my 99 limited has random power loss and bucking when wrm

[xspsi6]

This just happened overnight seemingly and no codes or even pending codes so new oem plugs and wires also new fuel filter made no change.
The back fire through the intake has me really scratching my head

It uses a ton of fuel and after its warm the hot start condition can be rough it also is very sluggish compared to my 2 other runners I have searched to no real hits as to the cause so today I will get out the parts cannon and start changing stuff like the maf cps etc etc with known good ones but the fact that it throws no codes has me baffled to no end oh and the mechanical timing is right on so not that either

i see people have had this problem before but found no real solutions so does anybody here have any insight to what I may be missing?

 

[Paperjam]

Back fire through the intake? You're sure the timing is right? That and poor power combined with no CEL screams timing issue. Unless you have a coil that's breaking down under heat or a crank sensor that's dropping the signal it doesent make sense that you have a backfire through the intake.

The next thing down the line is a burnt valve or a bent valve.

 

[gamefreakgc]

Try cleaning the MAF. It might be fouled up and putting in too much fuel or the Intake Air Temperature sensor (part of the MAF) could be fouled and reading the wrong temp. I would not just throw parts at it unless you've got spares or someone willing to swap since the OBD-II system will throw a code if it was getting a bad signal from a sensor.

Backfiring is sometimes a valve issued like Paperjam mentioned. Could be an intake valve stuck open. Have you ever adjusted the valves? How many miles?

 

[SpidermanGeek]

Clogged Cat?

 

[jeremyc74]

Try cleaning the MAF. It might be fouled up and putting in too much fuel or the Intake Air Temperature sensor (part of the MAF) could be fouled and reading the wrong temp. I would not just throw parts at it unless you've got spares or someone willing to swap since the OBD-II system will throw a code if it was getting a bad signal from a sensor.

Backfiring is sometimes a valve issued like Paperjam mentioned. Could be an intake valve stuck open. Have you ever adjusted the valves? How many miles?

MAF sounds like a likely culprit to me too. Sometimes you can tap on them while idling and hear it misfire. If it does that it's bad for sure. I had one on a Nissan fail like that.

 

[xspsi6]

it has 192k miles and I was able to spray maf cleaner on it and it ran fine all day but tonight started acting up again now it is throwing a system too lean bank 1 code

I swapped the maf from my wifes 99 limited and it it known good but made no difference and I am sure the timing belt is lined up properly also I am thinking a coolant temp sensor even though on the live data stream it shows proper temps.

The problem seems to be coming and going as of now.

 

[nissanh]

How about the throttle position sensor?

 

[xspsi6]

I thought about that and the data feed only shows 76% when wot so that may be an issue but I will have to hook it up to my runner and compare values.

 

[LittleCaesar]

Usually a backfire in the intake is caused by a fuel delivery problem, or for what I have seen. My friend had an old 96 318 Dodge that was dumping excessive fuel into the engine, turned out to be a leaking injector that did not throw a code. We could smell gasoline when pulling the vacuum line off the regulator so that was replaced at the same time.

Any leaks in the intake?

What where the fuel trim readings via the live data?

How old are the O2 senors?

 

[gamefreakgc]

How old are the O2 senors?

That was going to be my next suggestion. Bank 1 refers to the front O2 Sensor sensing a lean ratio.

Have you checked for vacuum leaks? I know I just posted this yesterday... but this video makes checking real easy:

https://www.youtube.com/watch?v=9CPqbaSgcok