1998 Chevy Tahoe Engine missing on deceleration

MULEY7

MEMBER
1998 CHEVROLET TAHOE
V8
4WD
AUTOMATIC
14,000 MILES

My 98 Tahoe 2-door had a new engine installed but the mechanic put the EGR valve in upside down. It was driven for 12,000 miles before I discovered the problem. Now the engine misses when I decelerate from 75 going down hill and hesitates when I feather the gas. It clears up again at about 60. The check engine lite flashes. If I accellerate hard the lite stops flashing. What.S wrong? Could the cats have gone bad? Help please?

Wednesday, August 20th, 2008 AT 7:04 PM

3 Replies

MERLIN2021

MECHANIC
17,250 POSTS

First thing you need to do is have the codes read, Autozone does it free, Post the results with the code number(s). Even if the service engine light is not on, there should be freeze frame data stored.
If it won't make it to Autozone, buy a cheap scanner, they can be had for 30-40 dollars, a good investment, since they cover all cars sold in the USA from 96 on.
If the light is blinking, it means possible damage to the converter. Service it right away!

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Thursday, August 21st, 2008 AT 4:57 PM

MULEY7

MEMBER
2 POSTS

I had the codes read and they are:PO171,174 bank 1 and bank 2 running lean, and PO300 multiple cylinder missfires. What does this mean?

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Sunday, August 31st, 2008 AT 10:53 PM

MERLIN2021

MECHANIC
17,250 POSTS

https://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm
Go here and checkout our video.
You can rent the test gauge at Autozone.
Not enough gas, or too much air...You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody

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Monday, September 1st, 2008 AT 9:02 AM