Running sluggish when warmed up?

[98f150base]

I have just recently got my truck running after it sat few months while I had the engine rebuilt . runs good but when I gets to operating temp it's really sluggish. First let me start with the rebuild. It's a 94 town car w vin Romeo block that I had done the pi head swap to after buying from a pull a part. It didn't last long it was worn and had low oil pressure. Sent it out and had if rebuilt and also had to replace the right side cylinder head because it was shot from the low oil pressure. Also had low compression dished pistons put in so it's now back to a stock pi compression not 10.5:1 like it was before the rebuild. Since the car block does not have the provision for the knock sensor in the top of the block I screwed it into the back of the right side head I just in screwed it yesterday and tired it up out of the way and the truck runs better but still sluggish. I noticed that the long term fuel trim for bank 2 is -4 and bank 1 is positive 1 to 2 at idle. Both banks look identical on short trim and also the o2 sensors. What's going on I feel like I'm musing something very stupid and simple. I work as a tech at. Local shop and know a enough about fuel trim and fuel injection to diagnose most problems but this is driving me crazy!! Is it a tune issue? I'm running pi heads but low compression pistons. It also has a slight miss under moderate acceleration. No codes. Other mods are cold air intake, throttle body spacer and dual exhaust with dynomax race bullets an x-pipe 2.5 pipe with the rear 2 cars removed. You can read my other post under modular engines if you want the full history of the truck.

 

[98f150base]

A little more info is I have noticed since the temp dropped below 90 it seems better I noticed a big difference at night when it gets below 75 in the evenings.

 

[F150]

Vacuum leak.?

 

[98f150base]

i wouldnt think so i will look at it tonight but i noticed that the timing goes into the negative when accelerating. At idle in gear its about 6 deg. but when i power brake it it drops into -5 deg and stays there it feels like its has no power and wont try to pull at all just stays at the same rpm till i let off and then the timing goes back up. In park or neutral the timing advances just fine you can rev the truck up just fine and the timing goes up to 25 or 30 deg. I think for some reason the timing not advancing or maby running the pi heads and cams with low compression is needing a different timing curve witch would need a custom tune but i dont have the money to spend on that right now. Does any body know more about how the ecm controls the timing and fuel this is the first 4.6 i have delt with so im not sure what thing contribute to timing.

 

[lil_dq]

sounds like your timing is a tooth off to me. also how is your oil pressure?

 

[98f150base]

Oil pressure idk I will have to get my mechanical gauge on it. They engine sounds really good I won't rule that out completely but I doubt it's low. I can call the guy back who built the engine and ask some questions. So far I have about 1200 miles on it after putting it in. I had a code p0340 about two weeks ago for the cam sensor circuit a malfunction and found that the connector was not fully seated because the lock on it broke so I replaced not only the connector but cam sensor also and it made a big difference in the way the truck ran but it just gets sluggish in hot weather when it reaches operating temp. Between the cam sensor and cleaning the mass air flow sensor it's a lot better than when I first got it running I also had the firing order wrong when i first fired it up after the engine was in the diagram I found had two wires on each coil backwards but I quickly straitened that up before driving it to much. Tonight I drove it home from my parents house which is about 35 miles and it ran so much better tonight because it had gotten down into the mid 70s I have noticed this more in the past two weeks because my wife has been out of town and I had to drive 70 miles each day for the first week . I then Started staying at my parents house last week and this week to save on gas I usually drive my wife's Honda to work. The truck idles smooth just runs like a dog when it's gets up into the mid 80s or higher.

 

[98f150base]

I've been researching in to the timing and what controls timing on my truck and I guess my question is what effects timing on the 4.6 I know the knock sensor is a big part but it's just tied up out of the way because the block is a car block and does not have a threaded hole for it. I did put it in the back of the right hand side cylinder head because there is open threaded hole but since removed. Since I unscrewed it and tied it up the truck ran better. I'm thinking about reflashing the PCM with the factory software because I have the equipment and access to ford factory programming at the place I work. There was really weird mix of wrong parts on the truck. The trans shop called me when I had the trans rebuilt and said they found that torque converter was wrong it had a car stall speed not a truck stall speed and the valve body was wrong too. So there is no telling what's been done to the truck before I bought it. And also there are no codes and all the data looks normal other than the fuel trim on bank 2 and the timing. I'm leaning towards PCM software or PCM has gone bad but maybe I'm jumping to quickly on the PCM.

 

[98f150base]

As simple and stupid as this sounds I changed the fuel filter yesterday and the truck seems to run a lot better. I had not even thought about changing it till now but it was a little clogged and had motorcraft on it. It could have been the original one. The temp here has not been above 85 so the truck didn't run to bad the last week or so I haven't driven it a lot it mostly sat at my apartment so I will see how it does on warmer days.

 

[98f150base]

Truck runs much better it got up into the 90's today and it didn't effect the truck at all. Even though it still feels like it is lean on hard a accel it's a lot better than before.

 

[98f150base]

Truck still runs a lot better thank goodness. Some times you have to take a step back and start with the basics and some times you just get lucky!! I am looking at sct and custom tunes to get the full potential out of my engine modifications but it will be Christmas time before I will have the money to drop on the tuner and custom tunes. Until then I will drive it ever now and then it's hard to do 70 miles a day at 14 mpg with gas at 3.78 a gallon I would love to drive it more but it's just not feasible at this point. I love my wife and her Honda is a nice car but its not my truck

 

[lil_dq]

I hear ya. I have an electrical gremlin I am dealing with now, and had to do the same thing. Take a breath, step back, and start with the basics...

 

[98f150base]

Electrical is not always fun I usually team up with boss on electrical problems at the shop he is really good at diagnosing them and I try to learn as much as I can from him so I can someday do it without help. With today's electrical systems on cars and the fact they tie all systems on board together it can get hairy. Hopefully it's something easy to trace down. Let me know how you make out.
Now I think I'm going to change my mufflers out for something a little better sounding and maybe a little quieter. Learned from experience 12" long dynomax race bullets are very loud and sound like strait pipes. I'm thinking about flowsound mufflers they are cheap but sound like flowmaster