EGR problem?
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EGR problem?
1986 2.9 bronco 2 with EGR. My bronco runs fine when cold but when it gets warm it runs rough and blows black smoke at the exhaust. When scanning for codes 31 came up. When engine is warm its not getting vacuum at EGR valve. Should I have vacuum there? I removed the EVR solenoid tryed testing it by blowing air through it, i could not. Then I hooked power to it could not hear the valve opening and closing, should I? Then with engine warm I tried testing for power at EVR solenoid plug, there was no power at plug. What sends power to this plug on EVR soleniod? I tried another 86 computer but had same problems. Tryed computer from a 89 bronco 2 and it runs well and only has small puff of smoke under full throttle. P.S have also installed new Oxy censor, EGR valve, distributor cap and rotor. What is wrong?
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From: UT
Question: Is the 31 a KOEO, KOER, or continuous memory code? KOEO codes are particularly helpful, because the fault has to be electrical in nature.
EVR solenoid, like so many other EEC-IV components, gets power from the EEC relay. If you don't have a wiring diagram to see this, I would strongly suggest you get one. The first thing I would recommend with most codes (including this one) is to inspect the wiring.
EVR solenoid is easy enough to test with a vacuum gauge using the EEC-IV output state test. If the EEC-IV diagnostic article in Ken00's tech info post doesn't have instructions for the output state test, read "tests" at www.dalidesign.com/hbook/eectest.html
EVR solenoid, like so many other EEC-IV components, gets power from the EEC relay. If you don't have a wiring diagram to see this, I would strongly suggest you get one. The first thing I would recommend with most codes (including this one) is to inspect the wiring.
EVR solenoid is easy enough to test with a vacuum gauge using the EEC-IV output state test. If the EEC-IV diagnostic article in Ken00's tech info post doesn't have instructions for the output state test, read "tests" at www.dalidesign.com/hbook/eectest.html
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PCM swap
Can I use pcm from a 89 2.9 in my 86 bronco ????????? IT will not run well with 86 pcm but with 89 pcm seems to work great drove it about 10 miles. IF I leave 89 unit in should anything else be changed? Thanks for your reply.
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The reason it runs well with the '89 PCM, is the '89 PCM doesn't read the EGR system, and it's your EGR system that is having the problem.
I really don't know how much modifying you would need to do to get the '89 computer to work perfectly. It might not take much. There are several differences between and '86 and the '89 engine management program (EGR is only one). Others include:
'89 doesn't have a knock sensor
because of the EGR system and knock sensor, '86 and '87 have a more aggressive timing curve.
If you have an automatic, the '89 computer will be looking for a 3-4 shift solenoid in the transmission which your '86 tranny won't have.
I really don't know how much modifying you would need to do to get the '89 computer to work perfectly. It might not take much. There are several differences between and '86 and the '89 engine management program (EGR is only one). Others include:
'89 doesn't have a knock sensor
because of the EGR system and knock sensor, '86 and '87 have a more aggressive timing curve.
If you have an automatic, the '89 computer will be looking for a 3-4 shift solenoid in the transmission which your '86 tranny won't have.
Last edited by mrshorty; Dec 2, 2004 at 10:30 AM.
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After testing it seems there no current at any time going to evr soleniod tested for power with engine hot then cold. Does PCM send power directly to soleniod or is there another part that could have failed. Am planing trip to salvage yard if anyone has any ideas where problem may be please post and I will try swapping suspected parts.
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mrshorty thank you very much for your help will check relay and all wires and post what I find.
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