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1990 740 GL Emission test problems 700 1990

First of all let me start by saying this forum has been a tremendous help in trying to resolve my issues over the past week. I recieved the car 05/21/02, and found this site 05/22/02 :) . So, the problem...

My 740 failed NV state emissions. CO2 and o2% are not a factor in the pass or fail of the test but listed as reference. Readings were:

2500 RPM test HC ppm 89 (Limit <=220)CO% 3.11 (Limit <=1.20) CO2 16.30 O2% .1
Idle test HC ppm 113 (Limit <=220)CO% 0.15 (Limit <=1.20) CO2 16.30 O2% .7

So I failed only in the 2500 RPM "enhanced" smog test for CO%. Due to my poor fuel economy & hesitation I suspected the fuel pressure regulator (knowledge from engine tune section in forum). I pulled the vaccuum hose and there was no rise in idle. Replaced and now here's my results (still failed, no CO2 or O2% test and no charge test):

2500 RPM test HC ppm 95 (Limit <=220)CO% 0.64 (Limit <=1.20) CO2 XX.XX O2% .X
Idle test HC ppm 207 (Limit <=220)CO% 1.12 (Limit <=1.20) CO2 XX.XX O2% .X

As you can see the engine richness problem has been resolved in the 2500 rpm test, but CO% and HC increased in idle. The tech said the vehicle would be failed if he ran the test, as the CO% peaked at 4% then dropped and HC's peaked at 600 and dropped. I'm going to perform a tune-up as far as plugs, cap, wires, air filter, PCV. Any other things to check or look for? I've read in the forums to check the water coolant sensor (2nd one?) Will check vaccuum hoses tomorrow (FPR has new hose). Sorry for the lenghty post but wanted to be as thourough as possible.

Loran Drellack






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New 1990 740 GL Emission test problems [700][1990]
posted by  someone claiming to be L Drellack  on Thu May 23 14:39 CST 2002 >


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