Misfires, engine shake

Recently my family drove from Fayetteville to Charleston. When we got there we filled almost the whole tank up with gas. As soon as we left the gas stating the truck immediately started shaking and misfiring. This was 2 weeks ago. Since then we drove back from Charleston and I have filled it up 2 times with gas to try and flush that bad gas out. One of those tanks was even premium in hopes of solving my problem. I have also put seafoam in the gas tank and brake booster and put heat in the gas thinking there was water in the tank. My truck has started to drive a little better but it still misfires and shakes when I get around 50. Also it normally idles around 1500 rpm and now it is about 1000 rpm (at first if idled around 500 rpm when I first got the bad tank) what should I check to try and fix this? Obviously it is not good for me to be driving with my engine like that but is it going to be doing a lot of damage?

 

Idling at 1500 when warmed up?

That is very high. It should be somewhere around 700 once the truck is warmed up.

 

I just repaired virtually the same problem today. My first thought was bad gas since it started misfiring out of the blue and shaking like crazy at 50 mph. Check engine light came on and the code was for Misfire cylinder #4.

Then I started going through the progression of fixes starting with the cheapest first. Tried filling up and adding fuel system cleaner, then changed the plugs. Still had the misfire, so I replaced the plug wires and problem solved. Cost me $50 in the end.

My next step would have been coil packs and possibly a fuel injector but fortunately didn't need to go that far down the checklist.

I would like to say that I am thankful for this forum because I read probably 30 threads that covered misfire issues and it likely saved me a bunch of $ by fixing it myself rather than getting hosed at the local shop.

 

Many times bad fuel can cause problems with the spark plugs, that simply changing the gas out won't fix. This can cause you to hunt and hunt for problems. The first thing I would suggest is to get a code reader to see what codes are in the system. Then replace your spark plugs. It is a simple process, and unless you have done it in the last 30k miles, you should be due anyway to have this done. Depending on how bad the gas was, you may still have some trace amounts left. How low did you run the tank before filling back up? How many tanks have you gone through since then?

 

Yes the check engine light is on. When I got back from Charleston I went to AutoZone and had them read the check engine light. They told me I was misfiring on cylinders 3,5,and 6. I was surprised it was that many. I have gone through 2 tanks since the original bad one. The first fill up I waiting till I had about 3 gallons left and filled. The second time I waited till my gas light was on then put in 16.6 gallons of premium.
Yes my truck did normally idle around 1500 and now it is around 1000 in neutral and 500 when in gear and stopped. Also sometimes when I am driving I can feel the engine get more power for a few seconds and speed up like it is getting good gas then goes back down.

 

Bamatoy is FAR more knowledgeable than me, but if this was my truck I'd change all the plugs and wires as well as the throttle position sensor. And while I'm at it clean the MAF, throttle body and IAC valve.

 

The high idle is suspicious. I would try cleaning the MAF sensor first with a can of MAF cleaner.

My '97 4Runner idled rough and had trouble starting for years. I spent $$$ at the dealer and he changed out all kinds of parts. I gave up. My daughter's POS Camry had the same issue and an independent mechanic replaced the $15 coolant sensor. Fixed. I did the same to the 4Runner and it also fixed that problem.

 

Well I am going to purchase new spark plugs tomorrow and see if that fixes my problem. Thanks for the help guys!

 

If it feels like ur getting good power n it cuts out under a load id try fuel filter. Its cheap n easy n nvr hurts if u think u have ran bad gas

 

Well I replaced the spark plugs and it helped a little. There is still some shaking. Tomorrow I am going to replace the spark plug wires and hope that fixes it.

 

Does the Check Engine Light blink when the truck is misfiring????

When were your plug wires replaced last?


My truck had a misfire happen and all i ended up replacing were the plug wires

 

I'm gonna guess Ignition Module/Igniter. Some relay or egr system or evap system. I hate this stuff.

 

Yes the light does blink when it misfires. I'm not sure when the plug wires were replaced last but I am going to change them today.

 

Also when I was changing my spark plugs yesterday one of these was orange at the bottom where the spark plug goes in. Sorry I don't know the name of it but would that need to be replaced?

 

That is just part of your spark plug wires, if that is what you are talking about with the picture.

As for the CEL flashing, all that means is that there is something currently going on in the engine that is or may be causing severe damage to your catalytic converter. If it is flashing, then the problem (Misfire in this case) is significantly severe. You need to get this fixed before you drive it much more, or you may burn out your catalytic converter. Get you a code reader and check your codes. At this point you can narrow down the misfire probably. Ignition coil is becoming more suspect at this point.

 

Yup, code flashing means there is no firing in the cylinder. Don't drive when it starts flashing. If the wires dont fix it, then it will be the coil packs

 

Well I went to Advance Auto today and had them read my CEL again. They said I was misfiring on cylinders 3 and 6. Bought a ignition coil and put in on cylinder 3. Did not fix the problem. Any more suggestions? Should I try plug wires?

 

Yes, I've been saying that from the start. They are much cheaper than coil packs. Thats what solved my misfire. A simple kink, loose or corroded plug wire will cause a misfire

 

It's gonna be the plug wires.... Glad I changed those before buying coil packs but that would have been the next step.