951 emissions please help

[Briguy280Z]

86 951 90kmiles

First time this car failed a emissions test. The car doesnt have any modifications, runs good and doesnt smoke.

Emissions test results
836RPM
12.6%CO2
0.0%O2
HC(PPM)
120max 270GP 193Measured
CO(%)
1.0Max 2.50GP 3.51Measured

2517
13.9%CO2
0.1%O2
HC(PPM)
150max 300GP 55Measured
CO(%)
1.2Max 2.70GP 1.26Measured

Used the test proceedure on this site for the O2 sensor. Measured the change of voltage wile running. Starts at .475v and increased but after 30 seconds the O2 voltage starts flipping out drops to 0 and fluctuates between 0 to .9v very quickly not sure what to do but i replaced the sensor with a new generic sensor. Cripped on a new and continues to do the same thing. Some times when starting it in warm temperature the car hesitates on start up. Apply gas and doesnt want to move. After turning on the headlights on and then off the engine runs normally. not sure what to do.

Any suggestions not sure what to look at next
Need help please!!

Brian Griffin

[IanS]

Since no one has any suggestions, I'll give it a shot.

First, your 02 sensor is supposed to flip back and forth quickly in closed loop mode, so I doubt thats your problem.

Have you pressure tested the intake? Given the age of the car, it probably has leaks, and that won't help your emissions. It would also explain your hesitation. I'd vacuum test your FPR, fuel damper, and bypass valve as well if you can.

The other thing to check, since you're high on all the measurements, is whether you're getting misfires. Do you have the good copper plugs with good wires and a good cap and rotor?

-Ian

[AaronM]

The engine is running rich. Very rich actually. Your O2 percentage should be between 0.5 and 1.0 if you have a proper mixture. Lower O2 means that you're running rich.

I think you probably have a vacuum leak somewhere that is causing the car to meter wrong. A leaky injector is also a possibility.

[nize]

things to check;
1) are your plugs new? what brand/model are they?
2) are your plug wires new?
3) what's the condition of the distributor cap and rotor?
4) when were the injectors last cleaned?

you can have the injectors flow-matched and cleaned here;
http://www.witchhunter.com/

[AaronM]

Originally posted by nize
things to check;
1) are your plugs new? what brand/model are they?
2) are your plug wires new?
3) what's the condition of the distributor cap and rotor?
4) when were the injectors last cleaned?

you can have the injectors flow-matched and cleaned here;
http://www.witchhunter.com/

The symptoms don't match anything to do with plugs. If the plugs were the problem, there'd be stumbling, etc.

The car's running rich, all the O2 in the combustion chamber is being used up before the fuel is and the excess HC, CO, and CO2 is being spit out the tailpipe. The readings that he posted are 100% consistant with a rich condition.

[Briguy280Z]

Things i haven't checked (smaller list)
-Fuel Pressure Regulator
-Fuel Damper
-Coil
-Air Meter (don't plan on touching eather)

Bosch Platnum Plugs with Clewett Engineering Wires
-Checked plugs look in really good condition
-Wires i found that two were loose i removed a rubber seal inside the wire and now have a positive connection. Engine runs better no hesitation, could this have fixed the problem??

New Distributer cap and rotor

Rebuilt the injectors with new seals and cleaned the injector itself none leaking

O2 runs around .6 and .8 so i guess its good

Replaced bypass valve, TPS, O2 rebuilt the whole vaccum system with tee connectors and elbows. Replaced cycling valve, cleaned idle stablizer adjusted idle. Replaced heater valve. Complete head job doesn't burn any oil, replaced turbo from a >30k mile car.

One thing i have had trouble is that the exhaust manifold keeps leaking!!

