1997 Trooper, changing fault codes, bogging, sluggish under load

Holoholo · 2025-10-06T18:00:09-0400

I have a 97 Trooper that had been sitting for a few months, drove fine before sitting. Recently charged up the battery and started it up, idle was rough, missing, and poor power. I had a CEL and initial code was a number 5 cylinder misfire along with P0441, Evap Control Incorrect Purge Flow. Later, the misfire code changed to a P0300, multiple cylinder misfire. I was told to pinch the vacuum hose from the solenoid to the canister and if the misfires disappeared, I would need to replace the purge solenoid. I pinched the hose and the misfires went away, revved okay at park, put in reverse and it would shudder and struggled under load. On flat roads it was slow to get up to speed, on any type of hill, it would struggled to power up and just bogging. Pulled the CEL again and this time I got P0102 Mass or Volume Air Flow Circuit low which is the MAF sensor, P0134 no activity O2 sensor B1S1, and P1133, another O2 B1S1 code. I will add that I can hear rattling in the passenger side catalytic. Fuel pressure at the rail is 37 psi, a bit low, pull the regulator hose and it jumps up to 42 psi.

I was ready to change out the O2 sensor, but can't reach the connector with my hands, I am ready to cut the wires and splice in the new 02. I was also thinking of changing out the fuel filter since it's a quick cheap fix to see if that fixes the low fuel pressure. I want to change out the catalytic, but obviously that's a much bigger job and was hoping to try to get this thing running better but the changes on fault codes got me running in circles.

Any helpful advice appreciated.

Izzy604 · 2025-10-11T22:00:09-0400

I intermittently have a similar issue on my '94. The fuel tank was filled with liner flakes and rust. So I changed the filter, pump and major tune up. I still have some bogging issues only during long treks up services roads (maybe caused by vibration), but on the hwy and city roads, the truck runs great. I'd say definitely change the fuel filter and see if there's steeped tea coming out from old unit. Hope this helps!

craigp469 · 2025-10-12T13:55:48-0400

My first thought is with the fuel as well as Izzy above. Having the trooper sit for a months plus whatever fuel was already in it, hard to know. What I did in a similar situation was to jumper the fuel relay and used a section of fuel line (don't recall exactly where I connected it but off of the engine or nearby). Then I pumped the fuel into some old gas cans (there wasn't much fuel anyway), then I added a gallon or two at a time and pumped it all out as well to flush the system and once clear gas was coming out I added ~10 gallons of fuel and that resolved my issues. I will add though that the old fuel was in bad shape color and odor wise which may not be the case for your trooper, but something to check imo.

1997 Trooper, changing fault codes, bogging, sluggish under load

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