Hi,
1990 240 non turbo, failed emissions test because of abnormal Nox levels.
Im looking at the egr system as the possible culprit. Here is where Iam at:
egr system checks out, except I dont think its getting the proper signal from the ignition computer. But I want to be sure before I get serious about replacing this computer.
Ive done all the tests on the system. Everything is good except: attached a vacuum guage to the outlet side of the egr vacuum solenoid, and I listened with my stethoscope. With a hot engine, when I accelearate it I can hear the solenoid click, click click click, and I can also see the guage register plenty of vacuum, but then the solenoid stops clicking and the guage registers 0. It appears to work only on the first rev of the engine, but if you hold it at a steady rpm level, vacuum level is 0.

ONe other thing occured to me: is this the way it was designed to work. It just doesnt seem to me that such a little shot of recirculated exhaust gas could have any effect on combustion temperatures.

Ive checked the wiring, so the question is; do I need an ignition computer? Or am I barking up the wrong tree entirely?

I really need some help with this. I must complete my smog test.

If you can help, thanks.

Lawrence