Under acceleration my engine misfires?

when was the last time you had a tune up because it sounds like the spark plugs got old. These guide will help us fix it.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

and

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

Please run down these guides and report back.

Thanks guys - I will do that tomorrow morning and return here. Thank you again.

Let us know what you find. Also, I noticed you didn't say the check engine light was on. Is it? if so lets run the codes.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down this guide and report back. We have directions and a video to explain how to check fuel pressure, the regulator. Let us know which direction you want to go. If the check engine light isn't on, you may not have trouble codes stored at this point. Also, after driving it, take a look at the catalytic converter to see if it glowing red hot which would indicate it is plugged.

Ok great - I will look at the catalytic converter tomorrow and yes the engine light is on and has been for about 3 weeks. I disconnected the battery about 3 weeks ago and a couple of days later it went off for a few days until I was coming off the expressway on a circular exit ramp and the engine light came back on. This happened about 2 weeks ago. Yesterday I started and finished the tune up thanks for the guide btw now the light is off and the engine runs nicely once again! thank you for your help.

Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help.

Repair shop said I had WORN PLUGs
How can plugs be worn at less than 25,000 miles

DRB code P0302 for multi cylnder misfires
TSB said replace plugs and wires and update PCM
What would the PCM update be??

What could have caused the problem so I can figure out what to expect next??

Why should an engine burn over a quart every 3000 miles. I have kept up with all the oil changes required, just don't' use it enough for more frequent oil changes.

Thanks
Meadson

Hello .. thanks for the donation .. much appreciated PO302 is a misfire on cylinder #2 ... it is possible this is because #2 plug is worn .. but more likely due to the PCM software needing to be updated ..as with all computer software updates are required periodically .. I am including the TSB FLASH: MIL ILLUMINATION DIAGNOSTIC TROUBLE CODES (DTCS) P0300, P0301, P0302, P0303, P0304, P0305, P0306 TECHNICAL SERVICE BULLETIN Reference Number(s): 18-018-04, Date of Issue: April 27 2004 GROUP:Vehicle Performance Related Ref Number(s): 18-018-04 ARTICLE BEGINNING SUBJECT NOTE:THE SOFTWARE IS AVAILABLE ON TechCONNECT. FOR MARKETS OUTSIDE OF THE UNITED STATES AND CANADA, THE SOFTWARE AND REPROGRAMMING INSTRUCTIONS WILL BE AVAILABLE ON ITIL/ISIS CD/DVD JUNE, 2004. Flash: MIL Illumination Diagnostic Trouble Codes (DTCs) P0300, P0301, P0302, P0303, P0304, P0305, P0306 OVERVIEW This bulletin involves replacing the spark plugs, ignition wires and if necessary, reprogramming the Powertrain Control Module with new software. MODELS 2004 - 2005 (RG) Chrysler Voyager 2004 - 2005 (RS) Town & Country/Caravan NOTE:This bulletin applies to vehicles equipped with a 3.3L engine (sales code EGA or EGM) or 3.8L engine (sales code EGH), built on or before April 2, 2004 (MDH 0402XX). SYMPTOM/CONDITION The vehicle operator may experience a MIL illumination. Further diagnosis may determine that the MIL was caused by one or more of the following DTC's: P0300-MULTIPLE CYLINDER MISFIRE P0301-CYLINDER#1 MISFIRE P0302-CYLINDER #2 MISFIRE P0303-CYLINDER #3 MISFIRE P0304-CYLINDER #4 MISFIRE P0305-CYLINDER #5 MISFIRE P0306-CYLINDER #6 MISFIRE DIAGNOSIS Using a Scan Tool (DRBIII(R)) with TechCONNECT and the appropriate Diagnostic Procedures, verify all engine systems are functioning as designed. If DTCs are present, other than those listed above, record them on the repair order and repair as necessary before proceeding further with this bulletin. If the vehicle operator describes or experiences the Symptom/Condition, perform Repair Procedure 1 and if necessary, Repair Procedure 2. If an "Authorized Modification Label" is present and states that Service Bulletin 18-016-04 has been performed, it is not necessary to perform Repair Procedure 2. PARTS REQUIRED PARTS INFORMATION Qty.Part No.Description 6SPRE14PLP5Spark Plug (04686742AD) 104686710AACable/lgnition (Cylinder #1) 104686734AACable/lgnition (Cylinder #2) 104686737AACable/lgnition (Cylinder #3) 104686738AACable/lgnition (Cylinder #4) 104686740AACable/lgnition (Cylinder #5) 104686741AACable/lgnition (Cylinder#6) AR (1) AR (1)04275086ABLabel, Authorized Modification AR (1)05011058AALabel, Authorized Software Update (Markets Outside the United States and Canada) SPECIAL TOOLS/EQUIPMENT REQUIRED NPN Battery Charger CH2002 General Purpose Interface Bus Cable Assembly CH6000A Scan Tool (DRBIII(R)) CH7000A/7001A J1962 Cable with Red DRBIII(R) TechCONNECT Workstation NOTE:An updated J1962 cable has been released. This cable has a red colored connector at the DRBIII(R) connection. Use this cable whenever a flash is being preformed. REPAIR PROCEDURE 1 Replace spark plugs and ignition cables Replace the spark plugs and ignition (spark plug) cables. Refer to the service information available in TechCONNECT or the Town & Country and Caravan service manual (publication no. 81-370-04062CD), page 81-10. If Service Bulletin 18-016-04 has not been performed, proceed to Repair Procedure 2. If Service Bulletin 18-016-04 has been performed, no further action is necessary. REPAIR PROCEDURE 2 Flash Reprogram PCM NOTE:Whenever a controller is programmed, the software in the DRBIII(R) must be programmed with the latest revision level available. NOTE:If this flash process is interrupted/aborted, the flash should be restarted and then follow the directions on the DRBIII(R). Before beginning the reprogramming procedure, remove any old flash reprogramming files from the DRBIII(R) memory. To clear the memory from the MAIN MENU: Simultaneously press the "MORE" and "YES" keys. A screen will appear requesting a "COLD BOOT". Follow the on screen instructions by selecting the "F4" key. When the DRBIII(R) reboots to the MAIN MENU, proceed to Step #2 With the ignition switch in the "RUN" position, determine the original part number of the PCM currently in the vehicle. Using the DRBIII(R) select: "DRBIII(R) Standalone" "1998 - 2004 Diagnostics" "All (Except Below)" "Engine" "Module Display" Record the "PCM part #" on the repair order for later reference. Connect the DRBIII(R) to TechCONNECT. Open TechTOOLS and verify that the "DRBIII(R) Status: Connected" message is in the upper right corner of the TechTOOLS screen. Enter the "PCM part #" recorded in Step #2 in the "Parts Criteria" area and select "Show Updates". TechTOOLS will populate the appropriate calibration. Select the calibration. Select the "DRBIII" radio button which is next to the "Download/Update" button. Select the "Download/Update" button. Monitor the "Flash Download/Update Progress" window on the TechCONNECT and follow the instructions on TechCONNECT. When the flash process is complete, proceed to Step #9. Disconnect the DRBIII(R) from TechCONNECT. Open the hood, install a battery charger and verify battery state is above 12.5 volts. Connect the DRBIII(R) to the vehicle. Download the flash from the DRBIII(R) to the vehicle. Using the DRBIII(R) select: "Vehicle Flash" Follow the directions on the DRBIII(R) screen. When the flash process is complete, proceed to Step #13. NOTE:Due to the PCM programming procedure, a DTC may be set in other modules (TCM, BCM, MIC, SKIM, etc.) within the vehicle, if so equipped. Some DTC's may cause the MIL to illuminate. Check all modules using "Module Scan", record the DTC's, and erase these DTC's prior to returning the vehicle to the customer. Erase any DTC's in the PCM only after all other modules have had their DTC's erased. NOTE:The following step is required by law. Type the necessary information on the "Authorized Modification Label" p/n 04275086AB and attach near the VECI label POLICY Reimbursable within the provisions of the warranty. You need to check oil levels under the same condition's each time you check, hot/cold oil will give different level reading's ... Hope this helps .. let me know

