Bonton

Friends,

I'm continuing to run rich after installing new O2 sensor and working MAF from Roger while my old one is being rebuilt

Symptoms before installing new MAF-stumbling from stop when cold until revs were higher, gassy exhaust. Start-up times pretty consistent hot or cold. Chuggy at low rpms-just off the line it feels like a hog. Sounds like an old '80's t-bird.

Symptoms afer installing loaner MAF-Crisper but stumbling under easy acceraltion when cold, gassy exhaust. Upon cold starts -starts right up like a champ, different than before. When hot - longer start ups for sure. It's chuggy as before until the revs go up then I presume the fuel that is being delivered is more appropriate for the higher revs.

One caveat: I installed an x-pipe and bought an equivalent, standard O2 sensor that I soldered into the existing harness. From the o2 sensore there is one black and two identical whilte wires.

Upon soldering in I marked the white wires and soldered them in using the same configuration as the ones that came out. My sharpie markings came off while I was installing and I'm not 100% sure that the white wires are where they need to be or got accidentally switched...Does this matter?....and why on earth would they not differentialte between the two white wires?

I do not know if the LH has been rebuilt - the car does not die suddenly and doesn't seem to be displaying any other symptoms other than described. I know with LH failure there could be several and/or the O2 sensor being perhaps installed improperly.

Speaking with Rich(?) who rebuilts LH's, if I can get a voltmeter on terminal 24 (I think) I should get 0-7 volts there if it's operating property.

How do I check this? Do I take the harness off? Wont't it not start if I do? OR should I just get her up and reverse the two white wires on the sensor and see what happens?

Thanks, Josh

Bill Ball

If you soldered the wires from the new O2 sensor to a cut off cable end from the old sensor, I don't see how you could have gotten it wrong or why you even had Sharpie marks on the wires. You've got 2 white and one black and that's all there is too it. So, maybe you didn't do it this way. I'm obviously missing something. If you hunt around you can find the correct Bosch O2 sensor for so little money that soldering a generic one is not worth the trouble.

You don't mention checking it, but one of the primary causes of running rich is leaky diaphragms in the fuel dampers and/or fuel pressure regulator. Pull the vacuum lines to each of them and sniff for fuel smell or observe the line for wetness due to fuel. Put a MitiVac or similar on the damper and FPR vacuum ports and verify that they hold vacuum.

Another prime possibility for running rich and hard starts when warmed up is a bad Temp II sensor. If it goes open circuit, the LH and/or EZK interpret that as a cold motor needing enrichment. You check each of the two pins on Temp II versus ground. With a warmed up motor the resistance should be only a few 100 Ohms. The area into which Temp II screws needs to be clean and free of any coating to assure a good ground for the sensor.

These are so well recognized as causes of over rich fueling that I assume you have checked them if you have been in contact with Rich and Roger. They would be checked before MAF replacement as MAF aging doesn't cause fuel enrichment.

Pin 24 on the LH is the O2 sensor input. It's not 0-7 volts and normally you would not test the O2 sensor there. Must be something else. Maybe Rich will pop in and clarify that.

GregBBRD

^^^^^^I think Bill missed your concern about the oxygen sensor.

Either white wire can be hooked to either white wire. It's a heating coil and doesn't care which wire is power and which one is ground.

Other than him missing that little detail about your concern, his advice is right on and you need to check those items.

Bonton

Great,

Thanks Bill and Greg; that's a relief on the O2 sensor; it is a bosch replacement, same sensor just doesn't have the harness with grommet etc. Glad it doesn't matter how it's hooked up. The other culprits that Bill Mentions need to be addressed, I do have a mityvac (just bought) so I'll soon be figuring this out-thanks for the help!

Bonton

Where is Temp II? On top?

MainePorsche

Josh,
Sounds like a Temp II Sensor issue. In the WSM There is a testing procedure for regarding resistances at various temperatures. If you don't have the WSM or the Morehouse CD's you can use this link.

http://www.2010.cannell.co.uk/manual...s_porsche.html

MainePorsche

Temp II Sensor is # 2.

GregBBRD

You need to test for more than vacuum....any leaks will be very small and the canister will be filled with fuel, making a "vacuum test" difficult, at best. Pull off the elbow hose and look inside with a flashlight and mirror. Smell the elbow and see if you can smell any fuel.

Temperature sensor II failures are rare. I can count on one hand how many of these I've seen.

Sometimes the two wires going to temp sender II will be shorted out, due to loom deterioration. That can cause problems.

dr bob

The 'sniff test' for 'running rich', using just the nose, is woefully inadequate. Way too many times, a lean misfire from a vacuum leak, or an ignition problem will seem to the nose to be too rich. It's only because raw fuel is passing through unburned. It takes a whole lot of 'rich' before it's too rich to support combustion.

Start by looking at the plugs to see if they are dark on the insulators. With correct combustion they are a light tan.


Take a look at This Thread for some interesting testers for intake leaks. It's maybe $20 worth of parts last I looked, and you'll need some compressed air via a regulator to do the actual test. You could use a tire pump compressor but it makes it hard to hear leaks while it's running. The thread was intended to help the supercharger guys, but the unit works on NA cars just as well.

If you haven't yet replaced the rubber hoses and connections under the intake manifold, you are probably due. The hoses include those connected to the breathers on the cam covers, the ISV (Idle Stabilizer Valve) connections around the throttle, and all the small-diameter vacuum hoses for the flappy valve, and the vacuum connections to the intake for fuel pressure regulator and dampers, plus the auto trans modulator. The whole mess ends up with oil inside from the breather system, and the hoses get tired and split. That project includes cleaning or replacing the fuel injectors so a weak one or eight will get 'cured' on the way.

dr bob

Reread th whole thread: The oxy sensor is 0 to maybe 1 volt. I suspect that the "7 Volts" is supposed to be 0.7 Volts from the sensor. Watch it with a good analog meter or oscilloscope if you can, as a digital meter doesn't sample and update as fast as the mixture changes. Probably OK for an at-idle measurement though.