Hi everyone, my truck (93 F150 5.0L/E4OD) was having some minor surging issues while cruising through town with light throttle around 1500rpm. I did some searching on here and found someone with similar issues that resolved it by blocking off the EGR.
I made an EGR block off plate and installed it on the weekend, took it for a drive around town and the surging is gone, that is the good news.
Today I took the truck to work and noticed that I am experiencing some detonation even under minimal load. Prior to the EGR block off plate I did the SixLitre tuneup and didn't have any detonation issues. Is the detonation a result of blocking off the EGR or something else?
In the meantime I am going to retard the timing a bit.
On another plus side, I got 18.97mpg out of the old girl today , not too bad for a 20 year old truck with 307,000 kilometers on it.
I would remove the EGR block off plate. I doesn't help you with your detonation problem. EGR helps to reduce cylinder head temps and if you haven't modified the engine to run without, then its only going to make a small problem, BIGGER.
When you developed a surge at light cruise, did you ever check for codes or perform the "Key On, Engine Running" test? I bet it would help and probably pinpoint your problem to either a carboned up EGR valve, malfunctioning EVP sensor, or the EGR Vacuum Solenoid has decided to go bad. And they do. Could even be a broke vacuum line for those above components that needs replaced and it would an easy fix.
Let us know what else you have troubleshooted and we'll try to help you out.