Okay, here goes! When I give my car gas, it bogs on the bottom, and takes forever to gain speed. If I graduadly give it gas, it will speed up eventually fine. And sometimes it will kick in, gear down and go, and then other times it just bogs like crazy! I have re-worked the TBI (cleaned, new gaskets ect.) new plugs, wires, fuel filter, fuel pump, new ECM (because of the 42 code)and ran injection cleaner through it, and none of this seemed to have done anything! If anyone would give me a hand here, I would greatly appreciate it. I know there are similar post on here, but I wanted to state what I had already tried to correct the problem.

 

I'm not sure what the problem is but my car does that too sometimes. If you find out please let me know.

Bill

 

hi,not knowing what kind of car you have,i have a few ideas.check to make sure the transmission isn't giving you problems,like maybe tryin to start out in 2nd gear or something,also check the throttle position sensor voltages.good luck.

 

list mods please... i can probably tell u something from there. what i am almost 100% positive on is it is runnin lean.

 

I'm sorry, I have a 1989 Pontiac Firebird. 305 TBI Only mod I have made is an open air K&N open air filter. Thanks for replying...I hope you guys can help me out on this!

 

thank's for the info.now let's see if we can solve your problem.once again check the throttle position sensor voltage,also if you have a scan tool read the MPH.if your not sure about what i'm saying if you don't understand anything ,hollar! we're here to help you and we don't laugh at anyone.let us know.good luck

 

I'm sorry man I am clueless! Bbut I am damn good at picking up on stuff, and following directions. Throttle posotioning sensor? What is it and how do I check it, and what do I reference it to? Scan tool? I'm sorry! I would gladly appreciate it if you could explain these items to me. I have learned allot about this engine in a the past 6 months, so hopefully I can learn more! Your help is greatly appreciated!

Also...running lean, does that mean the timing is set wrong?

 

a scan tool is something you hook up to the aldl to read codes and monitor engine stuff...like coolant temps, open/closed loop, rich/lean, etc. throttle position sensor checks the position of the throttle and sends info to the computer to send more/less fuel. it is opposite the throttle cable linkage on the tbi unit, near a spring or something. checking it is a different story though, i dunno how to do that.

 

the throttle position sensor has 3 wires,you'll need a volt meter,leave the wire connector to the sensor hooked up.with the key on and engine off,the middle wire[should be blue] should read .5 to 1 volt,now slowly open the throttle by hand and the voltage should increase,check the black wire to be sure it's grounded,[use an ohm meter for this].now check the gray wire and make sure it has 4 to 6 volts.let me know what you get.good luck

 

Cool! Thanks! But, I have one question, where is this throttle sensor at, is it near the TBI? Left or right of it, or on top of thwe TBI. Is it a distinctive looking plug? Again, sorry for the stupid questions, but I am still learning, but if you could point out where this sensor is...I will check it when I get home! Thanks again greatly for the help!

 

take off the air cleaner and look straight down at the throttle body. the line that goes straight across the middle of the throttle plates has 2 ends. one is the throttle bracket (drivers side) and straight across it is the throttle position sensor.

 

that's o.k. i wasn't born with my knowledge and i still have to ask questions myself.the T.P.S. is on the passenger side of the throttle body,mounted to the throttle body at the base of it,you'll see the connector look for black,gray and blue wires.let us know good luck.

 

I hadn't had a chance to look at it yet, but ya know now since you have told me the location of it...I think that is the plug in which that has like 3 round little barrell like plugs, and mine is cracked all to peices. I checked the local auto parts store and the sensor is like $30.00 for a new one, do you think it would be a good idea to just go ahead and get a new one. It's not like I haven't wasted money already trying to fix it. LOL! Thanks again for all the help!

 

if it's cracked,yes,get a new one.let us know good luck!

 

Would the o2 sensor cause that also. My car has been doing that also.

 

just to let yall know about O2 sensors thjey can do all sortsof things i have a new one orderd as mine is lazy it is reading but dosent want to respond to air fuel changes. it isanew O2 as well a niehoff and i am not impressed i have now orderd a delco factory one, this faulty sensor was causing the engine to have a form of missfire and hesitation i also am doin the fuel pump realy they can act up and are chep to replace.
Chris.

