JavaMan
OBS Enthusiast
Driving on the freeway late evening in my Suburban 2500 4x4 7.4L, engine suddenly changes pitch a little, and slows down. I adjusted the throttle a bit and kept my speed. It was enough of a difference that it was downshifting on the small hills, which it normally does not. Later, getting off the freeway, I notice it's backfiring while idling, then stutters as I accelerate again. We got to our destination, I played with the Suburban the next day. It backfires mostly at lower RPM. Couple backfires per second at 700, fewer at 1200, no backfire once I get to 1700 RPM. When accelerating, takes more throttle, and backfires till the RPMs get up over 1700. No CEL, no active codes or pending codes.
I took it into the shop near there. We were visiting my parents, three hours from home. The shop says it's a bad fuel injector, only way to replace them is all at the same time. Didn't fix it. They replaced the downstream O2 sensors also. So, $1400 later, still not fixed. They tell me the catalytic convertors are clogged, they want $1200 to replace those. I tell them no way, took it to a muffler shop, they had both replaced in 30 minutes for $350. Still backfiring, no changes. Shop now wants to replace the fuel pressure regulator for $450.
Our vacation time was over, so we got a rental car to go home, left the Suburban at my parents house for now.
The Suburban is three hours from my house, what should I check for next? These mechanics nowadays are lost if there fancy scanner doesn't tell them exactly what part is broken, and they just start swapping parts at my expense and say, oops, that wasn't it. So I'm hoping that someone here, knowing these vehicles, has experienced something similar.
I took it into the shop near there. We were visiting my parents, three hours from home. The shop says it's a bad fuel injector, only way to replace them is all at the same time. Didn't fix it. They replaced the downstream O2 sensors also. So, $1400 later, still not fixed. They tell me the catalytic convertors are clogged, they want $1200 to replace those. I tell them no way, took it to a muffler shop, they had both replaced in 30 minutes for $350. Still backfiring, no changes. Shop now wants to replace the fuel pressure regulator for $450.
Our vacation time was over, so we got a rental car to go home, left the Suburban at my parents house for now.
The Suburban is three hours from my house, what should I check for next? These mechanics nowadays are lost if there fancy scanner doesn't tell them exactly what part is broken, and they just start swapping parts at my expense and say, oops, that wasn't it. So I'm hoping that someone here, knowing these vehicles, has experienced something similar.