Engine will start to bog out under hard Acceleration and then Backfires
Hello Guys I have a question on this Nissan Titan 5.6L i pulled the codes on this unit only came up with a P0037 ( HO2S Heater Control Circuit Low B1S2) which the customer stated he had replace the sensor. Before my road test i pulled TSBs on the Vin number and found Recall Number 10V-517 ECM Relay on the Ipdm needs replacement. Perform my road test found that the engine will start to bog out under hard Acceleration and then backfires. I have not check fuel pressure yet but what i did check was my throttle and app sensor pids on my scan tool and notice something odd with KOEO my APP 1 Factory specs are 0.4V To 1.0V APP 2 is 0.2 to 0.6V fully closed no issue there I slowly push the pedal to floor Recheck APP 1 is 4.0V To 4.8V APP 2 is 2.0v to 2.5V no issues there, I check my TPS 1 And TPS 2 KOEO my TPS factory Specs Are 0.4V To 0.7 TBS 2 is 4.5V fully closed. I slowly push the pedal to floor Recheck TPS 1 is 4.5V TPS 2 is 0.5v to 1.0V What i fine on my scan tool is (TPS 1 0.79v ) and (TPS 2 0.81v ) at KOEO pulled the air intake off to check and see if the throttle plate moves i found no movement perform a idle relean no change, with KOER i recheck the throttle plate now it moves and the TPS 1 And TPS 2 are reading ,so not sure if this is normal strategy for this vehicle or am i chasing my tail on this LOL...
Sounds like it could be a fuel pump issue. I would definitely hook up a fuel gauge and reproduce the fault and see what the fuel pressure is doing. I have also seen a crank sensor acting up that can cause this as well as a clogged cat.. Fuel pressure spec is 51psi at idle.. would start there
Hello Steven Great tip Steven, I will following up on fuel pressure reading and post what i fine Thanks again for your input
Follow the symptom. If you had an issue with app or throttle body, it'd go into limp mode. What are fuel trims looking like? O2 sensor data will show whether you gave a fuel delivery issue or not
Hello Mario Will looks like i was chasing my tail about the throttle body, Lol I will be checking out my fuel trims and fuel pressure and will be posting them as soon as i get them... Thanks again for your input.
Ditto what Mario said. If the throttle body was messed-up that would be the primary concern. You have a bog and a backfire. Check fuel pressure FIRST then investigate wild crazy theories second. Watching the throttle body on an ECT engine in the bay, when all the computers know that the car is NOT moving is rarely very useful IMO.
Great Input Geoff Thanks again
Wondering if replaced with universal sensor. If so maybe signal and heater wires confused.
Michael i will check just to make sure.... Thanks Again for your input
What scanner are you using? It may be buggy and not show some correct values until after the engine starts. What were the oxygen sensors reading during your test drive, especially during the bog and backfire times? As others have said, the throttle issues would cause a limp mode problem not a bog/backfire issue. I would be looking at the fuel trims and oxygen sensor readings under heavy
If that code P0037 keeps resetting after erase, and O2 was replaced with a quality part. I would continue testing that fault. If all external circuits checks test good, problem may be a internal ECU fault causing multiple problems.
Hello Nicholas Great Input Nicholas I will post more data during the weekend..... Thanks Again for the input
Hello guys here some small date on the fuel trims under a load will be post some more information as i get it Thanks again for the input
Screen Shot also i uploaded a SCM file
At risk of being wrong, I'm seeing 1v is stoich. Then you are accelerating, it's leaning out, until it goes into open loop, and the downstream are steady lean at all times. Sure looks like a fuel delivery issue. It would be nice to see engine rpm and fuel status graphed. And of course fuel trims. But I'm leaning towards fuel delivery. Have you grabbed a pressure reading yet off of the truck?
Hello Mario Great input I will be doing a fuel pressure test and more date will be posting it soon THanks again
Here some more data
Hi Edward: I'm curious about something. Why are the rear O2 heaters commanded Off? Guido
Yes you are for sure lean . A quick VE test using your RPM , MAF and IAT puts the engine at about 89% volumetric eiffiency. Im a little curios why your IAT is so high at 125 F but i dont think its an issue because the VE seem okay otherwise. Need to check pressure volume and voltage drop at that pump.