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I purchased a 88 olds cutlass supreme and had to get it ...

Sent to Car Experts June 5 2006 at 10:31 PM
   

I purchased a 88 olds cutlass supreme and had to get it smoged here in Cali it seemed to pass every category exept for one, "NO (PPM)" the max is 762 @ 15 mph and 701 @ 25 mph my car meas @ 874 & 869 the guy said i have a small leak by the fuel filter could this be the prob if not where should i start and what am i looking at as far as cost?

 

Optional Information:
1988 Oldsmobile Cutlass 307 carb fed V8

Already Tried:
nothing/p>

Customer (name blocked for privacy)
Status:  Closed   Value: $10
Answer
June 6 2006 at 1:20 AM (2 hours and 49 minutes and 29 seconds later)
         
REPLIEDCheck Mark

hello!

High NOx (oxides of nitrogen) levels are formed if the temperature in the combustion chambers is too high. The manufacturer controls combustion temperature by diluting the air/fuel mixture slightly with a small amount of exhaust gas mixed into the incoming air/ fuel mixture as needed.

This is accomplished by providing an internal passage through the intake manifold for exhaust gas to flow, and the amount is controlled by the EGR (exhaust gas recirculation) valve.

If you have a high NOx level, then it is almost certainly an EGR related problem. Cheeck the EGR valve for any disconnected vacuum hoses, make sure it is operating, and if necessary remove it to clean any carbon deposits from the pintle area. When functioning properly, opening he EGR valve at idle should make the engine run very roughly or stall.

I hope this is helpful; if so, please click my accept button! Thanks!

Steve7654 -- Auto Service Technician -- 99% Positive Feedback on 1807 Car Accepts
27 yrs ASE L1 Master Technician, Service manager
Reply
June 6 2006 at 10:16 AM (8 hours and 56 minutes and 11 seconds later)
         
Reply to Steve7654's Post: So the leak near the carb is not the prob, and if the Egr is fine is there some where else i should look? Thanks
Customer (name blocked for privacy)
Answer
June 6 2006 at 12:14 PM (1 hour and 58 minutes and 12 seconds later)
         
REPLIEDCheck Mark
A vacuum leak near the carb can affect HC or CO levels, but not NOx levels. High NOx levels are formed when the combustion chamber temperature is too high... either the EGR system has a fault or the engine is overheating dramatically. SInce you do not mention any kind of overheating problem, the cause of the high NOx level must be EGR related.
Steve7654 -- Auto Service Technician -- 99% Positive Feedback on 1807 Car Accepts
27 yrs ASE L1 Master Technician, Service manager
Reply
June 6 2006 at 10:09 PM (9 hours and 54 minutes and 43 seconds later)
         
Reply to Steve7654's Post: The leak is a liquid fuel leak,and i also forgot to mention that the car is out of state where a test is not required, i will try replacing the EGR and hope that does it. Thanks for all the info.
Customer (name blocked for privacy)
Answer
June 6 2006 at 10:24 PM (14 minutes and 52 seconds later)
         
ACCEPTEDCheck Mark

An external fuel leak will not affect tailpipe emissions, as the fuel is not going into the engine. It IS a serious safety issue though, as fuel is flammable and can catch fire in the presence of electrical sparks or by contacting hot engine components.

I would not recommend just replacing the EGR valve on a guess; there are many other components to the EGR system. If one of the control components is not operating correctly, or if an EGR passage in the intake manfold is clogged with carbon deposits putting a new EGR valve on the car is not going to fix it. You should consider taking the vehicle in to a shop to have a technician familiar with how the system operates diagnose the problem before you start replacing parts at random... The problem is obviously somewhere in the EGR system, but not necessarily the valve itself, that is only one of the possible failures in the system. Getting it diagnosed correctly before beginning repairs usually ends up costing far less in the long run!



Edited by Steve7654 on June 6 2006 at 10:25 PM
Steve7654 -- Auto Service Technician -- 99% Positive Feedback on 1807 Car Accepts
27 yrs ASE L1 Master Technician, Service manager
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