Engine runs rough-REALLY rough- from startup all the way up to highway speeds. No check engine light came on for several days while emergency driving and trying to troubleshoot, but now stays on and flashes every time it's driven. Misfire gets worse when a/c turned on. Have checked/replaced plugs, wires, coil pack, pcm, wiring harness to injectors(for burning/melting/shorting). Pretty much ruled out a bad injector since the misfire never gets better at any speed, nor when I let off the throttle, but am about to test ohms with multimeter now. Dies/stalls at stops unless the 2-foot gas/brake method is applied. Does not overheat. No water in oil. Acts just like a bad distributor on motors so equipped. Ran perfect when parked for work one day; then this, out of nowhere. Did i somehow blow the head gasket while parked? I'm no stranger to mechanics, but this one has me perplexed beyond belief. Please help!

Hi Matt,

We need to start by finding out which cylinder is misfiring by scanning the computer and getting the codes then we can start narrowing in on the issue.

Couple issues with what you stated. First, injectors could still be the issue because if they are hung open overfueling then your misfire will not get any better with speed or decelerating. Also, the flashing check engine light means you are potentially doing damage to the engine or exhaust so you want to limit the amount of driving you are doing with this or you will have a larger problem.

Let me know what codes you have and then we can dig deeper. Thanks

Cylinder 1. It did throw the random cylinder misfire code once, but has maintained cylinder 1 misfire all along.

Okay. Great, we need to switch things from cylinder 1 to the opposite bank to see if when we swap something the misfire follows. This is the easiest and cheapest way to prove what component is causing your issue. If you already replaced the plugs, swap the injector and see if the misfire stays on cylinder one.

If it does, then take a compression reading on cylinder 1 and then at least two more just to level set. If it is not the injectors, then I suspect you have a mechanical issue (valve or piston ring).

