C/K :: 1998 K1500 5.7 Vortec Misfire At Idle But Only When Under A Load
Jun 6, 2016
I have a 98 k1500 5.7 vortec. I was driving and the next thing I knew my truck lost power and would misfire at an idle but only when under a load (in drive with foot on brake). The last time something like this happened an injector came out of place. So that's where I started. I wound up changing the whole spider injectors and ALL the gaskets, upper and lower. I put everything back together and the problem was still there so basically I am back to square one.
I then pulled spark plug wires while running to see if I could isolate the misfire and found that I could pull all 4 wires on the passenger side without any difference in while it was running. So basically my truck is currently running on 4 cylinders and they all happen to be on the driver side. I checked my compression on the passenger side and all 4 cylinders have 180 psi so that rules out the head gasket being blown. I am getting 4 codes , 520, p1345, p0155 and p0161. I know that i have to get tge truck properly timed with a computer but i don't think that would cause my problem.
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I had to choose the Yukon, as there is no Suburban?
Anyway, I have a very bad misfire in my truck. Lopes at idle stumbles under load. Through substitution, I have tested: module, coil, and crank sensor. I have replaced: plugs, wires, cap, rotor, air filter, fuel filter and upgraded from SCFI to MFI (can you say "expensive best guess"?).
Still getting P-0300, P-0302 and mostly P-0304, using a Snap-on Modis scanner.
Compression tested today: all cylinders between 160- & 170 psi. After this, leak-down seemed redundant.
Back pressure test: 0.5 psi at 2500 RPM, both banks.
Steady fuel at about 60 psi.
I am going to pull distributor (175K miles) and examine drive gear. Not too sloppy at rotor bearing. However, how do I set baseline timing when I re-install distributor? If the distributor is OK, what test or part should I look at next?
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1998 chevy vortec 350. replaced fuel pump(twice),fuel filter, blew air through the lines, replaced fuel pressure regulator. Getting correct voltage at pump. pump runs. still only get 30 lbs of pressure. Need 60. Thought I bought a defective pump took it back. Same result. Doesnt leak anywhere I can find. Pressure doesn't drop. Just plain don't get the 60 lbs it requires. New battery as well and new F.P. relay.
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My Sierra has the 5.7 Vortec engine with 230,000 miles. Ever since I bought the truck at 208k I've been having a random No-Start condition... It can be cold, warm, or not ran for weeks. I've replaced the Fuel pump (just the pump, not the sender too), MAP sensor, ICM, TPS, and Camshaft position sensor. I'm still thinking its a fuel issue. I get 61 PSI at the test port when ignition is on, 55 when cranking, and 54 while running.
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So I have had my 02' Camry for a little over a year. Love the car, it is a 2.4L SE with a 5-speed manual. Recently it has developed this mystery misfire/hesitation under a load and at idle with the AC on. I replaced the plugs with OEM Toyota Iridium and it seemed to clear it up for about a month, but now has come back. If I start the car and turn on the AC it will intermittently start to miss but not only when the compressor is engaged and it does it every now and then under a load specifically in 4th or 5th gear under a load with lower RPM's (under 2000).
The check engine light is not on and hasn't as much as even flashed on at any time so there must not be any hard misfire codes. I want to stop by Autozone and see if they will scan it to find any stored codes but haven't had time. I would think that if it was a coil pack that it would be a hard misfire. I'm stumped. This car is in great condition...no oil leaks, interior is near perfect (replaced a worn shift knob, and door panel pieces around the window switch). Also car has 160k miles.
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2005 Ford F150 lariat 5.4
I had a misfire under a bit of a load (acceleration) and up hills. I changed spark plus with OEM Motor craft ones, truck ran super nice for a couple week.
Had the engine light flash, slow down and the RPM go up a tiny bit then back down and the light goes off
Now I'm back to miss fire different location, and a rough idle. I've swapped coil packs around and the miss fire stayed on cylinder 4.
Spark plug screwed or injector or ?????
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126000kms on 03 explorer 4.6 truck started. Running rough at idle and under load.... Code came up for cyl 8 injector. Replaced injector... problem still there. Switched cop and plug with another cyl and plug.... same code and cycl 8 is definitely not working. Would a generic problem always affect i cylinder. I even checked wire clip on for injector... it appears ok. There is power to injector wire clip.
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Got my first truck with a 350 Vortec engine, 244K miles. I've got a SES light with code P1509,
"DTC P1509 Idle Speed High - Idle Air Control (IAC) System Not Responding"
That's the only code that's thrown. The engine idles around 1000 RPM and will sometimes surge while driving between 1200-2000 RPM. I googled this code but not much came up. I've seen that a multitude of things can cause high idle, but since I'm getting a code with the symptoms, is this a pretty clear cut case of needing to replace the IAC valve?
