Ford Fuel System :: Mild Stumble / Hesitation When Dropped In Drive
Nov 23, 2011
460, stock RV motor with LT headers, Alum Stealth intake. Carb is brand new, Holley 600 cfm, out of the box.
Elec choke, vac 2nds. Timing is set to 12 BTDC.
Truck idles beautifully. Drop it in drive, it will ever so slightly stumble/hesitate then go liked a raped ape. Has great acceleration (for a 8k dually crewcab). In my mind, I'm thinking a slightly larger than stock accel pump to give a bigger shot.
However, it does have a 1" carb spacer. That and the hi rise stealth, is it leaning out for a sec and causing the stumble? Would pulling that 1" spacer work? I was thinking the higher the carb the better to get less heat dissipation from the engine's heat. Replacing the heater core now. So I have some time to sort it out. I'd like to road test a tank of gas through it, but gotta fix the heater 1st.
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What would make a FI engine act like its flooding out and dying after a short run on the freeway?
Details:
1994 F-350 351W (just overhauled this winter)
has new TPS, ICM(?).
Dual exhaust dumps right before the tires
new filters in tanks, new fuel filter on frame rail
All fuel lines have been opened and blown out from the tank to the engine compartment fitting near firewall.
Fuel pumps hold good pressure when tested.
Symptoms:
smells like its running rich most all the time
after a short hiway run @ 70MPH it will stumble and die when returning to surface streets.
fuel smell near engine sometimes, but no obvious puddles or leaks anywhere.
May be related?:
When on a longer highway run, I can't use the FWD tank for a long period without the engine stumbling and cutting out or popping at times. But I can swap to the rear tank for a bit then run the FWD tank again for a while. driving up hills it seems to be worse, but I'm in the panhandle of TX right now..good grief!
I am having to drive this truck for work long distances. While I dont expect a vast fuel range, it would be nice if I could go a couple hundred miles on 20 gallons of gas....
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My 302 runs pretty good when all warmed up. It has some cold start issues every now and then, but is easily dealt with. My question is how to best "tune" the carb. It's a 600 cfm 4150/60 style Holley single pump, vac secondaries and electric choke. About as basic as you can get. I think I have the fuel level set correctly. I also think I have the "idle mixture" set right. I used a vacuum gauge and moved back and forth between screws till I got the highest vacuum. Is there a better way than that? I have the idle set correctly. the fast idle is a little high, but I can fix that.
Now, my real question is how to fix the hiccup and stumble I get many times when I step into it pretty good. I assume that this is the point the carb is going from idle circuit to main circuit. It stumbles when I get on it real hard from a standing start. I can roll slowly and step into it and it stumbles as well. I also like to blip the throttle when I down shift (it has a manual tranny by the way), and many times I'll blip it and get nothing. Now, it runs fine after the stumble all through the rpm range. That's the only time it stumbles. so, do I need more accel. pump shot?? To compensate on the transfer of circuits.
I also notice when I on it real hard, during the shift right when I jump on it, under the heaviest load, I hear a bit of spark knock. It's not running hot, and the timing is good. Do I need a bit bigger jets? I'm thinking it's going a bit lead during that time, but I don't have any real way to measure it.
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I have a really weird issue with my 2003 Ford Focus. Manual transmission, just over 50,000 miles. I've been noticing a stumble or hesitation (like the engine is cutting out) at steady speed, but ONLY when it is snowy out, more if it's windy as well. I don't recall that this happens if it's rainy or foggy. All maintenance is performed as specified, to include air filter changes.
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I recently picked up a 2000 Excursion with the 5.4 V8. Engine has 150,000. I got it cheap because it has a surging problem over 1500 RPM. This problem is intermittent.
I have 1 DTC. P1000 which is OBDII checks not complete. I cannot clear this even using the factory procedures. FYI..I have a snap on solus scanner. I think this is a voltage problem, If you try to start the engine with the scanner plugged in, the scanner shuts off, so I'm thinking the PCM loses battery power supply when the starter engages, resetting the PCM.
This problem is NOT a miss.... something isn't opening or shutting off above 1500 RPM. This truck doesn't have an EGR system, it has the EVAP system. This may be the problem, thats why I'm here. OK. heres a list of what I've replaced since I started working on it.
Engine oil and filter
air filter
fuel filter
8 COP's
8 plugs gapped properly
cam position sensor
IAC sensor
MAF sensor
Removed throttle body and cleaned.
Vacuum checks. 22" at purge valve,fuel dia, and vacuum canister
Checking with the scanner at 1500 RPM with problem
SFtrim1% bounces between5-15
SFtrim2% bounces between2-0
LFtrim1% bounces between11-13
LFtrim2% bounces between 5-6
O2S11(mv) bounces between 200-781
O2S21(mv) bounces between 200-800
Ssystem is in closed loop holding throttle at 1500 RPM... Note engine surges when at the RPM or above. I'm thinking the engine is lean, not sure how to read the trim numbers...
Idle is fine ... Problem is intermittent ... Also noticed that engine will only advance spark to 30 degrees @2000 RPM during this problem. I have seen it advance to 38-40 degrees when I do not have this problem, so I kind of understand the power loss,knock etc due to the timing, my question is whats causing it to do this?
