2005 slow throttle response

[moposcar]

2005 4x4 diesel. When you takeoff from a stoplight or go to cross the intersection this truck takes a couple seconds for the rpms to come up. This is even when you put throttle to floor. Once it spools up it runs great. Is this common for this truck, or is there something wrong? I bought it used and it has been like this the whole time. It has a Fas fuel pump on it but otherwise is all stock

My 2003 4x4 does not do this and it has bigger tires/rims but stock everywhere else.

 

[Darkbloodmon]

Is the air filter clean and are air intake passages clear?

How many miles on the truck?

Engine lights?

 

[moposcar]

Clean air filter, and passages. No engine codes. 183,000 miles.

Truck runs great, has plenty of giddyup after that one or two seconds. In fact it has more push you into your seat power than the 03 after it decides to go, it is just those one or two seconds at the start. You sure don’t want to try jumping in front of another car if starting from a stop.

It also doesn’t like to stop real good...like the torque converter is locked up and won’t stall if you let off gas.

So if I take off hard from a stop sign, go one block and have to stop again, when you let off the throttle, the engine rpms will stay up and not instantly go down. It acts similar to a manual transmission truck. The only reason I do this is to see what the lag time is. Otherwise I normally take off slow and don’t try “hotrodding”

Forgot to mention both trucks are automatic

 

[Topzide]

Would this be a candidate to unhook the batteries and do a full reboot? It could be a trans relearn moment. Maybe it needs to learn your driving style vs. the prior owners. Just a thought that was worth throwing out there.

 

[Ozymandias]

48re is as smart as a loaf of bread....

Keeping the rpms up is a bad thing, it points to worn injectors.
Mine did the same before I changed these to BBi.

Of course rpms stay up as long as the TC is locked.

05 should behave very much the same as your previous 03 aside from some refined shift patterns, and a shovel more torque.

 

[sag2]

Clean air filter, and passages. No engine codes. 183,000 miles.

Truck runs great, has plenty of giddyup after that one or two seconds. In fact it has more push you into your seat power than the 03 after it decides to go, it is just those one or two seconds at the start. You sure don’t want to try jumping in front of another car if starting from a stop.

It also doesn’t like to stop real good...like the torque converter is locked up and won’t stall if you let off gas.

So if I take off hard from a stop sign, go one block and have to stop again, when you let off the throttle, the engine rpms will stay up and not instantly go down. It acts similar to a manual transmission truck. The only reason I do this is to see what the lag time is. Otherwise I normally take off slow and don’t try “hotrodding”

Forgot to mention both trucks are automatic

Engine RPM that hangs up and does not return to idle is a good indication of an injector hanging open mechanically. It can be one or more, but generally one or two. You can cap off an injector at a time and drive it to see if it makes any difference. If no difference you can look elsewhere.

 

[moposcar]

Thanks for the replies.
Will the RPMs stay up even while in park with the bad injectors?

I lean toward torque converter staying locked because it doesn’t coast to a stop sign the same as the 03. When should torque converter unlock?
Also, I noticed yesterday that if you put the throttle down slowly (or only a little bit and wait for rpms to come up) it takes off fine, it only has the lag if you try pressing down a lot at once because you need to get out quick. So basically if you aren’t in a hurry to take off you don’t notice anything.

 

[Ozymandias]

Yes they step down quite slow, takes 2-3 seconds to come down from 3000rpm to idle.
The ECM wants a balanced torque output all the time and with a lagging injector it senses an imbalance that it wants to correct. So it it lowers the rpm like going down a stair, in steps.

Is the vehicle fitted with an Exhaust brake?

 

[moposcar]

The truck does not have an exhaust brake. I am the 3rd owner and I bought it with 139000 miles on it.

 

[moposcar]

I just drove it home and it looks like the torque converter is unlocking around 1250 rpms when you are slowing down. I revved it up and it does come down in steps, not a smooth return to idle.

Stuck injector sound like a correct diagnosis?

 

[Ozymandias]

I'd say so, let's see if someone else chimes in.

TC staying looked can be, I don't know the specifics of the 05 programming but it was way more sophisticated then my 04.5 as it came with the TTVA to control line pressure independent from Throttle input. Generally the newer the vehicle the more the TC stays locked and in more gears.
So for now I wouldn't overthink that as long as it opens before coming to a stop and is consistent the way it acts.