Truck not idling worth a damn...

Post by **mikel** » Fri Jun 26, 2009 11:54 am

If they were LS1 style it would be 8 individual o-ring type gaskets...

Ill_Born_SS · Post by **Ill_Born_SS** » Fri Jun 26, 2009 2:06 pm

Hey Homer
what specific cylinder/cylinders are you getting the 300`s on.

neonhomer · Post by **neonhomer** » Fri Jun 26, 2009 2:48 pm

Reread the thread, especially my 2nd post where I say ALL cylinder are misfiring. No specific 0300 (0301, 0304, etc), just P0300....

Ill_Born_SS · Post by **Ill_Born_SS** » Fri Jun 26, 2009 3:52 pm

I did read it , I was just wondering if there were more hits on certain cyls, in paticular 7&8.

anyhow if you like , try this:

If you were to hook up your Predator and go to the live PIDs and scroll down to STFT, then start the engine and watch the STFTs, normal range is +/- 8. If the number is +5 or higher the engine is running lean. If you now advance the RPM to 1500-2000 and hold it for a minute or so, and the STFT drops back down to a more normal reading, it confirms the engine has a vacuum leak at idle. If the STFT value does not change much, the lean fuel condition is more likely a problem (weak fuel pump, restricted fuel filter, dirty fuel injectors or a leaky fuel pressure regulator) than a vacuum leak.
If it is a vacuum leak, get a hand held propane tank and nozzle and a length of hose to fit over the end and with the engine running slowly move around your complete intake system while watching the STFTs for change, this would indicate a leak and show you where. There may be more than one. I usually keep a syringe of oil to seal an area so I can continue the search for more leaks.

neonhomer · Post by **neonhomer** » Fri Jun 26, 2009 5:23 pm

I don't play with propane... LOL... but I will look into the STFT's and see what they say...

I know my LTFT's without a tune run in the ballpark of +5 or so...

As for fuel problems... I hope it isn't a fuel filter... as this truck doesn't have one. (DOH! on GM!!) It has the sock in the tank and that's it.

Does anyone know for sure if the intakes on the trucks are "dry", or don't have water jackets? If not, and if it is not that hard, I will just change the damn gaskets. If I have to drain the cooling system, them I am going to go ahead and do my hoses, stat, belts, etc etc.... and of course if the radiator is empty, it's easier to remove.... so then I would have to pull the water pump and timing set, and do a cam swap!!

hodge9386 · Post by **hodge9386** » Mon Jun 29, 2009 7:37 pm

my truck did that one time and it was just a loose clamp on the intake piping

neonhomer · Post by **neonhomer** » Tue Jun 30, 2009 11:03 am

STFT's

Bank 1 - never goes below 0, never above +5 at idle
Bank 2 - between 0 and 5, with occasional dips to -1.56.

They bounce around fairly well.

Bank 1 LTFT is 2.34, Bank 2 is 0.78...

Ill_Born_SS · Post by **Ill_Born_SS** » Fri Jul 03, 2009 7:18 am

Homer
I see you mentiopn a product you use/used
http://www.bobistheoilguy.com/images/lucas/lucas.htm
and
Shell gas and some /most fuel additives have been reported to melt the bag filter in the fuel tank.

also the numbers you posted are incomplete for the STFT test recommended and LTFTs are no good at idle.

Post by **06MonteSS** » Fri Jul 03, 2009 8:50 am

and don't use Shell gas if you still are...

neonhomer · Post by **neonhomer** » Fri Jul 03, 2009 9:35 am

First off... I don't believe half the shit that is on that website. Second, I don't use Lucas in my OIL... I use their fuel system additive to my fuel. Third, I avoid Shell gas like the plague... unless I am empty and don't think I can make it to another station, then I usually will get 5 gal or so to get me to a decent station.

I normally use either Chevron, Hess, Racetrack, or Sam's Club (Which IIRC, is Murphy... same stuff as WalMart). I occasionally use BP, Sunoco, or Citgo.... I make it a habit to stay away from Shell...

Filter sock huh? I see nothing on that page that refers to filter socks. It all has to do with oil. I run Mobil1 in my truck, so I don't need additives for the oil... Now I don't know about the filter sock. Unless someone has proof, I don't want to go through the hassle of dropping my tank to find it. Besides, if it was the filter sock, I would be getting problems at speed, not only at idle.

Now for the Fuel Trims.... the LTFT's are tuned for cruise.... not idle... It is hit or miss... sometimes they will both be .78, and sometimes they are different.

As for the STFT test, I don't understand what you mean by incomplete...

Ill_Born_SS · Post by **Ill_Born_SS** » Fri Jul 03, 2009 10:23 am

The link was only to show you their main product, imagine the fuel system cleaner is no better.

I don`t think its your sock or it would be fuel starved all the time.

LTFTs are not going to tell you anything at idle.

For the STFTs you need 3 sets of numbers.

- Cold (first start of the day) write them down as soon as you start it up (predator is already running before the start)
- then 1500-2000 rpm steady for 1 min. write them down
- release the throttle and then write them down

neonhomer · Post by **neonhomer** » Fri Jul 03, 2009 10:29 am

Well, then I have to do that tomorrow or something, or let the truck sit for a few hours, as I already have driven it this morning...

The #'s posted were just at idle, after sitting for about 15 min from driving.

Now I did run it up to 2k and hold it for about a minute, and then let it drop back to idle.....

Or I could just take the laptop out there and log them.....

Ill_Born_SS · Post by **Ill_Born_SS** » Fri Jul 03, 2009 12:34 pm

Unless you live here: http://www.arcticcircle.ca/Baffin/Grise/ a few hours won`t do!

Yes you can log with your laptop or set your desktop up in the passenger side with printer, or just use the handheld for the 3-5 mins it will take. That choice is up to you.

Remember, you are looking for a vacum leak and the best way is with a small propane hand held tank and your STFTs live at idle.

Or you can just go by a local garage and slip the mechanic 20 bucks to check it for a leak and you can watch the STFTs while he is doing it.

neonhomer · Post by **neonhomer** » Sun Jul 05, 2009 3:43 pm

If I took it to a mo-kanik.... (inside joke....) I wouldn't to know STFT info..... LOL

Anyway, I managed to get a "cold" (if you consider cold w/ the air temp around 90) start reading...

-7.49
-6.25

2000 rpm for one min, then:

+4.69
+3.21

Then come back to idle...

-2.34
-2.34

Ill_Born_SS · Post by **Ill_Born_SS** » Sun Jul 05, 2009 5:54 pm

Awesome...mo-kanik, very good!

Your STFTs are perfect, NO intake leak. the first numbers are open loop and the little difference is from the fuel purge system. The second set are also in open-loop and adding fuel in a reasonable amount, below +8 is acceptable(I like to see +5 or below). The last set considering your outside air temp is better than most.
So a leak is not causing the stumble. Maybe to low of an idle, should be 550/600rpm with nothing turned on and 625 rpm max with the A/C on full.

Truck not idling worth a damn...

RE: Truck not idling worth a damn...

RE: Truck not idling worth a damn...

RE: Truck not idling worth a damn...

RE: Truck not idling worth a damn...

RE: Truck not idling worth a damn...