How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Tim's Auto Repair Your Own Question
Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 15486
Experience:  Have owned a repair shop for 25 yrs.
14541291
Type Your Chevy Question Here...
Tim's Auto Repair is online now
A new question is answered every 9 seconds

I just replaced my catalytic convertor and muffler on a 99

Customer Question

I just replaced my catalytic convertor and muffler on a 99 suburban with the 5.7, now the truck 'hiccups/coughs', like the transmission is temporarily out of gear then kicks into gear, it also completely conks out when I drive really slowly through a parking lot, sometime starts right back up sometimes takes a minute. This all happens intermitantly, I have driven close to 1000 miles since I changed the pipes.
Submitted: 1 year ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 1 year ago.
Hi,My name is Tim,
I will do my best to assist you
tellme,does the engine light stay on?if so,can you give me the computer codes?
Customer: replied 1 year ago.
the engine light does not come on when it 'coughs', but funnily enough the brake light came on some of the times. When it conks out completely the engine light only comes on as it normally does with the ignition switch on accessory, it goes off immediately after restarting, so I have not been able to bring it somewhere with the light on to get a code read.
Expert:  Tim's Auto Repair replied 1 year ago.
ok
if there are codes in the computer,they are still there even if the light isnt on..
from the way you explain the problem,it doesnt sound to me as if it is a problem with the exhaust work.
from the way you explain,you need to test the fuel pressure,these must have no less than 60psi at all times,to me,it sounds as if your fuel pump may be weak and sticking at times.
the fuel pump
1- scan the computer for trouble codes
2- check the fuel pressure
.
thanks
If you are satisfied with my answer, Please Rate my answer by clicking the rating button so I can get credit for my work. I’m not always going to be giving you good news, so please don't let this stand in the way of you accepting my answer. .it does not cost you more money and we will still be able to communicate, ,.please understand, i can not see, hear or touch the vehicle and only know what you tell me. Bonuses and positive feedback are appreciated.. if you are not satisfied with my answer, please do not leave bad feed back ,i will gladly opt out and let another expert handle the question. .if i have sent any diagrams, please print them. .sometimes you may need to right click the image [,then save picture as]to save it to your computer so you can open it with your picture program...Please ask if you need more help.
Customer: replied 1 year ago.
I didn't think it was an issue with exhaust work, I figured with new cat the engine is breathing better causing this new issue.So if I took it to my local auto parts store and have them scan to see if there is a code, they can tell me what it means or I can come back and you will answer? How would I check fuel pressure? I do remember we replaced fuel pump a few years back, I remember dropping the tank was a bit of a pain, so it is not original by any means
Expert:  Tim's Auto Repair replied 1 year ago.
ok
yes,,the parts store can give you the codes and the menings of the codes,,the codes may not tell you the exact problem,but it will tell you how the computer says it is running,,
to check the fuel pressure you will need a test gauge,the gauge conects to the fuel rail just behind the throttle body
thanks
If you are satisfied with my answer, Please Rate my answer by clicking the rating button so I can get credit for my work. I’m not always going to be giving you good news, so please don't let this stand in the way of you accepting my answer. .it does not cost you more money and we will still be able to communicate, ,.please understand, i can not see, hear or touch the vehicle and only know what you tell me. Bonuses and positive feedback are appreciated.. if you are not satisfied with my answer, please do not leave bad feed back ,i will gladly opt out and let another expert handle the question. .if i have sent any diagrams, please print them. .sometimes you may need to right click the image [,then save picture as]to save it to your computer so you can open it with your picture program...Please ask if you need more help.
Customer: replied 1 year ago.
will an auto parts tore have that or do I need to take it to a shop?
Expert:  Tim's Auto Repair replied 1 year ago.
some auto parts stores will have the pressure test gauge and will loan it to you,if not and you dont wont to buy one,yes,you will need to have a shop test it
thanks
Customer: replied 1 year ago.
I had someone tell me the throttle body goes bad on these 5.7's and that might be the issue, but online forums indicate that they only go bad if they actually crack, should I look at that and at a minimum clean it also?
Expert:  Tim's Auto Repair replied 1 year ago.
it is not likley at all for the throttle body on this engine to be bad..
you can check the plastic upper intake for cracks,but,i would think it is a fuel pressure problem
thanks