breaking up under boost when hot

[Vincent DeCicco]

So I've run into an issue that's stumped me, and I've searched on this forum as well as a few Facebook groups with no luck. I'm in Florida in the US, and it gets brutally hot at times. If I manage to take the car out when it's cooler in the mornings, everything seems to run fine, pulls through all the gears ok, etc. But once it's hot from coming home in the afternoon when ambient temps are 85 degrees F or higher, taking the turnpike for a short stint, and sitting in traffic for a while, the car seems be break up when it gets above a few PSI of boost in 3rd and higher gears. Along chasing this down, I've replaced the intake air temp sensor and coolant temp sensor on the intake manifold, ignition coil, plug wires (previously had Nology Hot Wires which I personally am not a fan of), fuel filter, fuel pump, new temp gauge sensor, new stock heat range plugs gapped correctly, confirmed the fan switch is working, and confirmed the thermostat is still working an is a 68 degree Celsius unit.

I haven't checked base ignition timing yet, but that's next on my list. Also the previous owner used a metal welded pipe for part of the intake off the turbo inlet, which I plan to replace with a silicone unit to my Apexi intake. I also ordered one step colder plugs that have yet to to arrive (not looking forward to doing these as the new plug wires seem really snug on the plugs in there at the moment).

Pretty much at a loss here though. My temp gauge never moves above halfway on the gauge cluster, and it does have full sweep when I hit it with my power probe at the shop. I only run 93 in the car, as expected, so it's getting proper fuel. I started to wonder if the IAC is stuck open, but I feel like that would also cause a miss at idle and even when cold, which it does not. When it's cooler out, it runs like a champ, so I assumed it was a sensor issue, but I'm running out of parts to swap out at this point. It just breaks up really bad once boost comes up under load, to where I'm thinking it may just be so hot out down here that I need to run 8's instead of the 7's in there now. Any insight is appreciated.

[Ian Linden]

One possibility is that the intercooler is not doing its job very well. I've heard they can become "oil-logged" with recirculated oil from the breather. Try draining it.

[Vincent DeCicco]

One possibility is that the intercooler is not doing its job very well. I've heard they can become "oil-logged" with recirculated oil from the breather. Try draining it.

Almost forgot I posted this. Thanks for the suggestion, Ian! I actually ordered a replacement intercooler that's slightly better design, but had debated cleaning out the stock one a few times with throttle body cleaner and such. I'll probably pull that off today at lunch and give it a go.