I was on my way to work and saw a possible smokey sittin with his trusty radar. I looked down to check my speed an lo and behold I was doing 17mph!!! The only problem with this is I was really doing about 45.
I accelerated/braked and the speed didn't change on the display.
I hit the english/metric button and nothing changed (except the temp display on the A/C)
I tried to get fuel info and couldn't
I tried to see trip info and couldn't

Then......everything started working like normal.

I didn't have time or think about wether the tach was working or not.

I have been having intermittent rich condition that seems like it isn't so intermittent any more...but can't seem to diagnose the problem.

Are these two things related? Could the ECM be at fault for both?

I did discover that one of the two grounds for the ECM was hanging loose under the car ( the one on the bellhousing ) It could have been this way for quite a while. Could this have damaged the ECM even though one of the grounds was still good?

I just bought this car ('96 CE LT4) and haven't been able to get it right

 

That shouldnt have damaged the ECM with the loose grounds, tighten them up, check all the other related connections, check the 4 ECM plugs, and see what you come up with there (is or has the Service Engine soon light been on besides first startup?)

 

I've checked all of the connections to the ecm and as far as I can tell they are fine--no corrosion, moisture or foreign material of any kind.

The MIL comes on and stays on when I start and drive the car. When I clear the codes ( P0152, P0132 ) They will normaly return as soon as the car finishes the warm up cycle. Sometimes, if I drive the car hard, they will not return for longer periods of time.

 

Ok, so its happening when the car goes into closed loop.

P0132 is O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
P0152 is O2 Sensor Circuit High Voltage (Bank 2 Sensor 1)

Does the car blow any smoke? These codes indicate an issue with both the primary O2 sensors (left and right). High voltage indicates rich assuming the sensors are working.

Do you know if this car is stock or modified?
Has it ever had the tune adjusted?
Does it run poorly when cold (open loop) as well as warmed up (closed loop) or only when in closed loop??

Check the fuel pressure regulator to make sure that its not leaking through the vacuum line, and check to see that it is a stock regulator and not an adjustable one, if it is adjustable, you should check the pressure and make sure its at or around the stock setting.

Also try unplugging the MAF sensor, the car will run in speed density mode, if this improves it, try cleaning the MAF sensor.

 

Thanks for the very good information--

The car runs just fine--no smoke at any time
I did replace one O2 sensor (with A/C part)
I have replaced the MAF
The car is modified and tuned by PCMforless
The car runs fine--just annoying check engine light
The fuel press. regulator is adjustable--no leaks--set at 45psi

I haven't pulled the injectors yet to see if any are leaking
I have spoken with Bryan @ PCMforless and we are going over
various parameters that I can pull with my digimoto software.
Right now I am supposed to get the long term fuel trims and
report them back to Bryan.

I am about to forcibly remove all of my hair

 

Ok, 45psi you say? Is this at idle? Have you tried knocking a couple psi off that? The injectors in an LT4 are 28 lb/hr as it is, which should be big enough without uping the fuel pressure.

By increasing the pressure the injectors flow more than the ECM thinks they are flowing and that is a problem.