Help Diagnose Engine Problem

[89stang10sec]

My 89gt has developed some serious issues. It is a stock bottom end topped with ported heads, comp cam, edelbrock intake, etc. The problem I am having is that it is "bucking" in most of the RPM range, very noticeable on the freeway. It has a lot of vibration, and I think I hear a knock coming from the bottom end. Also, at idle my oil pressure drops down to nothing, but comes right back at 1000 rpm. What do you think is causing this? I will probably have to pull the motor, huh?

 

[90silverstang]

My 89gt has developed some serious issues. It is a stock bottom end topped with ported heads, comp cam, edelbrock intake, etc. The problem I am having is that it is "bucking" in most of the RPM range, very noticeable on the freeway. It has a lot of vibration, and I think I hear a knock coming from the bottom end. Also, at idle my oil pressure drops down to nothing, but comes right back at 1000 rpm. What do you think is causing this? I will probably have to pull the motor, huh?

Might of spun a bearing. Try a compression test also. Are blowing any blue smoke?

 

[90mustangGT]

A compression check be a good idea but it's probally something else, so don't tear the engine down yet. The computer is probally in limp mode.

When you mean it bucks, do you mean it just completly cuts out, or just does it just tend to loose power a little?

Check to make shure the fuel system is working. Are you getting enough fuel pressure? Is you check engine light on? Maby you should have it scanned for codes it doesn't alway pop the engine for fast codes. It also could be a miss or bad timing as well.

Ford tend to buck and studder alot when the ECT (engine coolant temp) sensor or the EGR valve gets stuck. I work in a shop, this is what it is alot of times.

 

[89stang10sec]

-by "bucks" I mean it is down on power but not cutting out completely

-I pulled the codes and it shows EGR failure( It is deleted), and Fuel pump relay circuit failure, and lean EGO. I hooked up the fuel pressure guage and everything looks fine, consistent pressure. New plugs and wires and checked timing. Only other thing I see wrong is a small header leak. Any thoughts?

 

[89stang10sec]

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