Engine Sputter/bog?
 

Hi all, i have a 2000 GMC Jimmy, i know this is a Blazer site, but hey, what is a Jimmy but a blazer with different badges, grille and headlights? Lol.

But ok heres my problem. When i accelerate, expecaly from a dead stop, and get to 2,000 RPM +, it seems like the engine bogs down about 100-300 rpm and then back up then down and then up and then shifts. And when i lock in my cruise at 70 mph, it holds at 2k rpm, but then randomly it jumps up to 2,300 rpm, but still holds 70 mph. Also holding 70mph i feel like a pulsating feeling.

Replaced items: Fuel Filter, Fuel Pump, Spark plugs, Plug Wires, Cap and Rotor, Throttle Position Sensor, alternator, u-joints.

Service engine soon light is on, and when ever i scan the OBDII, it comes up P0147, witch is an 02 sensor. It has a Cold air intake, with a cone filter. And it Does NOT have a Catalytic converter (got the vehicle like that). And i am running one size bigger tires (235 75 R15) instead of the stock (235 70 R15).

Ive been told it could just be the 02 sensor telling the computer its poluting to much and to back down, but idk. and i was hopeing someone had the same problem, cuz i cant afford to keep playing replace this and that till its done.

Sorry this is so long winded, ANY help would be GREATLY appriciated.

The code relates to a possible problem in the heater circuit for the O2 sensor.

Not a fuel problem. Quite often a bad wire connection. Unlikely to cause the problem unless it's shorted somehow in the wiring harness to the transmission. And that does sort of sound like a transmission problem.

P0147 02 Sensor Heater Circuit Malfunction (Bank I Sensor 3)

I stopped at like 4 different repair shops and explained what was happening, and at one a guy told me it was more then likely the 1-2 shift solenoid. So I went to my local gm dealer, cuz apparently it's the only place to get them. But I got 2 cuz I figured if I'm going in to change one might as well do both, and they only l about $25 apiece. But changed them and that seemed to do the trick. Been in for a week now and hasn't done it.

cool. And you did it without pulling valve body, right?

Just had to pull off the tranny oil/fluid pan, and boom, they are right there. Takin the Pan off took longer then changing both solenoids. Took literally 2 min, including fumbling around for my flat head screwdriver, lol. There are a couple vids on YouTube. Just search 4L60E transmission shift solenoid.

Sounds like you did alot of guessing.

We try to promote troubleshooting a problem (Cheap) instead of guessing (Expensive)

I hope that solved your problem. If it didnt, search Random+hesitation and see if anything there could help you.

The 70 mph jump in rpm sounds like the lock up converter was kicking out. Just keep that in mind.
Good luck.

Well it seems I fixed the pulsating feeling too, put a catalytic converter on and replaced the o2 sensor. So I'm thinking it was either the o2 sensor or a lack of back pressure. Thank you for all the advise y

Ok so I accidentally lied. All that didn't fix it, aparently it was acctually my timing was WAY OFF! Took it to a mechanic and he has come across this problem before. And he said mine was -13 degrees off. He brought it back to zero and fixed the sputter problem. And has also told me that my mass air flow will need to be replaced soon.