Chevy 350 misfire under load. It feels like a very bad miss.

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. 7 Vortec Has 160000 Miles Andhas A Misfire Help with 98 Chevy 5. Total Queries: I have a mild build 350 in my 54 pickup that started missing under load yesterday after coughing back through the carb. Joined Feb Just picked up a 97 Suburban. It does help to have a scanner if possible. its timed correctly. Didn't have time to mess with it then, besides I had another truck ('06 Avalanche) to drive for the time being. 111 seconds. It feels like a very bad miss. The misfire seems to go away completely at higher rpms (no tack to verify what rpm but I would guess over 1750 or so based on the sound of my 95). P0307 Cylinder #7 Misfire. but it runs great when accelerating or about 60mph and faster almost like nothing is wrong with it. 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. The engine miss under load. These little pitas can cause all kinds of hell. 8K views 10 replies 6 participants last post by JTWard Mar 4, 2014. 91shorty Discussion starter. Rotor will actually be between two post resulting in misfire due - 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. P0304 Cylinder #4 Misfire. Under load (feathering clutch or driving) it runs great, Motor is a early 70's 350, bored 030, flat tops, 76cc heads, mild cam When you are getting the misfire hold the rpm steady and take a look at the timing marks with your timing light to see if it stays steady. 7 liter vortecs. What I did notice since replacing the Map sensor is driving it under 1500 rpms it's doing great but the scanner still reads -10 for map. 030 over 350 in 79 camaro having miss fire or skip above 4500rpm. All looked like the two you see. P0306 Cylinder #6 Misfire. 4l I had previously. It caused a miss at idle and under low rpm load, but no other time. 1997. The computer I have been trying to track down the cause of my backfiring under acceleration and have not found anything conclusive until maybe now. Found the electronic points unit wire was worn. 1994 tbi 350 misses under load and died. It almost sounds like irregular 2 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. 1988 chevy k1500 TBI 350. Vortec stumbling under load. So I put on a vacuum advance and that solved some of the problem. Much Appreciated Brian. 13 people found this helpful. 4L Caravan, Grand (I've Occasional misfires may pass unnoticed, but a steady misfire is hard to miss. 5:1 compression (flat top pistons) 350 Chevy that's freshly rebuilt and is run on 93 oct gas, ignition timing is set at 10-12° idle, 700 rpm, and 34-36° at 3500 rpm. it pops out the exhaust throughout the rpm range. 2000-3000 it's pinging My 1986 Silverado C10 with a small block 305 is having a weird misfire issue. After cleaning the system, we drove the vehicle under the same conditions we experienced the misfire, and we did not feel a miss. Whats the chances the new unit is failing and are they usually covered under waranty I Have 97 Chevy K1500 With A 350 Engine That Has A Misfire On Asked by pamelaleigh1961 · 4 ANSWERS. User Info. 1995 TBI 350 with 214k stumbles a little at idle, Originally mine also had an ignition misfire under load, so I did a full tune-up on it (plugs, wires, cap, rotor, coil, 02 sensor), This is almost identical to the issue I'm having. runs a little rough, while driving under normal conditions it sputters, hesitates, and When i have encountered a misfire under a load at mid to higher rpm's 9 times out of ten one or a mixture of the following have been the problem. it could be several different things. PULLING OUT THE JUNK AND GOING BACK WITH OLD SCHOOL 350 MOTOR AND TRANS. You can really feel it, especially at idle. We have scan readings that showed an issue, carbon on the spark plugs, and a drive test where we experienced the problem. When an engine misfire occurs, you may feel a strong or light jerk coming from the engine. A code P0302, for example, would tell you cylinder #2 is misfiring. 3, 6L80, typical cat back and intake tube, suddenly started this random jerking/bucking, exactly like a random misfire, but no codes, no misfires on counter. I have a 1993 Chevy Silverado with a 350 v-8 and tbi injector. 350 MisFire / BackFire. Timing set to 34 degrees total advance. Jump to Latest The shop figured it out on the dyno by injecting propane in the throttle body under load. Check your try Sea Foam - that helped quite a bit on my 77 Chevy Blazer. Any misfire codes. 94 Chevy truck. I have a 98 Silverado 5. 1999 5. 040, 305 H. Gassed up and it ran perfect for 250 miles so I dont think its a bad batch of fuel. I have replaced all spark plugs and wires earlier this year and all that stuff checks out good. 3l Z71 140k miles. This type of misfire is usually more noticeable and can cause significant drivability issues. At idle it has a slight miss, and under load any sort of load or while accelerating through mid range RPMs, it runs like absolute crap and will even feel like a shutter at times. 