perzn

hi guys i have a 77 280z with an ls1 and t56. i just got done with my swap. i have a slight problem. it runs fine in idle but when in gear it hesitates, when flooring it there isnt any power, it just gradually climbs. the ls1 is from a 98 vette and the t56 is from a 2000 camaro. ecu is from psi conversion. . im just suspecting its the maf but i need someone to help me verify the problem. i will buy an aftermarket fuel pressure regulator. i used a diagnostic scanner at work, all voltage was fine, my 02 sensors are not connected, dont know if that interferes with my problem. i am stumped. all help is appreciated.

perzn

bump..........

chrisfrost

iTrader: (8)

When starting You're engine for the first time , all the sensors need to be hooked up and preferably the pcm memory cleared and when You start it don't give it any gas for maybe 2 min , then be kinda easy on it with the revving and drive basically normal for the first 10 or 15 min ,,,,,,,,,,to allow the pcm to start calibrating fuel trims and timing ,,,,,,,,,,,,,,,,,probably the O2's not being hooked up is the main problem .

parks450

iTrader: (17)

^ agree, without your o2's your computer cant get the right air/fuel ratio. So when you stomp on it your most likely getting WAY to much gas. I would say hook them up before you go any farther. If you want to test your MAF just unplug it for a few seconds ypu sjould notice a change in idle. If not its most likely bad.

perzn

Just ordered the maf. Idle didn't really change. So if I get o2 sensors. Do they have to be connected to the exhaust if I just want to test that the car is running in a normal condition? Because I have some shorty headers and the rest of the exhaust is not fabricated yet and installed due to low savings.

parks450

iTrader: (17)

To just see if its going to start, no. but put them in the ends of your headers to get somewhat of a reading. If it still runs like ****, change the plugs since they will most likely be fouled out due to too much fuel.

perzn

Shouldn't be fouled. They are brand new. I guess I need to get o2 bungs welded and a full exhaust :/

parks450

iTrader: (17)

Yes on the exhaust. no they shouldnt be fouled.......but like in my case after I swapped my iron block ls1 into my s10 I fired it without exhaust and within 15mins I had lost 6 cylinders because the plugs had fouled out from so much fuel. Oh and ths plugs I had in their were $115. the plugs were the best you could get.

perzn

yea i hear ya i got ac delco plugs for around that price or more.

COPO9560

Get the O2s hooked up and with an exhaust system. On headers only, life expectancy for O2s is very short.

perzn

Thanks for letting me know. My o2 sensors should be coming in on Friday. Any one know an average price for a custom exhaust? I would have to have single exhaust since my Z tank keeps me from having a dual setup.

perzn

have my new maf hooked up and o2 sensors sort of. can the codes p0650, p0480 and p0481 interfere with running rich? i dont think p0650 should interfere its for my mil light and 480 and 481 are for my fan relays which are hooked up with fusible links and fuses to the pcm. help is greatly appreciated

Whiteaw57

iTrader: (2)

until you get the O2's hooked up correctly (not sure what sort of means) with a good amount of pipe behind them as well (youll need it for a good reading) I think were all still just taking a shot in the dark. If you just have the O2s behind open header thats useless. You're gonna get a very false reading that way.

perzn

thanks your answer is very helpful. "sort of" as in one bolt on each side cant be fully tightened, since the socket gets stuck when fully tightened with an impact gun. so their is a slight exhaust leak:/

Whiteaw57

iTrader: (2)

Ok thats not as big of a deal as open headers but not ideal either. If your codes arent the culprit then we've just got to keep looking.

perzn

fixed it, woo hoo! i noticed that their was a possibility that the driver side coil pack harness was probably flipped, as i was checking for fouled spark plugs. when i flipped it i made sure the wires were in correct position, i was thinking maybe one of those colored wires that get a signal from the pcm was probably getting the wrong pulse to the wrong coil pack. so i took a chance on flipping the harness. when i started it up it ran smoother and motor did not look like it was shaking. as i took it for a spin, the motor came alive with full power with no hesitation and stumble or misfire. so basically the plugs that were on 1 and 7 were switched and 5 and 3. and it solved my problem. before it sounded like it was cammed and now its really smooth. this extra info is for people who possibly ran into the same problem as me. hope this helps for future ls1 swappers.
p.s. but their is a slight back fire when slowing down and throwing the car in neutral fyi