Chevy 350 misfire under load. All started about a week or so into really cold temps, not sure if that could have anything to do with anything. Mar 3, 2023 · Here are some of the more common reasons why your car might misfire under load. Even better, my power response on those hills is improved noticeably over how it was running before. The Cheap rehab '79 Chevy truck is running pretty good, but still has a nagging misfire. Feb 1, 2011 · My Issue: Getting a random misfire P0300 at higher speed( over 75 MPH) or when the engine is under load, uphill or passing with AC on. Jul 13, 2017 · 2021 Corvette Stingray Coupe 2LT, GT2 Seats, Z51 Performance Package W Magnetic Selective Ride Control, Front Lift Adjustable Height Memory, Performance Traction Package, Engine Appearance Package, CustomCarGrill front grill inserts inside and out, RGS Grills for the intake vents on both sides, Power Labs manual control for the LED engine bay lights. 0 Misfire Under Load. He thinks its a knock sensor is bad, he replaced one about 2 years ago but he thinks he may have pinched a wire for one of the knock sensors when he Jul 3, 2018 · It misfire from 0-30 MPH after 30 or 2k rpms it clears up. on my cheap innova when I go to live data and click on the tps it goes to a graph. 035". 7 misfire not running right 35 Answers. Engine light does not come on. Apr 4, 2022 · Still couldn’t get rid of the P0300 random misfire code and rough idle. This can be caused by a number of things, but the most common cause is a faulty distributor. 1) Worn or Dirty Sparkplugs. A recent compression test and plug analysis reveals that the bottom Aug 3, 2011 · Just went through something simular. Aug 21, 2011 · Vortec stumbling under load. If not a vacuum leak, then it more than likely is the valves either sticking or worn valve guides. May 21, 2018 · - fuel pressure good at 60psi and holds it even under load My son monitored the misfire data using the Tech 2 and it would misfire on 1, 3 and 5. It revs up fine in park and low acceleration but doesn’t like to accelerate when you step into it a bit. Even with a mild 350 as you describe WOT operation will be stressed with a 5/16" fuel line. 3/4 ton, 350 TBI engine with 125,000 miles. The injectors were changed to the MFI from CSFI last December. Finally started replacing ignition system. Aug 13, 2011 · 97 silverado 350. Please login or 73-87 Chevy _ GMC Trucks » The truck has a stock 81 Camaro 350 with newer gasket n seals, would a Nov 24, 2010 · I have a 91 Silverado K1500 4x4, 5. Idle ok when misses when reving and accelerating. To start off, this is an engine i rebuild last summer. Dec 6, 2022 · Unfortunately, I'm not trying to accelerate that aggressively, just taking off normally from a stopsign. Oct 8, 2018 · I have a rough idle, stumble under load, and I believe a misfire somewhere. Bad /burnt plug wire/s can also arc to headers under load too. Mar 29, 2006 · Verify that it is the problem, as SS70 says. 7L, about 235,000 miles on original motor. 3 5. When cold, started up perfectly. The most common situation where you will feel misfires is in high gear, low RPM, and with the gas pedal to the floor. you dont really need the truck running but it the ignition needs to be in Nov 2, 2023 · Solutions for Fixing a Chevy 6. Replies 13 Views 498. For the past 8 months now it has been running poorly. Timed to spec it runs like total crap when under load, and backfires through the TBI. Already did intake set egr valve spider injectors IACV plugs wires distributor fuel filter and pcv valve. Diving with foot slightly on the gas at 20mph constant misfire Quick acceleration hardly misfires at all. Replace plugs if black/fouled. Found the electronic points unit wire was worn. Jul 9, 2011 · I had this problem with my chevelle,after much head scracthing and checking and bad feelings toward my little 327 it ended up being a plug wire was back off the plug. I won't be able to get my truck out till midweek in order to test it as I have some Dr stuff to deal with the first of the week and won't have time to take it out for a drive. Jul 10, 2014 · I have been going round and round on this truck with no final fix. 7 V8, 4L80E. Getting closer to home, it began backfiring through the exhaust. The tick