[sleeperls93]

Would anyone know why a car would stumble at the same rpm? My car stumbles pretty bad 28000 and again at 3000 rpms, resulting in the ecu throwing me a code. It only happens at those rpms. the ecu wont throw me a code if I stay above or below that range, if anyone knows what could be causing this please let me know, thanks.

 

[pantaloons]

We both have the same problem.

 

[MichaelDelaney]

a) what's the code?

b) what have you modified on the car?

c) what is your ecu, ignition timing, and any other electronic gadgets on the car that affect the engine?

we need some info....

 

[sleeperls93]

The code I believe is 45, it's set on stock ignition timing, the car is a rebuilt lsvtec with a p30 ecu; it's pretty much stock ignition and fuel. The weird thing is, when the CEL comes on, it's almost as if it corrects the problem. The engune doesn't stumble once the cel is on? So the car runs smoother with the cel on, but I hate staring at that bright yellow light that tells you something isn't right; I'm not a 100 percent on the code though, I'll make sure tommorrow morning, thanks Mike!

 

[MichaelDelaney]

http://www.c-speedracing.com/faq/05.html

code 45 too rich or too lean...O2 sensor....

it feels better because in CEL mode it retards the ignition timing to protect the engine from grenading.

stock timing means nothing to me. Is it 14 degrees or 18 degrees?

TUNE THE CAR!!!

 

[B18bgone]

just to chim in on this, I am having the same problem with my Ls motor, not sure what code its reading. My number 1 cylinder is running lean and 2,3&4 are running on the rich side. The compression across the block is 165-170, Im running crower 62404cams, P75ecu, accel external coil, timing advanced 18,and no fuel mods. Just looking for any ideas someone may have out there.

 

[MichaelDelaney]

check the clip for the injector in the cylinder 1 for breaks or malfunction. Make sure the cylinder 1 spark plug is gapped and not fouled. Make sure the cylinder 1 ignition wire is connected properly and seating both at the distributor and at the plug. I dislike aftermarket ignition coils/amplifiers...they only cause trouble and you don't need it in an NA setup.My old msd setup ages ago fried my distributor.

 

[GSRBlackout]

would having your engine in CEL mode retard timing on ANY bseries engine? btw, i have 98b18c1 bone stock? would it significantly affect performance? i havent noticed any performance issues (throwing code 9. code 9 i think is low oil level in engine. i have since gotten my oil problem straightened out. i didnt tighten the oil drain plug enough (slow leak, needed new washer, etc)

sorry to stray off your question sleeper LS

 

[sleeperls93]

It's ok man, we all need some help one time or another; I feel that with some good tuning I can fix my stumbling problem, there's the rub though, I can't find a dyno shop if my life depended on it...

 

[B18bgone]

hey just if anyone checks back to this post, I figured out why my car was having a stumbling problem. on my # 4 cylinder one of my intake vaulve retainer (titanium webcams), the clamp on the top of the retainer pulled through and left that intake vaulve closed al the time. what a weird one, never had that happen before

 

[MichaelDelaney]

www.dynojet.com

has locations of their dyno shops by state (trust me, here are several in the albany-NYC area) in their automotice dyno section.

an O2 sensor code won't retard the ignition..it's more of an annoyance as people with bad cats or testpipes will tell you.

improper retainer installs can get ugly...makes me nervous actually.

stumbling as I said is usually an ignition timing, spark gap/spark wire, fuel filter change, or poor fuel tuning issue.

common things being common, the ignition timing to 18 degrees and spark plugs would be the first things to check, then the fuel filter...