2.3 Running rich


stx4.0

15+ Year Member

Joined
Feb 24, 2008
Messages
120
Points
3,101
Vehicle Year
1994
Transmission
Manual
I have an 88 2.3 that has an annoying problem of running rich and hope someone out there can think of something I haven't.It only starts doing it right when it reaches warm up.After that it starts pouring the gas into the cylinders and starts sputtering and jerking.When you step on on it it will clear it up but when you try to maintain speed it will go right back to flooding out.To date I have replaced everything I can think of involved with the fuel distribution including the fuel pressure regulator,O2 sensor,air intake temp sensor,map sensor,coolant temp sensor,TFI module and pip,complete EGR assemby,EGR vacuum solenoid,air filter and fuel injectors.I finally gave up and took it to Ford which I absolutely hate to do and 80 dollars later they had no idea what was causing it.I had them do a fuel pressure test and vacuum test and both checked out perfect.I still think it is vacuum related and tied into the EGR valve somehow but everything was replaced and checked out.I even replaced the computer and still no luck.The other weird thing is after this truck starts sputtering and flooding out,I can park and kill about 10 minutes and get back in and the problem is totally gone.Anyone got any ideas on this?
 
How do you know its rich? Does the engine light come on? Any codes? Smoke?
What about the exhaust, any restrictions, cat.conv. plugged? How do the spark plugs look? Also double check to be sure the EGR is correct, I believe there is a code stamped on the top, compare with the original. Did you replace inj. with brand new and proper # ? Don't overlook any vac. hoses for cracking. Check connections of hoses and wiring. Did you try unplugging the battery for 15+ minutes?
 
What you describe is a problem when the engine switches to 'closed loop' operation. The Ford guys should have been able to take a 'picture' of all the values before the switchover and after for comparison purposes. Some have a 'flight data recorder' that can record some number of seconds of data, and freeze it at the push of a button, saving the readings just before and after the problem occurs.
Me, it sound like the MAP or fuel pressure regulator, the MAP adjusting fuel based on predicted engine load. If you have a vacuum leak, or a vacuum switch that opens when warm, that leaks too much, the vacuum will be low, and the MAP will think the throttle is wide open and will dump in lots of fuel...
tom
 

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