I recently put a set of long tubes on my ls1 z28 and went to go have the rear 02's, egr, and air deleted from my computer by CDB in Nixa, Missouri. When he ran my computer and had everything I didn't need deleted he ran a scan on the computer once again. I had 3 codes that kept popping back up. When I left I did not have my check engine light on, however after 2 days of driving it popped back on. I am needing help to figure out how to fix these problems and what is causing them.

The codes are as follows:
DTC U1000 Class 2 Communication Malfunction
DTC U1016 Loss of Communications with PCM
DTC U1040 Loss of Class 2 Communications with ABS

The reason I am getting a misfire which is what the computer was telling me is because I am running open long tubes without a y-pipe since I haven't made it up to the shop to get the rest of the exhaust put on yet. I have a digital fuel pressure gauge in my car and it is reading around 65 on average. I heard that the LS1's were suppose to run around 45-53 stock and my motor has very minimal bolt ons. They include a lid, descreen maf, bottom of the air box being cut out, the headers, and a ram III clutch. I didn't think much of this before until my car started smelling like gas a lot and thought I might be getting fuel foul. Pulled the plugs and they all looked fine. I'll finish this problem when I get the exhaust finished up.

The main problem is the loss of communication. I have noticed lately that when I get in my car my trip odometer resets itself and so does the odometer. I drove .5 miles from the gas station to home yesterday. Then 13.4 miles to work. When I left work it read .5 miles again and the odometer was set back. I know this problem will do nothing but cause hellacious problems in the future and could really damage something or cause me to be on down time. Any advice would be greatly appreciated and would help out a lot. I know there is a lot of tuners on here with experience and I need to get these problems fixed.

 

First off the codes are nothing to worry about

Second if you have no cats your car will smell like fuel

Third The maf/o2's will adjust your fueling enough to get you back to stoich or darn close for the most part

I've heard a few threads about people with dying batteries having similar odometer issues as you.

 

i just put in an optima redtop that we used behind the boards at circuit city in the car stereo part...possibly an old battery???

Time for dumb question...how to reset computer yourself to clear these codes to see if this is the problem???

however, why would this cause a loss of communication...and some people on the mofbody.com/forums were telling me that this could create a lot of bad problems for the car...any ideas?

 

PCM reset:

Turn key on, don't start car
Pull PCM BATT and PCM IGN fuses in engine compartment
Wait 5-10 min
Turn ignition off
Replace fuses
Idle will be grumpy until it relearns

My buddy with a '99 had the trip odometer reset, along with the gauges sweeping on start up (there's a TSB on it) - went away after he installed a new battery. Most auto parts stores will load test it free.

 

http://www.hptuners.com/forum/showth...ighlight=u1000

 

changed out the battery and reset the computer...engine light turned off for awhile tonight and the car ran better then ever...and faster then ever...so it was good.

however, when i was holding throttle at 2g's steadily and it started misfiring/backfiring the engine light came right back on...

i think i cleared the other two codes, however the misfire is coming back and i'm going to have it rescanned and see if that is the only code popping up...i'll keep posted if i need more help

 

I basically have the same setup as you (no cats, long tubes), but I get a P0135 and P0155, which is the O2 sensor heater circuit malfunction Bank 1, Sensor 1 and Bank 2, Sensor 1 respectively. I have LS1 Edit, with the rear O2s eliminated and I was wondering if these codes are a problem.

Also, my rear O2s are still connected and in the pipes. If they are eliminated, can you just unplug the connectors and cap the holes?

 

of course.

 

Thanks, any suggestions about the P0135 and P0155 codes?