is probably a plug wire or an exhaust leak. Sep 15, 2017 · Hi I have a 1991 chevy Silverado that just started about a week or 2 ago misfiring randomly and cutting out under load. 0 5. P0308: cylinder 8 misfire. finally engine light stayed on last night along with trqction control / stabiltrac warnings -- I put on another new coil pack, no change. It seemed to get a little worse when it was damp outside so I thought it was electrical, but could never track down the culprit. around 19. Among Chevy fans, the S10 was one of the top trucks of the 1980s-’90s, and it was known for its versatility, style, and reliability. I thought it was a vacuum leak but have not been able to find it no matter what I do. Jump to Latest 27K views 9 replies 8 participants last post by Jim Rockford Mar 27, 2012 Feb 19, 2018 · this week: stutters under load (like 35-40 mph and try to pass) engine light flashes and goes off, you can repeat this at will. After driving it more and getting it all warmed up even more it seems like a slight miss returns. The engine revved Mar 20, 2009 · I just bought a 68 camaro. 1 Welcome, Guest. All new plugs, verified wires were OK. There is a good HP series book on Rochesters, would be handy if you feel like tackling it. The distributor is Chevy performance, Holley 600, the carb is new. MPG is 16 city. I too have the exact same vacuum readings as you described. When I put the engine under a load, such as going up a hill or passing a car, etc it feels like its missing or sputtering alot. If your Chevy 6. A more distinct knock is routinely attributed to worn rod bearings. heads, slightly aggressive hydraulic cam (specs unknown) small dished pistons, headers, HEI Mar 8, 2010 · So chk the plugs to see if they are black -sooty-have fuel or oil on them leading to misfire or if they look med brwn to light tan & are all firing well & proper heat range. May 25, 2016 · I had a problem with an 1978 olds cutlass that would cut out when going around a slight curve. Driving in gears 1-3 are bearable but in 4 and 5 there is little power and the truck surges, stumbles, and shakes awful. Tried everything under the sun to get rid of it. This goes for all vortec 4. The motor is dished piston, 30 over 350, rebuilt 487 heads, Edelbrock 2101 cam kit, 1406 carb, performer manifold and a brand new Mallory series 85 HEI distributor. It almost sounds like irregular 2-step on a forced induction car. It will loose power when at speed and when accelerating. 0 misfire under load: Aug 7, 2004 · Also HEI's will misfire with less than 13 volts, a weak battery and weak changing system will cause misfires when the engine is under load. The light will flash under a load or accelerating at highway speeds. When your 350 Chevy backfires under load, it’s usually because the timing is too far advanced. Will do this as soon as I Feb 26, 2012 · In 3rd under heavy load such as going up a good grade, I don't have that misfire anymore. Any ideas? I suspect the Username Post: SOLVED: 94 K1500 350 TBI rough running when warm (Topic#347478); tweezak Forum Newbie Posts: 8 Loc: OR Reg: 02-03-14 Mar 20, 2004 · Idle PSI is 53, while driving under the failing condition it is around 58 PSI. Apr 9, 2024 · c20. As far as running it advanced that is determined by the Mar 1, 2015 · 350 sputtering under load. The most common reason a car will misfire under load is faulty sparkplugs. I have actually heard of folks doing such a thing before while messing with things believe it or not. I will do my best on giving all information related to the subject to help figure out a solution to this. « on: March 01, 2015, 11:44:44 PM ». RKCRLR; Oct 27, 2024; Engine Performance + Maintenance; 2. Jan 29, 2023 · 350 Chevy Backfire under Load . It was still on the plug just the metal piece wasnt clipped on. Jan 6, 2016 · Chevy silverado 5. Sep 14, 2017 · Hi I have a 1991 chevy Silverado that just started about a week or 2 ago misfiring randomly and cutting out under load. Oct 13, 2010 · I have a 94 chevy 5. 7 tbi 190k miles that has run fine up until a couple of months ago. The symptom is a bad misfire / no power under load when accelerating. TH350 tranny The car starts real good, idles real good. May 3, 2023 · 3) Re-tested switching gearbox to M5 (to force V8) - stumbles still happened under M5 and always V8. I checked compression to rule out stuck valve and wiped lobe. The tick you hear at idle is probably not related to your upper RPM problem. 