97 S10 Pickup Throws P1351/p0141 With Hard Start

NTL1991 · November 21, 2008

Hi, I have a Chevrolet S-10 Pickup 4x4 that had the 4.3L X-Vin V6 Engine. After about 165,000 miles, it threw a rod and the engine was replaced with a W-Vin V6 long block. Everything was brought over from the old engine except for a new intake manifold (might have just been the cover), Motor Mounts and the Oil Pressure Sending Unit. Distributor, Cam/Crank Sensors, Computer, Fuel Injector Spider, ICM, etc. are all original.

After putting this remanufactured long block engine in it seems like my gas mileage is much worse than before. I am only getting about 10-12 MPG, no matter how I drive... But the most important thing is driveability issues. With all codes reset and the engine computer unplugged, the truck might start up within 2 seconds of cranking and start fine. It might, though, like it does most of the time, crank for about 7 seconds, start, RPMs will rise to about 1100 and it will stall unless I floor it for about 2 seconds to get the RPMs to about 2500 and then slowly let off the gas. If it stalls, it will start up perfectly on the second try if I try again immediately after it stalls. When it stalls, the computer throws the P1351 code. This can happen when the engine is stone cold, or at operating temperature. Once the engine has run and I turn it off, if I start it right up again, it is usually fine.

I have changed the spark plug wires, distributer cap and rotor, along with a vapor canister purge valve. I have great engine vacuum and 60PSI of fuel pressure with the key on and also with the engine running. When I quickly open the throttle, the fuel pressure jumps up about 5PSI or so and then works it way back down to 55 or so and stays there. Though, When I check the fuel pressure after the truck sits for about 6 hours or so, it is close to 0. Overnight, there is NO fuel pressure. I have noticed though, that sometimes when I turn the engine off and take the key out and get out of the truck fast, I can still hear the fuel pump on for a second or two.

I've heard of leaky Spider Units using the old poppet valves and the new upgraded MFI unit that can be installed, I've heard of bad fuel pressure regulators leaking fuel into the cylinder so the engine has to burn it off before starting... What could this be?

I have also noticed that when I am crusing down the road or highway and if I let off the gas to maintain ENGINE speed, I will get a slight misfire. This also happens when the cruise control is on.

What I think is wrong might be, as mentioned above, a leaky fuel injector/whole unit/poppet valve, leaky fuel pressure regulator, improperly programmed crankshaft position sensor, distributer that's maybe off a tooth...

I mention the crankshaft programming because the engine replacement was done at a local shop here in town, and I doubt they have the means to repogram and train the sensor there. Wouldn't it throw a code if it wasn't trained properly, though?

I can post a "Data View Chart" from my scan tool if seeing Short Term/Long Term fuel trims would help or if Ignition Timing Advance would help. I did notice that last time I scanned, my fuel trims were erratic, they would go from like 80% to like -75% and back and forth...

If anyone could shed light on my problem, I would greatly appreciate it!

Thanks,

Nick

NTL1991 · November 21, 2008

Here's the freeze frame information right after the engine started up rough.10_7_08_Startup_FF.pdf

Here's the freeze frame information at idle10_7_08_Idle_FF.pdf

Here's the freeze frame information when maintaining 1500RPMs10_7_08_1500RPM_FF.pdf

Here's the freeze frame information when maintaining 2000RPMs10_7_08_2000RPM_FF.pdf

Nick

10_7_08_Startup_FF.pdf

10_7_08_Idle_FF.pdf

10_7_08_1500RPM_FF.pdf

10_7_08_2000RPM_FF.pdf

10_7_08_Startup_FF.pdf

10_7_08_Idle_FF.pdf

10_7_08_1500RPM_FF.pdf

10_7_08_2000RPM_FF.pdf

10_7_08_Startup_FF.pdf

10_7_08_Idle_FF.pdf

10_7_08_1500RPM_FF.pdf

10_7_08_2000RPM_FF.pdf

Frank S · November 21, 2008

Topic moved at OP's request.

NTL1991 · November 25, 2008

After starting the truck up this evening with the same long crank and stall, it started up find and I ran the truck down the street to pickup some takeout. When I left there to get back home the truck started fine. When I got home, I noticed that one of my plow light blinkers was out so after I turned the engine off and moved the key to RUN so I could operate the blinkers to test the lights, the fuel pump wouldn't shut off. After I turn to key to run, it usually only lasts for about 2 seconds or so, but this time it kept running. So I didn't turn the key off, but just started it from there and the engine ran very rough, almost like if two spark plug wires were crossed. The check engine light was already on, but I scanned it to check if any were new and there was a P1361 registered now...

Should the P1351 and P1361 lead me to believe that the Ignition Control Module is gone?

Nick

Draenor · November 25, 2008

After starting the truck up this evening with the same long crank and stall, it started up find and I ran the truck down the street to pickup some takeout. When I left there to get back home the truck started fine. When I got home, I noticed that one of my plow light blinkers was out so after I turned the engine off and moved the key to RUN so I could operate the blinkers to test the lights, the fuel pump wouldn't shut off. After I turn to key to run, it usually only lasts for about 2 seconds or so, but this time it kept running. So I didn't turn the key off, but just started it from there and the engine ran very rough, almost like if two spark plug wires were crossed. The check engine light was already on, but I scanned it to check if any were new and there was a P1361 registered now...

Should the P1351 and P1361 lead me to believe that the Ignition Control Module is gone?

Nick

I noticed on your LTFTs on Bank 4. The PCM is cutting the trim down alot, with the exception with the last screen shot. That is telling me that your running rich. Plus the leak down you mentioned before tells me, this could be from the spider(reg, poppet, injector). Try running a fuel cleaner, this could clean up the poppets, if not the spider may need replacing.

Now if the ICM is not operationg correctly it could cause the stumbling and rich fuel condition. If this is so, I would beleive the condition would be in both banks. Try disconnecting the battery and checking for codes. If the ICM comes back up you could have a short in a wire somewheres, or worse the ICM or PCM is bad.

IMO..its the spider.

NTL1991 · November 27, 2008

Thanks! I had a hunch it was the fuel injector unit so when I get the truck back I will look at that, maybe replace the spider with the factory MFI replacement unit.

I Appreciate Your Help.

Nick