Hi All, I’ve just joined this forum and look forward to becoming an active participant. I’ve enjoyed the five 850’s I’ve had over the years (tinkering, tuning, & troubleshooting). My current 850 is a 1996 ten valve B5252FS. It’s been great over the past two years. I’ve been trying to problem solve a loss of power issue over the past three weeks.
Situation: It starts well, idles a little high but settles back to 900rpm quickly. It will drive smoothly for about 4 minutes… or less if confronted with a small hill. Under slight acceleration (upto 2000rpm) there is a power loss, to the point of having to pull over. The car will still idle but has no power on using the accelerator to pull back out. If I shut the car off, and restart (even immediately) the car has power again and pulls out onto the road surface (I’m guessing that shutting the car off returns the computer to its base values?). The loss of power reoccurs after another short period of driving.
So Far I’ve: changed the oxygen sensor, and throttle position sensor, and cam position sensor; searched bumper to bumper for any vacuum leaks or deteriorated vac hoses, replaced vac hoses on air cleaner, cleaned and oiled the idle air control valve (I don’t think it’s working right but I also don’t think it should be the culprit - (can’t find the correct replacement) ; cleaned throttle body, replaced fuel filter, replaced fuel pump relay, checked fuel pressure at rail (45psi); checked and cleaned crankcase ventilation; pressure checked MAP sensor, checked IAT sensor with multi meter. Since it’s a 96 without Volvo trouble shooter, I used 2 different OBD II meters - no codes. I MacGuyvered a LED & switch circuit to plug into the OBD port, got a 5-1-2 “Volvo” flashing light code. The car has a Felix 5.2 management system so the code translates to “Short term fuel mixture too rich”. I’ll build a smoke machine this morning to check out all the vacuum lines and fittings for leaks.
After three weeks of trying, I‘m at wits end. There has to be something that I’m overlooking or missing all together … any and ALL suggestions are much appreciated. Sorry this post is so long!