General Maintenance & Repairs - Car breaks up bad under heavy load/high rpm!
05-13-2012, 03:03 PM
I have a 02 SS, MS4 cam, fast 78/78, etc "see sig if need more info'' and i recently have had a problem with the car. Ive been getting code p1134 for a while now, but was weird to me since the front driver was semi new. 'Running long tubes so rear ones are off'' And i can sit in drive and rev it, and it never breaks up... if im going down the road and get on it, it breaks up/misfire really bad. I have no other codes. Ive done so far.. put brand new corvette 02s on BOTH sides, clean maf/filter,checked for any vacuum leaks, new plugs, checked wires, reloaded the tune via hp tuners, ran some seafoam before i did plugs, and have got a few tanks of 93 since it has happened. Fuel filter is about a year old, so im going to change that, and fuel pump is about a year old also.
I can drive the car normal all day, just does this under load. I say i cant get more that half throttle before it breaks up.
And even after the new 02s the code came back. I have no extensions and the connections and grounds look great.
Thanks for sugguestions.. cant spray till i fix this. :bomb:
And sorry for the poor witting skills, im on my phone at work.
05-13-2012, 04:34 PM
U have HPT, do a data log and see what's whacked...
What's the fuel psi when this happens??
05-13-2012, 04:55 PM
Well my tuner does but I won't see him again till Friday, so I can't do either. I'm going to hook it up to a snap on scanner and see if it show where it has been missing.
05-14-2012, 08:24 AM
How old are the springs? That cam is going to go through springs quickly.
05-14-2012, 09:14 AM
Cam and springs where done Jan. 2011. Has around 10k on them.
08-20-2012, 03:09 PM
Havent messed with it much latley..
But we took the fuel pump out and found a small pinhole in the line, so we replaced that, seemed to clear up. But then about 2 hours later it came back. Check the rail pressure, it was at 80psi at idle... so swapped in a new rail regulator and that is normal now, but again, the car will instantly break up/ missfire if i get on it at all. All i can do is cruise around, but the car is only getting about 120 miles to a tank! Thats with no more than 1/4 throttle. Even tho it has a big cam/stall.. i would get double that before around city easy. Also the springs are fine, took the vavle covers off, didnt see any damage, changed the fuel filter. Maybe bad pump? Its a Walbro 255 pump. I was told there is a fuel pressure regualtor on the fuel sending unit? Maybe try and whole new oem unit?
Out of ideas. Any suggestion would be great. No codes, no missfire data log for any cyc. via Snap on scanner.
08-20-2012, 03:36 PM
When is the last time you change plug wires. You might have one arcing to ground under load.
08-20-2012, 04:01 PM
what kind of plugs are you running. my truck did same thing after cam install..went with br7 and tighter gap..problem cured
08-20-2012, 09:45 PM
120 to a tank........even though the 02's are new, might be a bad one. You are running horribly rich. Check how they are switching with a scanner.
08-20-2012, 11:58 PM
Plug wires have less than 5k on them.
Had tr7s, then went back to tr6s. Those are brand new.. that did nothing.
And I put both brand new Bosch 02s in.. then I figured they where bad, so I swapped a new pair of NTKs "NGK" o2s.. code hasn't been back.
So still, its safety to say when it breaks up it goes stupid rich. But why?
I'm going to throw some cheap wires on tomorrow and see if that does anything... even tho I doubt these Msd ones went bad so fast.
02s are switching fine
08-21-2012, 10:08 AM
Your pump line sprung a leak again. My car had the same problem. Previous owner put a new pump in with a rubber hose and radiator hose clamp and the clamp would just eat though the hose. Recommend new pump and sending unit
And mine had the exact same symptoms, I even got the same mileage
08-21-2012, 11:13 PM
i had this exact same nightmare
mine ended up being a brand new racetronix fuel injector, well for the most part
let me add more to this, i bought all of my stuff in sig and put it on all at once , from rear end gears , tranny ,motor , to exhaust was all dont in a week.
got it running , base tuned , drove around some and the TB was out of wack
back to the tuner a week later that gets cleared up and the fun began.
the next few weeks were a crap shoot of mis diagnosis and basically buying n swapping new parts
got another tuner to come tune it , he tweeked a few things ,s seemed to be all good.
few days later same thing back again.
back tot the shop , we take off every valve spring and check each one, new patriot golds , they were all fine.
swap the 85 maf to another one and it seemed to clear everything up.
few days later it comes back
by now we just seem to know its fuel relatated so he checks all the pres and seals again looks good , somehow , im sorry but its been like 5 yrs we deducted one of the brand new injectors must be bad.
so i bought some ford injectors 42# and that cleared it up about 95% of the time
still to the day over 5 years and almost 30k miles on my setup it still does it occasionally when at max throttle off a stop , or in between mid throttle hits.
cruising around it sounds awesome and works great , gradually on the throttle its great everytime, most full punches its great , most punches its fine
but every now and then the lil bugger jumps up and bites my ass
never could full get it gone.
and we tried everything