0 5. 1930 DeSoto CK Business Coupe- 350 Chevy Crate V8, 4-wheel disc brakes, TH400, S-10 Rear, Heidt's IFS, A/C Email Report docjns1 94 Chevy tbi 350 2wd automatic. I changed plugs and fixed it. The engine miss initially started this past summer when running in OD down the interstate 70 mph about 2500 rpm's. I About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright Hey guys, I'm having some trouble diagnosing a miss under load in my truck. i also have a 90 tbi truck that runs fine and the timing is the exact same as that one and advances the same as the good running truck. The Check Engine light should be on, and there should be one or more misfire codes for the cylinders that are misfiring. I had a wire that was to close to a header and became damaged. When they start to go bad, stumbling under load occurs. New posts Latest activity. A misfire also will cause a huge increase in hydrocarbon (HC) emissions, which can cause a vehicle to fail an emissions test. I have a 96 GMC that it got to where it would run fine on a flat road but would start "bucking" when going up a hill. Home; Chrysler. This is one of several videos in this series where I show you some easy ways to diagnose Yes, 5-6 psi is all you want. Higher throttle always seems to work and when under way. Timed to spec it runs like total crap when under load, and backfires through the TBI. The symptom is a bad misfire / no power under load when accelerating. Idle PSI is 53, while driving under the failing condition it is around 58 PSI. ) Iv pl 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. at idle, at slight acceleration, at full throttle (if it doesnt crap out when i step on it which it usually does) isnt '69 C10 327 SBC Off Idle Stumble / Misfire Help - I feel like I've tried EVERYTHING The 1967 - 1972 Chevrolet & GMC Pickups Message Board As it gets under load in higher gears it starts to sputter bad, especially in 3rd gear right before shifting into 4th (700r4 trans) Engine is a 10. I'd say it's a dead miss (as in, it feels like that cylinder is doing nothing) Anyway, guy I I'm planning to replace injectors, FPR, base intake gasket etc later on. A friend told me that it could be the timing chain is off a few marks or the valves are closing how they are supposed to. Chevy Forums FREE technical assistance for your Post: SOLVED: 94 K1500 350 TBI rough running when warm (Topic#347478) tweezak Forum Newbie Posts: 8 When driving it shudders erratically at idle when in gear (ie: at a stoplight). 030 over 350 . Partial misfire: A partial misfire occurs when there is some combustion in the affected cylinder(s), but it is not complete. #help 350 tbi 5. 4L; 2. The engine revved In this video I diagnosis and fix a bad misfire on my 1975 Chevy C10. CHEVROLET TRUCK. Initially I thought the plugs were bad(and they were), so I replaced them with AcDelco Irridium 41-993 I had a problem with an 1978 olds cutlass that would cut out when going around a slight curve. But then I "borrowed" the curved accel from my father's El Camino and put it in my truck. hey guys new to the group I have a freshly rebuilt Chevy 350, got it running yesterday but had some concerns, the timing was set dead on the distributor but it had a odd misfire. 1) Worn or Dirty Sparkplugs. I have a 71 Chevy Nova with a 350 motor. I'm open to any input. Since this was an intermittent issue we wanted to make sure the vehicle was completely repaired. about 2001 and older are equipped with a air injection system that is fed into the exhaust system when the engine is under load. New posts Search forums. Jump to Latest Great in garage, but when I took it out on the road it spit throught the carb and exhaust under load. It idles smoothly and revs fine in park. start the engine at night and look under the hood for a misfire in the dark, it much easer to see them like that. 40k on trans. it idles fine and revs in idle fine but when you drive it or brake torque it, it kinda missfires putts and when you let off the gas it dies. The most common situation where you will feel misfires is in high gear, low RPM, and with the gas pedal to the floor. 7 L 4L60E NV246 ARB '07 K1500 Suburban LT 5. Thread starter 87sub91; Start date Feb 22, 2016; 8. The engine usually feels rough, lacks power and uses more gas than usual. 90 Chevy K2500 350 motor TBI. Getting and engine shudder as well flashing SES light which then goes solid. to all who are having a miss fire or lack of power under load replace your fuel press. Chances are the misfire is due to a weak ignition coil. 7 TBI motor misfire FusionBB™ Version 2. Problem I am having is anything under 2000 rpms it will run just horrible like its not firing on all cylinders and driving it does not change the symptoms. 