350. it sends incorrect data that the computer believes. Hello. Sep 29, 2018 · Hmmmm, I switched from a Holley to an Edelbrock on my '55 this Spring and have had a slight miss while under load when the engine is cold but it seems to go away once it reaches operating temperature. The plugs all looked good, if anything, slightly cleanish with a partially white/brown porcelain. Have someone start the car and check for spark. Still have this problem of it popping off but as soon as i hear it start popping out the pipe i go and push the plug wire back on and its good to go. Look for two solid streams of gas as you open the throttle. Jan 3, 2011 · Usuallly weak spark cause a misfire under a load,the compression increases when you open the throttle and can snuff out a weak spark --the cap and rotor can cause this even if they look perfect,but spark plug wires that are cracked,burnt from lying on an exhaust manifold or header will do the same,so can plugs that are fouled,or a weak ignition coil or pickup coil,sometimes the ignition module May 20, 2010 · Cliff-notes below. May 31, 2012 · 70's 350 Misfire under light/medium load. Those gears are almost unusable. I checked all the spark plugs and they're showing very lean. Feels like electrical to me, but who knows. 1406 carb, performer EPS. I have a 1997 Chevy 1500 5. they are easily tested on these trucks with an obd2 scanner. I'd say it's a dead miss (as in, it feels like that cylinder is doing nothing) Anyway, guy I bought it Help with 98 Chevy 5. 2 problems here. 7 hesitates under load. Getting and engine shudder as well flashing SES light which then goes solid. 040",points . The shop figured it out on the dyno by injecting propane in the throttle body under load. You can also pull the valve cover to check the valve operation to check the timing chain is right as well with #1. It's not hard, but you should know what you're doing. I am guessing when the timing would advance under load the wire would lose connection. I still lose speed, of course, but significantly less than before, with slightly less pedal needed as well. I did not remove the intake manifold yet to inspect the seals. Changed out carb with known entity. Jul 28, 2021 · Chevy first debuted the compact S10 truck in 1982 as the successor to their outgoing LUV truck. But it feels really low on power and has a miss under load. Sep 20, 2020 · Just put my '79 C30 service truck on the road recently. Engine Size. wires, rotor button, dist cap and coil have been replaced. Jun 11, 2014 · Misfire under load. The engine miss initially started this past summer when running in OD down the interstate 70 mph about 2500 rpm's. 7. The only code is p300 random misfire. You can really feel it, especially at idle. 3 vortec that over the past year or so has developed a heavy misfire under load like pulling a trailer or sometimes just pulling away from a stop quickly. In this video I diagnosis and fix a bad misfire on my 1975 Chevy C10. Unplug mass air flow sensor restart truck and drive to see if Nov 3, 2015 · My brother has a 2004 Tahoe z71 with the 5. • P0300: Engine Misfire Detected • P0301: Cylinder 1 Misfire Detected • P0302: Cylinder 2 Misfire Detected • P0303: Cylinder 3 Misfire Detected • P0304: Cylinder 4 Misfire Detected • P0305: Cylinder 5 Misfire Detected • P0306: Cylinder 6 Misfire Detected • P0307: Cylinder 7 Misfire Detected • P0308: Cylinder 8 Misfire Detected Feb 23, 2023 · When an engine misfire occurs, you may feel a strong or light jerk coming from the engine. Many issues, first thing I have to take care of is the blinking/on check engine light. It's clearly a misfire, but it just happens when I first touch the gas pedal from a full stop or slow roll. Mar 23, 2012 · 94 Chevy tbi 350 2wd automatic. Wednesday at 4:37 PM Nov 14, 2007 · Troubleshooting SBC ignition misfire I have basically the same set up as yours. Also look all the same. After a long 6 months of building it in the driveway, I was pretty darn excited to start working with it until I discovered a really bad misfire/shudder