Let me know what you find and we can go from there.

https://www.2carpros.com/articles/how-to-test-engine-compression

Our van has been driving rough, hesitates at take off and sounds like it skips a bit at idle. runs fine at a normal operating speed. now the check engine light came on. I know that a computer check is in order, but does it sound like a plug issue? any other obvious reasons?

thanks

Hello, I'm Danny.

It could actually be a few things related to the ignition system. The first thing you need to do is retrieve the check engine light code that is stored in your vehicle's computer. Auto parts stores like AutoZone can check your codes for free and also have a tool loaner program and can rent you a scanner-code-reader. Here is a tutorial showing how to check diagnostic codes stored in your vehicle:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Once you perform this procedure let us know the code number or information and we can then properly diagnose your cylinder misfire issue. Hope this helps and thanks for using 2CarPros.

I have 2002 town and country 3.8 with 130,000 miles on it. I drove it one day and everything was fine. Parked it, went to a store, came out, started it and it was running rough. On the way home it was pretty bad, can was loosing power and shaking. Took it to my mechanic. He said it was showing a misfire on one of the cylinders, he also made the engine misfire purposely and notice the computer was not picking up the misfire, so he put in a new computer, plugs, wires, coil, I think a fule injector, changed the whole wire harness from the computer to the engine because the old one was melted and all the wires exposed. Compression was ok. It is still running the same, and still misfiring. He said the fuel is running lean?? I drove it the other day and noticed that on the highway at a steady 55mph the can seeme fine. When I would accelerate, around 2000 rmp, the problem was very pronounced. Once I got over 60 mph it seemed ok again. The problem still exists when driving normal in the city. I've dropped $860 so far and am looking for any advice. Should I give up? Is this a common thing with these vans?
Thanks for any help!

Go to this walk thru link:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

I had a broken valve spring which fixed it

i have changed the oil oil filter spark plugs and wires and coil pack what else can fix it

If we could diagnose it over a computer, mechanics and doctors wouldn't be needed. The biggest part of their job is to diagnose the cause of a problem, then they spend a little time fixing it.

You need three things to get power from a cylinder, fuel / air, spark, and compression. Missing any of those creates a misfire that is detected by the Engine Computer. Replacing random parts is the most expensive and least effective way to diagnose this type of problem but to waste no money, switch two injectors to see if the misfire moves to a different cylinder. Chrysler has extremely little trouble with injectors but this test won't cost anything. Next, perform a compression test to look for a leaking valve.

I have a miss at idol and will back fire when taking off from a stop soom times but seem to run fine at road speeds

Please include the engine size when asking about engine problems. If you have the 3.3 / 3.8L, a common cause of what you described is defective spark plug wires.

I have a 3.8L engine and I tried removing wires one at a time and it did'nt seem to make a difference, any other ideals

Replace the entire set of six wires. I never tried removing them so I don't know what to expect for the result of doing that. The 3.3 / 3.8L uses a coil pack with three ignition coils. When you disconnect one plug wire, you will kill two cylinders. Worse, those coils are capable of quite a lot of voltage and if it can't create a spark across both spark plugs, it's going to find a different path and that often leads to arcing internally. Arcing leaves a carbon track behind which promotes further arcing and misfires.

A burned valve can also cause a misfire but that isn't very common anymore. A compression test or a cylinder leakage test would confirm that. They don't typically cause a backfire but they will cause the engine to run smoothly at higher speeds.

put scaner on car told me misfire on #6 checked coil & #6 was not puting out like the rest put new one on & same thing happened could it be the computer

Info for 3.8L shows number 3 and 6 both fire off the same coil. I'm not sure what you mean by coil output not the same as other? Maybe I looked at wrong engine size? Plugs and plug wires ok? Cylinder compression ok? Fuel injector?

sorry; it has one coil took plug wires off 1 at a time when got to #6it did not bite me as hard asthe others they had good arch half inch from connecting to coil #6 wasvery weak

What is the engine litre size? If distributor, how about cap--rotor--plugs-- plugwires? Those are maintenance issues. If the problem is spark issue? I've been hit many times by secondary voltage, didn't like it when I was young, still don't like it.

no dist. new plugs & wires 3.3 does have a mis. ps dont like niether

I looked at the 3.2L, shows coil on plug ignition. The flow chart isn't worth much unless you have a scanner that shows live engine data, look at freeze frame data. I'd start by comparing voltage to number 6 coil to the others. Without more info, all I can do is hunt and peck.

scaner i used was from auto parts store borowed. do you know firing order for 88 v6 cougar

This is for a mercury cougar 3.8-- rear wheel drive.

Engine Performance problem
1996 Chrysler Town and Country 6 cyl Front Wheel Drive Automatic

P305 code.#5 cyl missfire,only happens when engine cold,otherwise runs good . what shoud I be looking for,since this only when engine is cold ?

A plug or wire or injector or even a weak cylinder. Any weakness shows up more under cold conditions. Use champion plugs. They seem to hold up longer if your going to replace them. You should have it looked at while running. If it has a miss, it may be more then just a plug.

thanks