idle missfire??

[gjp]

I worked out all my problems but one. My truck will idle fine but every 2-3 seconds it sounds like it missfires. it make a light puff sound out the exhaust. the guages show no problems and it idles at 800rpm. Once in a while the oil pressure will drop for a split second but its not at the same time as the missfire. The engine sounds fine and steady. It runs strong and pulls hard. It had a tune up about 3k miles ago. I replaced the plugs today. They plugs looked good. one of the wires had a crack in the boot. could that be it? Still cant find a datamaster cable. The truck runs fine except for the missfire. Thanks for any help.

 

[gjp]

Re: idle missfire??

ideas,anyone. Its worse today. it will drop the idle down to 600 then up to 800 every few seconds. It will not do it all the time. It will do it when it was cold or warm. I guess I will buy a datamaster cable for 100$ so I get more info.

 

[gjp]

Re: idle missfire??

The old plugs were ur6's gapped at 40. I put new ur5's gapped at 34. It got worse. Thinking its a bad wire and I might have pulled it more lose. I will replace the wires. What wires work good for our trucks???

 

[cloneman315]

Re: idle missfire??

it still sounds like igntion to me,i have had magnacore wires for 3 years and they are perfect still

 

[SnakeEater]

Re: idle missfire??

Wires for sure....using MSD 8.5mm here............

 

[gjp]

Re: idle missfire??

Help. Ok today a few times he idle dropped down to 500 when I turned on the headlights. The volt guage also drops below the halfway mark on the guage. Is it low voltage thats causing my idle problem??? please help, thanks. All the tuneup stuff is new. The coil looks stock. At idle the voltage was 13.6volts. have not checked it with the light on. Thanks

 

[syclonekid43]

Re: idle missfire??

mine has done it for about 6 years. no matter what plugs or wires i use. i just learned to deal with it for now.

 

[gjp]

Re: idle missfire??

Yeah, besides that it runs strong and drives great. I will just put a datamaster on it and if everything checks out ok I will live with it. could be the old stock chip thing. With the pitbull chip it does not do it as bad?? It seems to idle faster with it too. If a few months I will get a 3 bar chip and see what that does. Thanks.

 

[QUICK STORM]

Re: idle missfire??

4.3s aren't the best idling vehicles, as stated before make sure your ignition is good i.e. module, coil, wires, plugs, cap, rotor. then make sure your battery, and altenator is good(check with a vat 40 if possible). check your vacuum lines for cracks and check engine vacuum(best way to tell how sound the motor is). hope this helps.

 

[gjp]

Re: idle missfire??

Vat 40?? Coillooks stock. has a little rust on top. Wires, cap and rotar have about 4k on them. Plugs are new. Battery is new. Vacuum are silicone and I did check once for leaks.

 

[QUICK STORM]

Re: idle missfire??

vat 40 will put a load on the battery, called a carbon pile. this is the most effecient way to check a battery. what about your ignition module? check engine vacuum, cylinder compression/leakdown checks?

 

[Flyin Ryan]

Re: idle missfire??

I've had this popping sound for as long as I can remember.. with the stock chip it was extremly worse though.. that was because the idle was lean which I came to find out shortly after.

The atr chip is a richer chip so this could also be your problem if the atr chip made an improvement on your popping noise.. just my :2cents:

 

[gjp]

Re: idle missfire??

Ok. The test they did on my old battery tested the CCA of it. it was way low so I put in a new optima red battery. 100$ but its under my bed so I wanted a good one that wont leak. I dont have the guage for the compression test. I do have a fuel presure guage. Is there a vaccum guage??

I did not notice a difference between the 2 chips. Just the idle was worse with the stock one.

 

[QUICK STORM]

Re: idle missfire??

any difference now with the new battery? you can get a vacuum gauge at any auto part store.

 

[blk00z28]

Re: idle missfire??

I've had this popping sound for as long as I can remember.. with the stock chip it was extremly worse though.. that was because the idle was lean which I came to find out shortly after.

The atr chip is a richer chip so this could also be your problem if the atr chip made an improvement on your popping noise.. just my :2cents:

To spin off of this, I idle around 12.1 on the WB in park and mine does the poping sound. I drop it into a gear (any gear, r, d, 2, 1, doesnt matter) I'm in the low mid 13's. And while it doesnt do it often, it still does it every once in a while. (mostly when I'm getting on her hard alot that day in a short period of time.) But if I put it back into park it will pop like hell...

Do you know what arf you were at Boostedpimp? (this goes for you too GJP?)

 

[Flyin Ryan]

Re: idle missfire??

To spin off of this, I idle around 12.1 on the WB in park and mine does the poping sound. I drop it into a gear (any gear, r, d, 2, 1, doesnt matter) I'm in the low mid 13's. And while it doesnt do it often, it still does it every once in a while. (mostly when I'm getting on her hard alot that day in a short period of time.) But if I put it back into park it will pop like hell...

Do you know what arf you were at Boostedpimp? (this goes for you too GJP?)

Honestly Tim,

I can't remember off hand.. it was when I first made the switch from stock chip to pitbull which was something like three years ago, sorry

 

[gjp]

Re: idle missfire??

Car was bad today. died out 3 times going into drive. only after it got warm. I picked up a new set of wires and a compression guage. Compresssion was good. 162-175 on all. All plugs looked fine after 200 miles. Put on the new wires and noticed the vaccum tubes were replaced but with rubber not silicone. I was told they were replaced but i guess not with silicone. Went to 3 stores and no silicone tube. Try again tomorow. the idle changes when the ac controls are moved or the headlights turn on. Fix the tubes then I will see. Thinking throttle sensor may be bad too???

 

[QUICK STORM]

Re: idle missfire??

what does your oil pressure gauge show? if it is pegged at 80psi then the oil pressure switch for the fuel pump is bad and needs to be replaced. hope this helps

 

[gjp]

Re: idle missfire??

cold its pegged but comes down to about 60. it does bounce around when the idle is bad.(55-60) After what I saw tonight with it as I picked up dinner for the kids I would guess its a combo ov a vaccume leak somewhere and a low voltage problem. With my lights on the volt metter drops below the 1/2 way mark. (saw a lightning racing with a ss, lightning had him the whole way, man I was too far back to join in)

 

[Don W.]

Re: idle missfire??

Just thinking out loud...When they (you?) changed the bat did you load test the alt? Rock solid elec is very important. This means good bat (which you now have), good alt, solid connections (check everything from the bat to the starter since you have a relocated bat.) and all around including grounds. On my truck it was running in the low 13's last year, still had an occasional miss at idle. That's the way it ran when I got it. This winter (I'm still working on it.) I ran it briefly with new cap and rotor (Old one was almost 2 yrs old) and NEW Taylor wires. On that brief run after warm-up and timing reset idle was noticeably smother. Almost no miss at all. Seemed to start better also. All FWIW