CJHopper

Hello all, my issue started about a week ago. My 91 Accord automatic trans has a little over 200k on it, but has been taken care of well, routine maintenance and the full checks every 90k all that. Had new distributor installed 5 months ago. Car was/had been running perfectly. All of a sudden as I slowed to stop at an intersection, car started running rough. When I pulled out it hesitated badly, bucking and sputtering. Once I got up a little speed it evened out a bit but still intermittent sputtering. At the next stop it stumbled again, then the next two stops was back to normal. Then on the highway to home going 55-60 mph it seemed fine, if I went below 45-50 I could feel it sputtering a bit, off and on. So my first thought was some water in my gas. Bought and put in a bottle of Heet, it didn't help at all. For next 2 days drove it 10 miles to the store and back. Car would start up and idle fine, start out driving fine. But as it got warm would start acting up again, stumbling off and on. Day 3, halfway home, it gets worse. It lost power like I had let off the gas, I hadn't. I give it more gas, no response. I pulled over and sat for a few seconds, idling fine. I try gas again, it accelerates for about 5 seconds then again acts like I'd let off the gas. I let off the gas, then give gas, it accelerates again for just a few seconds. As I had no where safe to pull off the road and luckily a good friend who is mechanically inclined was only less than 1/4 mile away, I limp to his house in that fashion. Giving gas until it didn't accelerate, letting off gas, giving gas again. Left car at friends house. Next day put on new fuel filter, warm it up and short test drive, seems fine, except now the CEL is on. CEL isn't on when I start it for a longer test drive. Takes about 5 minutes and CEL is back on. After a bit longer, stumbling is back. Fuel filter seemed to help, but not fix. Yesterday we got the error code from my CEL, Code 1, O2 sensor. Put in a new O2 sensor. Test drove and again, seemed fine for longer but started the stumbling again. CEL did not come back on this time, however. Someone told me to drive it a bit more to work out any kinks of putting the new stuff on but I'd think if it was the O2 bad then putting a new one should have fixed it right away? I don't want to drive it and end up with it doing a day 3 again, leaving me stranded with nowhere to pull over, or damage my car into something worse. My Honda mechanic recently retired and I haven't got a new one yet, and need to come up with funds to take it in, so any ideas on anything else I can try myself? Maybe I just need a big stick to beat the gremlins under my hood...

Main points (in order):
Problem came on suddenly
Idles fine
Only once it's warm it hesitates/sputters when heavily accelerating from a stop and then evens out a bit but still intermittent sputtering
Worsened (this one time) in to sudden deceleration, giving it gas not doing anything, having to give gas then let off then give gas then let off to get it to go jerkily along.
Changed fuel filter
CEL came on
Got code 1, O2 sensor, from CEL, put in new O2 sensor which got the CEL to go off but did not fix the problem.

CJHopper

Solution was cleaning out clogged EGR ports. Posting this just in case anyone ever comes across this in a search and it may be useful.

brakedrum

Thanks. That's good info. First time I've really seen it described that the EGR flow symptoms can be almost identical to the bad O2 sensor symptoms. The way you kept your Honda moving when the EGR system was telling the ECU it was supplying something to burn, but nothing was getting through the passages, was exactly the way I had a drive my Accord when the O2 sensor was bad a few years ago. Compensating for lean/rich mix in the intake by playing with the gas pedal and clutch to take maximum advantage of what power was there. Your EGR ports must have been nearly 100% blocked.