accelleration lag?

[RED90]

when I accelerate in my truck, only at lower speeds and when engine is warm, there seems to be an "acceleration lag" like symptom. when I press on the gas pedal, the engine drops back down to idle speed and then one or two seconds later the truck rpms are back up and accelerating like I wanted it to in the first place. again, this only happens when the engine is warm and at lower speeds>> under 30mph. what could be causing this symptom? see sig for truck description

 

[magimerlin]

Well sigs don't show on tapatalk... So what do you drive?

Is your engine light on?

Short list...
Tps
Iac
Egr
Timing
Fuel issue

Could be a whole bunch of things

What have you checked already? And what was the outcome of said tests?


Sent from what use to be a great country.

 

[SkyHighColorado]

Start with checking fuel system.

 

[IOWNJUNK]

Sigs show on tapatalk if you tap his avatar. 1990 350 with tbi.
Fuel or timing is my guess.

 

[magimerlin]

^^^^cool. Never knew that it shows anything when you tap the avatar.


Sent from what use to be a great country.

 

[IOWNJUNK]

I only found out because I have fumble thumbs.

 

[RED90]

Well sigs don't show on tapatalk... So what do you drive?

Is your engine light on?

Short list...
Tps
Iac
Egr
Timing
Fuel issue

Could be a whole bunch of things

What have you checked already? And what was the outcome of said tests?


Sent from what use to be a great country.

I replaced the tps (it was destroyed). I recently rebuilt the engine and transmission so those are new. the timing is not fine tuned so I will do that this weekend. fuel is fine, I know that much. I will check the timing and fine tune it and see what happens. thanks for the list!

 

[RED90]

I found a bad coil in my searches so I replaced that, lag was still occurring. I checked the timing and it was fairly advanced so I retarded it, but I forgot to unplug the connector by the fuel pump relay (I had no clue this even existed). since I didn't unplug the connector, I was fighting the computer compensation for the timing and I ended up retarding the timing 15 degrees (I found that out when we unplugged the connector and re-did the timing). so...we got the timing set right and no more lag!!! she runs great now

 

[Cadon69]

Doh!


Sent from my iPhone using Tapatalk Pro

 

[Tweezak]

I found a bad coil in my searches so I replaced that, lag was still occurring. I checked the timing and it was fairly advanced so I retarded it, but I forgot to unplug the connector by the fuel pump relay (I had no clue this even existed). since I didn't unplug the connector, I was fighting the computer compensation for the timing and I ended up retarding the timing 15 degrees (I found that out when we unplugged the connector and re-did the timing). so...we got the timing set right and no more lag!!! she runs great now

Hmm...where is this plug? In fact where is the fuel pump relay? I recently bought a 94 Silverado with a TBI 350 and I'm still learning my way around it. Thanks!