engine chug/hesitation..HELP!!

[odie301]

ok i have an 04 tahoe w/ 135k miles on it.. been running like a top until lately. Seems like now (maybe started a couple weeks ago, which is when it got colder here but not sure if that is part of it)... when going down the road and trying to lightly accelerate i will get a hesitation. It will do like 2-3 good chugs and then smooth out and accelerate fine. If i sit in drive with the brake on for a while i will get a chug every now and then. Is this something to do with my fuel system or ignition or??

My wife even notices it when slightly accelerating down the road..it chugs hard..almost like a tranny problem but i don't think it is that due to it chugging a bit at idle. Under full accel u can hear it miss a bit but dont feel it.(my exhaust makes some extra pops instead of a smooth pull sound).

Anybody have ideas?? I did just recently change spark plugs and got an increase in mileage(put in e3's went from 16 to 16.5) but this started a month after the plugs. I also added lt headers, and haven't had a re-tune if that could cause it..but the headers were on for probably 2 months before this started.

HELP PLEASE

 

[Rivieraracing]

Fuel pump may be on the way out, but try cleaning out the throttle body real good with some TB cleaner, and while you are at it if you haven't done a fuel filter for a while do that too, worth trying the easier less costly stuff before the others!!

 

[lowAZhoe]

u got oil on your air filter? like a k&n or something? clean your mass air flow sensor if you do, and do the throttle body service. fuel filter is a good ides too. if none of that fixes it...its probably a fuel pump.

 

[Rivieraracing]

Yeah, also get yourself some MAF cleaner and clean it out as well, get only the stuff specifically for your MAF sensor and do as the directions tell you and DO NOT USE COMPRESSED AIR TO DRY IT OUT, you will be buying another one if you do!!

So do these:

Clean MAF sensor (just as lowAZhoe mentioned)
Clean out Throttle Body
Change out your Fuel Filter
Check your plugs and make sure they are good and gapped to .040
Do a "Seafoam" treatment through the brake boost hose
Dump some seafoam in your gas for the injectors

These are easy maintenance items that don't cost a ton, might do the trick without dropping the tank to change out the fuel pump!

 

[odie301]

Well i just did a 3-part fuel treatment a week ago, which cleaned the tb, intake and had an intake cleaner. My maf sensor was cleaned a month ago when i cleaned my AEM air filter...so no oil on my filter. I did a fuel filter a year ago so i is probably time to try that first.

Also on my e3's they are fixed at .060

 

[pmbiker]

O2 sensor, one or more of them.

 

[LazyAssLou]

Maybe the Cam Sensor, mine was doing the same. Ended up messing up my CAT too...

 

[odie301]

Well i did the fuel filter..so far it seems to have done nothing. the only o2's i have are the front ones. I have an off road y pipe and no rear o2's which were shut off during my black bear tune.

the part i don't get is..why doesnt a check engine light come on?? it chugs hard like a miss or a knock and does it in a series of 2-3 at a time...but never throws a code. Maybe it does 2-3 but they are all on different cylinders so a code isn't set??

 

[odie301]

fuel filter helped a little bit when i drove home. it made the slight acceleration chugs a bit less noticeable but still there.

Anyone know where to get a fuel pump for a good price?? mine is a flex fuel..so far the best price i have found is $240 through napa.

is there a way to test for the cam sensor thing?

 

[rigo_jones]

try ebay for the fuel pump.

 

[odie301]

ok..i finally got a check engine light..but it was not so helpful. it came up as a P0300..showed as a "random misfire detected" which obviously makes sense because of the chugging.

My dumb question about it being a bad fuel pump is..wouldn't it start hard? it starts right away makes me wonder about a fuel problem. My other thought was something to do with spark, either plugs/wires or maybe a bad coil?? It runs great cruising down the highway just when you get on the gas enough it acts up

 

[Suburbinator]

When one of my O2 sensors crapped out, it did the same thing. Never threw a light or code either.
I don't have experience with E3's, but I only trust the OEM style plugs. I had so many issues with Bosch Platinums back in the day, I swore I'd stick to the basic replacement plugs.

 

[odie301]

I think i finally figured it out...one of the E3 sparkplugs was all messed up... due to "someone" dropping it when installing them. Yeah i goofed and dropped it..and it hairline cracked it. So when i pulled it out tonight it had cracked enough that the ceramic around the elctrode slid up and down on it. So after replacing it with a good one, and not dropping it, it seemed to run better on my way home. so hopefully that is it, i hope i didn't wreck my coil or anything

 

[saturday]

Odie - my 04 Denali was just doing the same thing. its the throttle body or the gas pedal. one of them is failing to transmit or receive the signals. seems random i know, but i ended up replacing both before i figured out which one was failing.


DOH!
dee de dee

2 hours late and i still had the wrong answer! tomorrow will be a better day.

saturday

 

[odie301]

i thought it was better after replacing my dropped plug..well part of it is better but it still does it. I notice it a lot more if you accelerate hard that any time it goes above 3k rpm it really starts to miss and pop. I was wondering if it could be an ignition coil that is going out?? is there any way to test them?

is there a way to test the throttle body theory out?

 

[saturday]

my mechanic was able to test the calibration between the throttle and the TB. i dont know how to, but i know someone here does. My problem was only during low RPMs though. would die just about anytime it idled. frustrating on mopac @ 5:30.

 

[pmbiker]

When my O2 sensor(s) crapped out my symptoms were a little different. I had rough idle, hesitation at cruising speeds and black exhaust (too rich) at WOT.