the car is turning off when I decelerate, then is hard to start, the revs goes up and down fast as I try to keep the engine runnin with gas, it has backfires

this happens only when the car is "hot"

So I took the car to pep boys and 3 days later they told me to take the car to a local GM..here is the data that they had when they scanned the car
1995 LT1
Z28 m/6

vt-100 Live Data----
RPM 0 left int _128 right int_128

16 Low resolution pulse failure
42 est grounded
36 High resolution pulse failure
48 mass air flow system failure
33 map sensor or circuit too high

open/clsd loop open coolant F173
left 02s(mv) 752 right 02s(810)
left blm 128 right blm 128
a/f learned ..no ft cell --0
tps(v) 0.58 throttole%-0
left bpw (ms) 0.0 right (ms) 0.0
airflow (gm/sec) 0 IAC position 101
coolant 173'' mat(f)104
Fan 1 no fan 2 no
map(KPA) 103 map (V) 5.00
baro (kpa) 103 baro(V)5.00
knock no knock retard 0
spark adv 0 ignition 12.3
ccp duty cycle 0 egr duty(%) 0
time 0.00 desired idle 3188

the guy told me that the computer looks to be bad?

 

this is anothe info that I was able to take home

RPM 5005 left int 128 right int 128
code and data ok to drive
42 est grounded
36 high resolution pulse failure
33 map sensor or circuit too high

open/clsd loop .. open coolant 126''
left 02s (MV) 960 right 02s(MV) 159
left blm 128 right blm 128
a/f learned no ft cell 16
tps(v) 0.58 throttole(%) 0
left bpw (ms) 1.3 right bpw (ms) 4.4
airflow (gm/sec) 2 IAC position 10
coolant 126'' mat (f) 107
fan 1 requested yes fan 2 requested yes
map (kpa) 103 map (v) 5.00
BARO (KPA) 103 BARO (V) 5.02
knock NO knock retard 0
spark adv 21 ignition 11.1
ccp duty cycle 0 egr duty % 0
time 1:14 desire idle 800

 

Hello,

I've just returned from having a computer diagnostic on my 1994 Camaro. One of the reported problems was Low Resolution Pulse Failure. I did a search on Google and found your post at the CamaroZ28 forum, but no other hits for this search string.

Were you able find a solution to this problem? How is this fixed?

Reese

 

The low res pulse from the Optispark is, in effect, the cam position signal. The engine will not run without it, because it is required to time the sequential fuel injector pulses. When the PCM does not "see" the low res signal for two crank revs, it shuts down the fuel pump and injectors. It is not unusual to get a DTC 16 in a scan. If the engine is actually running, it is a "stored" code, indicating a past problem. Many of the problems you report can be related to poor signals for high and low resolution pulses from the Opti. Could be a failing optical sensor (heat affected) or it could be corroded teminals in the harness connectors. You need to check the harnesses first. Could also be related to a grouding problem with the ignition control module (ICM)... this can also be sensitive to heat, since it is mounted directly to the drivers side head.

The MAF sensor could also be a connector problem, a power supply problem, or a faulty sensor. You only have 2gps flow in that 2nd set of scan data.... that is way too low a reading at idle.

Your MAP sensor is totally fubar... it isn't working at all. The PCM is seeing 5V from it whether the engine is running or not. Again, not unusual for the harness connector to crack and cause problems in this area.

I doubt it is a "faulty computer".... that just means they don't really understand the data they are looking at.

In general, a single "frame" of data isn't very useful. The first data set is for the engine not running, so it doesn't tell you a whole lot. The second one, it appears to be running, and that's where the bad MAF and MAP data show up.

 

I totally agree with fred, first set doesn't do much and the second set is not much insight,The second set says the engine is at 5005 rpms and the throttle is closed? Sounds like a vaccum leak possibly cuasing the idle problem. A large Vaccum leak will cause a low map reading,low AFGS reading and will cause the car to idle poorly,(idle hunting) the car would probably surge up in rpms till it hits the fuel cutoff rpm and then die, when the rpms come down enough to add fuel it does it again. And it sounds like the opti is crapping out on ya to boot. After looking at your data the last thing I would point the finger at would be the PCM,it seem to be a standard dealer fix for anything they can't find. Good luck and let us know what ya find.

 

My car has had somewhat similar symptoms. I've posted it elsewhere both on the LT1 edit list and the National Fbody list. The thing that blows my mind is that the SES light won't go away , no matter what I do (PCMCOMM.EXE ses reset, Datamaster reset, PCM BATT fuse disconnect, etc) and the same "desired idle" value of 3,188 rpm like this original poster said. I've never seen that before. I just now googled "desired idle 3188" and got this thread. Apparently, it's a default of sorts. I'd checked everything I could think of and finally bit the bullet and bought a new PCM. As you suspected, no change...
Phark... Do any of you have anyother suggestions?

 

Well, it the great *Wilson* tradition, I replaced the PCM only to find....
THAT'S NOT THE PROBLEM.
Grrr.... I'm inspecting the wire bundle that cascades down the passenger fender well carrying the wires for the Right O2 sensor, starter, PCM Ground and Knock Sensor. I had that same place go bad on my '96 Z28 with the same Hooker Long Tube headers. I did a preliminary look and feel and the wires were definitely exposed/touching the primary. I'll verify if they are burned or not tomorrow. It's going to be a low of 7, a high of 23 degrees tomorrow and, no, I don't have a garage....