LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Question: obd2 lt1 owners

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Old Mar 1, 2005 | 03:45 PM
  #1  
Irocdriver89's Avatar
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From: san jose
Question Question: obd2 lt1 owners

i keep pulling a code that says low thrust hold in banks 1 and 2 on the catalyst what does this mean are my cats bad. i just replace one and is it time to do the other one. is there any other reason for this code to pop up. car feels fine only complaint is it takes two or more turns of the key to fire the car up unless it was just running them it would fire right up. also when i get to higher rpms the car seems to not pull as hard between 4-6000 rpms almost as if the clutch is slipping or like i broke traction.

clutch is brand new, tires are 50 percent what else could it be.

thanks in advance for any advice!
Old Mar 1, 2005 | 04:29 PM
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From: Arlington, TX
Re: Question: obd2 lt1 owners

Originally Posted by Irocdriver89
i keep pulling a code that says low thrust hold in banks 1 and 2 on the catalyst what does this mean are my cats bad. i just replace one and is it time to do the other one. is there any other reason for this code to pop up. car feels fine only complaint is it takes two or more turns of the key to fire the car up unless it was just running them it would fire right up. also when i get to higher rpms the car seems to not pull as hard between 4-6000 rpms almost as if the clutch is slipping or like i broke traction.

clutch is brand new, tires are 50 percent what else could it be.

thanks in advance for any advice!


Hmm...i had a similar problem with the whole turning the key 2 or 3 times to get it started. As much as you're not going to like it, i'd say you might have a fuel pump problem. Have you changed your filter lately and how many miles are on your car?
Old Mar 1, 2005 | 04:35 PM
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Re: Question: obd2 lt1 owners

i have 100,000 miles on the car and i have not got to the filter yet put when the car is hot it fires right up would that still be a fuel pump problem


also my friend add a kandn filter to the end of my stock piping because the air box that came factory kept coming off the end of the plastic pipeing could i be taking on to much air into my system if there be such a thing when i put my foot down to open the throttle the car fires right up even when cold!
Old Mar 1, 2005 | 06:18 PM
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Re: Question: obd2 lt1 owners

Well i'd definetely replace the fuel filter...the reason it starts back up when the car is hot is because the fuel pump still has pressure in it. When the car sits for awhile the fuel pump loses all of the pressure which is why it takes a few times to start the car up when its been sitting.
Old Mar 1, 2005 | 06:29 PM
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Re: Question: obd2 lt1 owners

All you need to do is cycle the key before you cold start it...no need in a new fuel pump.
Old Mar 1, 2005 | 11:24 PM
  #6  
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Re: Question: overheating

yea i do the cycle thing all the time to keep from getting talked about one more question when sitting still the car tends to run hot never over the red by then it cools back down. so i replaced the thermostat and now the car runs at 200 degrees no matter what until i hit traffic then it slowly goes up.never runs cooler than 200 since i replaced the thermostat. is there air in the system because i don't know how to bleed it any help would be great.
Old Mar 2, 2005 | 12:37 AM
  #7  
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Re: Question: overheating

What was the exact code(s) you got for the cats? Are you sure it wasn't "low efficiency"? There is no code for "low thrust hold".... could you possibly mean threshold?

If the cats were starting to plug, it would explain the loss of power at high rpm, bt it wouldn't necessarily explain the hard start. A faulty fuel pump, including a faulty check valve in the fuel pump might also cause the problems.
Old Mar 2, 2005 | 02:39 PM
  #8  
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Re: Question: obd2 lt1 owners

yep your right i have got both thoese codes 420 and 430 1441 403 are the codes the most common is 420 it is always in the system 420 and 430 are the codes i'm worried about so what could cause it. and how could i test my fuel pump.
Old Mar 3, 2005 | 01:03 AM
  #9  
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Re: Question: obd2 lt1 owners

P0403 is a problem with the EGR vacuum solenoid. Faulty solenoid, faulty wiring, connector off or solenoid missing.

P1441 is a problem with the EEC purge system showing vacuum in the purge line when the purge solenoid is not activated. The purge solenoid is stuck open, possibly stuck due to carbon particles, or the flow detection vacuum switch is faulty.

P0420 and P0430 are for the left and right cats, low efficiency. The PCM compares the after-cat O2 signal to the pre-cat O2 signal, and if they are very close together (less than ~10% difference), it assumes the cats aren't working. Could be missing cats, dead cats or faulty after-cat sensors, simms?
Old Mar 3, 2005 | 02:45 PM
  #10  
Irocdriver89's Avatar
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Re: Question: obd2 lt1 owners

thanks alot i;m thinking about getting o2 simms and a y pipe will that get ride off the codes and also i will replace the 402 sensor thing car runs good only at high rpms or on a hot day does it act up sometimes so i guess the cat might be plugged i replaced the passenger side cat but it was an aftermarket cat could that be a problem.
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