89 F-150 302 running bad

[Bruce Walters]

I got the code reader and it gave me an AC clutch code (AC inop). Then it gave me a 33 which is EGR valve not closing. I also verified that the check engine light comes on with ignition and goes out when started. To the static rev question, it behaves the same as when in gear. It will not take full throttle. I don't have a tach so I am not sure of RPM but it simply will not accept aggressive throttle application. I purchased an EGR which puts the parts total in excess of 425.00. I will change it but I am not hopeful of improvement. I am still at my wits end.

 

[smokey]

The EGR is most like the problem. It is creating a major vacuum leak. Make sure to clean out the EGR ports they tend to clog up with carbon.

 

[Bruce Walters]

OK I replaced the EGR and drove it and it still misses bad and backfires at near to full throttle. Any guess as to where else I can look. Its losing fuel or ignition but I can't determine which.

 

[dustybumpers]

Did you check the firing order of the plug wires yet?

 

[DieselDRW]

Check your vacuum hoses. I have an 88 mustang that was doing the same thing. I changed out some vacuum hoses and it got better. I still have a leak some where but i am not done changing out the hoses. Drivability did get better with the few I changed. You may also want to check your battery and alternator. May not be getting enough output from alternator at the higher revs/load. Is your engine modified? I would first swap out the vacuum hoses. I bet thats what your problem is.

Sent from my LGMS631 using Tapatalk

 

[smokey]

Wondering if the distributor it's self isn't bad. They can develop play in the shaft and the wobble screws up the timing. Just throwing out a rare thing that does happen from time to time.

 

[kiwi f150]

Here's the firing order

 

[kiwi f150]

It's just a matter of elimination until you get there Bruce , it can be very frustrating at times lol. I'd start at the beginning and check all the basics like spark plugs , leads ,cap ,rotor - these could be breaking down under load and it wouldn't be a bad thing to change them anyway. Also the coil maybe getting weak as well. It pays to check ground connections especially.

https://www.summitracing.com/int/se...s/make/ford/model/bronco/engine-size/5-0l-302

https://www.summitracing.com/int/parts/msd-8227/overview/make/ford/model/bronco

Try running the truck at night with the bonnet open to see if you are getting leakage from the plug wires - it'll show up as your very own personal lightning storm under there.
The way you describe the fault it sounds very much electrical in nature but vacuum leaks can cause this as well. Very unlikely to be fuel related.

I brought and assembled one of these to deal with vacuum leaks ...... works really well for the $$$ invested

http://www.ebay.com/itm/EVAP-Smoke-Machine-Diagnostic-DIY-KIT-Leak-Tester-/281916885243

 

[Bruce Walters]

Thanks guys. I will look at vacuum hoses and I am changing plus wires cap and rotor. I will keep you posted.