Car only has header and AEM intake. No further modifications. Use Amoco 93 all the time, change oil every 3750, fluids are topped off.
Car has 236,000 miles on it. Yes, alot. Runs perfect except the following recurring problem.

History:

When car had about 100,000 miles on it, I was cruising down the NJTPK at about 80 in the fast lane. Suddenly the car just bucked, then tries to stall. Throw it into neutral and the rpms dump big time. Car stalls, I pull over clueless. CEL light is on. Turn car off, and restart. It starts right up like nothing happened. CEL light is gone. Doesn't happen again for another 10,000 miles. This time, happens again, cruising along, maybe 65 mph. Car starts to buck, then tries to stall. I put it into neutral, rpms dropping. I put my foot to the floor and I can hold the rpms to about 3000 but it wants to drop like a stone. CEL comes on. I let go of the gas and it stalls. While still coasting, I turn off the ignition and start up the car in neutral. It was like nothing happened. Resumed speed. Noticed something new. Whenever this happens, my idle is all buggered up and starts to bounce while waiting at a stop light. I have to wait until I get home and turn the idle screw down. This kind of problem happened intermittently for the next 100,000 miles. Then 2 weeks ago, I started the car on a damp day in the parking garage. Put it into reverse and she bucked a little, the CEL came on and the car tried to stall. I turned it off and on again, since this always worked before, and it continued to fight me. For the next 14 miles of my 47 mile commute, she kept doing it. Eventually it stopped doing it and the idle was high again. I adjusted it down, yet again. Now, about 3 times per commute, each way, she will just buck for no reason. Won't stall, no code. Just cruising and then buck. Maybe even buck, pause, 2 more bucks, then resume like nothing happened. Bucks hard enough to throw my head forward. Anyone have a clue? I have a jumper in my car at all times now, ready to pull the car over as soon as I see the CEL, because it erases it once the car is turned off. Hopefully I will catch it before it gets too far into winter.

Help?

Jason

 

iacv most likely and did you bother to check the code

 

you can pull the code with the car at idle still. it could be anything until you find out what your cel, but here some suggestion o2, iacv, dirty fuel filter, clogged injectors. cause you had adjusted your idle; therefore you tps is out of spec.

 

I had o2 issues for a while that caused rough idle and stalling out when stopped. Replaced the sensor and it was fine. Never had any problems with the bucking though like you experienced.

 

what cel is it throwing?

 

I once had that problem with another car and found out it was distributor related....

 

Yeah, I'm hoping that will work. Once I turn the car off, the code and CEL are gone. I'm hoping that it will throw a code, I can pull over with the ignition still on, and install my jumper. Hopefully it will start flashing. For a couple of days I drove with it jumped the whole time. The engine light and SRS lights burning my retinas non stop. It didn't buck or give me problems on those days, so I pulled the jumper back out. This has been a very elusive problem and I have never been able to catch the code. I have the service manual, so hopefully I will nail it since it seems to be occuring more frequently lately. I too feel it is distributor related.


J

 

look iside the distributor something mite be losse in their

 

Fluxtuation of RPM at idle is usually indicative of a bad idle air control valve. Surging or bucking under normal driving conditions is also a sign of a completely blown IACV. My Si hatchback just turned over 251,000 miles and, presenting mostly the same problems (although she never stalled or threw a code), I replaced the bottom of the throttle body and she's never ran better.

 

Bottom of the dSV throttle body is the cold idle thermo valve. The IACV is on the back of the intake manifold behind the throttle body. I've been watching it frequently. The cold idle thermo valve is not controlled by a computer in any way. It is controlled by heat and cannot fluctuate rapidly. But I will continue to watch the IACV just in case

J

 

Finally, solution.

While coming home from a friends house over vacation, I was coasting down to a light and the car calmly lit up the check engine light. It was late so no one was on the road. It still drove so I pulled into a parking lot, and with the check engine light still lit, engine running, I put the jumper in. The light did not flash, but the SRS started flashing, telling me that I did it correctly. So there was no code. I turned off the car, started it up (with the jumper still in place) and it acted normal for about 2 miles, then it bucked (nowhere near as rough as before I polished off the contacts) and then lit the light again. I drove it home and it was grossly underpowered. Engine was going into "backup mode". I checked the service manual and indeed, there are 1,000,000 things to check if the engine goes into backup mode. The next morning while washing off my baby, the Fedex guy shows up (in a Penske truck??) and delivers my package, a new dist cap and rotor, and a fuel filter. I quickly found out why Honda charges $110 to change the filter, what a pain in the ***. I also pulled out my custom Dinan chip (supposed to be rev limiter raise only) from the ECU, just in case. Car drove weaker than normal but never bucked for 2 full tanks. I put fuel system cleaner in it as well. I put the Dinan chip back in last night. Still no bucking or hesitation and it runs super strong now, about 700 miles with no problems.

Cast closed, I hope.

J

 

Even if the CEL turned back off you should be able to have a shop pull the stored code in the ECU