0L, 2. . As for the symptoms, a nasty misfire in the 2000-3000 You'll need the proper catridge, aldl adapter and power cord. P0303 Cylinder #3 Misfire. I am working on a 90 Chevy G30 van with a 350. Mark helpful. 1995 Chevy 5. The engine starts easy and runs smooth at idle. Feels like what feels like a hesitation is actually ignition misfire rather than lean misfire. 10 deck clearance with flat top pistons crane soild lift cam 561 lift set @ 28 & 30 ex 310 duration 112 centerline weiand open plane intake 750 350 Chevy Engine Stutter @ 3,600 to 4,000rpm. 7 Vortec with a misfire, P0300 code for 3 months. My 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. It's literally only at idle that I notice the misfire (barely). Gm engineers don't live at 3500 feet and drive in real world conditions so don't beleive the crap they put out. Gen1 350 with an Edelbrock Performer manifold and 1405 carb Mild Crane Blazer cam, Keith Black pistons I timed it to about 10 btdc and it ran good under light load but when i tried to get on it, it wasn't happening. I plugged in a code reader, and it shows nothing out of the ordinary. I replaced the unit and problem was solved. The truck runs good other than under heavy load, and gets better MPG than the 94 2wd CCLB DRW 7. Also when I "gas on it" from slow speeds like from a Not in my experience. Replaced and all works well I have a 94 chevy 5. TH350 tranny. Joined Feb Under load (feathering clutch or driving) it runs great, Motor is a early 70's 350, bored 030, flat tops, 76cc heads, mild cam When you are getting the misfire hold the rpm steady and take a look at the timing marks with your timing light to see if it stays steady. When operating at slow speed, it stumbles and nearly dies when you lift off the gas pedal. Starts up and idles 3/4 ton, 350 TBI engine with 125,000 miles. '69 C10 327 SBC Off Idle Stumble / Misfire Help - I feel like I've tried EVERYTHING The 1967 - 1972 Chevrolet & GMC Pickups Message Board got an SBC 350. Sometimes, even tho' the Here's my issue, even though there are no codes set or CEL I have a seemingly random misfire at around 2100 RPM or so when under a light load (up a hill). Bad sparkplugs are a notorious The Cheap rehab '79 Chevy truck is running pretty good, but still has a nagging misfire. My 97 Chevy 1500 4x4 5. I have a new to me 1996 5. I recently had a water pump go out and experienced an episode of overheating in which the engine actually shut down. You can check for a clogged cat by removing your o2 sensors. Those can be a source of misfire too. Being able to rev it in park but misses under a load could be either a fuel, ignition or vacuum problem. As I mentioned when I lost 3 lobes in my 305 the car would idle perfect. 7 tbi misfire sputtering Disclaimer: Links on this page Verify fuel pressure at prime, at idle, and under load. Hi fam, long time Chevy owner, first time posting. While accelerating it goes smooth until about 35mph 89 Chevy 350 to backfire constantly. O. As long as I stayed under about 1/4 throttle, it was okay. I am guessing when the timing would advance under load the wire would lose connection. " Hello, I'm working on a 89 chevy with a 350 TBI and I'm trying to figure out this issue. ok so my truck has a misfire and when when driving over Just another Chevy truck, just another misfireright? Not so fast!There is more lurking under the hood on this 1998 Chevy K1500 than just a bad spark plug. As soon as the motor warmed up and was placed under load it would back firing like crazy. 1500-2000 she starts running rough but if you back out of it it smooths out again. Easy to replace, any junkyard with chevy/gmc trucks has a dozen of them. Considering the quality of I think I figured out what & why the rebuilt mild 350 misfires, and cuts out at higher rpm's. I was having a minor intermittent misfire on 1 cylinder and is not on any particular one because no matter what plug wire you un hook it still happens the same way and now its getting worse to where one will start to fail then another one will follow and is P0302 Cylinder #2 Misfire. the motor is a . This can result in a less noticeable misfire, but it can still cause poor engine performance and increased emissions. 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. 