5,300-5,500 stumble - Page 2 - SRT Forums

Stealth RT · 02-01-2007, 10:16 PM

Hitting a wall @ 5000 rpm...
Just went thought this with a chevy small block @4000 ish RPM.
Not saying this is your problem, but...
After checking all the usual suspects (Ignition components) for a # 5 misfire (sensed change in rpm between cylinder 6 and 7 firing) and burning my arms on the headers several times My problem ended up being a week intake valve spring. Broken would be more the case.
And yes this hole even passed a leak-down test. Not saying this is your problem. Just stating that there is more to look at.
Good Luck.

You'll find the problem and it will be something silly. That's the way it goes most often.

Peace

ilovemysrt4 · 02-02-2007, 12:23 AM

i have almost the same problem but ill be in third and it will happen. replaced plugs and there gapped correctly there are no codes or anything does anyone kno wat else to do? replace coil and wires? any ideas would be greatly appreciated

MASSSRT · 02-02-2007, 01:36 AM

i'm surprised you get any traction in 1st or 2nd at 5,3k.have you used more than one tank or is this the same gas?mine did that a couple times at the track one night and all I could think of was bad gas, didn't do it again, I didn't get codes.

MASSSRT · 02-02-2007, 01:44 AM

but that was 3rd gear, I can't wot 2nd on the street, anything over 3k and they bang off the rev limiter, so I couldn't say if I had this in 1st or 2nd....I wonder if temperature does anything, also, do you notice if your boost drops? I did notice when mine did that at the track, it was a rich spot on the datalog, so I assumed gas, but the rich spot made me wonder if it pulled timing

MASSSRT · 02-02-2007, 01:50 AM

another thought i'm having is the fpr filter, maybe if it was clogged, it would be like a clogged injector?

MASSSRT · 02-02-2007, 02:03 AM

or, maybe if your boost went up 2 or 3 psi due to the cold, (duno if that's possible with your bc) or if you turned it up, I believe the 750's run out without a returnline at like 23 psi, my af's started to creeo up up top on c16 at 23-24 psi, from like 12.5-12.9 over a couple hundred rpms,, and it was too quick to see it on my gauge (Lm-1 box lol), which looked fineI dunno if that would cause a misfire, but i'm just thinking of stuff that I noticed which affected high rpms, just brainstorming
did you try adding 1-2% fuel? I remember hearing the stories of cylinder 1 being leaner, due to the wg dump and log-style manifold, I know it's cylinder 4, but who knows

timemachine · 02-02-2007, 04:43 AM

maybe its fuel cut or a fuel pump going out. or sprk plug blow bye just a couple suggestions. I'm guessing but something to consider .

Ghowie · 02-02-2007, 05:44 AM

it's fuel related not ignition,^^^^ fuel cut could be very possible. I don't think you have a clogged injector etc.. cause your only getting it up top in 1st and 2nd but not 3rd and so on? I would try adding some fuel and see what happens from there

Rhunter · 02-02-2007, 06:21 AM

Quote: Originally Posted by 1badsrt-4

Quote: Originally Posted by BTR

what happens to the AFR when the stumble occurs?

Rich im not 100% sure but I think it stays the same or very close. Its not really a stumble per say, it sounds/feels more like the car is hitting the rev limiter

What is your boost level when this happens? I'm no expert (far from it) but If I run my boost higher than 18 spike My car will stumple. I'm on stock turbo tho. Just throwing an idea.

lilturbododge · 02-02-2007, 06:49 AM

i get the same, only at the top of 4th, around 115 every time, im at 18-20 psi when it happens...i think my problem is holding to much boost at 5k....what about dcr part they have out...it fixes the stumble at 5800-redline so i wonder if that could fix it...i think it is fuel cause if it get on it in 3rd at like 40ish when i spike to 22-25ish it does the same...i need to turn my boost down, but could just be running out of fuel

**Masssilversrt4** · 02-02-2007, 06:54 AM

Well we both have big turbo's.. I have a fully built motor/head with return kit and bottleneck fix.. I don't think it is a fuel issue per say..

elvis02330 · 02-02-2007, 07:58 AM

mine started doing that also... same thing #4 misfire code I did notice my boost higher than normal...I assumed from cold weather....I have not had a chance to pull the plugs yet ....I'll let you know if I find anything...I'm stock mopar BOV,Agp wastegate???? spikes 18psi holds15-16...came with the car...I'm ? fouled O2 sensor It seems rich but like I said haven't looked....

Ultimateone · 02-02-2007, 08:03 AM

Timmay,
when it happens watch your a/f and report back. It almost sounds like the typical stumble people have but around the 2500-3500k region. Maybe just a quick tune with the afc.

elvis02330 · 02-02-2007, 09:18 AM

mine started doing that also... same thing #4 misfire code I did notice my boost higher than normal...I assumed from cold weather....I have not had a chance to pull the plugs yet ....I'll let you know if I find anything...I'm stock mopar BOV,Agp wastegate???? spikes 18psi holds15-16...came with the car...I'm ? fouled O2 sensor It seems rich but like I said haven't looked....
__________________
....OH YEAH , Just a neon....
13.946@101.6860' 2.17 this will become a habit.....

MASSSRT · 02-02-2007, 09:51 AM

Quote: Originally Posted by Masssilversrt4

Well we both have big turbo's.. I have a fully built motor/head with return kit and bottleneck fix.. I don't think it is a fuel issue per say..

unless you both still have the stock fpr filters, but i'm guessing you changed yours, mine was soooooooo dirty, couldn't believe all the crap in that little biotch