Have a 99 si. Two codes are:

P0172 System running rich
P1457 Evap system leakage

The entire evap system canister (black box) that goes on the firewall is completly gone. There are hoses that are just hanging open and are not connected anywere.

For the running rich code, I changed spark plugs, wires, distributor, checked 02 sensors.

The car does shake at idle once it is warmed up.

ANY IDEAS?


Modified by 99sijet at 3:38 PM 8/2/2008

 

I believe you are not able to properly diagnose the P0172 if there are evap codes present, so I'd say fix the Evap code(s) first by replacing whatever Evap gear you're missing.

Evap systems are not as easy as other stuff to properly diagnose and repair from home. Dealerships have smoke machines, HDS scan tools that can block off and open individual valves along the Evap system, etc.

Start with the basics like installing any missing Evap gear.

I'll look up the flow chart for the P0172 - if it doesn't mention Evap codes at all then I'd start by having a proper valve adjustment. From there it gets trikcy. Fuel pressure, o2 sensors (lazy enough to increase fuel, but not bad enough to throw their oen o2 codes) are the next steps.

I'll be back with more concrete info.

 

OBD2 is picky with the EVAP system. Without it it will richen up things to the point of setting P0172. Especially with hoses dangling, which may be a vacuum leak...
All though P0172 may be due to your O2 sensor getting flaky.

You need the EVAP canister, the two purge solenoids as well as the fuel tank pressure sensor and valve under the tank.
If the canister is ripped out chances are the previous owner ran OBD1, so I'd expect all kinds of little things that will annoy you to get the OBD2 ECU to work again with no CELs.

 

Okay.

I looked up the P0172 and it lists a lot of codes that if are present must first be repaired/cleared in otder to properly diagnose and repair the code P0172.

While there is a code listed that has to do with Evap (code P0441 Evap purge solenoid flow incorrect) it does not list your P1457 code.

If we assume your rich condition is completely unrelated to your Evap pieces missing and Evap system not working right, then the list of possibilities is still pretty long for the P0172 alone.

Fuel pressure regulator
Fuel return line clogged
Fuel injector leaking
Gasoline doesn't meet specs
Primary 02 sensor deteriorated
MAP sensor range/performance
Evap purge control solenoid sticking/leaking
Valve clearance out of spec

Of all those items some of the easiest/quickest/cheapest to diagnose and repair are the valve adjutment and replacing your missing Evap equipment and seeing if the code goes away

How does the engine seem to run though? Does it accelerate well? Other than the low idle are there any other issues to speak of?

 

The car runs fine, but at idle it kind of fluctuates and shakes. Other than that it seems fine. I just had the valves adjusted and everything else seems good.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99sijet &raquo;</TD></TR><TR><TD CLASS="quote">The car runs fine, but at idle it kind of fluctuates and shakes. Other than that it seems fine. I just had the valves adjusted and everything else seems good. </TD></TR></TABLE>

Was the code P0172 there before the valves got adjusted?

 

Yes

 

ANY MORE HELP

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99sijet &raquo;</TD></TR><TR><TD CLASS="quote">ANY MORE HELP</TD></TR></TABLE>

My recommendation is to first fox your obvious Evap system problems, then clear the codes, and see if the P0172 returns.

 

Evap code now gone, but the p0172 running rich code is still there. I had a mechanic check it and he said my o2 sensor is good. What is next?

 

ever fix it? im getting this code, same car.