2011 CC 4x4, 152k, Lew tuned 5. M. Under part-throttle acceleration, the engine will pop/crackle out of the exhaust. It is a 70's chevy 350 bored . Unplug mass air flow sensor restart truck and drive to see if This problem does not occur when in park motor purrs like a kitten only under load. Anytime I put my SBC under load, the engine stutters. Many issues, first thing I have to take care of is the blinking/on check engine light. It has a harsh, choppy idle. 7 misfire not running right - Hello. Engine Misfire Diagnosis using a 396 Big Block Chevy as an example. It was night and day. Funny thing though is that he swapped in a spare PCM and it was now misfiring 1,3 and 7. P0308: cylinder 8 misfire. The most common reason a car will misfire under load is faulty sparkplugs. flow at the o2 sensor hole is about the same behind the cat as it is in front of the cat your ok. MEANSTREAK K30 1/2 ton status. Stock motor with e-fans, longtubes, wait4me tune. Misfires up hills under load replaced Plugs, wires fuel pump fuel filter ignition coil, distributor including cap and rotor and verified using scan tool Forums. Symptoms: Stumbling/missing (cant really tell weather its a fuel issue, or a spark issue) under high load/ higher rpm. All started about a week or so into really cold temps, not Hey guys, I'm having some trouble diagnosing a miss under load in my truck. I can't figure out what's happening with my sbc 350. Hello guys I have posted here before about my issue. 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. Sensor was bad. Timing is 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. Re: 72 chevy 350 running rough under load! A waste to try to explain your timing if you're off trying to find a reason to kill your eddy carb. Doing the major tuneup first. 7 hesitates under load. Its a 72 350 with a mutha thumpr hydraulic cam 194 heads with a Holley street dominator intake, 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, i have a . This is my small block chevy 350 with hei distributor. It was still on the plug just the metal piece wasnt clipped on. ) I’m in California and subject to smog 91 chevy misfire and shake under load. 0L Neon; 2. I already replaced the coil about a month or so ago. 9. 2. What's new. To best describe 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 1988 chevy k1500 TBI 350. It can be tricky to track down because it only happe 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 Hi I have a 1991 chevy Silverado that just started about a week or 2 ago misfiring randomly and cutting out under load. it sputters and bogs when it gets under load in gears. When i release the throttle during the missing it will generally recover the idle. Symptoms----cold drive-ability, bucks @ part throttle, worse under load, backfires, belches black smoke 98 Silverado k1500 4x4 350 Email Report Bill K. Jump to Latest I'm having a big problems with my engine, It all started when i changed intakes. Not only did it not pop under load, it had way more power. Under load it backfires through the intake. 7 TBI motor. 97 Chevy P/u Misfire. The plugs, cap and rotor look ok, must be something thing I don't know about. P0305 Cylinder #5 Misfire. 7 tbi 190k miles that has run fine up until a couple of months ago. 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. 179,xxx miles original motor. speed demon 650 carb. Anyway, it's a 350 with a Q-Jet running 8 degrees advance initial timing. I checked compression to rule out stuck valve and wiped lobe. It has ported 882 heads that are freshly decked with new valve guides, valves and springs, new cam and I have an 01 5. I have a scan tool and here is what I have determined: the misfires are almost all in the front half of the engine cylinder number 2 seems to be the worst offender most of the time, but it 97 silverado 350. This goes for all vortec 4. 7 k1500 misfire/backfire. 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. Recently replaced the PCV valve but having issues since then. And I could rev the motor up with no load. Execution time: 1. Here's what I have and what I have checked so far. Artificial Intelligence is no match for Natural Stupidity This was recently brought up in another thread where a 3500 series Chevy van w/the Vortec engine was cracking exhaust manifolds, presumably because of heat. A recent compression test and plug analysis reveals that the bottom Can someone please help with what I should check next, I have a 1998 Chevy K1500 5. Easier yet, the common problem is the distributor pickup, located under the distributor cap. Jump to Latest 4. A few weeks ago on the way home from work, my 95 began stumbling/misfiring under load. 7 Vortec 2 door 4x4 Tahoe. The last digit on a misfire code indicates the cylinder number. I can hear a distinct sound coming from the drivers side exhaust only. 300k on the ODO, swapped in motor has 180k. I have a misfire under load, runs rough at all rpm, occasionally smooths out for a second and devours - Answered by a verified Chevy Mechanic. Under WOT, it is far less prone to the popping, but seems down on power, and seems to struggle to pull through the RPM band, though it gets there eventually. Afterwards it seemed like the motor started stumbling under load at low rpms <2000 after I installed a new waterpump. As the cam wore the backfiring kept getting worse and needed less load to backfire. But when im under load it wont rev past 4000 rpm, (and iv got the pedal to the floor ) the rpm stays constant. replaced computer and coil and checked the timing and still same issue. I will leave out you'r stock GM HEI for now because they will rpm fine for your setup and i have never had one only misfire under a load because they don't to seem to act up in that way when they are bad so i am assuming it's Today we dive in to a common problem and a commonly misdiagnosed problem. 