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I have a 2002 F250 CCSB Lariat 4x4 with the Triton V10, I'm up to 232,000 miles so far and fairly happy with the old girl. Just this weekend, I noticed some hesitation when at idle and even more rough running when under slight load. The misfire/hesitation is worst when going up a slight hill, when the truck is accelerating at low RPMs.
I am getting zero trouble codes or freeze frame conditions on my scanner. What should be my order of diagnosis? Vacuum test at line from PCV to TB, COP test? EGR inspection? Plug inspection? Also, how do you test a coil if resistance is not a reliable method?
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I have a 98 gmc k 1500 350 5.7 . Was having an issue with the truck bucking it would die very briefly thought maybe bad gas. Added treatment and few days later it was doing the same this time back fire check engine lite came on checked code mass air and cam position sensor.
I pulled cap and when I was about to take rotor button out I noticed play I could actually push down on it. I pulled distributor and confirmed the play I replaced new complete distributor and yes I forgot to mark position so line tdc #1 compression stroke installed distributor timing was off.
But running rough so I re adjusted timing now it just cranks I have played with the timing alot so I tested the coil had some strange ohm readings ( high quality meter) and have voltage 12 vdc at coil and module replaced coil today still same thing I have fuel and 60 psi of fuel pressure and it holds with key off and it's not the pass lock security does not flash. Fuel pressure regulator can't be leaking.
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So my truck started to intermittently misfire about a month ago . I changed the spark plugs wires at first and it seemed to get better but it still had a misfire . I replaced the spark plugs and ignition coils and the misfire is still there . Up until the other day it was a noticeable issue but still drivable with . On my way home from work it got alot worse and started to misfire any time I tried to accelerate and now is noticeable at idle now as well.
I checked the fuel injectors resistance and they are about 14.8 ohms . I am not getting any codes for a misfire . I tried to pull the fuel injector connectors to try to find the source of the misfire but could noticeable change in engine rpm. Where to go from here and what I should check first? Would a clogged fuel filter cause something like this ?
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97 chevy k1500 with 305, engine rebuilt by shop 60k ago, last few months only drove truck 4-5 times, last time driving gave p0306, new plugs, wires, cap, rotor, cleared code, now gives p0300, took intake apart removed spider, sprayed/scrubbed each injector and poppet with cleaner, but no way of cleaning the line between the injector and poppets. No change after cleaning. Also ran injector cleaner through tank. All vacuum hoses look in good order, sprayed carb cleaner around intake to check for leaks at intake/throttle body, no leaks.
Checked TPS, IAC, MAF, Coil and fuel pressure, all good except fuel pressure was 52-54 while idle, replaced fuel pump, screen filter and main filter, cleared code, rough start and rough idle still gives p0300. Checked coil with ohmmeter, between posts A & C, Chilton says 0.1 ohms, i got 0.5 ohms, went to autozone and had them check a new coil, it have 0.5 ohms......? Can drive at higher speeds and runs smooth, but idle is poor almost dies.Checked fuel pressure after pump replacement, still ~54 psi. Stumped and don't want to throw more parts at it without a proper diagnosis. Have a OBDII pocket scan tool, but can't find manual, will try to find manual and see if I can pinpoint the misfiring cylinders.
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so this is my pops truck and its got 95k miles seems pretty clean. But it some times has a small miss fire at idle or when i put it in drive with the break on. and its just one cylinder thats missing. So iv tried new cap rotor plugs and wires but still not luck. and did a ohms test on the injectors and there all good...
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2000 Explorer Sport 4.0. I just did the heads, valves, decked, proofed. New wires, plugs. Followed the procedure to the letter. First two starts were a bit touchy, but now starts fine and purrs like a kitten at idle. The problem; under load it acts like it drops a cylinder. Bad plug, bad wire, fouled injector? This thing is driving me nuts.
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2004 GMC Sierra 2500 HD, 227,000 miles 6.0L V8.
While driving up hills or increasing load, the CEL will flash multiple times, I pull over as I know CEL flashing is not good. I turn the truck off, allow it to sit for a few minutes, whip out the code scanner, only code that was there happens to be P0300. Truck has poor MPGS, idles rough, loss of power. this happens every time I drive this vehicle as I use this truck to pull my trailer that weighs around 4000 lbs. Problems come and go. Some days I can drive the truck for an hour with no problems, come up to a red-light, BAM, CEL is flashing, truck is bouncing side to side due to the poor idle, other days this happens while sitting in the parking lot of my job with the ac on.
