runpasthefence

iTrader: (2)

Hey guys, I got my 1969 Chevy C-10, LQ9-4L80e running last week and now I'm trying to figure out why it isn't running right.
I'm showing the following codes.

p0171
p0174
p0753
p0758
p1860

p0171 & p0174 are lean codes for each bank. When I first saw this code I checked fuel pressure. It was only about 40psi at idle. I adjusted the fuel pressure regulator (truck manifold) until I reached 58psi at idle at the crossover rail.
I've checked for vacuum leaks and found none.
I'm running open headers at the moment with only front o2 sensors. Rear o2s have been programmed out of the PCM.
I'm running a new MAF, however I did drop it right after I bought it. I checked the fillaments and they didn't seem to be damaged.

The other codes are shift and TCC solenoid related. I'm running a 4L80 instead of the 60e, so I repinned the trans harness. I'm thinking I damaged the plug when I repinned. I plan to find another plug and give it shot, but I'm wondering if all of the codes are related....

Any ideas?

Shon Herron

iTrader: (25)

Probably getting dirty air since you do not have the exhaust on it yet.
And I think you have to have the PCM flashed for the 80 trans when using a 60e PCM.

I will be picking my my LQ9/80 (16k miles on it) next week to put in my 71 C10 LWB. Should be alot of fun!

runpasthefence

iTrader: (2)

Sweet, where in SC are you?

The truck runs great for 30 seconds or so, then it just progressively gets worse, gets really rich (computer correcting I'm guessing), then will eventually shut down.

12SEC SS

iTrader: (5)

running open headers is your lean problem. The o2 sensors are too close to fresh air, they signal the computer that its lean, and it dumps all the fuel it can into it making it very rich.

im driving open headers right now too with my '49 buick, and each time i connect my hptuners, turn off closed loop and fuel trims learning, if i dont i see fuel trims max out within a block of driving.

Shon Herron

iTrader: (25)

I am in Six Mile, or the Upstate of SC, about 4hrs from Charleston.

get the exhaust on it or go to OL will help a ton.

GA95DCMSS

iTrader: (13)

I agree. An exhaust would help out immensely. These engines don't like Open headers. Ask me how I know lol.

Why adjust FP so high at idle? Mine is at 48-50 at idle. I hit 58-60 as open the throttle more, closer to WOT. Might not be an issue with yours though.

runpasthefence

iTrader: (2)

Thanks guys, that sounds like that's my problem. Kind of sucks that I've got a 15 mile drive to my exhaust shop. Maybe I'll just clamp some straight pipes and turn-downs on just to get there.

I thought the fuel pressure was supposed to be around 55-58psi at idle...maybe I'm wrong? I'll check it out.

Thanks for the input guys.

1967 Yenko Clone

Did you get the exhaust on the truck yet? If so did it fix the problem? I am fighting the same problems. THANKS Wes

ryanvv355

iTrader: (17)

Unplug the MAF and O2's to run it down to the muffler shop, It will run of base fuel maps and should be OK to get you there.

Check the wiring on your trans plug, inspect the connector for recessed pins or corrosion, check power and ground.

The fuel pressure depends on what type of fuel system you installed. The rail mounted regulator systems should have approx 58psi and the returnless setups have about 50ish at the rail at idle. I drove mine with 30 psi for a week and it was able to maintain stoich until it was at high rpm, I dont think 40psi at idle is your issue. I bet its wiring or a bad sensor, who built the harness and programed the ECM?

runpasthefence

iTrader: (2)

Yeah, I went and bought a couple of header flanges, and a pair of turn-downs. I also found I wasn't getting 12v to pin E on the trans plug, fixed that as well.

The truck runs now with no major issue. It misfires on every now and then...I'm guessing because the exhaust is still on the short side. I've only driven it a couple of miles as I still need to tie some stuff up. I've got a date with a muffler shop on Monday.

I'm using a truck manifold with a rail mounted regulator and am now holding a solit 58psi at idle.

So yes, adding about a foot of exhaust solved my issue. I may unplug the sensors like you said anyway.

Leevon

iTrader: (3)

well if you get your exhaust and it's still throwing p0171 and p0174 it could be an intake manifold leak, had this on 2 5.3's had to switch to the new style GM intake gaskets. Prolly just what the others said though, mixed air at the o2's.