Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Hello. Been working on this truck for too long. Started with a massive vacuum leak 0n the intake manifold which I replaced then the CMCV actuator was bad. then the B1S1 o2 sensor. and finally have it running but barely. struggles to idle. STFTs are all over the place depending on RPM. They seem consistently lean at low RPM. I can't keep it running at idle but at 950 RPM its showing 12-14 g/sec MAF and a Baro indication of 86 KPa. I am not sure but that seems like almost twice the air I should have at Idle and the Baro reading would indicate I am parked on the moon. I know this truck doesn't have an actual Baro sensor. I don't know where the Baro is calculated from. My thought is its cutting back the gas because it thinks I am in the clouds. I don't want to just change the MAF because I am out of any other ideas, but I am basically stuck. Any help on this would be appreciated greatly.
I'm going to smoke check it again tomorrow. The smoke was so bad initialy I could have missed a smaller leak. I've reset and relearned a couple of times. I'm going to try a run with MAF disconnected although I don't know what bypass logic is in this truck. won't hurt to try. Thanks for quick response.
I am about 600 feet above sea level. My actual Barometric Pressure is 30.02"Hg. which is about 101.5 KPa if my math is right so my Baro reading of 86 equates to about 25.5 ' Hg. What should the MAF be at idle. I am assuming for a 5.4 it should be around 6 g/sec.
On Ford the baro is calculated from the MAF. You're correct, the g/s should be around the engine liter at idle... 5.4-6g/s. Unplug, if it runs better, MAF is most likely bad. MAF has four wires. Two grounds one power one signal. Grounds should be less than .1mv. Power is battery voltage. Signal, I think is half g/s at idle.
That bad MAF will cause the erratic 02 readings and the bad idle. Check the voltage readings before replacing the MAF.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Okay I tried unplugging MAF and it definatly idled better. I'm really leaning toward a bad MAF. I have bateery voltage on the red wire then a couple of milivolts on the next 2 koeo. and 35 mv at idle. 3.6 volts on one. i have more than 4 wires checking mitchels for pin out but I think I am putting a MAF in tomorrow. can i check grounds with test light to bat. Pos?
pin 6 red wire bat. voltage
pin 5 BK/Wh .015 volts koeo .036 idle ground?
pin 4 Tn/Lb ,015 volts koeo fluctuating 0 to .9 volts at idle Maf signal return
pin 3 Lb/Rd 3.6 volts at idle Maf signal
pins 1 and 2 are intake air temp sensor signal and return?
not positive my t-pins were good but i think it is still pointing to a bad maf
New MAF in. A bit better but still not drivable. I have to have a vacuum leak somewhere or possibly injector issues I suppose. For some reason I can't see misfire data. I have no codes but it won't idle. Especially after backing off throttle. It seems smooth at any rpm above 1000. But my Baro seems in the ballpark now. MAF at fast idle is about 9g/sec. Better than. 13 or 14 . Smoke test again tomorrow I guess. Ughhh!
I started it without clearing the memory so my LTFT was still in the 20's but Short terms were -7 to plus 9. i shut down cleared memory and LTFT went to zero but Short term started climbing immediately. i'll post some numbers tomorrow. I'm done with it for tonight
This morning I started it up cold and it went straight to a high idle of 920 to 1000 RPM. Fuel trims were B1 Short term 0 Long term 23. B2 short term 22 long term 9. MAF was at 14 g/s.
1500 RPM B1 STFT 8 LTFT 17 B2 STFT -3 LTFT 8.6 MAF 18 G/S
2500 RPM B1 STFT 17 LTFT 0 B2 STFT -15 LTFT 0
So both LTFTs at 0 at 2500 rpm and STFTs one bank lean and one rich. btw after I changed the MAF sensor baro is reading 96 KPa. close to what I expect.
I have cleared the memory several times. i relearned the electric throttle body. . It doesn't seem to want to run at low idle. it is not smooth at all until about 1000 RPM. on the KOER test it runs smoothly at higher RPM but dies when it backs down to idle. it starts cold and high idles without much problem.
I smoke checked it again. the only place I am getting smoke is the air filter housing. of course that is pre MAF and I don't think it is a problem but i pulled the filter and there is a gap around the edge which i suppose could cause some weird turbulent flow to mess with the MAF reading. O2 sensor voltages are cycling and look okay to me but I am going to try to get a picture of the wave.
I can’t remember but does this truck have an egr valve? That’d be something to check for it stuck open. Since it runs better at higher speeds. You got any screenshots of data for us??
So here is something weird. I changed the oil today. Went to 10w-30 from 5w-30 that was in it. But it' calls for 5W-20. So after the oil change. Crank no start. No Fuel pressure. tank was pretty low. put gas in fires right up. but wait! 2 pending codes.
p2106 Throt Actuator Control sys- Forced Limited Power and P061B internal control module Torque calculation performance
Also at elevated RPM it is surging. I can't maintain a steady RPM. almost like an injector kicking in and out. Also until today it would not rev above 3200 RPM in Park. only when in gear would it go above that. but now it goes way above that. like 4500 plus.
