 
     |
| 99 l67 swap sputtering under wot and over 3800 rpms (Page 2/3) |
|
jhobbins
|
OCT 09, 06:08 PM
|
|
| quote | Originally posted by Dennis LaGrua:
If your fuel pressure is up to spec and the exhaust unrestricted then you need to take the next step. I realize that many DIY mechanics don't like hearing this but a full diagnostic scan of the PCM will pinpoint the trouble. The symptoms you describe can be one of any number of things. Failing to do a scan is working in the blind. .
|
|
Correct me If I'm wrong, but the fuel pressure at idle going up to 50 with the fuel pressure regulator unhooked would mean that it is something related to that regulator.
|
|
|
|
OntarioKev
|
OCT 09, 07:17 PM
|
|
No, that is the expected behavior, the fuel pressure rises with boost. It should be higher at atmosphere (which is with the line disconnected).
Are you able to monitor fuel pressure while you are experiencing the issue? If the fuel pump is not up to the ask, or on its way it could provide the correct fueling during idle but drop under load.
But if you are really having fueling issues it can be damaging to the engine to go under load. If you do a quick check and your fuel pressure is good there are other things to look at.
I personally always have a wideband O2 sensor installed in my modded cars. With that you could see if your AFRs are too lean or too rich when the issue is happening, and that would help with the next steps.
|
|
|
|
jhobbins
|
OCT 09, 07:49 PM
|
|
|
The fuel pressure holds at 40, even when I hit 3000 rpms and it starts misfiring
|
|
|
|
olejoedad
|
OCT 09, 08:02 PM
|
|
|
Why would you unhook the vacuum line when checking fuel pressure?
|
|
|
|
OntarioKev
|
OCT 09, 09:49 PM
|
|
|
Verify the rising rate function of the Fuel pressure regulator. If you look at the testing procedure you will find this.
|
|
|
|
jhobbins
|
OCT 11, 11:09 AM
|
|
|
I was able to verify that as boost increases, so does fuel pressure. I had 50 psi at 3000 rpms and it was still climbing when the misfire started. I'm going to begin diagnosing the ignition components, I believe that may be where my problem is
|
|
|
|
olejoedad
|
OCT 11, 06:03 PM
|
|
Do you have data logging/scanning capabilities?
What is the MAF sensor telling you?
Tell us or post a picture of your intake air system.
|
|
|
|
jhobbins
|
OCT 11, 07:40 PM
|
|
|
I currently only have the torque pro app for scanning, I just ordered hp tuners though. I also don't see how to upload an image on here.
|
|
|
|
Buck531
|
OCT 11, 10:33 PM
|
|
It may not even be fuel related. It might be a spark issue.
So many variables here.------------------
03 Buick Regal. 13.0x @103
87 Fiero GT. L67, XP, Ported heads, SD headers, FSIC, 2.8 pulley. 12.018@113 1.7 60'.
|
|
|
|
Jay-ID
|
OCT 18, 03:22 PM
|
|
|
I saw a similar problem. Make sure you've got the speedometer (VSS) connected and feeding the L67 PCM. It can cut fuel.
|
|
|
