I've developed a run problem recentlly and am trying to troubleshoot it. Is there a way to "test" either of these? Could it be possible to have a problem with one of them, and not set off a SES light?

It has a cold start issue(hunts rpm and A/F varies bad) driving it has a bad tip in lean then does not want to settle out right, and WOT it is leaner than it should be.

I've got a new fuel filter, new plugs, check all of the obviouse, I tried a different A/F guage sensor thinking it might be a problem. Fuel pressure looks fine.

 

Casey, I hear your running the SCT racers package?

I am not a tunner by far but have you tried running a diffrent program?

Also my truck had almost the same type of issue as you are discribing. My issue was a cracked break booster line if it wasn't for Sal we would have never found it!

It was to late though cuz thats what caused my fried head problem.


Merry Christmas,

Suavy :santa:

 

Same program that was working excellent; that's what's got me stumped!

It acts like a vacuum leak, but not really. I'm wondering if my SCT maf is having a problem, or my 02 sensors are having a problem. I think I might have got some leaded race gas a couple of times when I was trying to buy unleaded.....

 

The way we found my vacuum leak was when I sent Sal my stats to include fuel pressures he noticed that my fuel pressure at idle was high 38 to 39 lb of fuel pressure. Sal e-mailed me back and said if the idle pressure was with the fuel rail vacuum line off or on. I told him on! He said you have a vacuum leak and to check the booster line. Sure as heck it had a hairline crack that you really had to look at to see.


Suavy

 

Did you find your problem yet?



Peace,


Suavy

 

Not yet; tonight I took the MAF off and inspected/cleaned it. Check all bolts/hoses on the intake/supercharger area. Got my datalogging software out and check things. My long term and short term fuel trims both are showing lean....

My fuel pressure is around 30 at idle(sometimes 29~31) Driving it is around 31 when just cruising, 29 when backed off the gas. On the gas it moves up, but I seem to remember it being very "jumpy" whick it is not anymore. It is kindof slow IMO.

 

Maybe bad fuel pump?Hard to hear if two are going.

 

Something to add; I pulled the vacuum line off the regulator and it went to 39~40 pounds which I believe is about right.

 

Yes that is right. However my idel fuel presure is at 34 psi with duel 255 pumps and 1/2" fuel lines.


Peace,

Suavy :santa:

 

What is a booster line? My fuel pressure is 37-38 at idle and 50+ at half throttle. I have the twin 255 fuel pumps though.

 

Booster line is the break booster line that comes of the side of the plenum and goes to the break booster.