99 yukon 5.7 vortec misfire HELP

[notboating]

are you sure it's not being starved of fuel by a restriction in the line/tank/filter?

 

[lifted_yukon22]

That's what it seems like being as weak as it is but pressure I good going to the spider. Unless it plugged up in the spider housing.

 

[SunlitComet]

If you see that pressure on your gauge then the spider has that pressure on the injector themselves. the poppets in the injector itself would have to clogged to still starve it of fuel.

 

[lifted_yukon22]

I got a better deal on mt2500 it will be here tomorrow. Does the igm adv supposed to advance the timing up to 30 degrees at highway speeds and 25 under acceleration.

 

[OR VietVet]

Still leaning toward the spider.

 

[notboating]

That's what it seems like being as weak as it is but pressure I good going to the spider. Unless it plugged up in the spider housing.

You can have good pressure until you actually use some of that fuel, if there is a restriction, the pressure will drop until you get back to no or low load and then return to normal

 

[SunlitComet]

The timing is control by the programming in the pcm. Can't give you exact numbers because I can't see the ignition maps in the pcm but your numbers seem just find And I have seen the same on others.

 

[ccapehartusarmyINF.(ret)]

I got a better deal on mt2500 it will be here tomorrow. Does the igm adv supposed to advance the timing up to 30 degrees at highway speeds and 25 under acceleration.

yeah unless youve been through any kind of aelectronics classes i dont much point in the graphing one because i didnt learn to use the graphing scantool untill i was in advanced electronics what the voltages actually look like when a sensor is bad

 

[lifted_yukon22]

The misfire history is
#1 =0
#2 =0
#3 =0
#4 =32
#5 = 687
#6 =0
#7 = 9

The battery was replace about 2 weeks ago so I lost power or it would've been more probably.

---------- Post added at 06:47 AM ---------- Previous post was at 06:45 AM ----------

The snap on says p0300 random cylinder misfire

 

[ccapehartusarmyINF.(ret)]

okay if youve already done something like this then tell me to shut up
but id swap llike cylinder 1 and 5s plugs see what happens if nothin then swap the plug wires then try swappin injectors
i cant remember but did you do a compression test