EVAP question.... The purge valve should open according to PCM command a certain value, correct? I can monitor the duty cycle % but cannot activate and check proper duty cycle through scanner . When I try to I get an error message of module error -unspecified.
Disconnected hoses at purge valve,Full manifold vacumn on one, nothing on other, no flow through purge valve, but scanner shows 30% duty cycle. I would think the should be a little flow at 30% Maybe my problem? Troubleshoot procedure for the EVAP would be good.
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First, a little background on my truck. 2007 with 5.4, 122000 miles, oil changes with 5-20 Motorcraft and Motorcraft filters, plugs done by dealer 40000 miles ago. The truck has developed a ticking noise, kind of like a lifter (I know these engines don't have lifters) that is most noticeable from the side of the truck near wheel. ticking speeds up with the rpm. Also around same time, between 40-55 under load there is a bit of a stumble, but I can gas thru it. I'm guessing these are related. I'm thinking spark plugs again, but shouldn't I get more than 40000 out of them? I might just take it in, since I've got oil leak somewhere around back of the oil pan, but figured maybe might get some clues first. Also, no CEL.
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When I drove the car on Monday a hesitation/jerking randomly came out of no where during mild acceleration at around 2500 RPM. The next day it was doing the same thing, but one of the times it made the check engine light flash a couple times then go off. On Wednesday I put fuel injector cleaner and a new tank of gas in it to see if that worked at all, but it didn't. The problem was still occurring then the engine light came on and stayed on. So I went to see what the problem was on VCDS and here are the errors that came up. Also I should mention that on Tuesday my battery died and I had to get a jump from someone, this didn't affect the problems, but I think it has something to do with the voltage errors.
A Summary of the errors is lots of things about "low voltage b+" and "engine misfires".
01-Engine -- Status: Malfunction 0010
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: Malfunction 0010
[Code] ....
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A couple questions I have about my truck. I'm still new to the F150.
First, my truck has an Ecoboost and I have a slight stumble/hesitation when you start the truck cold. It clears up within 10 seconds and doesn't seem to affect drivability whatsoever.
Second, it seems that only my driver side mirror has the "dimming feature" to it. Is this normal?
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I just bought a 5speed manual 2004 ford ranger 4x4 and when shifting usually upshiffter 1-2-3 I get a mi8ld clunk when I looked underneath I grabbed and can move the from drive shaft clockwise about 1/4 inch is this normal and if not how do I fix this?
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2003 F150 5.4 72852 miles
I have a Rough Idle & sometimes a hesitation or stumble on acceleration. I cleaned the MAF & IAC motor & Air & Fuel Filters are new. I got a 20890 scanner & ran test 6 53 as suggested in many posts by BlueGrass. Here are My results & what They Convert to.
1 00F5 .3675
2 0051 .1215
3 0000
4 0000
5 00A3 .2445
6 0000
7 0000
8 0000
I'm guessing the cop's are ok & probably need plugs? I was hoping to just swap a coil. Too cold to do plugs & truck won't fit in my garage.
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My 2011 stick shift no air Accent has a hesitation or stumble on light acceleration that comes and goes. It may not occur for weeks then re-occurs. It is hard to reproduce intentionally. It never occurs in cruise. The CEL is not on. Most often occurs at 1400 to 1500 rpm with slight acceleration or a slight increase in load as coming to a slight hill. I tried injector cleaner a few times and changed air filter. It seemed more reloaded to induction airflow so I changed the MAP sensor. I understand the 2011 Accent does not have a MAF sensor. It is still occurring. It is fine in steady cruise as well as in hard acceleration. I am wondering if it is a TPS sensor problem. It has 60,000 miles and otherwise runs fine.
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I have a 2004 Pontiac Montana with 90K. If the overnight temperature has been below 40ish, there is a noticeable hesitation or stumble (almost as if the engine cuts out for a second-but never actually stalls out) on the 2 to 1 downshift when braking to a stop while the vehicle is in open loop. As the engine warms up the stumble becomes less noticeable until the temp gauge reaches the 1/4 mark at which point the stumble is gone. It won't return until the following morning - the next cold start. Our mechanic has cleaned the Throttle Body and the MAF- no change. Their transmission guy said he did not think it was a tranny issue. It has no other symptoms and seems to shift normally at all other times. What to do next??
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I have a 2000 Tahoe with the 5.3L V-8, 351,000 (yes that is correct) miles. Runs great except it has recently developed a stutter, hesitation, skip, I don't really know how to describe it, under acceleration or at steady speed. This is an intermittent problem and it is driving me batty. The only codes are a P0420, maybe after 350k miles it needs replaced? Would that possibly cause this issue, or am I looking at something more sinister?
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When I take off from a start it will intermittently stumble or hesitate, seems to be around 1500 rpm. have also noted it at higher speed while cruising. its more like a momentary power cut than a miss fire.
So far I have done the following
new fuel filters
clean MAF
new PCV valve
new spark plugs
check all hoses and plugs etc
injector clean
checked techstream for codes. there is one for a heated O2 sensor but dont think thats it.
