I have been reading all the posts relating to this issue since I bought a 91 vert with the omp issue(code 27).Has anyone run into this problem multiple times? I replaced the omp and vehicle was still in limp mode.checked/repaired ground issues in harness.Replaced ecu and was able to drive vehicle and get it smogged.After about 60 miles,cel came on and back into limp mode.first question is can I save the ecu by unplugging the omp (have been running pre-mix since I started diagnosing and ecu still outputs codes for now) and has anyone had the rtek 1.0 upgrade and can give me feedback as to its value?

 

both omp and ecu were bought used.even with a discount a new omp is just way too expensive