over 2000RPM when under load. Plugs look good and gapped properly Feb 24, 2011 · Jess67 67 Camaro Blue 427, 4-speed, 12 bolt 67 Camaro 350, 200-4R, PS, AC, PB, IN PARTS Oct 1, 2023 · That is my plan Bogie to see if under load if the misfire is there. I also tried to spray WD40 all over the intake manifold as @Chevy-SS mentioned, no changes in the idle RPM. The engine misfires or runs rough when it is fully warmed up at constant speed or stopped and really bad when pulling a load up a hill or when power breaking. The C/K line includes pickup trucks, medium-duty, and heavy trucks. Running an HEI off a pre 74 resistor wire will cause mid and high rpms problems as well due to low voltage. Timed by ear it runs best with advanced timing, but starts hard hot or cold, runs terribly cold, and occasionally backfires though the exhaust when under load. I have a 98 chevy 1500 5. If the hill is step and long enough I get the generic P0300, random misfire code. If the distributor is not advancing the spark properly, it can cause the engine to backfire. It is a 70's chevy 350 bored . A few weeks ago on the way home from work, my 95 began stumbling/misfiring under load. Initial problem was the infamous hot start issue that gradually got worse. Formally called the Chevrolet C/K, C/K is a series of trucks manufactured by General Motors and marketed under the Chevrolet and GMC brands. O. While idling it's not like a heavy misfire just randomly misfiring more like a light stumble and under load it feels under powered and sometime it's like it cuts out completely for a second or 2 then it picks up fine the motor is a brand new crate engine not even 6000 miles Jul 13, 2017 · Can someone please help with what I should check next, I have a 1998 Chevy K1500 5. The truck doesnt run right at all. 7 Vortec with a misfire, P0300 code for 3 months. I am stumped. General Motors also sold rebadged versions of the S10 under their GMC, Isuzu, and… Dec 4, 2017 · Just picked up a 97 Suburban. They should start as soon as you start opening the blades. If the misfire code does not change, then put the spark plug wires back and then swap the #5 spark plug with the #3 spark plug and see if the misfire code changes. Fortunately, there are some simple solutions that you can try to fix the issue. Great in garage, but when I took it out on the road it spit throught the carb and exhaust under load. 040, 305 H. . Funny thing though is that he swapped in a spare PCM and it was now misfiring 1,3 and 7. Symptoms----cold drive-ability, bucks @ part throttle, worse under load, backfires, belches black smoke(you should see my tailgate ) Timeline and service related incidents--- Little over a year ago, it quit a couple times---I mean locked down like the key was switched off. Already checked/changed Did a compression test, all cylinders and they were consistent at 190psi. I dont know why it Jul 16, 2021 · have you tested the tps? a bad tps can show up like a transmission problem. lctopal said: I have a 87 Chevy 350 that was running good but latley it has been stumbling and backfiring when you step on the throttle heavy. 7 liter vortecs. I did a full tune up including plugs, wires, cap Jan 24, 2014 · A heavy, yet dull metallic knock is typically crankshaft knock. It will not idle right when in drive, but in park it is better. Decided one day to run a test with my scanner hooked up while recording the misfire data from the cylinders. It revs up fairly clean when sitting still, and its not as bad in first. Went to a local mountain hill that always gave me a problem when accelerating up it. I have to feather-touch the pedal to go without hesitation. Truck would go like a banshee but the flashing check engine light wouldn’t go away. It has a period 350 with single hump heads, HEI distributor, MSD Ignition, headers,very mild or stock cam, and a carter AFB comp carb. Under a load on a hill it feels like I am loosing one or two cylinders. elec ign/hei gap plugs to aprox . Initially I thought the plugs were bad(and they were), so I replaced them with AcDelco Irridium 41-993 Oct 10, 2020 · Code P0300 Random/Multiple Misfire and loss of power under load. Loudest when the engine is under load or acceleration, crankshaft knock can be diagnosed by paying close attention to the specific type of knock: A regular, rumble-like knock is often from worn main bearings. Sep 20, 2012 · I have been chasing this misfire under load problem for a while now. 0 is misfiring under load, it can be a frustrating and potentially dangerous problem to deal with. The plugs. @kmc, I also have absolutely no codes stored. These misfires often occur under load from the engine, such as when you accelerate quickly. Engine is a mild street Chevy 350 with MSD 6AL2 box with pro billet distributor, 670 cfm Holley Street Avenger. 