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K. Wiggins
K. Wiggins, ASE Certified Technician
Category: Car
Satisfied Customers: 1439
Experience:  Associates Degree
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Chevrolet Lumina: The issue is no acceleration power or intermittent

Customer Question

The issue is no acceleration power or intermittent acceleration.

I now have P0300, P0401, and P0446.



History:
just did a relearn on the computer.
replaced fuel Pressure valve two weeks and found broken vacuum hose for the egr system. EGR code went away.
replaced fuel pump eight weeks ago due to sluggishness and engine running lean.
two years ago did plugs and wires and did thermostat shortly after. had an EGR code from this point on.
three years ago did fuel filter.

acceleration issue has been ongoing, but never like it is now. two weeks after replacing fuel pump it started this bad issue. Wife said it has been doing it since she got the car at 120000 that was six years ago, car now has 165000. every time it happens her dad and I would take a look, we found no issues and no codes. it has been persistent after replacing fuel pump.
Submitted: 1 year ago.
Category: Car
Expert:  Gary replied 1 year ago.
so if you go out and drive it and floor the gas pedal will it bog down with no power ?
Customer: replied 1 year ago.

correct. if i go half way it takes off till it hits 3600-4000 rpm and falls back to 3000. it does this twice and then falls all the way down till 2200.


if I stay on the pedal, after 20 sec it takes off to 5g.

Expert:  Gary replied 1 year ago.
if you remove the O2 sensor in front of the cat convertor leave it plugged in electrically just lay it aside and take it for a quick ride will the power come back? It will be a little loud but its just for testing purposes
Customer: replied 1 year ago.

not sure, never tried. if it does, what will that mean?

I wont be able to try it until ground dries up more.

Expert:  Gary replied 1 year ago.

a lot of times a restricted cat convertor will cause this exact problem

by leaving out the O2 it allows the exhaust to escape enough to give its power back

if the cat is restricted it will bog down

we have to eliminate that first

if the power comes back replace the cat convertor will correct this problem

Gary, Technician
Category: Car
Satisfied Customers: 10484
Experience: GM master tech for 15 years/ASE master tech for 20 years
Gary and 7 other Car Specialists are ready to help you
Customer: replied 1 year ago.

okay, i believe it is the cat now. I just need to know if this test works to diagnose the cat issue. Vacuum gauge test on the vacuum system. put a gauge on it and vacuum never exceeded past the idle vacuum.

 

I notice where the o2 is and I just cant get to it due to i dont have the specialty tool to pull engine forward, but i just got an idea on how to do it.

Please let me know about vacuum.

Expert:  Gary replied 1 year ago.
ok can you loosen the front pipe where the exhaust meets the back exhaust manifold and drive it ?
Customer: replied 1 year ago.

Thank you


 

Expert:  Gary replied 1 year ago.
anytime
Customer: replied 1 year ago.

Okay, i broke exhaust loose. Got three full rotations on bolts. Started car and ot ran worse. By worse it had a slight rough idel.

Expert:  Gary replied 1 year ago.
and it had a very loud exhaust leak when you did this ?
Customer: replied 1 year ago.

Yes and inefficient fuel burn smell

Expert:  Gary replied 1 year ago.

are there any new codes?any codes at all now in the computer ?

Customer: replied 1 year ago.

It just has p0446. I erased, restart , ran 1min. Turned off and restart. Ran again 1min. Turned off and cgecked codes. No codes.

Expert:  Gary replied 1 year ago.

can you check what the fuel pressure is key on engine off ?

Customer: replied 1 year ago.

It be tomorrow. Starts great thou, no waiting or long crank.

Expert:  Gary replied 1 year ago.
lets see if another expert has any ideas hang on another expert will reply back to you
Customer: replied 1 year ago.

P0300, p0446, and p1381. I had a thought and took car out on a drive with exhaust leak. After 10min i got these codes. Have to wait till tomorrow to test fuel pressure, starts great thou. With driving it, no way can i get on the highway yet a busy street with how its acting. Will put exhaust back together tomorrow.

Expert:  Josie-Mod replied 1 year ago.
Hi, I’m a Moderator for this topic. It seems the Professional has left this conversation. This happens occasionally, and it's usually because the Professional thinks that someone else might be a better match for your question. I've been working hard to find a new Professional to assist you right away, but sometimes finding the right Professional can take a little longer than expected.

