TBI Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

Throttle Lag?

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Old Oct 5, 2011 | 10:28 PM
  #1  
Ron_90's Avatar
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From: Baltimore, Maryland
Car: '90 RS
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73 Open
Throttle Lag?

As I've been driving my car more I've noticed that there's a bit of lag after I punch the gas before it takes off- it's the engine, not the trans. I'm assuming this isn't normal, so what should I do to fix this? It's a 305 TBI that runs great otherwise.

While I'm asking about stuff, should I bother ordering a new A/C delete pulley, or should I just take one from a junkyard car?
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Old Oct 6, 2011 | 04:03 AM
  #2  
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From: West-Central
Car: 91 Trans am
Engine: built 360 TBI
Transmission: built 700r4
Axle/Gears: 10bolt/3.23
Re: Throttle Lag?

Could be too much or too little fuel.
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Old Oct 6, 2011 | 06:32 AM
  #3  
Ron_90's Avatar
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From: Baltimore, Maryland
Car: '90 RS
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73 Open
Re: Throttle Lag?

Originally Posted by thomas1976
Could be too much or too little fuel.
How do I determine this? Too much could be a possibility
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Old Oct 6, 2011 | 06:35 AM
  #4  
ex-x-fire's Avatar
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Re: Throttle Lag?

He shoulda said fuel pressure, they make a tbi fuel pressure test kit, spec is 9-13psi.
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Old Oct 6, 2011 | 01:38 PM
  #5  
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From: West-Central
Car: 91 Trans am
Engine: built 360 TBI
Transmission: built 700r4
Axle/Gears: 10bolt/3.23
Re: Throttle Lag?

Test FP, under load too. If it is good check injectors too.
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Old Oct 6, 2011 | 03:03 PM
  #6  
Ron_90's Avatar
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From: Baltimore, Maryland
Car: '90 RS
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73 Open
Re: Throttle Lag?

By TBI fuel pressure test kit, do you mean I'll have to get something other than a standard fuel pressure gauge?
I was thinking it could be running rich because when I get right out of the car I can smell a bit of gasoline for a few seconds
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Old Oct 6, 2011 | 04:24 PM
  #7  
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From: Manteca,California. Nor Cal.
Car: SOLD IT. Mopar guy only now.
Engine: gone
Transmission: gone
Axle/Gears: gone
Re: Throttle Lag?

you can use a normal kit if it has the right adapter to be installed on the tbi fuel line somewhere, again this is only for testing and not to be ran on there at all times. dctrumpet sells a fitting that goes inline that you can leave permently and install the gauge there when you need to see the pressure. I am goign to assume its either fuel pressure related, or Throttle position sensor related.
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Old Oct 6, 2011 | 04:24 PM
  #8  
bigreed91's Avatar
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From: Columbia, TN
Car: 1990 camaro rs
Engine: 5.0L 305 tbi
Transmission: 700r4
Axle/Gears: 2.73
Re: Throttle Lag?

i went to pep boys and spent about 15 bucks on a inline pressure gauge, i determined which fuel line was the supply not the return, cut it in half and put in my gauge my car at idle runs 11.5 psi and maintains pressure at higher rpms, only thing is i cant see it goin down the road lol
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Old Oct 6, 2011 | 08:01 PM
  #9  
Ron_90's Avatar
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From: Baltimore, Maryland
Car: '90 RS
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73 Open
Re: Throttle Lag?

Originally Posted by UnderCover89TBI
you can use a normal kit if it has the right adapter to be installed on the tbi fuel line somewhere, again this is only for testing and not to be ran on there at all times. dctrumpet sells a fitting that goes inline that you can leave permently and install the gauge there when you need to see the pressure. I am goign to assume its either fuel pressure related, or Throttle position sensor related.
That actually sounds more likely than running rich (I mean it's 20 years old, what are the odds it has high fuel pressure), or even lean for that matter. Plus, TPS symptoms seem to match up better with my problems. I know I'll need a battery voltage checker (pentameter), but how exactly should I go about checking it?
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Old Oct 6, 2011 | 08:36 PM
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From: Manteca,California. Nor Cal.
Car: SOLD IT. Mopar guy only now.
Engine: gone
Transmission: gone
Axle/Gears: gone
Re: Throttle Lag?

I dont know what wires you hook up too. I have a scanner and EBL to see where mine is at! I am sure thier is a thread somewhere on here or in the tech info part of the site.
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Old Oct 7, 2011 | 01:18 PM
  #11  
iggy1991's Avatar
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Posts: 491
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From: Hockessin, Delaware
Car: Red 91 RS Camaro
Engine: LO3 with Comp Cam
Transmission: 700R4
Axle/Gears: 4th gen rear
Re: Throttle Lag?

Use an old fashion volt/ohm meter, the kind with the needle, and just find the right combination of the 3 wires that gives u a reading on the tps. Should be a nice steady increase as u open the throttle blades.
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