I need advice on Fault Code readouts for NA engine w/auto trans. College daughter's car was having problems and located 100 mi from home. I drove up and did following repairs then left her my '96 850 and drove hers home. Problem: Intermittant hesitation upon acceleration at any speed. Work performed to date: New fuel filter and plugs. Found that temp was fluctuating and replaced thermostat (cured temp problem). Everything done has improved the performance, however problem with hesitation persists. I can not find the fault codes in Haynes manual. A-1 114 A-2 543, 453, 545, 553 A-7 113 A-6 ###.

The odd thing is I get nothing, no light at all from Socket # 6. I cleared all codes this morning and will drive it to work and see what codes reset. My frustration is intermittant hesitation with no common thing preceding the issue. I have not tested fuel pressure but feel if it were fuel pump, injectors, plug wires, rotor/dist cap, timing or fuel regulator that the problem would be continuous. Any advice or direction is appreciated.

I agree with folks that suspect one or more bad plug leads. I had similar problem recently...darn near tore whole engine apart, plus replacing numerous parts trying to get problem fixed. All to no avail. I took all plug wires out...checked continuity and ohms etc...all seemed OK. But then a friend suggested I check plug wires when re-installed and engine running at NIGHT...with the plastic cover that goes over top of engine removed. Guess what? 3 of 5 of my wires were arcing to the engine block. Cause? Wires were old and bakelite plastic insulation had deteriorated allowing high voltage to jump to the engine block.

Upon closer inspection - after cleaning wires - I noticed small spots/holes around shoulder of plug holder where electricity had burned through plastic and rubber insulation.

Now with new plug wires all is OK.

Good luck.

From Volvospeed's Bay 13:

114 Program selector open circuit or short circuit to supply
453 Misfire cylinder 3, emissions levels exceeded
543 Misfire at least 1 cylinder
545 Misfire at least 1 cylinder three way cat damage
553 Misfire cylinder 3, three way cat damage

So I think we have a guess at the main problem...

If you have a weak power stage or a weak coil, the car may run decently at light throttle but when you apply load, the higher cylinder pressures are difficult to light and the coil starts failing.

We had that problem with a buddy's 240 turbo - it worked great until about 3 psi, and then it would misfire and ping and all sorts of nasty stuff. O2 sensor output would drop during this, so we thought it was running out of fuel. We swapped out parts but nothing would fix it. We had new plugs and wires and a decent coil in there as well. As soon as we changed the ignition amplifier, the problem was solved.

Check the connections on the coil, check the ground right beneath the coil, check the connections to the amplifier (right by the coil as well) I don't know what the amplifier is worth, but that might be your next thing to check.

And then there's the possibility of a dead catalytic converter as a result of the misfiring.

I realized after posting that I should have been more specific about symtoms. By "hesitation" I mean loss of power upon accelleration. Engine sounds and feels like it is only hitting on 3-4 cyl. I can let off the gas and begin to gain momentum, but if I stay on the gas, it will not gain speed. It will run fine for a couple of days or for miles and miles on highway without acting up.

I also replaced battery before trip home. It failed when I picked it up. Car has approx 125K and 90% of the last 30K is highway miles. Car is parked for 1-2 weeks at a time between trips.

Sounds like a bad sparkplug wire, probably at cylinder #3. Install a new set of plug wires and see how it runs.


Mike

Yes, and cylinder 3 is right next to the oil filler cap which may be leaking under the plastic cover. I would not be surprised to see the No. 3 spark plug hole full of oil.