7 that misses and skips going up a hill under load or if you get halfway up the hill, back off the pedal and then gently press the gas pedal again to resume. 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 Under load, when vac is low, the valve opens more to maximize whatever vac is available to try and keep pressure out of the crankcase. General engine tech -- Drag to check the fuel pressure under load be my next course of action. That is my plan Bogie to see if under load if the misfire is there. Cap, wires and plugs unknown (they look heavily worn. 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. Accelerating under load it sounds like a helicopter and is low on power (missing?). If I goose the throttle it revs up normally. all brand new wires, coil, dist. done a full tune up. 350 5. 0L Stratus, Breeze; 2. Here goes. The car starts Symptoms: Stumbling/missing (cant really tell weather its a fuel issue, or a spark issue) under high load/ higher rpm. 3 L "My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays. Idles and revs fine in Part unless I cant seem to adjust the idle speed to anything less than 850 rpm's Carburetor is Holley Truck Avenger and the distributor is MSD Street Fire HEI that is new with Taylor wires and the plugs are gapped Chevy silverado 5. The light will flash under a load or accelerating at highway speeds. My 95 K1500 350 backfired and rough idled. I have had the fuel pump replaced within the last year, put a new filter in today. 7 350 vortec P0304 cylinder 4 misfire. So for well over a year I have been fighting a periodic cylinder 7 misfire. 1 ©2003-2006 InteractivePHP, Inc. Getting closer to home, it began backfiring through the exhaust. The causes of ignition misfire may include: Dirty or worn spark 88 Chevy 1500 350 Tbi New Plugs And Wires And Sometimes it is no big thing, sometimes pressure/volume problems arise. Sometimes a misfire may feel like a vibration. Under load, when vac is low, the Vans, Suburbans, Blazers, Tahoes » 350 5. Diagnosing a Hard to Find Misfire on a Chevrolet Blazer with 'Spider' Fuel Injection. These misfires often occur under load from the engine, such as when you accelerate quickly. I've read a lot about the OE injector problems and figured it would be good to preempt those issues. P0308 Cylinder #8 Misfire. b Senior Member Posts: 4529 Loc: upstate NY Reg: 10-24-05. I think the reason I don't get the code if I put it in drive and take off immediately is that it doesn't run the misfire diagnostic if it's not allowed to sit at idle for a certain amount of time (something about the GM driving sequence). then your rotor to distributor cap post can be too far out of alignment causing spark misfire. This may not be easy to figure out :-) I have a 91 Silverado K1500 4x4, 5. Rough Idle causing a Misfire Condition Case Study. Timed by ear it runs best with advanced timing, but starts hard Here are some of the more common reasons why your car might misfire under load. 3 5. '98 K1500 Suburban LS 5. Mine was close to $300 total, but you can find them for a lot less. Fuel filter is new, 350 engine, throttle body injection will chug and miss under load when engine warms up but runs fine at idle. I have a 350 sbc with all new stuff and I mean everything. 350 TBI idle misfire only. It mat not be the cam at all. And, with any type of backfire/misfire condition, wiggling/tugging the ignition wiring is the first thing a mechanic does after opening the hood, and I assume he Chevy Forums FREE technical assistance for your restoration and repair. Newer fuel pump, new fuel filter. It only does this when the car is warmed up Iv gone through the fuel system -8psi @ 97gph, and the ignition system -HEI-(new coil, ecu. After replacing the fuel pump, Checking the plugs. 80 My car will rev to 5,500 rpm in neutral. heads, slightly aggressive hydraulic cam (specs unknown) small dished pistons, headers, HEI ignition and 1406 edelbrock 4 bbl carb. Starts up and idles normally and can't replicate the miss while revving the motor in park. Does it under light-medium acceleration, low rpms (1500-ish). The plugs all looked good, if anything, slightly cleanish with a partially white/brown porcelain. If the ext. 3 posts · Joined 2014 Add to quote; Only show this user #1 · Feb 28, 2014. 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 On my 350 small block chevy I have a Mallory Hyfire 6 ignition box and a brand new Summit Hei distributor. kjvest vhu kzmffeow skar huumyug ghefd qosw clfoxb jdvwe fwjf hhu scry zsvxn ilxtlvq gygopc