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

 

Probably not a good choice of cleaners. The zirconium membrane inside the metal housing is fragile. That's why they put the housing around it. Carb cleaner is extremely harsh, and is not even recommended for throttle bodies. Was the carb cleaner marked "sensor safe"? If not, you shouldn't have used it.
Makes no sense at all. The O2 sensor is located before the cat, so whether the cat is there or not there, it will not affect the O2 sensors, as long as there isn't a huge open hole to the outside a few inches past the sensor. While eliminating the cat may produce a small increase in exhaust flow, which improves volumetric efficiency and puts more fresh air in the combustion chamber, that increased air flow has been measured by the MAF, and the PCM has added exactly the correct amount of additional fuel. In the event it missed on the fuel calculation, the whole purpose of the O2 sensor is to "see" the excess, unburned air, and tell the PCM to add the extra fuel using the long term fuel corrections.

When an engine runs rich, it reduces the tendancy to knock (detonate), doesn't increase it. But your engine isn't running rich because "the oxygen sensor is getting too much air". How bad is it knocking? Why didn't you mention that as one of the problems?

Replacing the cat will not solve your problems, because it isn't causing your problems.

Do you mean move the O2 sensors closer to the engine? Why? Your 95 has 4-wire heated sensors. You keep mentioning "sensor" (singular).... you are aware that there is a pre-cat O2 sensor for each bank of the engine? Have you checked both of them?

What tells you this.... the BLM's? Which cells/banks are above 128?

Have you checked the fuel pressure, at any time during all these problems? Have your scans ever indicated any trouble codes at all?

Vehicle speed sensor (VSS) on the tailshaft of the tranny sends a signal to the PCM. The PCM calculates the speed, based on the tire diameter and rear axle ratio, and send an electronic signal to the speedo. There is no cable. Sounds like either a faulty VSS sensor, or a bad ground. All your problems may relate to bad grounds for the engine and PCM.

 

Hey, thanx for some good ideas man...

I will start by checking the grounds... but why would it still run OK when started up??? i guess there is still that jumping speedometer problem though... So I will check the grounds, I wunder if the SHBOX site has some diagrams, will go look in a second... cant scan it during start, as it takes a minute for the laptop to establish communication with the pcm...

I will also check the fuel pressure, but I dont think thats it... can I adjust the pressure down somehow and will it help with running rich?

Now, Datamaster shows TWO o2 sensors, but when I took my Y-pipe off a while back in April, I think I remember only one... Will have to double check today... As far as "moving" the sensor(s), I've read that some people use sparkplug non-foulers to move the o2 further out of the airstream, but I think thats only used for cars with the downstream sensors, so I dont think that will work for me.

As far as "knocking" - I dunno what it is really, its just the car vibrates more than it should, and has a very strong vibration at 45-55 mph in 4th gear (AT) and low throttle... before my friend talked to me, I suspected that could be caused by the turbulence inside of the gutted cat, and so eventually I will either replace it with a resonator or a straight pipe... Knock count is shown as 14278, but I have no idea what that means...

Last night I found some great info about how the PCM works HERE. In a nutshell, according to the guy, when the car starts first, the PCM is functioning in an Open-Loop, only using ECT, MAP, and MAF, because cold O2 sensors dont work well. After a few minutes, the PCM switches into a Closed-Loop mode, using MAF and O2 sensors. So, my start-die situation is probably not affected by the O2 (although I still want to figure those out)... <== any ideas as to WHAT is causing the car to die right away?

Datamsater has a hitstogram of RMP vs Mass Airflow, and each cell can be a different color, depending on rich or lean... I can see Right or Left o2 sensor, and Long or Short Term vs Airflow... All long term cells are bright red, indicating a Rich condition, however short term, it fluctuates all over the place, from lean to rich. Also, Datamaster shows a few ransom codes, but they only pop up for a second and go away, and none seem to be related to anything...

Also, it shows Long Term (BLM) Averages all in red:

cell 02 ==> LBLM=108.0 , RBLM=113.1
cell 05 ==> LBLM=108.2 , RBLM=114.8
cell 06 ==> LBLM=108.0 , RBLM=111.0
cell 07 ==> LBLM=108.1 , RBLM=115.0
cell 09 ==> LBLM=121.0 , RBLM=120.0
cell 10 ==> LBLM=109.3 , RBLM=114.1
cell 11 ==> LBLM=109.8 , RBLM=115.1
cell 14 ==> LBLM=115.9 , RBLM=125.9
cell 15 ==> LBLM=119.4 , RBLM=126.0
cell 16 ==> LBLM=108.0 , RBLM=117.0
cell 17 ==> LBLM=108.0 , RBLM=118.4
cell 18 ==> LBLM=108.0 , RBLM=115.3

If anyone wanted to try TTS Datamaster, you could read about it HERE, the list of all cars and profiles is shown HERE, and I was using the DM35xEE file (9.67Mb), which is suitable for 94-95 F-, Y-, and B-body... The way it works, once you install the Datamaster, you can READ any file for free as many times as you want, but you can only RECORD for free up to 20 times, then gotta buy a license (or re-install ), and you'd need an ALDL cable as well... If you are interested, I could send you my files...

