AWSOME lack of power... Help

[offroadbob]

Well lets start off by saying search is an awesome feature... This all started after I built up a engine from spare parts. The engine is all stock except for a spectre filter modified to work on the stock intake piping. At full throttle the engine is very doggy it almost feels as if it is getting too much gas. At around 4500 rpm it gets even doggier (all at full throttle). Once it reaches 5500 rpms it cuts off and bounces down to 5000 then slowly reaches 5500 again but wont go past. Now if I let off the throttle a little, at the high rpms I can milk it all the way up to 6300 rpms. I can't figure it out.these are the things I have tried... 1-Cleaned MAFS. 2-unplugged O/D sensor (5th gear sensor).3-changed out TPS.4-Re-grounded engine and chassis.5-checked and rechecked timing.6-removed cat.7-new fuel filter (300zx filter).8-new spark plugs (ngk iridium).9-high octane chevron fuel (after that didn't work I tried octane booster).10- checked and rechecked to see if any vacuum lines were missing or leaking

if anyone can help please I beg you please help!! I thank you in advance

Peace,Matt

[niemczykj]

timing.

[niemczykj]

clogged, or dirty injectors... run some injector cleaner through it... ^ sorry i didnt see that u had checked timing

[offroadbob]

Well at the moment I have a can of seafoam running through my fuel system. I am going to buy another to run into the main vacuum to clear out my intake. we will see... I might as well re check my timing again, just in case. It almost makes me want to pull the engine tear it all down again and clean and replace everything. If anyone else has any ideas please let me know.

Peace,Matt

[eazye2000]

Man, my SOHC KA did that same crap man. I never figured it out totally. I took the car to a shop(back before I knew how to work on cars) and they said it was 2 teeth off with timing. So they fixed it, and it brought the RPM's up a bit higher, but still bogged up high. But STILL taking about 10% of the throttle away, made it rev up the rest of the way.I had the ECU reset, the timing chain corrected, and timing set to I think 15 BTDC.. Even put in a Blaster MSD coil an a 6AL box. Didn't fix it.

This was totally irrelevant, and a waste of your time guys. I apologize..

[offroadbob]

Yea it's weird... My car was doing the same thing before back when I had the bottom end that I am using now in my car. but that is the only thing that is the same as before. It has a new timing set, newer head and cams. I have a video of what it is doing. here is the link... http://media.putfile.com/car-bogging . the p0446 code is just a stupid code because of an emissions evap canister vent control valve (which I replaced and is brand new but the code is still there after clearing it. I think it is a bad boost sensor <- a sensor that measures the vacuum pressure). i couldent get a good representation of how high I can go with partial throttle cause of stupid traffic. Oh well maybe soon enough I'll have my built engine w/ my turbo and all in my car and all will be great. I appreciate all the help, and anymore that I can get.

Peace,Matt

[offroadbob]

bump

[offroadbob]

Well today I'm tearing into my engine again... I'm going to try and replace my timing set again maybe there is something screwy there.

Thx for the advice...

Matt

[Rekless KA]

While your in the engine check to see if your valves are opening and closing fully and correctly, that also could be a issue!

[offroadbob]

Well, after pulling the valve and timing covers I didn't notice anything out of the ordinary. The timing marks were all lined up and everything checked out. I buttoned her all up again and she was running the same (go figure after not changing anything). I have a feeling it may be something in my fuel system. I have been to lazy lately but I need to go and buy a fuel pressure gauge so I can see the output that my fuel pump is putting out... Hell its time to upgrade anyways. Recently, for the last 2 days it has been surging... it will be all doggy and then out of no where it will have a burst of power. So, I am pretty sure it has to do w/ fuel or w/ my computer. I'm pretty broke at the moment so it will have to wait till next month to start buying parts again. Luckily I have a spare IACV that my buddy pulled for me at least thats what I think it is (looks like the one in the FSM) so I think that may fix my Check engine light. We will see.

These are pictures of the IACV that I have. This is what it is Right??

thanks for all your help and patience reading my posts

Peace,Matt

[maik21]

u need to check ur fuel pump pressure and ur fuel filter... i have the same problem with my dads truck... it cant past from 3000 rpms on any gear.. but in neutral... i was able to slowly reach to 6k rmps. so check it. maybe ur fuel filter is clogged.

[offroadbob]

I replaced the fuel filter w/ a brand new 300zx filter about a week and a half ago w/ no remedy. I am now getting another code on the scanner P0505 which actually is the IACV according to the FSM so when I get the ambition to take off my intake manifold (which is a pain in the a$$ because of bolt placement) I'll change it out w/ the one I got from my buddy assuming it is what I think it is. Again thx for the input.

Peace