@bsa07eagle,
I’m not sure exactly what you meant when you mentioned that the car was “highly tuned”, but if it has been modified from the stock setup in various ways, I suspect that one of the mods is causing the issue.
I’ll leave it to the more knowledgeable posters to suggest which one it might be.
@Fender1325 hit it on the head with cam or crank sensors. They die without warning and don’t always throw a code. They are Hall Effect sensors that are susceptible to heat. A leaking injector would cause your cough and sputter in the morning. You can try running a bottle of Techron through it.
I doubt this is the cause of your symptom, but an overly rich mixture could show up as a drivability problem only at higher temperatures. The optimum mixture varies depending on temperature, and at higher temperatures the optimum mixture is leaner.
As mentioned above, crank and cam sensors adversely affected by heat are a pretty common complaint here.
Be careful if you decide to replace the fuel filter or pump. Working w/gasoline, esp when it is under pressure, is very dangerous. There’s common-sense safety precautions that mechanics use, like disconnecting the battery and having a big fire extinguisher at the ready and sometimes even moving the car away from other cars and structures before doing any fuel-related work. If you could get a friend who has done something like that before to show you, that would be a good idea. You might consider db4690’s idea too, ask a pro to do it, but find someone who will let you watch how they do the job. Then you’d know how to do it yourself the next time. Best of luck.
98 Caddy asked an important question. You mentioned that the engine was “highly tuned”. Have you done any modifications, and if so what were they?
Mods to gain power work by allowing more fuel to be burned. Done properly and in a coordinated manner, they can be fun. Done improperly, in an uncoordinated manner, or just plain poorly designed mods, can cause rich operation under various conditions. If you have done modifications, it’s important for us to know so we know what we’re dealing with.
For the record, by “uncoordinated” I mean, for example, adding larger CFM capacity injectors without reprogramming the ECU to direct the proper pulsewidth for the new injectors.
I have revo stage 2 remap on my ecu, numerous other bolt on’s like exhaust, inter cooler, cold air, turbo inlet, bov. Still have stock injectors and pump, only thing that was replaced was the 3 bar fpr was upgraded to a 4 bar fpr as part of the revo tume. It is a pretty reliable tune though, so although It might be, just because my car is tuned doesn’t mean they are the source of the problem.
“just because my car is tuned doesn’t mean they are the source of the problem.”
Says you
By the way, your car is not “tuned”
It is modified . . . highly modified, some might say
It is extremely, highly likely that the modifications you made are the source of the problem.
The only thing I can suggest is that perhaps a good speed shop can go over everything and reprogram your ECU to operate properly. They’re going to have to evaluate exactly what every sensor is providing under every condition, and “map” your ECU such that it properly operating the injector pulsewidth as well as probably your spark timing based upon your specific conditions. Your engine is way too modified for any of the normal ideas to help.
Kudos to 98 caddy for catching that crucial detail.
+1 to both db4690 & mountainbike.
You can count me as a third forum member who believes that the modifications are the mostly likely source of the problem.