Help with interesting Rich running problem **Updated**

[AutoSHO]

Hello everyone. I have an interesting problem with my car. The thing has had the 60K done on time, and seems to run perfectly. But, while driving it yesterday (and this only happened this one time) it threw a CEL, and stored codes of 173 and 177, RH and LH banks running rich. I'm inclined to think that this isnt an oxygen sensor problem. It doesn't smoke, use any oil, or have any driveability problems. Car got 24 mpg with about 65% highway and 35% town driving, with a couple runs up into the higher revs. This seems like a weird problem, and since it only happened once, I'm inclined to think it may have been some sort of fluke. The MAF is clean, the TPS has no dead spots, and it has lots of power. The one thing I havent done is a KOER test. Any help/suggestions are appreciated! I'll try to get the KOER done tomorrow evening. Thanks for the help!

I ran the KOER Test tonight. Came up 111's, but the starting problem made itself apparent today. However, I may have discovered a clue. I noticed that this time, I had turned the key to "on" and fiddled with my CD's for about 10-15 seconds before trying to start the car. It cranked but did not fire until I held the pedal down approximately 1/2 way. At that point it started up like usual. I know my fuel return line check valve is bad, but i am not sure I see how it would affect this. I am lead to believe one of two things: either the injectors are leaking, allowing extra, raw fuel into the intake so that the car is flooding on startup, or the fuel pump has some sort of anti-backflow valve in itself that is malfunctioning, allowing pressure to bleed off through it. I still do not have a fuel pressure gauge, which might provide some clues. Anyone have any suggestions? I think at this point I am going to run a bottle of fuel injector cleaner through it, and see what that does.

<small>[ January 23, 2003, 10:17 PM: Message edited by: AutoSHO ]</small>

 

[sdpatt]

Chris, I think you are on the right track about taking care of the car. Time will tell if the rich condition was a fluke or not. Chances are that it was a sign of something in the engine control system starting in a less than optimal state.

It could have been something as trivial and hard to find as a loose connection in a sensor that still allowed the signal to stay in the normal range. The TPS and MAF are the two sensors that come to mind that might cause this. Keep your eyes open for the CE light and give the KOER test a try.

 

[AutoSHO]

Thanks for the advice Scott. One thing I forgot to mention is right after I got the car, when it was run for a couple minutes and shut off, it didn't want to start right back up, and it took holding the pedal to the floor to get it to take off. This continued until I reset the computer. It always starts now, but sometimes hesitates a little upon starting. It seems to pause at 4-500 rpms and then jumps up to ~1500 the way it normally would. I am not sure whether these two problems are tied together or not, but they would seem to be. I'll run the KOER test tonite and see what that turns up.

<small>[ January 22, 2003, 12:21 PM: Message edited by: AutoSHO ]</small>

 

[AutoSHO]

I also know that the fuel check-valve gurgles a lot, would this have anything to do with the problems I am having? The fuel pump is pretty quiet, so I don't think its the problem, and the car does run very well.

 

[AutoSHO]

^^bump^^

 

[Jr's Sho]

I don't know if this will help but I also had the problem of my car having trouble starting and sometimes it will fire up but idle real low until after a few seconds it would raise up to normal rpms. I checked my fuel pressure and got 39 psi and everything looked good. Yet my starting got worse and worse. Finally a high flow pump took care of that. Hope you solve yours though.

 

[AutoSHO]

Jr's Sho:
I don't know if this will help but I also had the problem of my car having trouble starting and sometimes it will fire up but idle real low until after a few seconds it would raise up to normal rpms. I checked my fuel pressure and got 39 psi and everything looked good. Yet my starting got worse and worse. Finally a high flow pump took care of that. Hope you solve yours though.

Thanks for the help. I think that my pump may be allowing a bleed off of pressure back into the tank, but I guess we'll see. Time to start saving for a fuel pump and check valve.