'97 Formula, OBD-I conversion from madwolf. Rest in the sig. Optical part is 5K miles old, cap/rotor has 75K.

Threw a rev at my buddy the other day, higher than I would have liked. The engine got between 6500-6700 . The engine died, I coasted over to the side and restarted, no problem, no noises, good oil pressure... runs fine. Whew. Time to lower that RPM limiter.

It was parked for 2 days at my work, and when I left, it had a definite miss and stumble under load at low RPM. Idle was fine, and above ~2300 RPM was fine.
No SES.

Scanned the car and got codes
36- Faulty Hi-res pulse
41- Ignition Control circuit
51-EEPROM Programming error

Cleared all codes, and they have not come back

Watching freescan, while in open loop, the car runs great, just like normal. Not bent valves or pushrods or anything. As soon as it hits closed loop, the stumbling symptoms come back.

Any ideas? Opti? Did the whole thing hiccup on my trip to the higher RPM's?
Something tied into closed loop I'm thinking.

 

Looking farther in freescan, my passenger side O2 seems dead. While the drivers side moves around, up to .900, the passenger stays down in the 1XX to 3XX range.

Hoping the opti/PCM code was a fluke....

 

If its a fresh build (don't know the parts used....) then 6500 should not hurt anything.

You checking those o2 readings still in open loop (you didn't say lol) cause they have to be warmed up...

Bad sensor in the opti is easier to see on a scanner than a cap/rotor. If the sensor is bad (you got a faulty pulse code once) you can normally see the rpm signal going crazy. Last one I replaced while cruising at 2k it would spike to 6k for one reading then back down to 2k.

I think my cap/rotor is toast now though

 

The rebuild was stock parts, with ARP Rod and Head bolts. New heads and LT4 valvetrain, so I'm not overly concerned about actual engine damage.

I did wait till closed loop to look at the O2's, and the moment it hits closed loop it runs bad again. I'm picking up a couple O2's this afternoon....

 

Good luck.... I guess that is one thing I miss about having a small cam, I can't tell how mine is running at idle (unless its really bad)

 

You can still be in open loop once the o2 sensors warm up.

 

I was using the light up dialog on freescan that shows when closed loop is active.

 

Welp, a new 02 sensor, and all is well in the house of the Formula.

Thats a welcome relief.