Performance Issue - Need Input

Hey there
My 2014 TRD Pro started having an issue recently. It has the TRD Supercharger, Doug Thorley long headers, Magnaflow exhaust. Between 3rd and 4th gear while accelerating, it jerks like it wants to backfire, then it goes into 4th. When I'm at interstate speed and I put my foot down, it does a similar hesitant jerk, then accelerates. Weird thing is that it's inconsistent, doesn't always happen. Can't decide if it's a transmission issue or engine issue. Just had plugs replaced and had a local shop look at it, but they couldn't make it happen. Not throwing any codes either. Probably gonna end up taking it to a performance tuning shop, but wondered if anyone had any thoughts.

 

If it was a misfire under load it should throw a code. The trans should throw a code if it has a shift solenoid issue. You would need to check live data to see what it's doing

 

Makes sense. Appreciate it.

 

Sounds like you need to do some data logging. I think you bought the Nitro truck? That thing has been worked. Sure, it can handle hard times, but like anything else, things can only handle so much.

I had the same issue on a couple of turbo cars I've owned in the past. It was spark both times. Once it was a plug, another time it was a coil. Both times, the spark was probably getting quenched. Basically, it couldn't jump the gap at a specific load/rpm event (or specific load/rpm eventS) and would cause the car to feel like it hit a brick wall. I "upgraded" to a colder plug and a "better" coil. This event will not throw a consistent code, but it MAY throw a stored code.

Basically, air and fuel are not very good conductors of electricity. The more air/fuel in your mix, the more resistance through the gap. The spark has a harder time jumping the gap. With boost and increased fuel, you've increased the resistance over the gap. With degrading components, the resistance increases through the ignition components and makes this condition more prominent. A cheap, and dirty way to test this is to reduce the gap. Squish it down a few thou, and MAYBE even a hundo or 2 if you're feeling adventurous, and see how it runs. Again, this is quick and dirty, not accurate. Another thing to do is check coil pack resistance. Data logging will tell you more.

 

My first guess was spark plugs but sounds like you have changed them. I know of a one car in the family that did the same and was the plugs.

 

When the plugs got changed, it didn't seem to make a difference. I hear you concerning the gap and I don't know what brand was used. Think data logging is a good idea. Really haven't had it performance tuned since I bought it and probably should find a shop that understands the complexity of this engine and its modifications.

 

I run on premium, and also recently did a fuel system flush/cleaner. Didn't make any difference.

 

The plugs are only 1 part of the equation. I have found that stock gap plugs designed for N/A applications don't work too well in F/I applications. I'm not sure what Nitro was doing in the past, but shrink the gap in on your new plugs and see what happens. It's not terribly difficult, just take it in small steps. The coils can also be gaining resistance, so that's why I'm saying check their resistance and see if it's similar across the board. If the coil resistance is getting high, they can't fire off a hot enough spark to jump the gap.

 

Cool. I'll give it a shot. Appreciate the help.