 

But you said after a dozen tries is will start and run??????

You seem to want to rule out the major diagnostic steps. Not sure why. And, why would you want to turn down the fuel pressure, rather than try and find out why the car is running poorly. Turn the key on and read the fuel pressure. Turn the key off an see how fast it bleeds down. If it bleeds quickly, it may indicate leaking injectors (would make the engine hard to start, and would explain why its running rich), or it may indicate a problem with the fuel pressure regulator (which would also make it hard to start and run rich due to fuel pouring into the intake manifold via the vacuum line.

Trust me, you have two O2 sensors. The one on the drivers side is screwed into the base of the exhaust manifold, not the Y-pipe. The one on the passenger side is screwed into the Y=pipe, below the manifold. Again, you don't fix a problem by going to oddball band-aid repairs like non-foulers. That's fine for a high HP engine with a huge cam that pours fuel into the exhaust during idle, but unless you have an engine like that, you find the problem that is fouling the O2 sensors (if that's what is actually happening), and fix that problem.

You have a misfire, or the PCM is pulling timing. Its not vibrating because of turbulence from a gutted cat. As noted, when you are in O/D the converter locks up, and you are more likely to feel engine irregularities than when the converter is not locked. At low RPM in O/D, you are also more likely to experience misfires.

We know the PCM starts in open loop and doesn't use the O2 sensors, because they don't work when they are cold. But the engine uses the long term fuel corrections (BLM's) that the PCM learned in closed loop. If youre problem is so bad that the PCM can not come close to controlling the A/F ratio with the BLM's (and yours are bottomed out at 108 on many cases) it has to use the short term corrections. But the short terms (INT's) are not available at startup, so the PCM may not be able to pull enough fuel out to keep it from flooding. Flooding can also be caused by a faulty coolant temp sensor. What does Datamaster show the coolant temp at?

What happens if you hold the accel pedal on the floor when you try and start it? Does it start any easier?

Its normal for the short terms to jump all over the place. That's how the PCM controls the A/F ratio in closed loop. Your engine may not actually be running rich. The 108 BLM's indicate that the PCM is pulling out at least 15% of the normal fuel quantity to keep it from running rich.

That's a disaster. Either the PCM is getting bad data (MAF sensor is always suspect), MAP sensor could be a problem. Or, the O2 sensors could be totally messed up by your carb cleaner application or past problems, and telling the PCM the engine is running rich, when it isn't.

Most of us are familiar with DataMaster. How about you send me your file(s) and I take a look at them? Just make sure they are not converted to .zip files by your e-mail server, include your screen name and the words "data files" in the subject, or I won't open them. I'm way backed up with a long list of files people have sent me to interpret, but I'll try to squeeze yours in.

In the meantime, you might want to read my online guide to interpreting scanner data:

http://members.aol.com/InjuneerZZ/ScanMast.htm

 

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 pretty weak warm, but I though that was the heater core

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

 

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 for 2 minutes 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...

 

MAP is a "sensor", not a "valve". Was the oil plugging the hole in the little nipple that sticks down into the intake manifold? If you were seeing 18kPa at any time other than closed throttel decel from a very high RPM, you should have a code for low MAP. Did you check the harness connector? They dry out and crumble, making poor contact, and producing an erratic MAP reading.

Let's also make sure you are using the correct terminology...

Left Side (as seen from the driver's seat) = driver's side = cyls # 1/3/5/7

Right Side = passenger side = cyls # 2/4/6//8

I got your files, I'll try to take a look at them on Monday.,

 

ok, so i had left and right confused i guess

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???

 

I took a quick look at the "hardstart" file. The "Data Err" flag keeps popping up. I hardly ever see that in data logs. Here's what DataMaster says about that:
Do you have an MSD ignition box?

Then all of a sudden, it shows a DTC for high system voltage, but the voltage is only 12.8-12.9V. Something screwy with the PCM. Often the DATA ERR flag is accompanied by the DTC flag, and the trouble code makes no sense at all.... just a random number.

There is never any knock retard, and all of a sudden the knock counts jump in on frame from 14,278 to 37.778, and you get a 10.0* knock retard spike, accompanied by the "DATA ERR" message. This happens again later on twice in the log.... exact same numbers.

Near the end of the log where you stop and let it idle, it is peppered with the "DATA ERR" message. The MAP is weak, showing ~42-45kPa, which is not good vacuum at idle, unless it has a mild cam.

Left bank long terms are bottomed out. It is running extremely rich for some reason, and the PCM is pulling out as much fuel as it can. MAF readings look OK.

I'll try to look at it some more, but appears there is some sort of problems with Datamaster communicating with the PCM. Again, could be bad grounds.

 

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 bitch to get to... now I am back to my other problems... continued here: https://www.camaroz28.com/forums/sho...55#post5004755