Truck has been to the shop several times as I'm no mechanic. Parts replaced are as follows:
- Fuel pump
- Throttle Body
- All plugs
- All wires-All Coils
- Intake Manifold Gasket-
- Battery
- Sensor 1 Bank 1 O2 Sensor
- Sensor 1 Bank 2 O2 sensor
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I have a 2006 Ford F150, king ranch, 4x4, super crew 135k miles. I bought the truck and shortly after noticed the miss under a load at 40-60 mph while in OD, or at higher RPMs at WOT, but never a CEL. Well 3 months went by and I couldn't take it anymore so with lots of research I decided to change the plugs. Ran seafoam through 2 tanks of fuel prior to this job to break up the carbon in hopes of none of the plugs breaking.
All 8 plugs came out with no issue and I replaced them with the Motocraft SP 515s (old ones were very nasty and brittle, most likely the original). I put copper anti seize on the end that goes through the channel in the head, however none got on the end near the electrode, and also on the threads. Put it all back together and it had the worse misfire an pretty much not drivable....flashing CEL and codes p0308, p0355, p0356. So I decided to buy 8 new coils as well, got all 8 of them on and now the truck is drivable but the miss is still there (no CEL).
Feels like maybe just one cylinder and I believe I got it pin pointed to cylinder 8. I put a vacuum gauge on it and unplugged the injectors 1 at a time and cylinder 8 is the only one that there is no change while unplugged. So I switched out the coil thinking maybe I got a bad one, still does it. My COP electrical plug has 12v Constant and also confirmed with an led it is getting signal. The injector is ticking or pulsing as i confirmed with a mechanic stethoscope. What am I missing????? Today when I get off I plan pulling the spark plug, checking for carbon tracking, check compression, check actual visual spark, and pull and clean the injector.
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I have an 05 F150 with the 3v 5.4 with 170k on it. Last fall we changed the timing chains, cam phasers (aftermarket), plugs, coils (OEM), VVT solenoids (OEM), Cam Position sensors (OEM) and swapped in a GT500 oil pump. Recently under moderate load (fairly heavy acceleration onto the freeway, pulling a large camper) I get a pretty rough misfire. Tonight I pulled the codes and it was Cylinder 5 misfire. In the past I have also had Bank 2 Over-Retarded code. What are the next things to verify and check? I plan to clean the throttle body and change fuel filter but I'm not sure either of those would cause the misfire code?
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I have a 2003 f 350 6.0, when under a heavy laod such as towing a 3000-pound trailer up a long hill at approx 60mph and 2000 rpm it intermittently mis fires.The boost gauge bounces up and down and i here a poping sound from the engine compartment.I have had it to several dealer and independent shops but with out the trailer or a heavy load it runs perfectly.They have told me fuel pressure is good and changed all fuel filters with OEM parts.
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I have a 2005 f150 4x4 with a 5.4 it was studdering on the highway under light load, i changed the plugs and coils it worked great for a day now working worse and giving a misfire #7, so i swapped the injectors around still misfire #7.
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I have a 2002 Ford F-150 with a 5.4 Triton. 212,xxx miles. I replaced the cops and the plugs about 6 months ago. I was pulling a trailer up hill last week and the engine was under a load doing about 3000rpm. It began to misfire and give me a flashing mil. However, before I went very far the engine began to run fine. It happened 3-4 different times. However, there is no code recorded. I've driven the truck nearly 100 miles with no problems, but I'm going to be pulling that trailer uphill again next week.
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I have a 98 4x4 with 145k miles and 4.0 OHV. Symptoms are as follows;
Uses ALOT of oil. 1 quart per 230 miles. Burning bad in rear cylinders, some in middle cylinders, none in front cylinders. Screams intake or PCV issues to me, not rings or valves. Never any smoke, not even on startup. No significant leaks. MPG always 18-20mpg.
Slightly rough idle.
Miss under load below 2k rpm. Not a terrible miss, but you can feel it. Has never lit the CEL. I know the CEL is good.
Never loses coolant. No coolant in oil or vice versa. Haven't done compression test, but doesn't seem like they ever tell you much anyway.
This weekend I replaced all intake gaskets, plug wires, cleaned oil residue off and regapped plugs (they are 3 months old), injector orings, and PCV valve. Flushed and burped radiator.
It's too soon to tell on the oil consumption, but I thought the intake gaskets would have cured the rough idle and misfire. The idle IS much better, but still not perfect. But the low rpm load miss is actually worse now. Still no CEL. Could it be storing codes without lighting the CEL? Also, how do you clear codes on these, can you just disconnect battery, or do you have to clear them with a scanner?
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