I have a couple of questions about the MAF sensor. I have a bucking going on at about 2000 rpm. I am leaning towards a MAF sensor problem. What problems will it cause if I disconnect it and take it for a drive. If this stops the learching and improves proformance, would this indead indicate a dirty or bad MAF? Still learing this truck. Had it at the garage for testing, but I had unhooked the battery the day before and it did not relearn the programming yet. They thought possibly MAF or ECU but did not want to waste the time($$$) until it had relearned the program. Trying to just solve this and move on without loosing another day at the shop and spending a lot of money for something that I could have solved. I have replaced spark plugs, wires, fuel filter, and air cleaner. It looks like the timing belt is original, and has 156,000 miles on it. The next thing to get changed either late this week or this weekend.
I don't think it will run with out the MAF sensor. Pull the codes and see if there are any set. And then go from there.
It will run with the MAF sensor unplugged. The PCM will use the TP sensor for fuel controll as a default. If it runs better with the MAF sensor disconnected, either the MAF sensor is dirty/contaminated or defective. BTW, a defective MAF sensor will not always set a CEL .
'03 F150 XLT Reg. Cab 4x4 Flareside,True Blue/Arizona Beige Accent,4.6,4R70W,3.31 GR,Pwr.everything,SRW, Tow Pkg.,Cab Steps Ford Snapless Tonneau Cover,Bedrug.
What's the fuel filter status? Time for a new one?
The truck will run with the MAF sensor unplugged, but it will probably shift lousy becuase of how much the PCM relies on the MAF's "load" signal for shifting. Make sure you take the poor shifting into account when you try and determine whether or not the motor runs any differently with the MAF unplugged.
Thanks. Just got back from autozone where they pulled the following 2 codes form me. P0303 - Misfire in cylinder 3 and P1443 - Evaporator purge valve problem. The P0303 is new and was not there when they checked it the first time(one week ago). It stalled when I started out today when I went to leave to run there. Not sure if that would cause the P0303 or not. It has new plugs and wires along with new fuel filter. Timing belt is getting more suspect as I go and will be replaced this weekend. From my reading the Misfire can be coming from a problem with the cam sensor, maybe stretched timing belt. Looks original and has 156,200 miles on the motor. Does not use oil and when it ran right seemed strong.
At 156K, I'd be thinking that the timing belt would have been changed already at least once, but it could easily be in need of another. So go for it.
It's possible too that a malfunctioning EVAP system could be a contributing cause of the misfire. In any case, the P1443 code should be resolved so you can focus exclusively on the misfire if it persists:
I am unsure of the age of the timing belt. Looking through the gap between the outter and inner timing belt cover I can see a lot of cracks in the belt. I am at least the third owner and have no knowledge of the owner before last. If the brakes are any indication, then it may be original. I had never seen drums worn with a taper to them before. Had to do a complete rear axle brake job including wheel cylinders and lines.
I did try to pick up the purge kit from the local ford dealer after work today, but no luck, had to order. I did inspect the eva hoses and found where the hose between the sensor and the valve had worn down to a just the inner skin of the hose from rubbing. I replace that hose with some vaccum line and am hopeful that may fix the problem with the 1443 code. I did take it for a short ride after fixing the hose and it is a little better.
Each change I make seems to make very small improvements to the bucking and stuttering. I am going to put a timing belt on this weekend and put new bulbs in the dash including warning lights.
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