My jeep backfires like crazy power goes in and out with constant idle changes in the first quarter mile, then with flooring the vehicle it goes away, leave the car for five minutes and it starts all over again. The jeep has been in and out of dealers no code comes up, just put a new exhaust maniforld on it same problem, anybody with any answers out there thank's
Fairly common problem. Typical scenario is start vehicle, runs fine
for 15 to 30 seconds and begins to backfire when placed under load as
customer tries to drive vehicle. Flooring usually makes the problem go
away. Usually does not throw a code.
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COULD BE GROUND PROBLEMS OR THE TACH GOING BAD.EVEN THOUGH CAR SEEMS TO BE RUNNING GOOD IDLING GOOD.SOME TIMES A SPARK PLUG MISFIRE.CAUSING A LITTLE ROUGH IDLING CAUSING TACH NEEDLE TO GO CRAZY.I SEEN ALTERNATOR WITH VOLTAGE REGULATOR GOING BAD CAUSE A POWER SURGE CAUSING HEAD LIGHTS TO DIM A LITTLE THEN BRIGHT WHILE ENGINE IDLING.THIS WILL CAUSE TACH METER NEEDLE BOUNCE AROUND ALSO.
1994 Wrangler with 200,000 miles on the odometer. Similar problem here: Severe bucking and backfiring, and engine misses when traveling down the road. I did an entire tune-up (plugs, wires, distributor, distributor cap, and ignition coil), but got the same thing. I thought it was dirty fuel injectors, so, I poured a bottle in a few times on fill-ups. The final solution, was a bad alternator. My mechanic said it was sending voltage spikes to the computer, causing the engine bucking and back-firing problems.
This is a broad spectrum of possibilities. I would first start with a simple approach of insuring good gas.
When these symptoms occur, get a bottle of fuel additive and add to your tank. Possibly you have some condensation issues. This could be just the ticket... I hope so. Good luck.
It sounds like an intake air ( vacuum ) leak, or ignition timing. Was it doing this before you changed all the above? Or did it start after?
Check all the intake mounting bolts, and carb bolts for tightness. Use a lenght of fuel hose against your earto listen for leaks while the engine is running. A hissing sound will be heard if it's leaking. Wiggle all the hoses with the engine running. You might get lucky and make one hiss at you. A soapy water solution will also detect leaks. ( use hot).
It also could be a leaking egr, or plugged pcv valve, or air filter clogged, or leaking head gasket, bad timing chain, or your camshaft lobes could be worn.
You'll just have to keep looking, and stay calm. It'll feel good when you find it!
As long as it's not going down, and the engine isnt knocking, you do not have a terrible problem. I have used marvel oil in ones that do this and most times it clears up. If not, change the pressure switch. (Takes a few days before it get's better with mm oil)
'till you do some in depth testing of all systems, I'd place equal weight on every possibility. Make sure you cover the basics like fuel filter etc before getting crazy with it though. Also check cap. rotor, coil and wires. Idle cylinder pressure is different than that encountered when driving. This additional pressure will cause ignition spark to seek a better easier ground,(not the spark plugs where it should be going) causing missing under load.After checking , if you haven't found anything, its time to begin testing fuel pump pressures, modules and controls. good luck