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Hmmm, Never noticed that vid before and I have the same truck. Numerous similarities to my issues at hand. Definitely a person of interest. Must pursue further….
Lemme ask this. Has anyone ever encountered a vacuum leak that only leaks at higher RPMs/ vacuum? I notice the white locking tab on the spider harness plug is disconnected so someone has been in that neighborhood before for some reason. Can’t know if they were in the plenum and when I cleaned the throttle body it never occurred to me to peak inside and see if the spider is factory or not. I don’t think the replacements have those two black locking tabs on the poppets. What I’m getting at is the sucking burst comes from the throttle body area… or… the spider harness fuel island oring to the plenum. When I punch the throttle, vacuum gauge plummets like it’s supposed to and that sort of leak would not be detected. I know its a stretch but ima pretty stretched out ;]
@Oddball0045 Idles ok. Only hesitates on acceleration or even punching the throttle while parked. Also ok if I bring up the RPMs slowly. Not at all worried about this sort of job. I just can’t get past that sucking burst when I do throttle up. But I have run out of any other ideas. My chevy & Jimmy both have the 4.3 so I’m familiar. Ima thinkin might be worth a cheap try at a fuel cleaner. I never really used any of those products such as seafoam, so I don’t know how effective they really are. But, something in an effective cleaner seems cost effective before ripping in?
Thanx
UPDATE:
TPS – Throttle position sensor tested by monitoring voltage output. No trouble with full range of motion ( .6v – 4.5v )
Neglected to mention thoroughly cleaned throttle body some time ago.Thanx,
@Jonmon1 Cleaned MAF with MAF cleaner and Swapped MAF with a spare. No change.
Fuel trims were a little wacky till I put fresh gas in.
@peshewa 1 ignition coil. Diagnostic procedure basically says either it works or it doesn’tKewl, thanx. I don’t even know what ima find in there. Vans @ 350k. Bought it last year. Was told the motor was rebuilt @ 270k (seemed believable… ran well and smooth). But, I don’t even know what ‘rebuilt’ means LOL
O, fyi… I dought it pertains to you. but there was a 24 valve 5.4l I’m kinda sure Ford only put it in the F’s and I think 2003-2008 ish. But the spark plugs were a nightmare. snapping off in the head and all. Just sayin, important enough to mention.
LOL, yea my people kinda get miffed at me when I say if we didn’t fix anything, it’s prob not fixed. OK, kewl. lemme know.
Well, weak fuel pressure and random misfires, it could happen… As in NOT ENOUGH fuel in the combustion chamber to ignite. But, you don’t have random misfires (randomly across all 8 cylinders). You have a very specific misfire, P0302, consistently in cylinder #2. The flashing CEL is an indication from the O2 sensors that the exhaust is way too rich. Think TOO MUCH unburned raw fuel going out the exhaust… For example, as in a fully functioning fuel system and a dead spark plug…. or ignition coil. Further, it’s been thought that this unburned raw fuel scenario could become a runaway freight train and by extremely rapid switching of the O2 feed back to the PCM interpret a lean condition (P0171 also bank #1), whereby PCM increases even more fuel flow.
So, just saying it’s fairly painless, quick and cheap test that can tell you a lot whether the problem cylinder moves with the COP or not.
Well, my .02 says to start with change the fuel filter especially if it’s been a while. I like to change mine every fall. Secondly, swap the # 2 coil pack with another (#1 or #5 is prob the easiest) and see if the problem cylinder follows the coil pack. Right around 200k my 5.4L coil packs started dropping out.
Well, Instead of while it was running. KOEO, de-installed with harness connected… I injected 12V (less than 5 seconds at a time) from battery to the PCM 12V feed (which doesn’t seem to be there from the PCM) and can eyeball the pintle move as well. Yes, pretty freely. So I;m convinced the EGR itself is working properly and reporting back properly. I want to call the PCM, but when I looked at my 2 other 350 vans, they all seem to have a missing 12V feed in the identical manner also which has me questioning myself here.
which, come to think of it… again, there shouldn’t have been any ground for the soleniod to energize?
This one’s the electronic one. I wondered maybe it was jammed open a little causing my grief. But removing it, it was fine. cleaned it out some. reconnected to wire harness. I can watch the pintle movement on my scantool while I push the pintle around with my phillips head. That’s what got me pokin around the egr which lead to my voltage issues.
@Jotmon1 Hi, thanx. If I understand you correctly, I measured KOEO across Battery & EGR harness connector (disconnected):
B+12V – PCM control circuit = 3mv
B+12V – pintle circuit ground = 12V
PCM 12V feed – B- = 40 mv
5V pintle ref – B- = 5VOk, I would swear I saw different before, but I stand corrected regarding the ECM control circuit. But I should still have 12V feed, right?