Ok, I have been fighting with this problem for weeks now talking to several people and I can't seem to find and resolution. Maybe someone can help. I have a 97 Z-28 with a 383 Stroker, ATI Pro-Charger running 12lbs of boost, 50# injectors, OBDI conversion done by Bryan Herter from PCMforLESS along with tune. Other specs in the profile. Now the problem: the left bank O2 is constantly reading around 200mV. The right bank is reading around 900mV. The O2s are constantly loading up and failing. It has recently also started dumping fuel into the cylinders and fouling plugs. Now, what I have done to try and fix it: Replaced the O2s atleast 12 times. checked the continuity from the O2 connectors to the computer. Checked the impedance of each injector which read 12ohms. Put a noid on each injector plug and checked for firing. Pulled the fuel rails with injectors and pressurized the fuel system, no drips from any injector. Did a compression test on each cylinder, not one was under 170. Replaced the coolant tempature sensor on the water pump. Replaced my plug wires with MSD wires and replaced my plugs several times. If anyone has any ideas please let me know. Your help is greatly appreciated.

http://mywebpages.comcast.net/orionspl/ssss.jpg

 

Explain exactly how the car is acting. Is it running correctly? Low rpms, wide open throttle, part thottle, idle? How about your MAF sensor...is it stock or ported? Where is it mounted...before or after the blower? Did you check to see if there is any leaks in the piping from the supercharger to the intercooler to the throttle body? I am not sure but I thought the limits of the stock PCM on injectors was like 42lbs/hr. Did you talk with Bryan Herter to see if it could be a tuning problem? How about the knock sensor...what is it reading? Is it hooked up? Sometimes that can cause these issues. Just shooting out ideas. Any answers to these questions could help me diagnose the problem.

Matt

 

The stock PCM is capped by the impeadance of the injector not size but usually 50's are max

 

Hey Matt. Thanks for the reply. First. I don't think it's a leak in any of the tubes from the Procharger output to the intercoolers to the TB. When I first set it up I forgot to tighten the clamp on the blow-off valve and when the hose "blew-off it wouldn't even idle. The car just shut off. You could keep it barely running by keeping it at almost half throttle. Also, when I get into when it does run I do see 12lbs of boost which I don't think I would if there was a leak.

It seems to idle fine and when you initially start driving it, it seems fine at first. Then as the O2s load up it oif course starts stumbling at around 1500 RPMs all the way up. When this happens if you go WOT it will stumble bad hesistate stumble and then kick in (it will stumble for a few seconds).

I don't know how familiar you are with the D1-SC kit. But the MAF mounts in the corner on the intake piping before the supercharger. It is a stock MAF without screens.

http://mywebpages.comcast.net/orionspl/twinint1.jpg


I have been working with Bryan and he wanted me to check wiring to the O2s which I did. He tuned the PCM for 50# injectors which is the highest you can use without going to low impedance and needing to change out the computer. However, if you do use 50lbs injectors he said to use an OBD1 conversion. The OBDII has trouble with MAF and the blower and the injectors burn up the resistor packs for them in the PCM. So I went with the OBD1 conversion.

I haven't checked the knock sensor but I am getting a count through datamaster. Not sure what I should be looking for.

 

Have you checked for a couple of crossed plug wires. If you have, check again.

 

The spark plug wires are all completely covered in split loom from the opti to the plugs and the at the ends have fiberglass heat boots.

 

So it runs fine when its cold but once it gets warm or in open loop it starts to run crappy? What happens to your timing when it stumbles? Do you have a boost retard for your timing so that your timing retards when you get boost? What kind of ignition do you have ...also what plugs do you have? Have you tried to swap PCM's and/or disconnect the blower? Do you know what your BLM's are doing? If you reset the PCM does it run better at first? I might have some time to come check it out on Sat afternoon if you are free.

Matt

 

I meant accidently having two wires or so swapped around and installed on the wrong plugs. It can be a PITA to read the #s on the opti sometimes and correspond them to the right cylinders. I had the exact same problem a while back and I knew for sure that they were installed right...guess what, they were'nt.