Will a code get thrown CHECK ENGINE not on?

[tannerc]

Will a code get thrown even if the CHECK ENGINE light does not come on?

I either have a tps or o2 on the way out and sitting at 50mph if i eez into the throttle it will sound like it misses or starves out.. little surges and such.

but i do not get the check engine light to come on..

will i still see a code register?

 

[JeremyH]

Not necessarily, but it doesnt hurt to have it read. Most auto parts stores will have an OBDII reader that they can use to get you the code. They'll also even look it up and help diagnose it for you (because they want you to buy the replacement parts at their store).

Let us know what you find wrong. I made a long road trip this past weekend (1000 miles) and was pulling a trailer and thought I was feeling some surging when I got into the throttle in the mountains.

 

[GoHideTheAsian]

yeah adding on, not necessarily also, i had 2 fouled out plugs and was mis firing at WOT the check engine never came on until it was so bad merging on the freeway was almost impossible. and that was after driving a good 400-500 miles after it started to go bad.

 

[tannerc]

random mis fire

I had the codes read and i gave me random misfire on one and then a random misfire on two.

The problem is much more noticeable in the wet crappy weather we are having here today.

I am seriously thinking its the o2 sensor, but i cant get a code saying so..

any thoughts?

:frog:

 

[tannerc]

2 o2 sensors

So are there 2 o2 sensors on this thing?

 

[Qyota]

Yes, there are two O2 sensors. One before the cat and one after. But, I doubt that's the problem, since wet weather would have little effect on that.

I'd stick with the ignition check-up. Plugs, wires, MAF, TPS (both of those sensors can be checked, I think.

 

[Pikeman]

Just went to wash my truck and got a temporary misfire, if your plug wires and boots are worn even a little bit of water can cause a misfire. I would start with new plugs and wires.

 

[tannerc]

passenger side done, driverside when i get back from work this week.

 

[JeremyH]

Just went to wash my truck and got a temporary misfire, if your plug wires and boots are worn even a little bit of water can cause a misfire. I would start with new plugs and wires.

Yep, agreed!

I just went through this the night before a 1000 mile trip. The code was 306 and it ended up being a bad cylinder #1 plug wire.

 

[tannerc]

well plugs changed

http://www.toyota-4runner.org/showthread.php?p=460978#post460978

weeeellll i got the plugs changed and maf cleaned.. found some terrible looking shat on cyl 5

new topic and pics in link above