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My LTFTs were both over 20%. I smoked the intake with a homemade smoke machine. I found 3 leaks. Air Assist Control Valve (AACV) hose where it connects to the passenger side between the injectors. The same hose where it connects to the AACV on back of TB. And the third and probably the worst was the small vacuum line going from what I think is the purge valve to the bottom drivers side of TB. This little vacuum hose was hard as a rock and basically just broke off.
I did a hard reset and the LTFTs are now 9 and 11. Have drove it for several days and she runs great in every way but idle. CEL has not come back on. Doublechecked for leaks by doing another smoke test. None found. Fuel pressure is 34 at idle hose connected. 42 with it off. So the pressure is good. MAF numbers good.
She is running a little rough at idle like the idle is just too low (600). The spark advance at idle is only 2-4 degrees. Load PCT at idle 22.7...is that normal. Lamdas are both 1.
Can any of you smarter folks tell me what is wrong now? Not throwing any codes but something still isn't right.
Good job evaluating your initial issues...
Have you checked the adjustment on the throttle cable?
Also check and replace #8, it takes about 20 minutes to include putting her up on ramps....
If you have 9 & 11 LTFTs at idle, do they drop markedly when you rev to about 2500?
(If not, you'd not be hunting for an air leak but instead for something else.)
I take that back JagV8. They go down 50%. Bank 1 10/5. Bank 2 12/6. Idle/2500. In park. Is that enough of a difference for me to still have a leak somewhere?
You had mentioned your purge valve tube was hard and brittle. Thus your canister valve had to compensate, and may have been in that position for awhile and seized. So I would suspect it could be stuck closed and it really isn't that costly and is a quick replacement. Ford components take a good effort to trigger a hard code, so once you take care of those weak points, the next weak point will rear its ugly head.
Example, ....I had a 97 Expedition and I could feel it had a bad coil pack, it was intermittently chugging. Rarely it would send me the code that day, but generally it took almost a week for it to trigger. I waited for the trigger so I could go directly to it. It sucked waiting, but I carried 4 with me always...it ate them.
That sort of drop does look like a smallish air leak.
Possibly you'd find it if you watch the STFTs and spray small amounts of a burnable gas (e.g. propane) near each joint / suspect item. STFTs go mad if some of the gas is sucked in.
That sort of drop does look like a smallish air leak.
Possibly you'd find it if you watch the STFTs and spray small amounts of a burnable gas (e.g. propane) near each joint / suspect item. STFTs go mad if some of the gas is sucked in.
You and I are thinking very much alike. Before I read your post I looked for another leak with the engine warm and running. I used starting fluid and watched the STFTs while spraying it in areas of suspect. I got a drop negative on the bank 2 STFT when I hit the left side connection of the Idle Air Assist Valve hose where it connects between the injectors. I fixed it by replacing the Oring.
The idle issue seems to have improved but so far the LTFTs (especially for left bank) are out of tolerance. So I disconnected the battery and performed a hard reset. I will have to drive it some now to see if they drop to less than 8.
I drove it about 8 miles to work. The problem isn't resolved. Long fuel trim bank 1 is 9 and bank 2 is 13. Idle is still a little rough sometime. The fuel trims off idle are good. Could this be a Air Assist Control Valve (AACV) issue?
I'm beginning to think that my LTFT problem is because they are not actually resetting when I do the hard reset. I did my reset by disconnecting the negative battery cable and touching it to the positive for a while. This seemed to reset them because at first they were at 0 until I drove it a few miles. But when they come back they come back to around 10. While driving the car I never see the STFTs that high. At idle they always sit near zero. To reset the LTFTs do I also need to turn the ignition key on while the negative is touching the positive?
I always turn the ignition key to position 2 when doing a hard reset on the basis that a lot of circuits are not powered up when the ignition is in the auxiliary poistion 1. At worst, doing so won't do any harm and at best it could help.
If I am in fact resetting them and they are relearning and are actually that high at idle than I have some sort of strange problem that is so far kicking my butt. I found several vacuum leaks and greatly improved the fuel trims and am no longer getting the P0171/P0174. But she has a idle problem and the only thing I can find wrong in the live data PIDs is the LTFTs. The STFTs seem to always be good which has me scratching my head. I think I may need to start a new thread with the proper title because the lean code problem has been fixed and this now is only an idle issue.
There is a possibility it could be the MAF (I know you said the numbers read good, but this is an easy check)...in that case you can disconnect it and the ECU will go into a default and the trims should balance. You will get a code, but you can clear it easily.
Also, have you done a fuel rail pressure test?
Have you pulled any of the plugs to see what condition they are in? Whether in good condition, worn, burnt or wet, plugs can tell a lot, especially the color.
There is a possibility it could be the MAF (I know you said the numbers read good, but this is an easy check)...in that case you can disconnect it and the ECU will go into a default and the trims should balance. You will get a code, but you can clear it easily.
Also, have you done a fuel rail pressure test?
Have you pulled any of the plugs to see what condition they are in? Whether in good condition, worn, burnt or wet, plugs can tell a lot, especially the color.
Thanks for your help HighHorse. I will try your suggestion and see what happens. I also may have another MAF I can try.
Yes, I pulled a few plugs. They didn't seem to bad but they are not the recommended brand so I ordered a new set of higher quality NGK. Changed 3 of them on the left side and then ran in to a striped coil bolt. Of course it is the back cylinder and the hardest to get to. Now I have to resolve that and get the rest of them changed out. Numbers didn't change on the left side so far though.
Fuel pressure is 34 plugged in and 41 unplugged. No fuel in hose.
Last edited by 2001 White XJ8; Feb 8, 2020 at 03:18 PM.
[QUOTE=Highhorse;2188690]There is a possibility it could be the MAF (I know you said the numbers read good, but this is an easy check)...in that case you can disconnect it and the ECU will go into a default and the trims should balance. You will get a code, but you can clear it easily.
Highhorse, I unplugged the MAFS and cranked it up. STFTs went to approx -15 and LTFTs remained the same at 11 and 12.5. The scanner said that my A and B fuel systems were Closed Loop (CL).
I put my spare MAFS in and so far the S and L FTs are about the same as the original MAFS.
One thing I did notice though that might be important is that when the car is cold and in Open Loop (OL) the LTFTs are good at 4 and 2%. As soon as it switches to CL the LTFTs go up.
Last edited by 2001 White XJ8; Feb 9, 2020 at 05:53 PM.
First, apology for overlooking where you said earlier about the fuel pressures.
Well, then the MAF is probably not in play, so that's another check mark to narrow it down. But the status of OL vs CL is the OL is when the system is getting to operating temp and once there it hits CL barring any encumbrances like a faulty part. I recall reading a thread in the jagrepair.com manual once regarding an issue with a intermittent knock sensor, no hard code and fuel trims, ...food for thought. Not saying that's it, it just sticks in my head.
P0171/P0174 Resolved but something still wrong
