MORE EEC-4 DIOGNOSTIC TIPS

Diognostics on the EEC-4 system are not really all that complicated. First thing is to determine if the problem occurs cold, warm, or both. If it only occurs cold there are only a couple sensors being used during warmup. The air charge temp sensor, engine coolant temp sensor, throttle position sensor,and the pip signal to let the ECM know that the engine is indeed running. In fact, if you encounter a no start, and see no fuel, make sure you have spark because if the pip signal fails to get to the ECM, because of either a bad TFI or mag pickup, the ECM shuts off the fuel pump. Any cold driveability could only be those sensors, or the ECM, as it runs on fixed fuel tables in the memory. If it runs ok cold, but runs like crap warm then any sensor could be it. Before pulling out the codes, make sure the cooling system is full ( this sets ECT codes from time to time), and look the vachum hoses over. Be prepared to perform a 'dynamic response' during the self test with most retrieval tools. This is usually quickly flooring the accelerator and releasing it, turning the steering wheel a little, and appling the brakes. This tests sensors in the power steering, brake pedal, and TPS.Retrieve codes, then it is wise to pull the battery cable off for about 15 minutes to clear codes, then drive it again for an hour or so then recheck codes to see if they return. The codes 10 and 11 are codes you want to see. The 10 code separates the first codes, known as memory codes or codes that have occured in past but may not necessarilly be occuring now, and the second group of codes which are hard faults, codes that are currently occuring. Remember to warm the engine up good before pulling codes, then run engine at 2000 RPM for a little over 2 minutes to warm up the O2 sensor.

A common problem that results in codes and a high idle are a sticking EGR valve, and a mis-set base idle. To set the base idle, warm the vehicle up, loosen the idle air control valve, slip a piece of cereal box beneath it, and snug it down. Start the engine back up. Adjust the idle screw til it idles around 600 to 650 RPM. Remove the cardboard, then verify the idle is ok now. A little advise would br to clean the throttle body first, a dirty TB will effect the idle setting.

Having trouble locating an erratic, hi, or low idle problem? First clean and check the throttle body, and the idle air valve. Remember to pull the battery cable for 10 to 20 minutes to clear memory, and relearn idle strategy. If this isnt correcting it, use carb cleaner and spray around the injector area where they fit into the intake. I see many bad o-rings on injectors cause idle problems.

Most of these tips are geared towards the 2.9L, but can also be applied to the other engines too. I intend to keep expanding my page in regard to diognostics, and soon plan on the diognostic procedures for TFI's.