STFT/LTST question
Thread Starter
|
Freshman User
Joined: Sep 2012
Posts: 34
Likes: 0
From: Elkridge, Maryland
STFT/LTST question
I bought a 99 F250 SD 6.8L about a month ago and it's running much better than when I got it, thanks to all the information I found here. I'm having difficulty passing the state emissions testing, my hydrocarbons are about 3x the limit. Bank 2 has some sort of fault but no code. The Bank 1 STFT is currently -2.39, LTFT is 10.16 while Bank 2 STFT is 0.00, LTFT is 10.16. The bank 2 STFT doesn't change, so my question is what could cause this and could that be causing the high hydrocarbon failure? Any help/recommendations will be greatly appreciated.
Last edited by boj760; Nov 20, 2012 at 11:39 AM. Reason: hastily written original, so I cleaned it up.
Thread Starter
|
Freshman User
Joined: Sep 2012
Posts: 34
Likes: 0
From: Elkridge, Maryland
STFT/LTFT developments
OK, the values for the STFT started updating
. Idk what was going on there, but they're changing now. I got a P0310, so I made the time to change #10 plug (using dielectric grease and copper antiseize on the new plug) the plug was jacked- the point was broken off and the gap was like .40. The code remained so I swapped the COP with #6 and the code still pops up P0310. Just about all that's left is the injector, right? And the wiring I guess. Is swapping injectors worth the trouble or just get a new one? What do you guys think?
. Idk what was going on there, but they're changing now. I got a P0310, so I made the time to change #10 plug (using dielectric grease and copper antiseize on the new plug) the plug was jacked- the point was broken off and the gap was like .40. The code remained so I swapped the COP with #6 and the code still pops up P0310. Just about all that's left is the injector, right? And the wiring I guess. Is swapping injectors worth the trouble or just get a new one? What do you guys think?
Thread Starter
|
Freshman User
Joined: Sep 2012
Posts: 34
Likes: 0
From: Elkridge, Maryland
STFT/LTFT question
BigPigDaddy, thanks for saying hi. Hi back! I'm sorry if I'm confusing folks and not making sense, I thought I was
. The first posting was asking if anyone might know why my STFT (short term fuel trim) on bank 2 (sensors on the driver's side of the engine) wasn't updating, it just read 0.00 for a day or two while the LTFT (long term fuel trim) on both banks was changing/updating and the STFT on bank 1 was also changing/updating.
The STFT and LTFT is used by the computer to maintain the proper fuel-air ratio (not too lean, not too rich). I failed the state emissions for hydrocarbons, so I was curious to know if the non-changing fuel trim would cause that.
The second post stated that the STFT/LTFT was now updating, that I saw I had DTC code P0310 (misfire cylinder 10), swapped the COP and nothing changed. So I changed the out the plug and again got the P0310. The cause of the misfire, I think, has been narrowed down to the fuel injector or the wiring. I just would like an experienced opinion as to whether I should swap the injector with one from another cylinder or just get a new one?
BTW, there isn't any other codes popping up besides the #10 misfire.
Thanks
. The first posting was asking if anyone might know why my STFT (short term fuel trim) on bank 2 (sensors on the driver's side of the engine) wasn't updating, it just read 0.00 for a day or two while the LTFT (long term fuel trim) on both banks was changing/updating and the STFT on bank 1 was also changing/updating.The STFT and LTFT is used by the computer to maintain the proper fuel-air ratio (not too lean, not too rich). I failed the state emissions for hydrocarbons, so I was curious to know if the non-changing fuel trim would cause that.
The second post stated that the STFT/LTFT was now updating, that I saw I had DTC code P0310 (misfire cylinder 10), swapped the COP and nothing changed. So I changed the out the plug and again got the P0310. The cause of the misfire, I think, has been narrowed down to the fuel injector or the wiring. I just would like an experienced opinion as to whether I should swap the injector with one from another cylinder or just get a new one?
BTW, there isn't any other codes popping up besides the #10 misfire.
Thanks
Elder User
Joined: Feb 2006
Posts: 545
Likes: 5
From: FL
You said you had already swapped the COPs (between #10 to #6 ) and the error code remained the same PO310 . That eliminates a bad COP and/or bad rubber boot . Except a bad wiring connection at #10 .
