: Can 'sticky' EGR cause misfire or similar?

06-25-06, 11:04 PM
97 SLS running rough. I can't figure it out, but I got a P0300 today (general misfire code). I was starting to think it might be a fuel problem since I have checked plugs, wires, coils, ign mod... Now I am thinking maybe ignition again... or vacuum (anybody have a link to a good vacuum system diagram for the 97?)?

I have been reading a bit on the EGR and I recall that I have gotten P0404 several times in the last few months and I am wondering if that may be the culprit?

Could an EGR problem cause a misfire or a condition that could be perceived as such?

Any thoughts?

06-25-06, 11:56 PM
EGR flow at idle can cause the engine to run rough, even stall. I've gotten the P0404 code a few times over the past few months as well, and lately my engine has been running a little rough (with my bad tranny, the engine didn't see over 3krpm for two whole months resulting in some carbon buildup). I've been meaning to pull it off and clean it out, but just haven't had the time. If your plugs and wires are in good shape, try cleaning the EGR out, and see if it makes a difference before you try anything drastic.

06-26-06, 12:04 AM

Thanks for the reply. I will give that a go... Any ideas on where I might find a vacuum system diagram online?

06-26-06, 12:15 AM
Not too sure.....there might be something in the Tech section. I'd scan the diagram out of my FSM, but my scanner isn't working currently.

06-26-06, 08:21 PM
The EGR on the Northstar is not vacuum operated. It is electrical. Tech Tips section has a good write up on cleaning it.

Have you had the fuel rail recall done? A misfire afterwards is quite common due to moving the aged and heat cycled plug wires. Do a search for "stutter, engine or trans" and see if that sounds similar.

06-30-06, 10:23 AM
FYI... had it hooked up this morning to a machine, #7 wasn't firing (intermittent). It was a cracked spark plug. Everything else I tried prior is clean as a whistle. Three cans of carb cleaner to get 'er done on the TB, but she is shinin' like chrome.

All of that stuff helps. Running good now.

Thanks for the help that was given.