QuestionI own a '92 Ford Explorer, 4L, 5 spd std trans, 3.27 rear end with 80K miles. Over the years I have tried to get rid of the Ford knock which seems to be a design problem with these engines. The knock is a function of the air temperature, when the ambient temp is high (air is less dense) the engine knocks bad under load. When air temp is cool there is no knock. I have tried the following to no avail:
1. I have been running the truck with the spout connector removed for three years. The 3 degree timing advance corrected some of the knock but over the years it has returned to the original level when the spout connector was installed three years ago.
2. I have tried higher octane gas (89 and 93) but this doesn't seem to make any difference.
3. I have switched the MAF sensor with my 93' Ranger. No help. The Ranger is a 4L with 3.73 rear end, 130k miles with no knock. Ford either corrected the problem in 93' or the lower rear end helps with engine load.
4. I have tightened the intake manifold bolts, no help.
- Could this be a carbon build up problem in the cylinders? I would hate to rip into the engine if this is not a correction for the knock problem.
- Are there new software proms that can be purchased to fix the timing problem?
This engine does not have a knock sensor. Any thoughts ?
AnswerHello and thanks for the question...I'll try to help.
Yes, it could be a carbon build up problem on the pistons as well as a build up on the valves. I would also suggest that you have the cylinder heads checked for coolant leaks. This was a serious problem in the early Explorers.
As far as a PROM update goes......on that particular year there is no PROM to up date. It is either replace the PCM or live with the one you have. I would suggest that you get the OEM number off of the PCM and call the parts counter at your local dealership.
Hope this helps,
Erik
