Stumped lacking power under 3000 RPMS

[poorboy1964]

I'll try to explain this, I only drive the expy on weekend trips or to work every once in a while. A few months ago I started noticing that when I would take off at a stop light or try to merge she would fall on her face this was not consistent very hit and miss but bad enough that I really thought hard before pulling into traffic. As I paid more attention to what was happening it has not done it when cold only after driving awhile as soon as I get over roughly 2800 rpms it like a turbo kicked in and I take off. last weekend it got much worse pulling a small 12' trailer with my side x side on it I could not maintain 65 mph on level ground without it dropping into second gear.

so where to start the only thing I have changed since this started is the TPS
no codes on my scanner

The hit and miss of it has me thinking sensor but????

 

[1997SCEBFEX]

could be a myriad of things; how many miles on her and recent maintenance?
Fuel filter or fuel pump, how old is the gas; do you treat your fuel since it sits quite a bit?
MAF cleaned/air cleaner
COP/plugs
...

sure others will chime in.

 

[poorboy1964]

140k miles, burn through a tank of fuel every other weekend ran Lucas through the last two tanks. very fresh oil & filter fresh air filter stock, Cleaned MAF and throttle body when I change TPS,,, COP and PLUG are a strong possibility will pull this weekend to see I have no idea how they are. Fuel filter is this weekend also as I don't know?

Fuel pump I have a gauge any idea where to connect to???

 

[ExplorerTom]

Was the AC on? Ambient temps 85+ at the time?

Mine has a noticeable lack of performance under those conditions.

 

[docraymund]

Check fuel trim data on your scanner after checking the plugs and COPs. You might have a lean condition.

 

[poorboy1964]

Check fuel trim data on your scanner after checking the plugs and COPs. You might have a lean condition.

Possible Thanks

Was the AC on? Ambient temps 85+ at the time?

Mine has a noticeable lack of performance under those conditions.

yes to both of those questions but the hit and miss of it is strange, sometimes it will change from one stop light to the next.

 

[1955moose]

Well poor boy, you need to post year, engine, and model. I'm assuming it's a first edition 97 to 02 model, since that's the category you posted it. The fact that it doesn't act up when cold, only when warmed up, tends to lean towards fuel issues. Most first edition expeditions/ f150's can check fuel pressure at the fuel rail. Sounds like you've got either a partially clogged fuel line or failing pump. Pressure test should tell. Other thing to do is run a dtc codes test. You could have something else going on with a sensor as well. Another issue if your suv is 2002 or later, could be that dreaded fuel pump relay connection at fuse box. Check these items out, and report your findings.

Sent from my N9131 using Tapatalk

 

[poorboy1964]

Well poor boy, you need to post year, engine, and model. I'm assuming it's a first edition 97 to 02 model, since that's the category you posted it. The fact that it doesn't act up when cold, only when warmed up, tends to lean towards fuel issues. Most first edition expeditions/ f150's can check fuel pressure at the fuel rail. Sounds like you've got either a partially clogged fuel line or failing pump. Pressure test should tell. Other thing to do is run a dtc codes test. You could have something else going on with a sensor as well. Another issue if your suv is 2002 or later, could be that dreaded fuel pump relay connection at fuse box. Check these items out, and report your findings.

Sent from my N9131 using Tapatalk

Sorry guys I thought that was all in my signature on here
2000 5.4 140k

So I change all the plugs and new boots nothing was very bad plugs had a little wear gap had go 60 on a couple, ohm tested and cleaned contacts in coils all within spec.
Fuel pressure held at 32 on the rail

I had fuel filter on order it did not show yet so that is still to be changed but I feel this is unlikely because at high rpm it runs fine that is when I think a restriction in the fuel line would show test ride??? had same results after warm up lacking power.

But on my test drive I was all over the road steering was bad so I found this

 

[poorboy1964]

Was the AC on? Ambient temps 85+ at the time?

Mine has a noticeable lack of performance under those conditions.

So Tom you are correct 2" lift is to much for shock with an articulation in your driving off to your post to see which shocks you went with lol

 

[ExplorerTom]

I haven't done anything about my front yet, but I was noticing that at full droop during my ball joint replacement, my shocks were trying to do this same thing.

Rancho has RS5000 shocks for a 2.5" lift. I put the RS5000X in the rear but I'm not sure they will work on the front (only listed for 4" lift).

I'm not really sure on the difference between the 2. The X costs more.