I hope someone can help me out and possible come up with some other suggestions of things to check. I have posted twice with no responce. I have searched the post for Ideas and they have been a great help. There seems to be a lot of pinging posts out there for Fords in general. Here is a break down off everything that has occured. Also would you recomend sea foam or marvel mystery oil? Hope to do some work this week end. Its been hot here in Seattle about 90. Any help would be appreciated.

Bronco: 1994 with 302 automatic.

Symptoms: Pinging/Surging under light load between 1500-2000 RPM. Especialy in Hot weather. Clears up with increase of throttle. Idels like a champ and ping does not accure when reving the engine in park.


Repairs done prior to symptoms (approx 2K miles ago):
1)Tune up which included Plugs, wires, rotor and cap.
2)New Oxegon sensor,replaced due to check engine light.
3)New Pvc valve
4)cleaned egr valve (was not dirty)



Repairs done since symptoms:
1) Pulled codes 3 times myself with no errors detected.
2) Had Schucks pull codes and came up wit a 46 with KOER (Thermactor error). I believe he took the test wrong due to the fact that I have since taken my Bronco through emissions and it passed with flying colors. Readings were better than 2 years ago.
3)Pulled codes again still with no errors detected.
3)re-routed Spark plug wires paying extra attention to #7 and #8 wires. (They were not crossed before)
4)New fuel filter
5)upgraded to supreme fuel for 2 tanks with gas dryer and injector cleaner.
6)Replaced coil.
7)checked for vacume lines for leaks. None found. I did find a small crack in drivers exaust manifold.
8)Watched for wire arch at night (none to be seen)


Results: Surging/bucking is gone (only been 3 days so wait and see). Pinging has reduced but is still there. Same RPM range.

Next on list:
1)clean MAF sensor
2)Pull plugs and check and possibly replace. Maybe put old wires back on. New parts have been known to go bad.
3)Try temp fix on exaust manifold with JB weld to see if condition corrects itself. Even if only teporaly for trouble shooting.Than replace. New manifold is around $125 from NAPA.

 

maybe reset base timing
i have been having timing and ignition issues and done alot of searchin and askin around and if ur timing is advanced to much it will cause pinging under load
maybe you coulda bumped the dist. when u did cap and rotor? it doesnt take much to push it off a couple degrees

do a search for pinging and timing and there are post with ways to set it under a load

 

beastybronco, thanks for the reply. I thought my Chiltons book said never to attempt to adjust the timming for my year of Bronco and engine. I will double check. Even if it says not to adjust I imagine it can be done. Do you know of any place I could find the procedure for doing this? I will check out some other posts to see if they do. Thanks

 

hmm i have an 88 but i think we both have the eec IV computer the actually timing cannot be adjust only the base timing when u hook the computer up it pretty much takes over but i know that if u have the same set up i have the base timing can be adjusted and from doing some research too advanced of timing can cause pinging under load

maybe we can get some experts in here i dont want you to mess up good timing from hear-say

 

https://www.ford-trucks.com/forums/s...t=timing+btdc+

there is one post talking about it

if u search some more there are some with detail descriptions on the actual process

 

Just looked in my Chiltons and they describe how to set the initial timing on the Dura Spark II Systems only. Says With the TFI-IV "system no ignition toming adjustment is possible and none should be attempted". I believe that I have the TFI-IV?? does anyone know what years had what systems thanks.

 

Could be the crack in the exhaust manifold - mine pinged when my ps exhaust manifold cracked.

 

These ignition systems with lots of electronics can be very sensitive to certain parameters -- even a small amount of vacuum leak can throw them off.

Try measuring the vacuum and advance in the pinging range, and see if that's normal or not. (of course putting load on the engine to simulate the driving condition might be a bit tricky, but I guess you can put the rear on cinderblocks/jacks and slightly set the parking brake) I think most other things have been mentioned. I have a '95 and no pinging whatsoever with 87 octane, right here in Seattle and eastern WA.

 

Base timing on the Bronco 5.0 is 10btdc. You set or check base timing by warming up the truck to operating temperature. Make sure your timing indicator on the engine is clean and visible and use a chalk marker or something to highlight the line on your balancer. Remove the spout connector (little two wire plug that will be by your distributor if the ign module is mounted there, will be near the fender mount if ign module mounted there). With the SPOUT connector removed, check your timing, set to 10btdc. Shut down and reinstall the SPOUT connector. I agree with JBronco, get that manifold fixed. But rather than spend $125 for a replacement factory manifold, sound like a perfect excuse to upgrade to shorty headers. I run JBAs on my '96, cost about $350 with excellent results. For a '94 there are several manufacturers that offer shorty headers, give it some thought.
Another possible solution is to run a slightly cooler thermostat. OEM is 195, do not recommend going down into the 160s, the computer will not like it.

 

When the exhaust manifold first cracked, it pinged like mad for a day or so. Then it seems like the computer adjusted it so the pinging stopped. I did replace my stock manifold with a new one from eBay, apparently this aftermarket manifold is better than the stock one as it is designed not to crack like the stock ones do. I think it was around $89 and fit perfectly.

I did not want to spend all of the money to get headers and the subsequent exhaust upgrades that would be required to maximize the potential of the headers, although it would have been nice. I simply wanted the exhaust leak fixed and no more possible pinging, which was accomplished by the new manifold.

 

Here is the driver's side version of the manifold that I got. It is from the same people on eBay. It comes to $99 with shipping. I don't know about the NAPA one but this one fit well. They also have them for $39 if you don't have emissions, same seller.

http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

 

Oh you have a 302, you're in luck! Same seller, $39!

http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

 

Thanks for all the feedback. The temporary fix I put on the exaust manifold this weekend seemed to do it. I think I will save up for the JBA headers.