Emissions Help

[gzeleniak]

I have a 1987 Bronco II with a 5.0 Liter V8 from a 1993 Thunderbird installed. I did the conversion a number of years ago, and have had no problems passing smog (all factory controls are installed). This year, I cannot pass, the NOX test is way high, once before I had the same problem, it turns out the pipe from the exhaust header to the egr was broke, fixed the leak, passed with flying colors. Now I have checked all the components and they all test OK, but the EGR is not activating when I drive. The EVP, the EGR valve and the position sensor all work fine, but there is no activation when I drive. It is like the signal (the ground from the EEC) at the EVP solenoid is not being sent to the solenoid. I have checked the continuity from the EEC to the solenoid, it is fine. If I hook a ohm meter up no ground is seen, but if I manually ground the solenoid, the egr opens fine.

My question, what conditions have to be met for the egr to begin to function. Does the ECT have to show a certain temperature? I have a 180 thermostat in place, instead of the 195, but I did force the system well over 195 and road tested it, but still no egr. I verify the ECT signal matches spec. What else would keep the egr from operating? I find it hard to believe the EEC is bad, but that is my next best $300.00 guess. I did pull the codes It passes KOEO test every time, If I run the car, but not let it get near 180, the KOER test passes, If I run it and it gets over 180, the KOER test throws a 332, insufficient EGR.

Any ideas would be helpful.

Thanks

 

[RonD]

Yes, engine needs to be in Closed Loop(above 160degF) before EGR system will activate.
rpm for EGR is 1,800 and up.

There should be 3 parts to EGR system(4 with computer)
EGR valve on intake
EGR position sensor
EGR solenoid(computer control of EGR valve's vacuum hose)

The EGR position sensor can be part of the EGR valve(look for electrical connector) or a separate unit with 2 hoses and electrical connector, this kind is called a DPFE sensor.

A faulty position sensor will almost always cause a CEL, and 332 could be it.

Some EGR systems have a large "tin can" as a vacuum reservoir, follow the EGR position hoses and check where they go, also check the "tin can" if you have one.

 

[gzeleniak]

Thanks for your reply. I have checked the position sensor operation manually, applied vacuum to the egr read the signal to the eec from the egr position sensor, voltage matches the chart I found.

I have heard the 1800 RPM number before, but this vehicle almost never reaches RPM over 1800, and it is no where near those RPM at the test the CA DMV mandates. 15 mph and 25 mph.

I have even road tested the car, and observed the evp vacuum and ground signal there is no action when the rpms go over 1800.

thanks again

Greg