I wonder whether you're OK with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you. Thank you!
Customer: replied 1 year ago.

I need ideas to fix this problem, so i'll continue to wait.

Expert:  Josie-Mod replied 1 year ago.
Thank you for your continued patience. We will continue the search for a Professional for you.
Expert:  K. Wiggins replied 1 year ago.
Hello, new expert here. What are the current codes and did you ever get around to checking the fuel pressure?
Customer: replied 1 year ago.

I thought i sent this last night. i guess i didnt.


these are the codes I have with exhaust at manifold loosen, P0300, p0446, and p1381.


 


these are what I had before, P0300, P0401, and P0446.



I am going to re-tighten the exhaust and hopefully that gets the car back derivable. before loosening exhaust I had no rapid acceleration, but if I drive easy it does fine. Now it wont even accelerate when driven easily.



when I get that done I'll go looking for a fuel pressure tester.



will too much pressure cause my no rapid acceleration?


car starts and idled great

Expert:  K. Wiggins replied 1 year ago.
Looking at everything so far you have a misfire code along with an EGR code. A po300 (multiple misfire) is usually the result of low fuel pressure or a vacuum leak. If the egr valve is stuck partially open it will cause the po300. Since the car is idling well we can rule out the EGR being partially open. This points us to a possible low fuel pressure problem. The fuel pressure can be enough to sustain idle but not enough to handle the demand of acceleration.
My suggestion at this point is to bolt the exhaust back up, clear the trouble codes and check the fuel pressure. Correct pressure for this car is 52-59 PSI. Check it first with key on engine off and then while idling. Also check it while accelerating to see if the pressure stays at specs or drops off. Let me know what you find and I will help you further.
K. Wiggins, ASE Certified Technician
Category: Car
Satisfied Customers: 1439
Experience: Associates Degree
K. Wiggins and 7 other Car Specialists are ready to help you
Customer: replied 1 year ago.

okay, will do

Customer: replied 1 year ago.

okay first thing, here is the old codes and old fuel pump psi.

"

okay, about 48psi. right when turn ignition on it went to 53 then fell down to 48. running hang out about 50psi.

p0131, p0171, p0300, p0401.

"

 

reconnected exhaust and codes are p0134, p0300, p0401, and p1381.

psi 35 with ignition on and 45 when running. hi rpm is 50psi

 

so need a new pump, or could it be fuel filter

 

it is strange that it starts better and idles better with this fuel pump then the last one.

Expert:  K. Wiggins replied 1 year ago.
The fuel pressure is definitely below specs. I'd change the filter and see if it comes up any. Also if you have one put a hand held vacuum pump on the pressure regulator and see if the regulator will hold vacuum and see if applying vacuum raises the fuel pressure any.
Usually when the filters get super clogged it tears up the plastic impellers in the fuel pump. If the above tests show no improvement in pressure I would recommend a new pump after the new pump is installed clear codes and we can work from there.
Customer: replied 1 year ago.

well car has a new Fuel pressure regulator. but yes I have a pump. I guess i'll break down and replace the year old fuel filter. fuel filter is after pump.

Expert:  K. Wiggins replied 1 year ago.
If the regulator is new you can skip that. let me know how it goes, I'll be in and out all day
Customer: replied 1 year ago.

well, out of funds now till friday. then we'll see


thank you

Customer: replied 1 year ago.

I might be hosed on the fuel pump too. bought it off ebay and did read a fine print of "Certified Technician"

Customer: replied 1 year ago.

okay, got new pump. no codes. but running and idle still bad

Expert:  K. Wiggins replied 1 year ago.
No codes is a good thing. Hows it running, bad I know but how? Is it skipping, sluggish under acceleration, etc?
Customer: replied 1 year ago.

yes to the skipping and sluggishness. it did shoot out p0134 and I erased it and has not come back. I found out what the evap issue was and when I installed new pump i made sure it didn't happen again. i am going to check fuel pressure. lastly the exhaust smells rich now.

Expert:  K. Wiggins replied 1 year ago.
If the fuel pressure is good you might want to run down the troubleshooting steps for PO134 as that would definitely cause the problems its now showing.
Customer: replied 1 year ago.

okay, can you send me the wire diagram for that o2? Also, will have to see what happens when driving further distance. will let you know.

Expert:  K. Wiggins replied 1 year ago.
Sure thing, also I'll be around all day.

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