Hi all and Happy Holidays,

About a month ago, my 91 coupe (L98 engine) was idiling pretty rough and kind of sputtered sometimes when I stepped on the gas, especially from a stop. Got a code 45 and took it in to a mechanic to get it looked at. He said running rich could be many things, but it really needed a tune up. Got new plugs, wires, fuel pressure regulator, and he found the EGR valve was bad, so he replaced it and said it wasn't running rich any more.

Ran good for about a week, and then I noticed it was sputtering, just a little big,again. The idle is better, but on a cold start I notice it's still a little rough. Check engine light came on again, and it's showing code 45 again. The light ONLY comes on at highway speeds, and itusuallygoes off after a few minutes. I haven't taken it back to the mechanic yet - I'm waiting to get some advice and save some $$$ before I get it fixed. I'm wondering if you all think it's fuel injector or vacuum leak related or something else? (I haven't noticed black smoke when I start it up, but I also haven't had someone else start it while I look at the exhaust...) How long do you think I can wait before it causes serious problems?

Thanks much!!

 

Check this article, there are several things that can cause a rich condition.

http://www.misterfixit.com/code45.htm

 

Have you replaced the 02 sensors ever?

 

There are several main causes for rich condition in an L98. 1st, check your fuel pressure, should be around 35 lbs. Next, monitor O2 voltage @ idle on a warmed up engine, should be active switching from .1, .2 volt to .7.8 v. If not and stays on the rich side, create a vacuum leak to see if the O2 goes lean (> .3 to .4 v) for about a second or 2. This means your O2 is responding to conditions. Next thing to do is an injector balance test to see if all injectors are getting equal pressure drop. Might have a leaking injector. Good luck. [8D]

 

Thanks all!! This is very helpful... I'll take a closer look after the holidays. For now, she gets to rest in the garage at home and enjoy some rest.

 

very well said. i can tell ya twisted a few bolts in your days.i dont think hes got a meter for the o2 cross counts

 

Bout 30 years of it. [8D]

 

me too 30 years selfemployed.sold the shop 4 years ago,but i kept my snapon big red brick [which is about to go the dodo bird route] last 2 updates 1700.00