIM recommended .030 (damnit i just did plugs 3 months ago)

also installed an 8" maradyne fan to the intercooler. Did not wire it up yet though. Any suggestions where i can pull a 12v ignition hot wire from? want to wire the fan to a on/off switch, but key must be on.

Has anyone installed an MSD Box to their bird? worth it? and what parts needed, such as MSD DIS BOX, Tach adapter, etc

rzimmerl
03-12-2010, 10:01 PM
Plugs sound good.

See this link for the IC fan wiring and other helpful write ups: http://tccoa.com/articles/mn12how-to/mn12how-to.htm

XR7 Dave
03-12-2010, 10:18 PM
10% OD on an internally stock 95 isn't going to work out for you regardless of what you do.

bowez
03-12-2010, 10:25 PM
I have the Ground on the IC fan wired to the Stock Oil pressure sending unit, so that it only can come on with the engine running.

Dave, what is needed to effectively run 10%?

As for the Cats, I hear that using the highflow cats is the best solution, no cats means resonance.

slowpoke
03-13-2010, 12:17 AM
I have the Ground on the IC fan wired to the Stock Oil pressure sending unit, so that it only can come on with the engine running.

Dave, what is needed to effectively run 10%?

As for the Cats, I hear that using the highflow cats is the best solution, no cats means resonance.

od on the blower means more air into the cylinders. at the least you need some head work and good exhaust. a cam wouldnt hurt. when i ran my motor full stock i had a 10%od that worked well but also had about $600 worth of exhaust work done that helped and a strong ic fan.

Pablo94SC
03-13-2010, 12:37 AM
I made 17lbs of boost on a stock 94 bottom end with a complete, catless exhaust from the manifolds back with only 5% OD. Not only do you need to run a tighter gap on your plugs, you might want to check for vacuum/boost leaks. I get 18" at idle in gear, and 19" at idle in park/neutral... and that's with a cam.

XxSlowpokexX
03-13-2010, 12:48 AM
17 psi just wont make more power,,You will knock, cut timing and go slower...Thats what Dave is basically saying. Flowmasters will give it a deep idle......But it will sound ricey on open throttle!

KillSwitchNY
03-13-2010, 12:50 AM
Guys this is all awsome info. As far as vacuum I'm pulling about 18 idle....sometimes it will go to 15 tho. And 20-21 on deceleration
I may have a tiny leak somewhere. Not sure.
And as far as the pulley.. Its a march and suposedly a 10%. Either way I'm making that 16-17psi. Believe it or not I picked up 2psi just by putting on my mac fenderwell intake!

KillSwitchNY
03-13-2010, 01:07 AM
17 psi just wont make more power,,You will knock, cut timing and go slower...Thats what Dave is basically saying. Flowmasters will give it a deep idle......But it will sound ricey on open throttle!

I got what you're saying. Its like these honda dummies that constantly run 116 octane leaded fuel on their little turbo civic. And have to change plugs and oxygen sensors every week. Just ignorance.

Ok so I might just have to go back to my stocker pulley or maybe a 5% I guess?

And with my stock exhaust with just the flowmaster delta 40 on it don't sound ricey right now. I guess when its opened up up front it would right?

decipha
03-13-2010, 02:17 AM
Change the resonator and rock on.

David

I love this guy :p

XxSlowpokexX
03-13-2010, 08:45 AM
a 5% would be good in my opinion. 94/95 have a larger pulley then earlier rmodels so in reality for the engine its more then 5%.

I got mettalic core cats on ebay from thunderbolt performance cheap at 69 bucks a peice. those with a resonator and teh flows wont sound bad on a stock cammed sc

KillSwitchNY
03-13-2010, 09:44 PM
Hmmm. So I wonder if I were to put an early pulley on for now if that wpuld be worth it

Pablo94SC
03-14-2010, 03:52 PM
Guys this is all awsome info. As far as vacuum I'm pulling about 18 idle....sometimes it will go to 15 tho.

If you are pulling anything less than 18" of vacuum at idle in gear or park, you have a leak somewhere. Find and fix that first, and change to stock early model blower pulley while you're at it so you don't damage anything else. That should be fine with .045-.050 gapped Autolite 764 series plugs (or possible 763 if available). You have an almost stock car. Don't go running colder plugs gapped ridiculously tight until you need it.

XxSlowpokexX
03-14-2010, 05:45 PM
If you do lower your boost..You probably wont have to think about regaping plugs. As far as a vacuum leak.. If its idling fine and your getting good boost...Probably not an issue...Try reducing boost first see if miss goes away then work from there

KillSwitchNY
03-14-2010, 07:15 PM
Try reducing boost first see if miss goes away then work from there
Yes, that was the plan.
Same reason i did not do my Throttle body and mass air while also setting the cam sync and crank angle. Adding too many things at once that could all cause the same problem.


also i needed to know, since im having custom down pipes made. what size is the ball socket off the manifold? Tne guy at the shope is saying 2"... That is scary small to me. I really want 2.25 if not 2.5 from front to back. If anything i can get a 2-2.5 reducer coupler and flare it for the ball and go from there. any input appreciated.
was also looking into fitment of mustang 3.8 headers, could not find much reputable info on that.