I have a 2000 Bravada 4.3l that’s started misfiring hesitated with a p3001 code and a p3000 code when I bought it. so I switched the spark plugs wires distributor cap and rotor, and that didn’t seem to fix the issue but now with no codes. Someone told me it could be the coolant temperature sensor bc it wasn’t reading the right temperature so I changed that and it reads cold all the time so I’m changing the thermostat this weekend im not too sure if it will change the way it runs. I don’t get it it seems to run fine for a few minutes of driving but the longer I drive the worse it gets but recently it’s been doing it randomly. Like if I go to work one day it’ll run fine with barley any misfires there and back and some days it’ll misfire and backfire all over the place on the way there and on the way back run fine. Now my service awd light came on a few days ago which worked fine in the snow a few weeks ago. I’ve been all over the internet and talked to numerous people and I can’t seem to figure it out. At this point I’m not really driving it anymore. I knew it was going to have its fair share of problems when I bought it but I wasn’t expecting it to be this complicated. I hope someone can help me on here I’m pretty lost at this point

 

Misfires can be caused by many things, sometimes you get lucky and it’s one of the first things that you look at or try and sometimes it can get more involved and take a while to resolve..

Yes an improper temp sensor input can cause the engine to run Rich (usually). What did the old plugs look like? This can be confirmed with fuel trims in live data on a scanner. It can be the sensor, wiring, instr cluster or engine computer.

These trucks are sensitive to the brand of certain components like ignition parts, it’s always best to use AC Delco brand. That said, make sure that you have the distr wires routed correctly as there is a crossover in the pattern. Next up you need to get CMP Retard within spec with a capable scanner. Does the old distr cap have evidence of crossfire under the cap with carbon traces?

If funds or testing capability is an issue then a low cost diagnostic step is to mist the engine with water in the dark at idle to look for arcing in the ignition system around wires, distr cap, coil, etc.

Once you have scanner capability to set CMP retard then we have many things that we can start testing.


George