BAD detonation

[1977 EXPLORER]

Well as of lately my truck (302/AOD) has developed a pretty heavy detonation under a load (OD acelleration under 60 and low speed passing and WOT) Ive tried several differant stations and grades of fuel (87-93) and with ethanol and without problem remains the same,Tried disconnecting the air pump,EGR etc with no differance.

I done a Fresh FULL tune up around 4k miles ago (90k miles) using motorcraft plugs and autolite wires,brass terminal cap,new rotor,cleaned T/B,PCV valve,new fuel filter,airfilter,crankcase filter etc..timing is set to 10* BTDC with the spout out.
Looked and listened for vac leaks This thing idles like glass and otherwise has no issues.


Its gotten so bad it now rattles and shutters badly when you are passing on the interstate and I know this will hurt it. So im having to drive this truck everyday now and need to remedy this issue quickly.

 

[Fellro]

I'm trying to remember if these trucks have a mechanical advance or not. It could be sticking if it does.

 

[1977 EXPLORER]

I'm trying to remember if these trucks have a mechanical advance or not. It could be sticking if it does.

it's a 90' so it is controlled Via the computer

 

[Fellro]

Not necessarily Ford, but I have seen mechanical advance work with the computer as well... Otherwise, you either have a timing over advance problem, or bad carbon buildup. If it is total computer control, then something is telling it to advance too far.

 

[conanski]

Check the condition of the smog line at the back of the motor and the valves attached to it, a leak here will cause the motor to run lean and detonate badly. This line is right down behind the intake and connects ports on the back of the cylinder heads so you may need a flashlight and mirror to see back there, here's a pic so you know what to look for..

http://www.flickr.com/photos/motorstuff/3668578727/in/set-72157606256666474/

 

[1977 EXPLORER]

Ok a update

Seafomed it

seperated the plug wires better

turned the timing down to 8*

inspected the smog tube no leaks or breaks

unplugged the knock sensor to see if it was any differant (no change)

Still rattles bad

 

[fordrka1975]

Sounds like a partially clogged catylitic converter to me. Randy.

 

[5.0Flareside]

Sounds like a partially clogged catylitic converter to me. Randy.

me too......

 

[1977 EXPLORER]

Sounds like a partially clogged catylitic converter to me. Randy.

doesnt seem to lack any power? passed emmisions with flying colors also

 

[5.0Flareside]

doesnt seem to lack any power? passed emmisions with flying colors also

ok even with the missing/detonation? wow. thats odd. have you checked the codes yet?

fordfuelinjection.com

 

[1977 EXPLORER]

ok even with the missing/detonation? wow. thats odd. have you checked the codes yet?

fordfuelinjection.com

Ill try to scan them at work tommorow I doubt it has any though the stutter seemed to go away after the stuff i done tonight but the pinging remains at part throttle acel

 

[1977 EXPLORER]

Well,

Gutted the converters ( now ill have to replace to pass emmisions)
replaced o2 (O2 rich code)
replaced map (map out of range code)

Still pings low speed cruise to mild acell


I cant keep throwing stuff at this truck I have to have it to drive

 

[5.0Flareside]

Well,

Gutted the converters ( now ill have to replace to pass emmisions)
replaced o2 (O2 rich code)
replaced map (map out of range code)

Still pings low speed cruise to mild acell


I cant keep throwing stuff at this truck I have to have it to drive

you wont have to replace the convertor to pass emissions. i know many many people who have gutted there convertors and still passed emmisions with flying colors.

 

[conanski]

replaced o2 (O2 rich code)
replaced map (map out of range code)

Exactly what codes did you get? And did you clear the codes or reset the computer after changing these parts?

 

[emtzach]

it sounds dumb but it has fixes drivability issues for me take out the engine temp sensor clean or replace theyr stupid cheap but it has help me before when i was chaseing problems befor

 

[emtzach]

i had those same codes on my ranger replaced everything mass air, o2 and it ended up being the engine temp that was throwing everything off

 

[1977 EXPLORER]

Exactly what codes did you get? And did you clear the codes or reset the computer after changing these parts?

I didnt write the numbers down I used our snap on scanner at work and it gives the code Definition when it reads .and yes I cleared the codes several times.

rescanned it today and had a EGR position code so i replaced the EGR and sensor.

 

[5.0Flareside]

I didnt write the numbers down I used our snap on scanner at work and it gives the code Definition when it reads .and yes I cleared the codes several times.

rescanned it today and had a EGR position code so i replaced the EGR and sensor.

did it solve the problem?

 

[1977 EXPLORER]

did it solve the problem?

no still pings.. cant wait to park this thing.....

 

[1977 EXPLORER]

no still pings.. cant wait to park this thing.....

ended up running some tranny fluid and water through it smelled like burining carbon for the past couple days. ping is gone

guess the seafoam is just snake oil.

but i do have a exhaust leak now so guess ill have some duals put on it