Car jerks at 5000 RPM, Jake, Joe?

[gstclips]

My car is almost ready for summer...BUT, I am having one problem. When I hit 5000 RPM my car jerks like I am hitting fuel cut.

My setup:

97 Eclipse Gs-t
Walbro 190lph fuel pump (had a 255lph but replaced it with a smaller pump in hopes i would cure the problem...no luck)
FIC 650cc injectors
Apexi SAFC II
Geddy profec B spec 2 boost controller
Evo III 16G turbo
SBR Big FMIC
VRS turbo back exhaust with ported o2 housing
2100lb clutch
K&N filter with adapter plate
Lotek Gauge pillar pod with AF, Boost and EGT gauges
NGK BPR7ES Plugs
Accel wires
Greddy type S BOV
Short throw shifter

tokico 5 way adjustable suspension (shocks and drop springs)
17" rims with kuhmo tires
front strut bar

---Is a fuel pressure regulator the answer, a boost leak or is there something that I am overlooking...

Thanks for any suggestions,
Joel

[joemathews]

Check your plugs and plug wires. My car did this when one of my plug wires had a crack and was grounding out on the valve cover. Have you checked for boost leaks?

[96spyderman]

Originally Posted by joemathews

Check your plugs

Sounds like mine when I was tweeking the gap...it would sorta stutter a bit under boost... I ended up with a sweet spot of .027... as for the wires...best way to check if they are arcing... open hood w/car running in the dark and look for little sparks... rev it up and such...
Last.. check for boost leaks...

Good luck and really like the set-up ya got!!

[SLoe]

Mine did the same thing when my EGR solenoid was busted, only I got a CEL.

[JoeWagon]

plugs/wires problem is going to be more like stuttering, but when the ECU cuts fuel, there's a different feeling. i have to suggest checking for boost leaks.

[kjewer1]

I dont see a plug gap listed by the original poster, so I'm going to start there. Dont forget that poeple suck at describing the symptoms of thier problems. I would trust the comparison to fuel cut.

[KevinE326]

do you get black smoke out the back?

with the upgraded fuel pump you could just be running to rich at the high rpms. When this happens on your a/f gauge is it sitting in green(rich)?

if so you might just be running rich and your car may not have been tuned up that high.

afpr or/and tuning would fix this.

had similiar prob when i got my car back from shop originally. only thing that fixed it was a aeromotive fpr and driving around and tuning.

[gstclips]

no my car is tuned with the s-afc, the plugs are gapped right and my plug wires are in great shaped, I have no CEL...It is definetley the same feeling as fuel cut...so I am going to run a boost leak test this weekend...thanks for the help

[KevinE326]

but when you hit this at 5k is your a/f gauge telling you that you are running rich?

[EclipseRST]

Fuck the A/F gauge... They are worthless unless you have a wideband O2 sensor. Almost impossible to get a good accurate reading!

[KevinE326]

dont need a accurate reading. if he hits what is or seems to be fuel cut and he is running rich he is in actuality hitting fuel "soak" or whatever it is called. this is just a simple way to see if thats what it is. with his 190lph and 660's with no afpr I'd put money on hes hitting fuel soak and it starts to stutter. Problem would be to MUCH gas not to little as in fuel cut.

[kjewer1]

See this page for how useless O2 sensors are on our cars, www.posracing.net/afr.html, near the bottom. There is a datalog showing the WBO2 reading vs Front O2 voltage. Everything between 10:1 and 13.5:1 shows up as .96 - .98 volts. Completely useless, and dangerous. I see the point you are trying to make, and you are correct, but using the front O2 voltage just isnt reliable enough to use this idea as a diagnostic tool. Hope that makes some sense.

[gstclips]

I ran a boost leak test and found 2 leaks...I adjusted the S-AFC alittle more with my new EGT gauge and the car runs better than ever....thanks for all the help