What did you mean by "#10 plug was jacked" ?
Was there a physical damage with the old plug ?
Good luck,
What did you mean by "#10 plug was jacked" ?
Was there a physical damage with the old plug ?
Good luck,
Thread Starter
|
Freshman User
Joined: Sep 2012
Posts: 34
Likes: 0
From: Elkridge, Maryland
There was, but not too bad. The point was broken off. It looked like whoever put it in may have busted it off trying to gap it, then messed up the gap trying to compensate for the broken point. It didn't look like impact damage from the piston or anything. It's coming down to wiring. What's the best way to check that?
Trending Topics
Elder User
Joined: Feb 2006
Posts: 545
Likes: 5
From: FL
You had replaced #10 plug and the truck has been running awhile . May be you can remove the new plug at #10 and visually check see if it is still OK . At least this way you can eliminate an internal cause that might have damaged the plug (interaction with a bent valve etc.).While you were at it, double check the #10 COP electrical contacts.
If you suspect any problem with #10 cylinder , a compression test may be required .
Good luck,
If you suspect any problem with #10 cylinder , a compression test may be required .
Good luck,
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Elder User
Joined: Feb 2006
Posts: 545
Likes: 5
From: FL
boj760,
I never have to check injectors but here is the recommended way by Haynes Repair manual;
1-With the engine running, place an automotive stethoscope against each injector ,one at a time , and listen for a clicking sound , indicating operation. If you don’t have a stethoscope , you can place the tip of a long screwdriver against the injector and listen through the handle.<O
</O
2-If an injector isn’t functioning (not clicking) , purchase a special injector test light (sometimes called a “noid light) and install it into the injector electrical connector. Start the engine and check to see if the noid light flashes. If it does , the injector is receiving proper voltage . If it doesn’t flash , further diagnosis should be performed by a dealer service or other repair facility.<O</O
3- with the engine OFF and the fuel injector electrical connectors disconnected , measure the resistance of each injector . Check the Specification (injector resistance 11 to 18 ohms).
<O</O
Good luck,
I never have to check injectors but here is the recommended way by Haynes Repair manual;
1-With the engine running, place an automotive stethoscope against each injector ,one at a time , and listen for a clicking sound , indicating operation. If you don’t have a stethoscope , you can place the tip of a long screwdriver against the injector and listen through the handle.<O
</O2-If an injector isn’t functioning (not clicking) , purchase a special injector test light (sometimes called a “noid light) and install it into the injector electrical connector. Start the engine and check to see if the noid light flashes. If it does , the injector is receiving proper voltage . If it doesn’t flash , further diagnosis should be performed by a dealer service or other repair facility.<O
</O3- with the engine OFF and the fuel injector electrical connectors disconnected , measure the resistance of each injector . Check the Specification (injector resistance 11 to 18 ohms).
<O
</OGood luck,
Thread Starter
|
Freshman User
Joined: Sep 2012
Posts: 34
Likes: 0
From: Elkridge, Maryland
Wolfboro, thanks for the tips. I have heard of 'niod lights but haven't used them and the Haynes procedure is something I'll check out tomorrow. Hopefully I'll have something more to go after listening to the injector and check the plug.
-Keith
-Keith
Thread Starter
|
Freshman User
Joined: Sep 2012
Posts: 34
Likes: 0
From: Elkridge, Maryland
Either I'm getting old, truck's too loud or I just couldn't tell- but the long screwdriver didn't work very well (no stethascope). I'm picking up a 'noid light in the morning and give that a shot. In my other thread I stated that a friend suggested that maybe a valve wasn't seating right/fouled? Could that cause the gas/air ratio to change and be the culprit? I'll get some Sea Foam motor treatment along with the light. I didn't have a chance to check the plug, do that tomorrow too if the light checks out.
-Keith
-Keith
Thread Starter
|
Freshman User
Joined: Sep 2012
Posts: 34
Likes: 0
From: Elkridge, Maryland
No 'noid lights in stock. Put in the Seafoam but can't tell if it's done anything as the code remains. Noticed some surging at WOT (mentioned in other thread). Any thoughts?
Thread
Thread Starter
Forum
Replies
Last Post
TexFinn
Modular V8 (4.6L, 5.4L)
5
May 10, 2004 10:55 PM