Should of's
Replaced all the hydrolic lifters wile head was off-Errrr

[nize]

bosch platinum plugs are a scam. replace them immediately with the ngk BPR7ES, more details here;
http://forums.pelicanparts.com/showthread.php?s=&threadid=231731&highlight=ngk+pl atinum

clewett engineering's wires are good, but not the first version. a local 951 owner had the first ones, and broke the connection at the spark plug boot. he contacted clewett and received the version2 plug wires for no charge. make sure you have the version2 wires for a solid connection.

how did you 'rebuild' the injectors? the stock bosch injectors are a sealed unit and not rebuild-able. and how did you clean them?

[IanS]

Agreed, change back to copper plugs, either stock or 1 heat range colder(ie: BPR7ES).

The fact that your numbers are worse at idle still makes me think you have a vacuum leak of some sort.

[Briguy280Z]

Rebuilding the injectors is no more than replaceing the caps and seals on the outside.

The proceedure i used to clean the injector was to use a 12 volt source and actuate the injector wile carborator fuid was forced down the tube after a few flushings i hooked it to the car and verified that it sprayed with an even mist

noticed a lot better flow and even spray afterwards.

I'll get those plugs tomarrow and install them. I never replace the plugs my father gave me the car about 3 years ago.

I'll check the vaccum lines again but i don't think there is a problem...thanks for all your help fellas

[nize]

you may have actually made the injectors worse if you cleaned them yourself. the most important thing is that all four of them are flow-matched. if one is flowing more than the others you can have a 'too rich' condition in one cylinder, which the o2 sensor detects, which leans out the 'normal' injectors, which leads to all sorts of other problems.

[AaronM]

Originally posted by IanS
Agreed, change back to copper plugs, either stock or 1 heat range colder(ie: BPR7ES).

Stock heat range is 7. One range colder would be BRP6ES for NGK or WR6DC for Bosch.

[AaronM]

Originally posted by Briguy280Z
O2 runs around .6 and .8 so i guess its good

Not in the numbers you posted...

You posted emissions readings with O2 at 0.0% at idle and 0.1% at speed.

Which is it?

Emissions test results
836RPM
12.6%CO2
0.0%O2
HC(PPM)
120max 270GP 193Measured
CO(%)
1.0Max 2.50GP 3.51Measured

2517
13.9%CO2
0.1%O2
HC(PPM)
150max 300GP 55Measured
CO(%)
1.2Max 2.70GP 1.26Measured

It just smacks of a vacuum leak or an improper connection somewhere.

[Briguy280Z]

I think you might of missunderstood that O2 sensor runs at .6volts to .8 volts when its closed loop with a multimeter. Sorry about the miss communication.

I am going to change the plugs today with the BPR7ES and take it to the smog station and have a precheck. I feel pretty confident that its running much better now that i fixed the plug wires.

I'll see later to day and let you know how it goes

Thanks again

[AaronM]

Originally posted by Briguy280Z
I think you might of missunderstood that O2 sensor runs at .6volts to .8 volts when its closed loop with a multimeter. Sorry about the miss communication.

I am going to change the plugs today with the BPR7ES and take it to the smog station and have a precheck. I feel pretty confident that its running much better now that i fixed the plug wires.

I'll see later to day and let you know how it goes

Thanks again

I still say that your problem is that it's running rich. The incredibly low O2 percentages and high HC indicate that the oxygen is being used up before the burn is complete, which means there's too much fuel.

For it to have been the plugs, you'd need BOTH the HC and the O2 to be high.

[Briguy280Z]

Changed the plugs and made sure the wires were tight and here are the results


Emissions test results
830RPM
14.9%CO2
0.1%O2
HC(PPM)
120max 270GP 35 Measured
CO(%)
1.0Max 2.50GP 0.11 Measured

2544
14.8%CO2
0.1%O2
HC(PPM)
150max 300GP 7 Measured
CO(%)
1.2Max 2.70GP .14 Measured

I was floored and thanks for all your help just some stupid spark plug wires. I did feel a difference when i changed to the NCR plugs, pulls harder at the top end.

Thanks again

[nize]

grats!

[IanS]

Wow, those are actually some really good emissions results for a 951.

Congratulations!