Slow starting and bad lag

[dsmupcomer]

ok so i did an engine swap and now my car takes about 10 seconds to start on crank, but when its cold i have to continually pump the gas so it dont die out. now i wasnt really worried about that ### the car ran perfectly fine other than that. now i changed the exhaust out from the header back and now my car sputters but not to where its gonna die out. It only does it while the car is under movement and not during idle. I changed the crank sensor, cam sensor, plugs with ngk 7s, wires and ignition coil and fuel pump. The thing that gets me is it will happen rarely in 1st and second but always in 3rd, 4th, and 5th and when i keep it at a steady rpm it dont do it, just when i give it some gas. fp sits at 30 psi before start and 50 psi while idling. my only cel that i had was my o2 sensor which i dont have and my cam sensor which i changed out but have not yet been able to retest the computer. im clueless as to what it can be. now what if i was losing back pressure on the exhaust? would that make a big difference?

 

[Wil_Own]

Have you tried cleaning your IAC someone was having a problem kind of like yours but you IAC has alot to do with Idling your car and so fourth try that before you spend more money on it

 

[Perkul8r]

a free flowing exhaust should not make a car run like that. I mean, i have had alot of straight piped cars, and never had a problem with it.

Have you tried resetting the computer since you changed the sensor?

 

[dsmupcomer]

i honestly dont have a problem with idling. the car idles fine. it only seems to lag when its under a load. now resetting the computer just consist of unplugging the battery. i ordered a new iac but when i got it in the mail it was the wrong plug so i gotta see what i can do about that.

Yesterday while i was driving i lost power as it seemed to be a miss. while the car was running i unplugged the #4 spark plug wire and the car died. plugged it back in and started it and still seemed to be a bad miss. unplugged the #3 wire and the car didnt die, still a miss obviously, plugged it back in and the miss stopped. weird ocassion is that the spark plug wires are as tight as they can be. im lost.

 

[clipto]

Are you running NGK BKR-6 gapped to .045ish for plugs? I heard Granatelli spark plug wires where good not sure tho. Check over everything make sure everything looks good. Did you replace fuel filter too when you did the swap? What spark plug wires you using? Fuel pressure should be no less then 45 psi close to 50psi. Fix those things then let me know.

 

[dsmupcomer]

im running ngk g bkr - 6 power platinum plugs gapped at .45 with import direct wires from autozone to see if it was my wires which it cant be because im getting a good spark from the wires. now is 45-50 psi with the key turned forward or the car running?

*****update.. changed out the iac and still nothing. have a little more power and it does not lag as bad. any other suggestions?

 

[dsmupcomer]

how do you expect to get help on this website if no one replies to your post?

 

[drobin8]

Did you check tps. Mine did similar to what you explained and I changed it out after checking several other things. Also I seen this problem like you described when the cat converter is plugged. Idles fine then when you get up and go flow is decreased and the problems start.

 

[dsmupcomer]

its a free flow catalytic converter. and thats about the only sensor i have not changed.