Well some of you may remember the problems I've had in the past couple of months, they are still here and I'm really begining to think I should have sold my car long ago, but anyways. My car has a brand new delphi opti, so i don't think it's it. I got some delphi 50# injectors and ditched the fmu. New plugs tr6's and same issue, My fuel pressure is rises now when it goes under a load like it did with the fmu is that normal? and it's at 44psi at idle. rises a bit with rpm. The car ran perfect last spring and I blew a head gasket and decided to pull it out and rebuild the engine. It drives and idles fine and will not break up at 6k if I'm not in boost, it also is not building more than around 5psi at 5k. Where do I need to look, I've gotten code 55 lean fuel system which is what I thought was happening even with the new injectors.

 

I am aware that I would benifit greatly from a msd box but it ran good for a couple years and the only thing that changed was I lowered the compression. fuel pressure is fine plugs at 30 new coil, fuel filter. I just can't understand why after a rebuild with lower compression ratio and bigger injectors I've got a problem, with 50# injectors, around 9:1 cr and a hot cam dual fuel pumps and only 8psi I would think I'm fine. Hell I ran 8psi with 30lb injectors and it ran great, What's going on??????????? Help

 

Don't concentrate on your PSI number- lowering your c/r and adding a bigger cam is always going to lower your "lbs of boost" number you will see. I would venture that your blower is prol still putting out the same amount of CFM- your motor is just able to take in more air per intake stroke- hence the lower boost number.

As far as it breaking up- is it all of a sudden at a certain RPM or does it gradually start to break to up? I would venture to say that you might still be running lean even with the larger injectors if the computer wasn't tuned for them.

You also said that you know if would benefit from an ignition box and yes you are correct. Also- what gap are you running on your plugs? The gap might be too big and you might actually be blowing out your spark at higher RPM's.

Drop your gap down to around 25-30ish and see if that makes any difference.

 

My plugs are gapped at .030, I guess I can tighten them up a littel bit more, It seems to "break up" all the sudden but since it's not something I really want to do a bunch assuming it's hurting my engine I can only describe it as "feels like it's vibrating or hitting some sort of ceiling", it's not like a miss it's weird, looses all power all at once and as soon as it happens I naturally clutch it and let off the throttle. It does not do it if I gradually raise the rpm's up while not getting into boost, so it's likely spark or going lean I just have to find out how to fix it. I would suspect either of my pumps could be weak but I maintain good fuel pressure via my in car gauge. I'm gonna tighten the gap up, put the fmu back on and see what happens,

I've got windows seven and for some reason it finally allowed me to use freescan so I'll post a log

This feels like some sort of valvetrain vibrations thats causing everything to go wild under boost, if that's what breaking up is then I'm breaking up.

 

Maintains the fuel pressure throughout the RPM? Your pumps could probably maintain the pressure, not the volume.

Who did your tune? Could be as simple as needing a re-tune since the car is going act different under full throttle with boost and part-throttle with no boost. Having the car hooked up to a dyno and a wide-band will help you considerably since it is more of a controlled environment.

 

Well I guess your correct, my tune is an old one from pcm4less that has not been updated since the piston change. and a dyno tune has been a want for me but I just don't feel like pulling the car 4 hours to tulsa pay him 500 bucks to tell me I have a issue somewhere else. The car ran fine before, I lowered the compression, do you think now my pumps can't keep up now? I really just don't know what else to look at at this point. my 02's stay in the .9's while it breaks up, according to my freescan log.

 

I found something out that I think is my problem, I decided to check my valve adjustment and took the rockers, and pushrods out to inspect them, I noticed that on the back side(side where pushrod is) my pushrod has or looks to have left an indention in the rocker. A couple month's ago I did replace two intake valves and it looks like the two valves are not the same as the factory valves. also on the other rocker where the tip meets the valve it has rubbed into the retainer or valve. I'm not a valvetrain pro so could someone help me out here, from the top of the groove (where the keepers go) to the tip of the valve seems to be .020 inches shorter and I think this is causing things to go wild at high rpm in boost. Could this be causing me problems?