I just bought a 1996 e-150 4.9 quigley 4x4 to haul around bikes and motorcycles. As excited as i am i know almost nothing about them except it looks like an animal and for 1000 bucks i couldnt say no. The day after buying the van a y pipe in the coolant system busted and the van overheated. Had it towed home and replaced the t connection. After this the van had been throwing engine codes. p0171 p0174. So basically bank 1 lean bank 2 lean. I had a mechanic check for vacuum leaks and it was leaking around the pcv valve. I got a new pcv valve and boot slapped it on the bad boy, cleared the codes and i was off..... for about 20 miles. Then i get the codes back. The next day i take it back the guy says maybe its an 02 sensor. Ok maybe its the o2 senor doesnt seem like confirmation enough. And no o2 sensor codes were thrown anyways. That line of thought got put on hold because the Next morning i fire it up and it stumbles after start for 30 seconds then clears up. After it threw two new codes in the mix p0300 and p0385. Something to do with misfiring? I read a little about this and that all the while the van starts up fine after its been driven but leave it over night or for a few hours it starts up and shakes and rattles for about 30 seconds and then calms down. Its been about a week. I got a fuel pressure tester last night and hook it up. 45-49 psi idling, 45 - 55 while driving around. Leave the tester on there for 45 min after i came home and vandolf is down to around 20 psi. On start there is no smoke as i was under the impression leaked fuel through the injectors might throw off some smoke. When it is running there is a smell of fuel but i cant see any fuel leaks anywhere and it could also be the rust hole in the floor. Not to sure on that one. (1000 dollars and it came with rust. I live in CA so thats rare, i thought, meh rust is the new black). So far ive checked the volts on the maf and that seems to be ok, while im driving around i have my scanner hooked up to the car it shows the three 02 sensors reading between .1v and .9v. Fuel trim seems to stay between -13 and +13 (i dont know if this matters but since i am clueless about this thing any info might help). the obd reader does say when i have my foot off the throttle the throttle position is 18.8 percent. I thought that was odd but again what do i know. Im not sure what this could be. I feel like the fuel pressure shouldnt die down like that and that may be whats causing the van to start so ****ty after being left overnight. but does that cause the 171/174 codes after ive been driving 15 min to 45 min. Not sure if the two problems are connected or not. Im trying to narrow down what is causing this before i start throwing money and parts at it. Any help or info would be appreciated.

 

Hi mytilll,

The fuel pressure dropping that fast sounds wrong. If it is bleeding off through the injectors that is a lot of fuel which could end up passing the rings and into the crankcase.

I have pulled and cleaned O2 sensors. I know all the experts say it won't work but I gently scrapped the crud off mine and wire brushed them by hand and they began reading correctly. Worth a try at least to troubleshoot.

Before starting it the next time, cycle the key from off to run several times to see if the pump will build pressure before starting. If it is starting with 20 PSI, the mixture will be very lean and that could be causing the stumble until the injectors get the right pressure.

jim

 

When i cycle the key there is a little difference in the cold start but not much, it still runs bad and throws misfire codes for about 10 seconds then it settles down. Ive been running the scanner while driving checking the fuel trim. The long term fuel trim on bank one when idling or letting off the gas goes to about +13 for bank 1 and +20 for bank 2. While driving it goes down to about +3 bank 1 and +8 bank 2. Any ideas? I replaced the downstream 02 sensor and no difference. is there a reason the bank 1 and bank 2 would be about 5 percent different most times?

 

Here's a link to a discussion very similar to yours, might help:
https://www.ford-trucks.com/forums/1...rame-dats.html

jim