So I have low RPM hard stutter and backfire. Smooths out at high RPM. Very intermittent. I have changed the plugs as recommended with Denso 5346 Plugs gapped at 0.022. and the car is still running like crap. I talked to my service tech at my dealership to see if he thought it was a cool pack but he thinks it’s an issue with my JB4 tuner. Any help on this would be much appreciated. Thanks!
Um normally I'm a fan of pops and backfires but this isn't good. No codes? Try running it with jb4 off or set to map 0 or something so that it's out of the picture. See what happens then.
Ah, this now sounds exactly like my problem with a much older vehicle that I had before this car. It was eleven years old when I bought my Voyager. On full throttle it worked smoothly. Anything less than WOT and it had the stutters. Turned out to be a faulty fuel mixture Module. (whatever they're called; they're electronics where a carburetor used to be). So, something in the vast complexity of the modern engine is not mixing fuel smoothly unless it is WOT, or something close to. That's my free, tyro diagnosis.
So it’s actually worse on Map 0...still did it on Map 1 but not nearly as bad and only does it when the turbos first start to spool up. I am getting absolutely no codes or check engine light. It almost seems like it’s got something to do with air/fuel mixture? Wish I was more mechanically inclined on these types of cars...ugh
Well, you could always unplug the cable from the OBD2 port and undo the other jb4 plugs - should take like 5 minutes max. But if it's doing it on map0, then most likely your problem is elsewhere.
I had a Legacy GT with a flaky coil pack that would start to shudder and shake (and stall at idle) around 2-3 minutes after starting, when colder out (i.e. around 35-40 overnight here in CA) warming up, at lower rpm, say 2000-2500 rpm. If I floored it, it would be ok, and once I was able to run up to redline, it would be fine. I learned to live with it until it FINALLY got bad enough that I got a misfire warning. Then, swapping coil packs, I was easily able to figure out which one.
Maybe logging with the jb4 can help pinpoint it? Maybe manually turn on the logging, and see which cylinder acts weird?
So I have low RPM hard stutter and backfire. Smooths out at high RPM. Very intermittent. I have changed the plugs as recommended with Denso 5346 Plugs gapped at 0.022. and the car is still running like crap. I talked to my service tech at my dealership to see if he thought it was a cool pack but he thinks it’s an issue with my JB4 tuner. Any help on this would be much appreciated. Thanks!
Check the spark plugs. Make sure you didn't crack one when you gapped/installed them. Just verify they look fine in general and that the gap is still at .022. The coils are $60-$70 each. The dealership won't be replacing them for you (for free) but you could have them check to see if any are bad.
Or, if you want to be dastardly frugal you could remove the JB4 and take the car to a different dealership and have them figure it out and repair it under warranty.
So it’s actually worse on Map 0...still did it on Map 1 but not nearly as bad and only does it when the turbos first start to spool up. I am getting absolutely no codes or check engine light. It almost seems like it’s got something to do with air/fuel mixture? Wish I was more mechanically inclined on these types of cars...ugh
Nope, seems completely random at this point, happened like 6 weeks ago the first time, I managed to get a a CEL one time but I couldn't see a code on the jb4, then it disappeared and I swapped the plugs to HKS. Now it came back last week. I usually get fuel at the same place BP 93, so idk wtf it is. Possibly fuel
Nope, seems completely random at this point, happened like 6 weeks ago the first time, I managed to get a a CEL one time but I couldn't see a code on the jb4, then it disappeared and I swapped the plugs to HKS. Now it came back last week. I usually get fuel at the same place BP 93, so idk wtf it is. Possibly fuel
The only thing that seems a little odd on my logs lately has been consistent small timing corrections on cylinder 4, not sure if this would point to a coil pack as I know the plug is fine
The only thing that seems a little odd on my logs lately has been consistent small timing corrections on cylinder 4, not sure if this would point to a coil pack as I know the plug is fine
You read my mind lol.. we just got a bunch of snow here so now I'm screwed with taking logs since jb4 is out now. I'll give the service tech a hint that it might be coil pack 4.. weird it would only show itself at initial WOT
You read my mind lol.. we just got a bunch of snow here so now I'm screwed with taking logs since jb4 is out now. I'll give the service tech a hint that it might be coil pack 4.. weird it would only show itself at initial WOT
Posting this idea--just in case it might actually be the issue.
Way back in the mists of time I had a 1991 Pontiac Lemans--the P.O.S. 1.6l econo-can Daewoo rebadge version. Being young, stupid, and not knowing much of anything about cars at the time, I, like many teenagers at the time, swapped out the old AM/FM radio with a more powerful CD head unit so I wasn't stuck listening to ClearChannel's garbage play lists du jure.
Well, that stereo was more powerful than what my alternator could pump out, so the alternators would start dying after about 6 months or so (and I didn't know enough about cars at the time to put in a beefier alternator), and when the alternator would start dying, it would behave just like you described--rough low RPM idle and backfiring, but once the RPM's went up the issues smoothed themselves out.
I think the easiest way to tell if it is an alternator/charging issue is to add more electrical load to the system and see if that affects your rough idle/backfiring. If you add more electrical load and it gets worse, I'd say change the alternator out and try to figure out if you need a beefier one. It might not be as easy as it was way back when what with the move to LED's over filament bulbs which sucked more juice, but it certainly can't hurt to try.
