Jim Speer

My 93 runs badly prior to warming up (195 degrees). It idles fine but on light acceleration it hesitates and sometimes bogs so bad as to almost shut off. But after complete warmup runs fine. The check engine light has come on twice in the last year. I rarely drive the car but do use seafoam once a year. The only codes are 28 and 64. 28 = quad driver #3 64 = medium egr fail or right o2 sensor. no idea as to quad driver unless it's in the ecm. could a egr fail or 02 sensor cause this problem but right itself once warmed up. 02's are just 2 yrs old. ??????

Thanks guys/gals

billschroeder5842

Check you coolant sensor as I bet it is wonky. You have all the classic symptoms. A faulty sensor will tell your engine it is hot, when it is actually cold so your computer runs the engine lean causing bogs. Once you engine heats up, the lean condition disappears.

richardgharris

All good stuff, Thank you all!

Rich harris