Brandon587

5.12 source voltage to tps.

Brandon587

On the way home from work, I was watching my tablet stream live data from the trucks comuter. I noticed that my fuel trim is all over the place for both banks, both long and short term. My under standing is it should stay within ~5% of 0. Well I had anywhere from -18% to 23%. So it is trying to compensate for something, It seems like I may have a vacuum leak somewhere.. Time to break out my vacuum gauge. And, my o2 sensors appeared to be cycling normal.

Brandon587

Watching fuel trim closer, I get about -19% at idle, and all the way up to 32% flooring it onto the highway. didn't know it could compensate that much. Sometimes I get pinging when getting on it, like its running lean. The exhaust does smell rich at idle sometimes, I've had others at work point that out as well. I filled up today and my mpg is down, got 12.5 when I normally get 14-15.

Brandon587

Sprayed a mistof water around my plug wires and coil a couple nights ago, and found I was leaking a lot of spark and some was arcing to my exhaust manifold. Replaced my plugs and coil with motorcraft, and wires with BWD. Cleaned my cap and rotor up, they are still pretty new. Truck runs better but still sometimes hesitates.

Chris_1

iTrader: (1)

That should be fine. .98 at the signal wire is high. .9 would be better - that tells the ecm that the throttle is closed. .98 tells it that you've opened the throttle slightly (when you haven't) so it will start to feed more gas. And the signal will be higher than actual all the way through.
I'd suggest dialing that in a little closer to .9 and see if it works better. Loosen the 2 screws and turn the tps till it reads .9 at closed throttle to do that.

Brandon587

Ah I guess that is why it smells rich at idle. And I guess the o2 sensors are trying to tell the computer to pull back fuel and that's why my fuel trim at idle is so far into the negatives. Doesn't make sense why it goes so high under heavy throttle though. I will try adjusting the tps like you said and see what that does.

Brandon587

Checked fuel pressuer today, both tank had 32psi at idle running, and both went to 42 with the vacuum line off he fpr. It has been a while since I changed my fuel filter ~40,000 miles. So tomorrow Im changing it along with an oil change.

Brandon587

changed fuel filter, and unrelated my oil today. Its all I had time to do after work. Old filter had some dark and nearly black fuel come out once it was near empty, cut it open and the filter was pretty dirty inside. It needed changed, but wasn't the problem. Checked fuel pressure after changing, it was the same as before. Checked the leak down time, it was leaking about 1 psi per minuet.

Brandon587

Still having my hesitation, it sometimes is pretty bad. It seems to always happen (when it does happen) at 45 to 50 mph. It less often happens again around 75 mph. I read up o the tps, some say the computer finds the voltage of the sensor at start up and uses that as a reference as closed throttle while running. Others say nay. So which one is it? I still plan on adjusting the idle to .9 vs .98, but Im not counting on that to fix my problem. So what all should I test. The only code I have gotten once through all this is the crankshaft position sensor. I cleared the code and checked mthe wires continuity, which it had and that was all the trouble shooting I did with that. Light has not come on in 1800 miles and two weeks. The problem is worse after the truck has been running, or the warmer the weather is. Everytime the hesitation happes, my fuel trim, both long term and short term drop drastically. It goes from around 15-20% to say 3-5 %. Then jumps back up. I know it is too high, but it is also too low at idle. As said before, at idle the long term is down around -20%. So what is everything I should test, getting tired of this problem. Drive the truck too much to not have it running right.

Brandon587

Alright, so tested my tps and went to adjust it and found it had no adjustment. Resistance was out of spec, so I went ahead and replaced it with a motorcraft replacement. Still runs the same, but no longer wants to just die at idle on warm days. Truck seems to be losing power in the low end when it starts acting up. Now fuel trim is slow to respond. Ideas? Reading up on testing the tfi, don't know how and never even really noticed it. It hides under my cruise control module. Which I another thing that started acting up. Works sometimes, normally again when cooler out. It almost consistently works in the mornings going to work, and not in the afternoons coming home for work. Im about to start checking grounds. Sometimes now just cruising up a small hill I feel misfires more than hesitation, kinda like when a 5.4 starts loosing a coil in its first stages. So, Ideas?