THIS POST IS NOW EDITED TO REFLECT THE CORRECT INFO...

ok, so I've been commuting over 200 miles daily lately, and my car is not liking it, I guess...
Well, I got this car with many problems, and I am still trying to sort them out. First there was a long fight with the Optispark and all the related things. Then I found out that this car has a gutted catalytic converter. The car has been running fine throughout the summer (about 5000 miles), although it had this strange strong vibration going 45-55 mph in O/D at low throttle. My guess was that the turbulence caused by the gutted cat was causing the car shake... but why would that not happen in any other gear???
Now, I got two problems - that may or may not be related...

1 - The car starts, reaches 1000-1500 rpms or so, and instantly dies, within 1second. After doing it over and over about a dozen times, I can get it started, and then it runs like it has been. As soon as it is turned off, cold or hot, it becomes very hard to restart... Only started happenning today, but happened all day long... After reading THIS I found out that PCM starts up in open loop mode, using ECT, MAP and MAF but no O2 sensors...
2 - A few times, at different speeds, my speedometer needle started jumping up and down... It is controlled by the signal from a VSS, so what does such behavior mean?

so far I had some good suggestions:
-check the grounds
-check the MAF
-check TPS voltage
-replace ignition switch on the bottom of the steering column(?)
-i hope its not my PCM itself

 

Your theory on how the O2 sensor works is totally wrong. The O2 sensor looks at the % of oxygen in the exhaust and does not care how much exhaust goes by it. A rich fuel mix does not cause knocking, but a lean mixture might. A bad O2 sensor can make he fuel mix go rich because it is giving erroneous data to the PCM. The car has two O2 sensors, one in each exhaust manifold, and if you are going to change only one, you need to know which one is in trouble. The rich condition can also be due to a bad temp sensor,IAT or ECT, bad fuel pressure regulator, stuck or leaky injector, dirty or bad MAF, dirty air filter. Is the check engine lite lit? If it is get the car scanned and go after those problems first. Also take a good look at the ignition system, such as the ignition module, ignition coil, Optispark and all connecting wires and plugs.

 

I just edited the original post...

how could i check iat or ect? maf was cleaned with alcohol in April, and i just cleaned my k&n

 

It easily done with a scanner. Scan the engine while it is still cold andboth sensors should report the ambient airtemp. When the engine is hot you can compare the reading on the temp gage and the ECT sensor, they should be close. The IAT is a little harder to do when the engine is hot because there no easy way to check the temp of the air in the intake pipe, but if it gives ridiculous readings you know it lost its mind. It can also be done with an Ohmmeter, by removing the sensors andpacing them in a pot of water with a thermometer, measuring the resistor of the sensor as the water is heated and see if the resistance tracks with the chart.

 

So, today I dinked around with a few things:

1 - cleaned the PCM Grounds that are on the coil and my spaced-off ICM
2 - checked both important Temp Sensors, ECT and IAT, as per directions on shbox,
the sensors were ok (0.004 ohms on 2M scale), the harness was ok too (at 5v, no shorts)
3 - tested IAC ok, coil A-B is at 50.0v and coil C-D is at 49.8v
4 - pulled MAF Sensor, it looked ok, I wiped it off with a qtip anyway, dunno how to test it...

so, all the above things checked out ok and can be ruled out for now, in my humble opinion...

5 - finally, I pulled the MAP Valve from the LHS of intake, and it was all gunked up with oil, the rubber gromet is quite squished, and the harness connector is also soaked in oil, indicating that its leaking a tiny bit somewhere... The PCV looks like its leaking a little too, but the PCV was replaced 6 months ago... MAP is kinda concerning here, as, correct me if I am wrong, it is supposed to adjust timing and fuel depending on load conditions based on vacuum iside of the manifold... I found one for $40 at autozone that I can get tomorrow maybe...

6 - I also pulled plugs 1 & 3 from RHS and 4 & 6 from LHS, pix are below:





I also have a few things planned for tomorrow:

- can try starting with a pedal all the way down to the floor
- test the fuel pressure, to check for bad FPR or leaking Injectors
- check the Battery voltage and connectors, as I messed with them recently
- maybe I can look for the rest of the Grounds
- maybe it could be that remote ignition switch on the bottom of the steering column
- someone suggested checking TPS voltage also
and sooner rather than later, I will replace both o2 sesors and put a resonator or a straight pipe instead of the gutted cat...

* * *

Here are 3 of my Datamster .UNI files, two of them (from 11-05) were recorded when the car had no starting issues yet, but wasnt running too good either, and the last file (from 11-16) is from the day when the hard starts started happenning... If you want to view them, you will need the DM35xEE module of TTL Datamster scanner program...

http://www.mediafire.com/?doiamworn4a = 11-05 EUGENE1
http://www.mediafire.com/?4vjrybbnlzt = 11-05 EUGENE2
http://www.mediafire.com/?6fzvyzdtymw = 11-16 HARD-START



*edit: I watched the Datamaster files, and noticed some things:

- it outputs 12.7-13.1 volts running, isn't that kinda low? yet it still seems to charge ok
- the MAP kpa jump up for no reason at 1800 rpm or so, from 18 kpa anywhere to 92 kpa...
- the car apparantly runs 201-209 degrees F when warmed up, isnt it kinda hot?
- by the way, the heater inside is prettyweak warm, but I though that was the heater core

A big thanks to everyone for your time and expertise!!!

 

On a start the MAP sensor is in control, the PCM refers to it and the temp sensors for the right AF mixture. The running temp is fine, that is how GM designed it. The running voltage should be up around 13.8 Volt but it is not low enough to cause problems. The MAP reading shows a sudden loss of vacuum, as if the throttle was suddenly opened fully.

 

well, I just went and checked the Fuel Pressure, as the car cranks and starts, it goes up to about 48 psi, then, as the car immediately dies, it drops down to 34 psi and stays there - I watched it for2minutes and it did not move a bit... so, I say, the fuel system can be rulled out at this point as well...

I am off to the store to get a MAP and PCV and I will post what happens then...

 

so, its not the MAP Sensor, as I replaced that today with no results...

when I installed the MAPS and it didn't start, I tried cranking it over and over again, but this time, not every crank would result in a "start", sometimes it would only click, like with a dead battery or bad connection... however, the battery reads 12v and its an optima... So, I replaced the Battery Terminals, as I wanted to convert to the top mount ones anyway... Still no change though... I noticed that the power wires had considerable amount of corrosion inside, but I dont think thats enough to actually cause the car to die...

It is definitely something electrical... like that remote ignition switch on the steering column or something of that nature... also, where are the rest of Grounds are connected??? any other ideas???

 

and so it turned out to be the Remote Ignition Switch Module located on the top center of the steering column... it was all burnt up, and was a ***** to get to... now I am back to my other problems... continued here:https://camaroforums.com/m_134485/tm.htm

 

I had this same problem for about 2 months, I finally got it to quit when I replaced my ignition switch. I was really fed up with it, almost sold the dang thing. That should fix your problem.