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Date: Thu, 06 May 2004 23:33:12 -0400
From: cs <>
Subject: Re: can't pass emissions  - NOX too high


Walt, thanks for the reply. I'm not sure my car even has an EGR - not all of these cars did, but then I'm not even sure what an EGR valve looks like for this car, or where it is located As for octane, I am running 93 - would changing to 87 make a difference? As far as the test procedure and/or dynamometer test, while they don't tell you 'what up,' it appears that Ohio runs the car in the 25 MPH range for several minutes (in adddition to taking a sample from the exhaust). Your comments, re vacuum hose integrity are noted - while I have replaced some vacuum hoses several years ago, it might be time to replace them all, given the age of the car. I'll report back if/when I'm sucessful in getting the car passed. On Thu, 6 May 2004 09:01:14 -0500, "Walt Kienzle" <wkienzlenospam.net> wrote: > ><cs> wrote in message news:kbcj90ttsadjc0bb84pp0a4skvei5e7j6nnospamcom... >> My biennial proiblem is back - can't make it through the Ohio e check >> with my '88 9000 turbo. For the past two cycles I have taken it in, >> it flunks, then without doing anything to it, I'll take it back the >> next day, and it passes (in 2002 they flunked it because they said >> they couldn't get a reading on it). >> >> However, I've a feeling it won't pass this time - the tech told me >> they just started measuring NOX, and while I'm way under on everything >> else, the NOX is high. >> >> Any suggestions? FYI: this is the 2.0 litre turbo, re-chipped (SAAB >> issue) to bump it to 175 bhp (from 160). The oxygen sensor was >> replaced aproximately 4 years ago, and the MAP sensor was replaced ~3 >> years ago. This car is still a rocket - my 2.3 litre HPT CSE can only >> keep ahead of it from dead stops, but then any lead is lost on >> high-speed rolls. >> >> I'm wondering if premium fuel might be the culprit - i.e. 93 octane >> Amoco (re-chipped, SAAB recommends nothing less than 91 octane). Any >> suggestions? > >High NOx levels are related to the EGR system in most cases (disconnected or >plugged for some reason). Changing to 89 or 87 octane is unlikely to give >an improvement. The amount of NOx formed is directly related to the >combustion temperature in the cylinders. The EGR system feeds exhaust gas >back into the combustion chamber. Since exhaust gas is inert (or is >supposed to be) it doesn't do anything to promote combustion and reduces the >combustion temperature. My Haynes manual simply says that if there is a >fault in the EGR system, a fault code will be stored in the LH-Jetronic ECU >and a warning light is lit (as usual, not much help). Since you have a >pre-DI model, maybe you can retard the timing by about 5 degrees to see if >that would help. > >Here is another suggestion. The Haynes manual (it may be of help this >time!) says that a vacuum advance diaphragm is used on your model year to >retard the timing when the turbocharger is in operation. These things go >bad - particularly after 16 years. Maybe this is the cause of your problem. >In Illinois we have the same type of test where the car is run on a >dynamometer at various speeds up to about 60 mph. If your test works the >same way and this diaphragm is broken, this could be your problem. They >used to just measure the emissions at idle; that kind of test wouldn't have >revealed this problem. Was a dynamometer test performed on your car? > >The EGR and the distributor vacuum advance are both operated by engine >vacuum; a check for cracked or loose vacuum hoses would also be beneficial. >I hope this helps. > >Walt Kienzle >1991 9000T >

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