00 Denali - Random Misfires under load

[TurboGSR96]

haha you dont have to tell me about a completely worn front suspension my truck was un-alignable 50k miles ago... I was told you cant buy bushings from GM so i hope someone makes aftermarket stuff.

These trucks should of came with rear wheel disc's, my truck eats the rotors/pads on front so fast.

 

[TurboGSR96]

That will take a while but I will eventually. My suspension is gone to shit with worn uppers balls/bushings, broken leafs spring packs, leaking shocks and cracked drums and rotors. Once that stuff is done I will start full tanking the truck and using my diag software to process the mpg. I am hoping by the end of this month. I did take for quick freeway run for 3 miles and at 235k it hauls the mail now.

any mpg updates?

 

[SunlitComet]

I have got poly suspension kit from Energy Suspension but have not put it in yet.

---------- Post added at 05:58 PM ---------- Previous post was at 05:57 PM ----------

any mpg updates?

Unfortunately not


read:
http://www.tahoeyukonforum.com/forum/showthread.php?t=26610

---------- Post added at 06:01 PM ---------- Previous post was at 05:58 PM ----------

I actually got my brakes, shocks, rear air springs, carpet and electronics in and put in the k&n the day before my newest problem showed. Still have to do ball joints and alignment. But the vehicle certainly looks a lot higher than before. And is more stable as well.

 

[TurboGSR96]

Apparently me and you have the same luck, I installed the Delphi MFI upgrade today and I still have the same issue as well.... I am starting to think its the pump, does anyone know what the fuel pressure should be at on a 00 denali and do I check it with the truck running or just keyed on?

 

[BattelWagun]

Hook up the gauge and turn the key to the RUN position (dont turn it over yet). The PCM should run the pump until the system is pressurized (on my '99 hoe, i think its ~60 psi). If that checks out, turn it over and see what you get, these are fuel injected, so the pressure is constant, there shouldn't be much fluxuation at all. The fuel pump runs constantly and there is a regulator on the engine that opens up a return line to send excess fuel not needed by the engine back to the tank instead of regulating pump speed, etc.

 

[SunlitComet]

engine not running should be around 60psi.

Mine actually worked great for a little while I just did not have money to full tank it a few times for mileage runs and out of the blue something new crops up with different cylinders. Will compression and fuel pressure test system before Friday.

 

[BattelWagun]

engine not running should be around 60psi.

I knew it was something like that haha. But yes, pressure tests can be extremely helpful.

 

[TurboGSR96]

Thanks for the replies guys... I hooked it up a few months back at my friends house, I cant recall the exact pressure but I am pretty sure it was like 55 I dont remember it being 60. My pump whines just as loud as the dual external pumps that I have on my race car and has been for probably 80k miles. I hope its the pumps and I am not chasing some bs issue that requires me to replace everything.

I have a cheap scan tool with data on it, what should my LT and ST fuel trims look like and vacumn? I did notice both O2's on Bank 1 sweeping from 5-50% while bank 2 was not, I replaced an O2 last year and I am thinking I might need to just change all of them as well....178k on the truck right now.

Cant blame the regulator the MFI comes with a brand new one.

 

[SunlitComet]

What software do you use.

 

[TurboGSR96]

Not using any software, my friend at Race Proven Motorsports is going to tune it using EFIlive when I get the issues sorted out. I am just reading the data off the brick sized scan tool I have.