Misfiring with no codes

[browningcrew24]

So first time poster cause i cant get the answer I need via the search tool. ive got about 500 miles on the 97 limited 3.4 V6 I just bought....there is 171K total. There is for sure a misfire going on and it seems to come and go mostly at idle and when ive been stopped for more then a min but the CEL has not come on for anything but P0120, P0446, and P0420. Regarding the 446 I was told its just the gas cap and not to worry about it, the 420 (cat) sounds like it might be happening because of the misfire or an o2 but isnt going to be the cause of the misfire, the 120 (TPS) is the only thing that I think could cause this but based on some threads ive searched ppl think it cant cause a misfire or poor running?? Anyways the maintenance ive done on this is:

plugs and wires (attached pic what the plugs coming out looked liked and what the plug I put in was)


changed oil and filter
new fluids in diffs and t case
cleaned MAF and throttle body
just changed fuel filter which seemed to help but not fix......had a fram on it?

oh i also changed one of the coil pack boots cause it looked bad all cracked and rusty... but not the other ones...they had some hard white residue that i removed and just reused them...is this bad?



anyways before I replace the TPS I just wanna know any others opinion! any help would be greatly appreciated! :yo:

 

[kball]

What's your idle speed? Maybe your tps is messed up or maybe your IAC needs cleaning and you're idling to slowly.

 

[browningcrew24]

I heard that I shouldnt try to gap the platinum plugs which I gaped when I changed the spark plugs which could have ruined them?? I bought six new ones but the are all gaped at .40 but they are spose to be at .44 for the runner! Is it ok to use them at .40? and could this ultimately be the problem?:help::help::help::help:

 

[browningcrew24]

so I replaced the PLugs this morning and its running 95% better I believe i must have messed the other one up when I gaped them (broken electrode?)...the only thing that is happening now is a slight hesitation every 5-10 seconds when stopped at a light or in park...could this be a TPS? Havent had any other codes come back since I cleared them...been about 150 miles. And to answer your question no there is no play in RPM when at idle even with small hesitation!

 

[BlazeRunner]

You need two pronged plugs for that motor. If you haven't noticed already, there is one coil for two plugs, each being fired simultaneously. I just did my fuel filter and plugs, along with cleaning my MAF and throttle body and it has eliminated all problems of hesitation, long starts, sluggish throttle, rough idle... in other words - it feels like a new motor. Start with some correct plugs and go from there. Try NGK BKR5EKB-11
Edit: reread and saw you cleaned throttle body and MAF, should help. Sorry I really don't have experience with TPS issues but I just wanted you to have the right plugs

 

[LittleCaesar]

If you have not replaced the O2 sensors, start there first.

Also this engine due to the ignition system it utilizes shines using the aformentioned dual electrode plugs in it. Don't believe that all plugs have the correct gap out of the box.

 

[browningcrew24]

OK well I'll throw the duel electrode plugs in and see if it helps...if not I'll look at o2 sensor...could this have anything to do woith the timing belt the previous owner did himself about 2000 miles ago??

 

[the1998sr5]

What condition is your alternator in? I ask because if it is not producing enough power you can misfire-this typically will produce no codes.

 

[browningcrew24]

doesnt seem to have any other symptoms so I think its prob fine.