#3 Misfire
- Thread starter knucklehead_vol
- Start date
vac. leak at the upper or lower intake gaskets? Look at all the ports near the throttle housing and make sure the cap is on the one (pass side i think?) Then sure the o rings on the injectors but that don't happen much. The lean condition could be your misfire. The o2 sensor just sees o2 so all that raw fuel dont mean nothing when its in there with unburned air. Truck sees it as a lean condition
Get a can of brake cleaner with the straw on it so you can direct the spray at small areas ans start spraying areas that could be vacuum leaks. When you find the leak the idle will change. And no that is a picture of your fuel inlet port on the fuel rail. Thats at the very back of the engine and the throttle is at the front.
Replaced the coil, spark plugs, and wires and it runs great...with the exception of at idle. Still shows lean bank 1 and #3 misfiring. Gonna check out vacuum leaks and the injector tomorrow.
I would smoke test the whole top of the engine. Get a smoke machine like you would check for Evaps leaks and do the same thing
When does it misfire. If you think it's happening on a hot restart or cold restart it could be coolant getting in the cylinder
Well I found one of the upper intake bolts, the rear was loose. So it was a vacuum leak there. Now it still has a little of a rough idle. But it is running much better. I am still taking it to the shop. There are two lines that are open and I can't find where they go. But if it was leaking coolant wouldn't it lose power? This motor has 134000 miles and is strong. I was actually surprised.
The first pic looks like it is going under the ps pump. The second maybe to the back of the lower intake or something.
I think you could figure this bitch out. We can help. You gotta tell us when it stores the misfire fault. Even if you can't feel it misfire, you know when the light comes on or starts flashing. So when do you think it drops the cylinder? Cold start/ driving before fully warm? Heavy load or at idle? Answer those questions and we can start to help. I'm never very confident in independent shops trying to fix these trucks. Sure there are some great ones out there. The chances of you finding one by accident are slim to none. Slim just left.
They are Taylor and if your upper plenum bolt(s) were loose you are leaking between the intake ports and probably outside. When you pull the upper plenum you'll see it will be wet and trails between the ports. Put in a New upper plenum gasket and try again
It seems once warm. When above idle plenty of power. But it is noticeable after driving and at idle. The light stays on. And the 1-7 plugs have carbon and show as running lean.