View Full Version : smooth at idle, sputters under load.

10-15-2012, 12:37 AM
My 94 was running very rough, sputtering, knocking, and smoking. I did an engine swap(7a for 7a). The engine i put in runs perfect, at idle, but still sputters under load. The "new" engine has different injectors, different MAF senser, a brand new fuel filter, and I checked the cat. Im running out of ideas, and would love to hear any you have.

10-15-2012, 03:19 AM
Check your fuel pressure under load.

11-11-2012, 09:35 PM
did you do a tune up on it?

11-12-2012, 06:05 AM
Simple check -- misfiring cylinder. An engine can run fairly smoothly with one cylinder not firing while at idle or at a steady speed. It is as engine speed changes that the misfire becomes evident. First thing to check is whether all cylinders are firing. Pull the spark plug wire from one cylinder at a time. If the engine doesn't react, you've found a dead cylinder. The most common issue in that case is a bad spark plug wire.

11-12-2012, 02:39 PM
Is the 7A-FE engine you installed from a different model year, and/or a different make vehicle? If so, did you swap out your old ECU with the proper ECU for the engine you swapped in? If not, your old ECU may have the correct parameters for the new engine you installed, given the differences (injectors, MAF, etc.).