What is wrong with this srt4?

[97sle]

My friend has a 04 srt4, around 20,000 miles on it, the only thing done to it is an aftermarket downpipe and intake. For some reason just in 3rd gear if he is on it, it seems like it backfires and looses all boost and then boost up again after it goes down. It doesn't do it at a certain rpm, just does it randomly. Sometimes it does it and sometimes it doesn't do it at all. The thing that is getting me is that it only does it in 3rd gear and doesn't do it all the time. Any idea's about what might be wrong with it?

[rsublime4life]

Gap the plugs down to around .30 and see if it still does it

[97sle]

Ok, I'll tell him to do so, but what is the reason why his car is doing this?

[TEXSRT4]

his plugs are fouled, i bet they are the originals arnt they. the SRT plugs need to be changed every 10,000-15,000 because of how rich the car runs. he is getting spark blow out. too much cylinder pressure, too big of a plug gap, and not enough spark energy means that the sparkplug doest fire. this is the bog that he feels. have him get ahold of his local speed shop and get a set of NGK 4306 sparkplugs. gap them to .035-.040 (i am running more boost and more mods and have mine gapped to .038). the car will run awesome with that setup

[Turbodog97]

I just got my NGK's I'll be putting them on tomorrow. I hope they are worth the 9 dollars a plug. What gapping do you suggest for 18.5-19 psi? I was thinking 40 but not too sure.

[TEXSRT4]

i dont see anything in your mod list that will allow you to run more than 18psi (spiked) and fall to 15psi. if you spike over 18, your car will be SLOWER than if it spikes 18. timing makes more power than boost. with that much boost, if the mods can accomidate, gap to around 35, i am assuming they are the iridiums at that price, if so then you can get away with 38 or so, but its not worht going more

[97sle]

Me and him got some new plugs and gapped them to what u said and still just in 3rd gear it does it. But also if he is flat on it through every gear it doesn't do it, it only happens if he shifts reg. in 1st and 2nd then if he punches it in 3rd it is when it does that. Anymore idea's?

[Turbodog97]

Have you tried resetting the pcm?

[TEXSRT4]

how are your wires. look at the cyl4 (drivers side). look at the boot, is it white or discolored at all? buy a set of MSD or CRANE wires, that should help as well. also make sure he's running good gas (91 octane or better)

[ponchonutty]

Actually, the SRT4 reqires 92 or better octane rating. This might be a long shot but I think he may have a problem with the TPS harness. Mine started with wierd idling then bogging while driving. So, I did the check by wiggling the TPS harness then the engine bucked and threw and engine code. I had DCX dealer repair the harness and it's been good to go from then.

[TEXSRT4]

if you want to be technical...dodge recommends 93. thats what it says in my 03 owners manual . however, most of us dont have access to anything more than 91, so thats what we run. race gas is too expensive.

[BrodyP]

.35 gap ? .40-.45 I would say. Also the owner manual says 91 octain.

[TEXSRT4]

.04-.045 is too much for anything more than stock boost levels, and even then it wont last.

i double checked my owners maual yesterday, and just what i thought, it says 93...but this is one of the first srt's off the production line. it still says run 10w30 oil instead of the 5w30 like most others.

[BrodyP]

Originally Posted by TEXSRT4

.04-.045 is too much for anything more than stock boost levels, and even then it wont last.

i double checked my owners maual yesterday, and just what i thought, it says 93...but this is one of the first srt's off the production line. it still says run 10w30 oil instead of the 5w30 like most others.

So strange they would change the octain rating in the later years. Any ideas why? I only use 93 anyways but I'm just curiouse.

[TEXSRT4]

in 2003 the srt was sold only in cali and florida. so they recommended the good fuel because its available...well in florida atleast. after that, they realised that 93 wasnt available everywhere so they got smart...im totally guessing, i dont know the real answer