Alright I will try to explain this as best as I can in hope that someone on Honda Tech can help. So ive been having this problem since i got back from deployment a month ago and I've taken my car to numerous shops to no prevail. I have an EM1 Si with 65xxx miles thats set up for show (stereo, custom box and what not) so its a little heavy. Has DC headers, Apexi N1 exhaust, AEM V2 intake, AEM fuel rail, stage 2 clutch and flywheel, and a couple of other small mods. Ive been getting horrible gas millage, like 150 miles to a tank on premium. My problem is that when i start my car after its been sitting all night or for a few hours, its picks up great, no issues. it feels like the car is light as a feather. after about five minutes of driving it begins to feel bogged down. i have to rev it higher to get it rolling in first and it takes off slow almost like the ebrake is on just a bit. when shifting it just feels like im towing something, like something is pulling it back. also in usually in 2nd and 3rd, the car sputters while picking up, not the engine, but while accelerating it feels almost like its getting too much fuel and its getting bogged down, you can feel the car go then hesitate then go then hesitate but it happens fast so its more of a shake. What doesnt make sense is that for the first five minutes when its still cold it feels like its a miata with a v8 in it and then 5 minutes later changes. I take very good care of this car, i never shift past 3500 rpms with the exception of when my car does this and im pulling onto the highway and i always take meticulous care of it. HOPEFULLY!!! someone can help or atleast give me some ideas on what it could be. Any help is much appreciated!!! Thanks in advance!!

 

Have you pulled your spark plugs and read them?
Heres a good guide:
http://www.ngksparkplugs.com/tech_su...qs/faqread.asp

 

Sparks plugs are new... well 8 months ago they were but the car sat in my garage for 8 months. my wife started it and let it run a couple times a week. but i checked the gap and they are good. Also, forgot to mention no CEL and i did a service on it a week ago including professional injector cleaning. Ive found some other threads with people having the same problem but the suggestions are everywhere from dizzy to timing, thermostat, all sorts of stuff.

 

Does your temp gauge still act normally?
If not then its the thermostat

I don't think it's the ICM or distributor since you are getting such horrible mpg, I would think it is fuel related instead and would lean towards it being the knock sensor which means you are probably best off getting a chipped ecu with it disabled.

Also don't get those professional injector cleaning services, they are rip offs, unless you mean your injectors actually got pulled and sent off for a cleaning then that is fine. But usually garages just run a $5 bottle of junk through your engine and then charge you $90 for it, just seafoam your car next time.

 

I think when i get off work tomorrow im gonna check my timing to make sure thats good. I dont see why it wouldnt be but just to be safe. My car idols fine though and runs fine but i guess we'll see. and yeah im pretty sure it was just the bottle of **** through my engine thing, it was a whole package thing cuz when i got back i got all the fluids changed. but to note, it was doing this whole thing before i left. what about my vacuum lines. would that even make sense if the car pulls fine when cold but not when in normal op temp?

 

Also try running the car till its warm then turning it off and pulling the o2 sensor and turning it back on to see if it still bogs.

 

No it wouldn't be your vacuum lines, if it was a vacuum leak then it wouldn't bog constantly, the RPMs would bounce. I'm putting my money on a bad O2 sensor or bad knock sensor. I'm leaning more to the knock sensor though because an O2 sensor is pretty much a guaranteed CEL whereas the knock sensor isn't known to throw a CEL.

 

Just wanted to give an update here. I know its been awhile but ive been working a lot. So after reading the other threads with this same problem a lot of people found it to be there timing. I checked mine and found it to be a couple teeth off so atleast thats something in the right direction. My buddy said he had a GSR that did the same thing and it was timing. my belts pretty bad right now too so this weekend im gonna replace it and fix the timing issues. hopefully thatll fix it. Thanks for the help and ill let you know what happens