2002. SC430
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First... Items I have replaced:
- New EGR valve
- New sensor
- New Fuel filters
- New Oil filter
Problem:
While driving I have a stumble along with a small amount of black smoke at this time ( was white/bluish smoke ) previous. I have dis-connected the batteries to force the computer to relearn the EGR valve. The turbo spools up .. getting about 20 psi @ hard throttle and then about 5 psi after it goes into the final drive gear. Speaking of which ... the stumble is always worst on the final drive gear...
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I have a '99 E-350 6.8L. Where is the check valve that maintains fuel pressure on the system?
I have been experiencing a starting issue when the engine is hot. Cold starts are usually fine. I've replaced the in-tank fuel pump (pump only, not the assembly) to no avail. I was out of town and didn't have access to a fuel pressure gauge when the problem started so I couldn't say what I had prior to replacing the pump. But now, with a new pump, when I check pressure, I get about 40 psi when I first cycle the key on, but it drops right back to zero as soon as the pump shuts off. If I cycle the key on a few times, sometimes I can get it to hold pressure at about 32 psi, and it starts fine. When I shut if off, it goes back to zero psi, sometimes gradually, like a bleed down, and sometimes immediately.
My conclusion from this was that the check valve was bad. I was told it was part of the in tank fuel pump assembly. Since I didn't replace the entire assembly, this made sense. So I just dropped the tank back down, but I don't see anything as part of the pump assembly that serves as a check valve. There is a rubber nipple on the end of the return line, but I don't see how that can hold any significant pressure.
So, before I go out and spend another couple hundred bucks on the complete fuel pump assembly, which apparently can't be purchased without the actual pump, I thought I'd ask. Where is the check valve that holds the pressure in the fuel system?
BTW, I also have replaced the fuel rail pressure regulator, but it made no difference (I went there first since that was much easier than dropping the fuel tank a second time).
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Typically here in the Phoenix area the coldest it gets in the morning is mid to upper 30s for about 2-3 weeks in dec/jan for the low and 50s for the high. Half of November, Jan, Feb & March temps are around 40s for the low & upper 50s-60s high
With these temps is it worth grill blocking?...and how much of a MPG gain would I get?
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Once warmed up, while sitting at a stop in Drive, there is what feels like an engine stumble every so often. Good guess is every 45-60 seconds, so it only happens once, maybe twice at long stops. There is a sudden change in pitch the engine, and the car - for lack of a better term - shudders. The thing I have noticed is that when it does this there is no indication anything has happened with the tachometer - RPMs hold perfectly steady. Additionally, there is no shudder when sitting in park or neutral, only drive.
I initially thought it might be an ignition fault, so when I replaced the balance shaft belt I also replaced the crank sensor. No change in behavior. I did some googling, which suggested the issue might be related to the EGR not closing properly. I changed all the vacuum hoses and removed the switching solenoid to test - it seems to be doing its job. I have not removed or inspected the EGR valve itself. However, because there is no symptom in engine speed and the sensation doesn't happen in park or neutral and only happens when warm, I am starting to suspect the transmission itself is the culprit - I can imagine if the torque converter quickly engaged and disengaged - and a little power made it to the wheels - the same result would happen.
There is nothing else odd about the engine or transmission. No codes. Runs like a top. Transmission always shifts perfectly. Fluid was changed two years ago, about 15,000 miles. What came out looked good as well. I'm okay with replacing EGR components, but I don't want to throw money at the problem unnecessarily. Maybe try driving around with the EGR vacuum hose pinched off or disconnected?
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I recently installed a glow shift fuel pressure gauge. All seems good.
@ idle 58-60 psi
@ WOT drops to 50 psi, no less.
Tonight I went to catch up to a car that had no lights on at all to tell them and during WOT fuel pressure gauge showed it dropped to less than 30! I let off immediately and it went right back up. I tried to repeat it with another go @ WOT and it would not go under 50 psi like normal.
Motorcraft fuel filters less than 3000 miles ago .. Blue spring installed over the winter.
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My neighbor stopped me this morning saying her 2005 prius was acting up.
When we started off the MFD was showing all blue bars, ac lights radio all turned off.
Drove less than 3 blocks and it dropped to one purple bar and had hesitation on acceleration.
Went around the neighborhood about 3 miles and it was showing full charge green , parked and restarted, it dropped to all blue bars.
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Ok. So. 2005 excursion v10 270k miles. Never ever had an issue starting. Today it was about 30 degrees in Detroit. Had to crank for about 4 seconds. Usually it turns over within one second of cranking. So I get to work and hook up a fuel pressure tester to it. Got to 35psi while running, upon shutting off it dropped to 0 within 30 seconds. I have no codes. And absolutely no drive ability issues. No gas smell. And I'm really hoping its just z fuel pump check valve cause then I can just prime it by doing key on key off then crank...also hoping not injector cause I won't be able to pull the injectors till Sunday snd I really don't wanna hydro lock my motor >.< best way to test injector/fuel pump valve? I like to fix issues as soon as they pop up. Wanna get my v10 to 400k.
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