97 C1500 "Service Engine Soon"

97C1500&84Z28 · June 9, 2003

My 97 C1500 with the 5.7L vortek just started acting up. It began last week when I first started it in the morning, ran rough for several seconds and check engine light came on. Then ran smooth and was fine all week. I cleared the check engine light by disconnecting the battery. Saturday I started it, ran rough briefly then cleared up. Check engine light didn't come on. Yesterday, went out to do a few errands and ran fine when I went to the store. When I came out 20 minutes later and started the truck, it began to rough again. Check engine light comes on. Now the truck is running rough and won't clear up. Check engine light starts flashing, then stays steady for a bit, then flashes again. This pattern goes on and on. Engine feels like it running on 6 cylinders.

I checked all my plug connections and all seems fine. I did replace plugs, wires, cap, & rotor, and fuel filter a couple months ago. All OEM parts. The truck has over 80,500 miles on it. Had the intake gasket replaced about 3K miles ago. Before I go to the dealer (have an extended warranty that's good for another year), any suggestion as to possible problem would be appreciated.

bigtruck21 · June 10, 2003

maybe some carbon buildup and injector problems, especially for short trips. Maybe check o2 sensor or fuel pump

seadoons · June 10, 2003

Sounds like a bad oxygen sensor to me. The symptoms you are describing describe that exactly. My girlfriend's dad's expedition started doing the same thing last week...his is a 2000 with 60 thousand miles on it. He hasn't gotten it checked out yet, but we think it is the o2 sensor. Good luck!

Fishhunter911 · June 10, 2003

check the EGR valve as well might have a piece of carbon stuck in there and wont seat properly

griphon · June 10, 2003

Exactly where is the EGR valve located? I have looked for mine, but not very hard.

Scott

bigtruck21 · June 11, 2003

http://www.carcarecouncil.org/emission_con...ntrol/egr.shtml

http://autorepair.about.com/library/glossa...y/bldef-165.htm

97C1500&84Z28 · June 11, 2003

Exactly where is the EGR valve located? I have looked for mine, but not very hard.

Scott

On 1996 - 1999 5.0L & 5.7L Vortek engines it is a black cylinder with an electrical connector on top, on the front of the intake manifold. Very easy to spot. Kind of expensive too, Wells EGR1067 - $119.99 or Wells EGR 1043 - $159.99 at Autozone. I don't know the difference between the 2, that's what shows up on their site.

As for other years, not sure where it's located. Hope this helps.

varmint2506 · June 11, 2003

Check engine light starts flashing, then stays steady for a bit, then flashes again. This pattern goes on and on. Engine feels like it running on 6 cylinders.

I'm not sure if this is correct or not but, I was told that if the light flashes there is something major wrong. If the light comes on and everything seems ok, it is probably just an intermittent problem and it will correct itself after a set number of key cycles. (basically no worries) If the light comes on and flashes and there is a noticeable problem you should not run the engine.

Like I said, I'm not sure if that info is correct. It came from a GM Tech. though.

Autozone will scan for free, if you have one near by.