Pop on Startup
 

About once or twice a month when I start my v4runner there is a quick loud pop that comes from the intake. It ussually happens after it has been sitting overnight, but not always. Any thoughts?
96' 4Runner 3.4L

Jeff

You may have a leaky injector causing unburnt fuel to ignite on startup. :dunno:

cubuff4runner i have the same problem, and people on this board said that it maight have a lot to do with teh deck-plate mod. i dont know if you have done this since you dont have it on your list.
jason

I do have the deck-plate mod. It startedd doing it after the mod

that might be it ... heres my post from a while ago https://www.yotatech.com/forums/show...hlight=popping

That is strange.....mine is always open but never pops. :dunno:

It has nothing to do with the deck plate mod. Just forget about that.

The first thing I would look at is the lack of cold start enrichment inducing a lean back fire. Use a scan tool and interface with the ECU and look at what the engine coolant temp sensor is reporting for a temp and then fire it up and watch it as the engine warms up. If it reports fine and you have the proper fast idle that slowly goes down during warm up then I would look at the ignition system starting with the plugs.

Gadget

www.GadgetOnline.com

I agree with Gadget that it is likely a sensor problem but without hooking it up and watching at startup it will be almost impossible to find the culprit. Check the plugs just to be sure all are good (no bent electrodes or excessively worn ones) before going through all the trouble to find the problem. Then hook it up and watch all the sensors carefully. If you need a good diagnostic reader, just look at the one in my signature.

Do you guys think I should even worry about it since it only does it about 1 out of every 100 start ups?

Until you know exactly what is wrong, it would be irresponsible for anyone to tell you not to worry about it.

Gadget

www.GadgetOnline.com

Good point

Sadly most feel that ignorance is bliss.
If it were my truck I would find that "pop" unacceptable even if it rarely happened.
That is just me tho. :bigok: