1998 Dodge Intrepid P1297 and P0300 Fault: Fuel Pressure Diagnosis and Tool Requirements

The symptoms you're describing—intermittent misfires with P0300 and P1297—are more consistent with a faulty crankshaft or camshaft position sensor than an EGR-related issue. A fuel pressure test could still be valuable, but it should be paired with diagnostics of these sensors.

I’ve reached out to several local tool suppliers in my area, all of whom say I need a $150 kit to connect a fuel pressure gauge to the Intrepid. The required components are: Miller Tool C4799 (fuel gauge) and adapter 6539 (a 5/16" T-fitting with one male end for the rail, one female end for the line, and a branch for the gauge). None of them can deliver these parts within the next three months. I’ve provided the exact Miller Tool numbers from my local dealer’s shop, which helped clarify the requirements. Since I haven’t yet tested fuel pressure, this remains an open issue. The good news is the car hasn’t misfired recently—so it's still drivable. I’ll update if I find a viable alternative or complete the test.

A dealer-performed fuel pressure test shouldn't cost $150, especially when you can buy a reliable gauge from Actron for under $100. You could also check pressure at the rear of the vehicle where the fuel lines connect near the trunk or rear seat—some 1998 Intrepids allow access to the fuel pump through the trunk or under the back seat, enabling direct testing without removing components. This might be a more cost-effective and accessible option.

I don’t believe a standard pressure test at a dealer would reveal the full picture—especially since my symptoms only occur intermittently under specific conditions (like hot weather). I want to install a fuel pressure gauge on the windshield so I can monitor it in real time while driving. The issue is not consistent, and I’d need to drive for at least 30–60 minutes in heat before parking and restarting. A dealer would likely have to repeat this several times to reproduce the fault. Given that, I suspect they'd charge more than $150. I’ve declined the $150 kit offered by suppliers—though I may consider it if no alternatives exist. As someone who does most of my own maintenance, adding a fuel pressure test kit to my toolbox makes sense for future troubleshooting. Also worth noting: my car has now reached 290,000 km. While I’m not ready to replace the engine yet, this rare issue may be less critical than the vehicle’s overall lifespan. If it continues to occur infrequently, I might just keep driving until the engine fails and then consider a 3.5L conversion.

The idea that 2.7L engines are 'boat anchors' is mostly based on poor maintenance. If owners regularly use high-quality synthetic oil (like Mobil 1) and change it every 5,000 km, these engines can perform well for over 300,000 km. My own 2.7L runs smoothly with good power, fuel economy, and low oil consumption—despite the high mileage. The real issue may be in maintenance habits rather than engine design. A failing fuel pump could also explain intermittent misfires, especially if it's a volume issue beyond just pressure.

I agree with the 2.7L engine’s reliability—many of its critics claim they use cheap department-store oil, which leads to sludge and performance issues. I personally use Mobil 1 synthetic oil and change it every 5,000 km without any sludging or performance decline. The engine runs well under normal conditions (except during hot weather). If I eventually need a replacement, the extra power of a 3.5L engine would be appealing. A fuel volume issue is an important consideration—pressure alone isn’t enough to diagnose misfires accurately.

So you’ve ruled out EGR-related causes now? The P1297 and P0300 codes suggest a broader system issue, possibly fuel delivery or sensor failure. While EGR can cause misfires, the intermittent nature and hot-weather trigger point make it less likely. A fuel pressure test combined with sensor diagnostics may provide better insight than assuming an EGR problem.