Hey guys,

My setup:

2005 coupe
Vortech v3
600cc injectors
AAM Stage 1 Fuel kit (rails and return line)
UTEC EMS
Fuel Pressure at idle is 3 bar

Rich (str8dum1) suggested i post my problem over here. I took my car to the tuner yesterday and whilst the car was idling the ecu threw up code p0300 which suggests "multiple Cylinder Misfire"

I changed the sparks plugs there and then which made no difference. We tried switching round the coil packs too. Its not a major misfire just a very slight one that the tuner was wary of and didn't want to risk it on the dyno.

So my car now has the s/c belt disconnected with my utec connected with str8dum1's map. I took my car out and it drives pretty well and pulls like it should (no boost)..At around 3000 rpm the ecu light comes on.

One thing rich was wary of is that my car has been tuned with uprev previously. Could this be a contributing factor to my misfiring and would a tune settle the misfires? My tuner is happy to put it on the dyno once i have diagnosed the problem and i am happy the car is running well.

Thanks for any input

 

P0300 is a common FI code mate. Just stick some tap over you cell light and drive the car! lol..

Ps. i am joking mate i hope you can fix it! lol..

 

dont know but my grand am just threw that code and is a multiple misfire and it runs like ****..trac off light popped on too at the same time the ses light came on and misfired and is stuck on..not sure what my problem is, looks like we are in a similar boat, i think my problem is a sensor problem as i have changed the coil and didnt fix it, maybe u have a similar problem?
any GM techs here ?

 

I get the same code on my z with the Utec... I swapped plugs and coil packs around also. I believe mine to be partly the utec and the other to do with the valve covers leaking slightly into my 5th cylinder. It only happens when i'm NOT WOT.

It can also have alot to do with how rich the A/F is also, if the cylinder is getting flooded with fuel, then that will cause a misfire also.

 

I regularly get that code as well. It was because of the overly rich startup because of my 650cc injectors; it couldn't be helped without a return fuel system. But even with that code my car ran fine with my Vortech. I just got my RFS and I hope it fixes the code when I get it tuned.