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Sputtering and does not accelerate properly

Tiny
BODINERAY12
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
Hello, I need help. Might be on right track but want to be reassured. So far I have replaced the following: Fuel pump, fuel filter, spider injector, plugs, wires, tank (had a hole), intake (went to cold air), coil, cap, rotor. I'm having a problem where when I smash the gas to the floor it's a dog, the truck doesn't want to get out of its own way. When I hook OBD tool it says bank 1 bank 2, misfire. It still says misfire after changing spider injectors. (I do the work myself so I don't have fancy tools). I was thinking my distributor gear could be worn and also thinking my cats are clogged or at least one causing a misfire? It has really been bugging me. I have done a lot of work to this truck. I'm from the east coast. Frame behind both front wheels was rotted out (back plated and 1/4 plate welded to both sides took a few days fabricating). Anyways, i'm also having a problem with my oil pressure gauge it reads like 15 psi. Engine makes no noise. Runs great cold. When driving and stop. When I start up it stalls on first crank and second crank it starts. Anyone else had this problem before? Please help? Thanks
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Monday, March 9th, 2020 AT 6:51 AM

9 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,896 POSTS
Hi,

The idea that it has a loss of power always makes me want to check the catalytic converters first. If they are plugged, that will cause an issue as described. Also, you indicated there were diagnostic trouble codes. Can you please provide all of them to me.

Another things is an engine vacuum leak can cause the issues as well. So we need to check that as well as fuel pump pressure. I no you replaced the pump and other things, but we need to confirm the pressure is within spec.

Last, if you have a live data scanner, check the shot term fuel trims and let me know what they are.

Here are a few links you may find helpful:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, you mentioned concerns about timing. Has anything been done to change it?

Let me know.
Joe
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Monday, March 9th, 2020 AT 6:32 PM
Tiny
BODINERAY12
  • MEMBER
  • 6 POSTS
Yeah, I replaced the cap and rotor but nothing done to the timing itself. Friday I am going to get a fuel pressure gauge to see what it tells me. I have not done that yet. Yesterday I took a heat gun after driving my truck for 25 mins and both catalytic converters read 380 degrees. Front and back. I also wasn't getting a reading yesterday on the scanner so I cleared them and still waiting for the check engine light to come back on. The last codes I remember were po300 and then the other one was bank one sensor 1 heater bank efficiency low or something like that. That's the code I figured my catalytic converter would be clogged. I will get the numbers to you as soon as I can. Thanks a lot.
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Tuesday, March 10th, 2020 AT 4:58 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,896 POSTS
Was it a P0420 (catalyst below threshold)?
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Tuesday, March 10th, 2020 AT 8:33 PM
Tiny
BODINERAY12
  • MEMBER
  • 6 POSTS
Possibly, I think I had that. I also had bank 1 sensor 1. I will check today at lunchtime. Light turned on this morning.
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Wednesday, March 11th, 2020 AT 6:27 AM
Tiny
BODINERAY12
  • MEMBER
  • 6 POSTS
Yes, only code I am getting now is PO420.
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Wednesday, March 11th, 2020 AT 10:43 AM
Tiny
BODINERAY12
  • MEMBER
  • 6 POSTS
So I do have exhaust leaks? My exhaust stops at the muffler because I cut it off it was rotted. Muffler has holes on the inlet. There is another coming from before the 1st catalytic converter. Don't know where haven't had it up in the air to check it out. O2 sensors are bad. Should replace? Or should I gut my cats and replace the o2? I'm on a tight budget and whatever will save me money as of right now.

High fuel pressure? I have a new fuel pump, 3000 miles ago. Its also not a Acdelco. And I heard those vortec like OEM fuel pumps.
But, the problem I have sounds like a misfire. I was getting a PO300 code but not anymore.
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Wednesday, March 11th, 2020 AT 10:51 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,896 POSTS
A p0420 indicates the converter isn't properly working. In most cases, it will need replaced. As far as gutting the converter, that is against federal law, so I can't recommend it. Plus, that will not eliminate the light.
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Wednesday, March 11th, 2020 AT 6:54 PM
Tiny
BODINERAY12
  • MEMBER
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Okay thanks for the info.
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Thursday, March 12th, 2020 AT 11:21 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,896 POSTS
Happy to help. Let me know how it works out for you. Also, I don't know if you want them, but here are the directions for replacing the converter. The attached pics correlate with the directions.

_______________________________

1999 Chevy Truck K 1500 Suburban 4WD V8-5.7L VIN R
Catalytic Converter Replacement (Gas, Below 8600 Lb (GVWR))
Vehicle Powertrain Management Emission Control Systems Catalytic Converter Service and Repair Procedures Catalytic Converter Replacement (Gas, Below 8600 Lb (GVWR))
CATALYTIC CONVERTER REPLACEMENT (GAS, BELOW 8600 LB (GVWR))
REMOVAL PROCEDURE

pic 1

1. Raise and suitably support the vehicle. Refer to Vehicle Lifting.
2. Disconnect the oxygen sensor electrical connections.

pic 2

3. Remove the nuts from the Y-pipe flat flange.

pic 3

4. Remove the nuts, the studs and the flange seals from the Y-pipe and the exhaust manifold.
5. Remove the Y-pipe and the catalytic converter assembly.

INSTALLATION PROCEDURE

NOTICE: Refer to Fastener Notice in Service Precautions.

pic 4

1. Install the new flange seals, the new nuts, and the new studs connecting the Y-pipe, catalytic converter assembly to the exhaust manifold.
Tighten the studs to 22 Nm (16 ft. lbs.).
Tighten the nuts to 64 Nm (47 ft. lbs.).

pic 5

2. Position the Y-pipe and the catalytic converter assembly to the flat flange.

pic 6

3. Install the nuts to the flat flange studs.
Tighten the nuts to 64 Nm (47 ft. lbs.).

pic 7

4. Connect the oxygen sensor electrical connections.
5. Check for clearance and alignment.
6. Lower the vehicle.

__________________________________

Also, here is a link that shows in general how one is replaced.

https://www.2carpros.com/articles/catalytic-converter-replacement

__________________________________

Let me know if this helps.

Take care,
Joe
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Thursday, March 12th, 2020 AT 5:32 PM

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