 

So I bought a new tps and the pig tale to it, and it is actually running worse. So, what now? I have no clue what to do. It used to on occasion, run okay at times, but now, it runs slow all the time! Let me know!

 

this can be a good thing.check the voltages at the sensor.black ground,gray 4to 6 volts,blue .5 to 1 volt.key on engine off and remember to slowly increase the throttle by hand on the signal wire[the blue one]it should increase in voltage.let me know.

 

Man! I think I am going to cry! LOL! Okay so, I did exactly what you said do, I bought a volt meter and tested the wires...when I hooked it to the blue one, and moved the throttle with the key on and car off, and it went up to like 6 V or whatever! So what now, and I was wondering??? Why could this be good? I thought that this TPS would fix it, it made perfect sense after you explained it to me. And one more thing...could the O2 sensor cause any of this? Just something my friend mentioned, but he is no porfessional mechanic. Anyway, thanks a whole bunch again for your help! I really do appreciate it. I look forward to hearing from you again!

 

the reason i said this could be a good thing is because obviously the old T.P.S. wasn't working,you said you put on a new one and now it's worse.this tells me that your problem is getting pissed off from the new sensor,don't get upset these things can take time,i know it's frustrating.been there done it.remember we're like a doctor tryin to fix a pain over the phone.first let's go back and double check everything,start with the basics.timing,tune up area etc.keep in mind the reason i first asked about if you had a scan tool is because this can be very helpful.with a scan tool you can read all the sensors activities.if the computer reads 20 M.P.H. at an idle this can screw up your take off from a dead stop.also a new computer isn't always perfect,i've gotten many,many defective new computers.one thing to check,pull out the computer and remove the prom plate,make sure the prom is fully seated[tight].there'll be 4 letters on the prom.give me those 4 letters and i can check to see if there's been a prom update for your vehicle.you'll be surprised how a prom can screw things up.let us know.

 

I've been having the same problem. I just drained my coolant and put in a 180 degree thermostat (and found out I didn't have one at all) and after I'll floor it and the tach will go up to 5000 rpm's
before it begins to accelerate and still won't accelerate like it did before. What's the deal?

 

Okay! I had the timing fixed on my car it was off like 4 whatevers. Anyway it probably fixed 95 % of the problem. I actually have some get up on the take off. I can pass people now! Who Hooo! Thanks for all your help!

 

my 99 trans am starts but then idles rough then dies. i can keep it on by pumping the gas pedal.but if i hold down the gas pedal it dies. whats the problem? someone help me out.

 

You need to check the basics, fuel and spark. Most likely the problem is fuel delivery, a bad pump or pump connector, relay or wiring or split pump outlet hose.

Check the fuel pressure right at the TBI inlet, it should be 10 to 12 psi.

When you turn the ignition on without starting the car, the pump is turned on for 2 seconds. You should see the pressure go up to 10 to 12 psi and then drop down. When you start the car it should go back up to 10 to 12.

If you're not getting full pressure check for the voltage right at the pump terminals going into the tank, it should be at least 12 volts. If its good, you need to pull the pump out and check for a split outlet hose or bad pump.

If the voltage is low, check the wiring for corrosion at connections and the fuel pump relay, typically you have a A/C relay sitting right next to the pump relay on drivers side of the firewall, you can swap these two relays to see if the fuel pump one is bad.

You can get an idea on if the fuel delivery is right by taking off the air cleaner and watching the injectors while the engine is idling. While idling you should see smooth cones of gas being shot down into the bores. If you see any dribbling the injectors are leaking. If the cones don't look smooth and steady you probably have a fuel pressure problem.

When the ignition is turned on without starting the engine, for the first 2 seconds while the pump is on you shouldn't see any gas come out of the injectors, if you do you have a bad o-ring or leaky injector.

Paul T.

 

When you replaced everything did you mess up the timing, sounds like a episode i had when my timing was 180 off.

 

mikeybird, I have the same problem as you. I also noticed if I keep pumping the gas to keep it running say maybe 2 minutes or so I get this hot metal smell. Does your do that?

 

Ok, old link although I search as a reference. Most don't post the fix. I had the same situation. Fix was the pressure regulator on the carburetor.

 

FIFY.

 

running lean = not enough fuel
Rich = too much fuel

Many things could cause these things to happen. Timimg being one.