Failed Emissions with over 2x the limit of HC's

Did a couple of datalogs driving through town and on the high way
All of my BLM cells were at or around 108.

Even after I flashed the stock PCM settings and re-logged everything. Same result. (Thought maybe my self-tuning was making run rich perhaps, wanted it to be stock again until I get this fixed)

From my understanding, correct me if I am wrong, that's when the O2's say the engine is running rich over a period of time and the PCM adjusts the pulse width of the injectors to lean it out to get the Int values avg. out to 128. ??

My Int values averaged out to be around 128, jumping from 123 up to 133 throughout the logs.

My O2's voltage after warming up were jumping from .1 to .9 volts. Appears to be okay right?

But I am still smelling fuel when I start up and running rich.
All my plugs on my driver's side were fouled, only had 10K miles on them (ac delcos) got them replaced with ac double plats. Those quickly fouled up too.

Check fuel pressure with engine off. Goes to 43, but quickly drains back down to close to zero. Guess that's why my engine doesn't start right up and I have to sort of "prime" it with the key.

Fuel pressure does stay stable with the car running though.

Fuel pump was replaced with an O.E. one 2 months ago or so.

The fuel regulator was old, and smelled of fuel. Replaced. Check it the new one out. Working. Pulls 5-8 lbs off of 43 when idling and goes back up to 43 with no vacuum.

I'm running Taylor Wires, pretty new, 10k miles on them. No burns or leakage out of them.

No codes thrown

No vacuum leaks

Check the coil out, ShoeBox's site said around 8500 ohms, it was 11k+ so I just went ahead a threw a MSD coil in there. No improvement in the richess, seems like throttle response is a little better, but that could just be me.

No leaky injectors

All injectors fire

Injectors ohm'd out to be around 12-13 ohms a piece.

No misfires or backfires, engine "seems" to be running strong at WOT and at normal driving conditions.

Just did an oil change 3 weeks ago.

Cat converter is only 2 years old. Magnaflow High flow direct fit replacement

Cleaned the MAF

Ran Seafoam throughout 1 tank of gas...couple tanks later Lucas Injector cleaner. No improvement.

Things I haven't done yet:

Check fuel pressure at WOT

Do the injector pressure down test to see if each injector drops fuel pressure the same. (hard to do when the fuel pressure won't stay at 43 with the engine off)

Pull the plugs on the pass. side. (about to in just a bit)

Check out the Opti or ICM

Compression test on all 8 cylinders. (Did one, it was 120lbs on the number 3 cylinder)

Full check out the EVAP or EGR System.. Wouldn't think EGR would make me run so rich though??
Couldn't smell any fuel near the rear driver fender



Any advice will be awesome. I've been searching these and several other forums for the past 2 weeks on getting this fixed.

Thanks for taking your time to read through my mess and issues.

 

I just had a similar problem with running rich and hard to start it turned out to be the connector for the coolant temp sensor. you can do tests for the sensor and the wiring. they are on shoebox site. For my problem both tests showed that everything was working ok when i changed my connector the problem was fixed.

I scanned with freescan no codes were thrown but coolant temp was reading -40

 

My logs show normal temps, but i'll double check the connector and ohms it out and see.

Thank you!

Update:

Check it out, pcm was sending 5v to the sensor and the sensor omh'd out to the correct temp range.


Also checked fuel pressure at WOT.
Isn't suppose to go back up to 43 lbs? If I hit my throttle fast, it will go up to 43 and go back down before I let off.

If I go into the throttle and hold at WOT it stays at around 33lbs.

Passenger side plugs are fouled also.

And after running my car through several WOT, I took of the oil cap and white smoke was coming out?

 

What you have written is contradictory.

Since the 2 don't agree, I suggest you change the plugs and unplug one of the O2s. Then see how it runs for a while and then check the plugs. If the engine runs good and the plugs are then cleaner, change the O2s.

Incidentally, my GM's never like Bosch sensors. Stick with either GM, AC Delco or the company that makes them for GM, Standard.

 

Alright will do hopefully tomorrow (if I have time) or by the latest, this Sunday.

Thanks for the input!

Is Delphi's O2s okay to put in? (Something tells me Delphi is related/is a GM product)

 

Yes, GM spun off Delphi as an independant company about 10 years ago, and they took a lot of AC Delco parts with them. Delphi went bankrupt, recovered, and started changing the product names from AC Delco to Delphi. Then a while back, GM repurchased controlling interest in Delphi. I would assume the AC Delco and Delphi parts are the same. The design of the O2 sensors (at least the outer metal shield) has changed over the years, but everyone seems to get the best results with the AC Delco/Delphi parts.

 

Delphi makes their own oxygen sensors.

I've heard several times on here that SMP makes GM OEM sensors but I've found no evidence of that in the marketplace. How can one tell?

I've only ever had good luck with AC Delco / Delphi parts. Bosch gave the strangest performance. I put NTK O2 Sensors in my wife's formula but got rid of it before being able to learn anything...

 

What do you mean by bosch sensors giving strange performance, I've seen the same basic statements a few times on threads where people say they're vehicles don't take well to bosch sensors but I don't know what exactly they're referring to, only reason for questioning is because I have bosch sensors and would like to know. thanks.

 

Several times when running scans the values would freeze at 450 mv instead of fluctuating as normal. At the time my car was emissons legal and I always had high HC levels. Changing to AC Delco sensors solved the high HC level and the readings were more normal. Maybe I got a bad pair of sensors but others, as you've mentioned, have reported 'weird' results as well. I stay away from all their engine products, plugs, wires and sensors....

 

One can tell when one goes to the schools put on through the auto parts suppliers sponsored and taught by Standard. Where they tell you, "We(Standard) make the sensors for many OEMs including GM and it's affiliates". I've attended 3 and every time, they've said that.

 

A long time friend, Snap-on dealer and long time mechanic at a F--d dealer told me this about aftermarket sensors.

They make as few sensors as possible to get manufacturing profit from them. As such, they are made to operate at just slightly different ranges to fit the requirements of as many different units as possible. Some operate outside the tight tolerances of OEM requirements. Either that or the ones I bought were defective.

 

Thanks...