Shaking at light throttle
- Thread starter madman1234509
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Jeff@Spartan
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Looking back through the thread, it looks like you guys are seeing it at a higher rate of speed than what I was seeing. And I have traction bars as well. I'm leaning toward my tires being the cause of my slight shaking.
madman1234509
New member
Yes. It only happens with the tc locked between like 55-62 mph. Even win cruise on. Frp jumps all over. As soon as you touch the throttle or let off, or hit the accel/decel buttons it clears up. I have a new converter, and Trac bars. My buddy literally has a brand new precision converter that he put in thinking it was the problem. I honestly don't think it's my clutches. And his truck is a 10 with 60k easy miles on it, trans fluid and pan was spotless
madman1234509
New member
Update. .. my buddy hooked up a lift pump gauge. Seeing 35-50 psi lift pump pressure. Truck runs great other then the shaking. Nice smooth idle. Completely stock fuel system... what would cause that?
I thought the lift pump (stock) put out about 3 PSI (I could be wrong)..is it just the units off??? Where was the gauge hooked up at...Shrader valve?? How many miles on the stock lift pump??
Corb@CorbinShipping
New member
Well..... I had what sounds like the exact same issue with the shaking... I thought it was the U joints... All of my tires were recently balanced. spartan 275 EL, no egr, and a dpc converter.... light throttle shaking, half or better throttle, smooth as silk. BANG... trans went... I was on base, in a 25 MPH zone, doing about 30 MPH. No forward, no reverse. Tony helped me out with the trans swap in my office parking lot, and I took my busted trans to Rudy's. Trans was fine... TC was destroyed. Only had that setup for 2 weeks. Towed 17 k once. Towed my boat, 5 K from NC to FL once. Ill keep an eye on this thread, as I wanna see whats up with his rig...
madman1234509
New member
Lift pump is only supposed to put out 3 or so psi. As stated truck has 60-65k on it. Never beaten on. Tuned with an edge for last 10k and Spartan last week or two. New precision converter put in last week. Was shaking before the converter and Spartan. Also egr delete with no gate.. Sounds like today he brought it to his friend that is a ford tech to hook it up to a ford tool to see what the valves in the injection pump were doing while it was running, vs what they were being commanded to do. And apparently happened to throw a gauge on the lpfs while doing so. I'm going to talk more with him tomorrow to find out a little more about his readings of the lift pump pressure. I highly doubt he read the wrong units.
madman1234509
New member
My truck has the same shake/surging at light throttle between 55-60 and so did my other friends Spartan tuned 6.4... not saying it's Spartan, just trying to point out they are all tuned trucks with the same symptoms
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could very well be lack of traction bars if the converter is locked.
What tunes were you running when if first started shaking/surging?
madman1234509
New member
Anything between 275-310 tunes. My truck has traction bars and it still does it. Its not at a point where you need traction bars. Its cruising at light throttle between 55-60 on flat ground with little to no load. His truck did it in 210 tow and still does it in the 250 tune that I loaded up. My other friend that I mentioned daily drove in anything from 210-310 and they all did it
So I talked with Eric, we decided the best thing is for me to get the truck reflashed by Ford.
Reason being is if he reflashes the truck via livewire, It only flashes the pcm/tcm. When Ford flashes it, it does the instrument cluster, abs, security modules, and etc. Pretty much everything.
This also seems to back me up with what I think is the problem computer related as it started doing it when he flashed me from the new flash to the older flash and that is when everything started so Im wondering if maybe something on the pcm/tcm old flash isnt being compatible with something that was up-to-date (modules, abs, etc) with the new flash
Let me also state that Gearheads tunes run great on my truck, and also the new tunes Eric emailed me run great on my truck, but they are setup like the xtreme x and do not get the fuel mileage that the preloaded did. Customer service from Eric and Matt have both been outstanding and I would recommend them to anyone.
Reason being is if he reflashes the truck via livewire, It only flashes the pcm/tcm. When Ford flashes it, it does the instrument cluster, abs, security modules, and etc. Pretty much everything.
This also seems to back me up with what I think is the problem computer related as it started doing it when he flashed me from the new flash to the older flash and that is when everything started so Im wondering if maybe something on the pcm/tcm old flash isnt being compatible with something that was up-to-date (modules, abs, etc) with the new flash
Let me also state that Gearheads tunes run great on my truck, and also the new tunes Eric emailed me run great on my truck, but they are setup like the xtreme x and do not get the fuel mileage that the preloaded did. Customer service from Eric and Matt have both been outstanding and I would recommend them to anyone.
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madman1234509
New member
My buddy's truck was just flashed at ford a few weeks ago when it was getting a plow installed. It also had the edge installed at that time and it didn't do it before the reflash ( just found this out today). Also found out today that the high pressure reading he got was done by a ford tech the other day. It was at the Schrader valve. Which was engine off key on. I guess these readings are normal in that part of the circuit due to some part in the injection pump that recirculates the fuel. Also found using the ford techs lap top today that when it shakes one of the valves in the injection pump stays perfectly smooth on the graph where as the other is a complete saw tooth pattern. From my understanding the valve duty cycles are supposed to be within 2% duty cycle of each other. So it is in fact something in the injection pump doing it. But why is tuning causing this, and is it something to do with the new ford flash? It shakes on all tunes. Including stock dpf/egr off. Again, it only bugs out at light throttle/load on a flat road, 55-60 mph
That is really interesting. I was starting to bet on the LP being the culprit, not the HPFP.
madman1234509
New member
Well from what he was saying. The ford tech checked the pressure key on but engine off at the Schrader valve and seeing pressure like that is normal due to the injection pump recirculating fuel in the circuit up there on top of the engine. But what he found when the shaking started with the valve cycle definitely shows that one of the two valves goes nuts.
madman1234509
New member
He has contacted Spartan once and they claimed they have never had complaints of this nature and it didn't really go anywhere. I did tell him to try calling them again now that he has some more evidence of what's going on