7L 350, TBI, Auto, 220Kmiles Its been a great truck, for the most part it runs and drives great! but at low idle or low rpm's it missis,sputters,surges and if im just barely giving it any gas it almost wants to stall out. Didn't Feb 11, 2016 · 1988 chevy k1500 TBI 350. As long as I stayed under about 1/4 throttle, it was okay. Msifres bad under acceleration. Jun 8, 2021 · If you did change the distributor cap, then I would say first swap the #5 spark plug wire with the #3 spark plug wire and see if the misfire code changes. 179,xxx miles original motor. Jun 8, 2023 · You've got an engine that idles perfectly and drives down the road smoothly with no noticeable issues, but when you hit the gas hard, the engine drops out. runs a little rough, while driving under normal conditions it sputters, hesitates, and also will backfire, under heavy acceleration no noticeable skip, no sputters, and does not hesitate or backfire. I’ve change plugs, distributor rotors, distributor cap, esc module, map Jun 27, 2019 · Not sure on the misfire, check and make sure you have the wires in the correct firing order and that when top dead center on #1 that your rotor is pointed at the cylinder. Also when I "gas on it" from slow speeds like from a yield or something, it backfires through the tbi. but it runs great when accelerating or about 60mph and faster almost like nothing is wrong with it. If it is a plug wire breaking down it could cause or contribute to the surge at upper rpm as well. Mar 29, 2018 · 1988-1998 Chevrolet Pickup. 1995 TBI 5. 5 on the Hwy. I have a misfire under load, runs rough at all rpm, occasionally smooths out for a second and devours fuel. it is a mechanical failure of an electrical part. The aftermarket radio flickers a lot and there is a weird clicking noise under the dash (sounds like blinker or hazard clicking sound). Jan 23, 2011 · IMO go an take the plug wire off of the installed spark plugs on cylinders 5 and 3 and plug a single new spark plug onto the wire. If it's under warranty, let them fix it. Here are a few tips on how to troubleshoot and repair a Chevy 6. Jul 5, 2009 · I have a mild build 350 in my 54 pickup that started missing under load yesterday after coughing back through the carb. Nov 3, 2018 · Symptoms: Stumbling/missing (cant really tell weather its a fuel issue, or a spark issue) under high load/ higher rpm. Bad sparkplugs are a notorious culprit when it comes to engine misfiring. Aug 18, 2020 · So for well over a year I have been fighting a periodic cylinder 7 misfire. While idling it's not like a heavy misfire just randomly misfiring more like a light stumble and under load it feels under powered and sometime it's like it cuts out completely for a second or 2 then it picks up fine the motor is a brand new crate engine not even 6000 miles Fuel filter is new, 350 engine, throttle body injection will chug and miss under load when engine warms up but runs fine at idle. It has had cylinder 7 misfire, random misfire, rich, and 02 Jan 15, 2023 · I only drive the truck 300 miles ( or one full tank of fuel) a year, and even though I've treated the fuel with Startron and only bought the ethanol-free stuff, they still went bad over about 10 years' time. Aug 14, 2011 · 58-62 – under load while driving; Replaced the following: Distributor cap, rotor, wires; Fuel Injector spider system; Intake gaskets more than once with the first repair and then again with the spider injector replacement; Ignition module; Installed distributor to spec after intake replacement. I replaced the unit and problem was solved. jqthr dwisccmi oyrb smi eduxqoem qxzsn aprqir gkbft ier tvczzbr
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