Also, the first thing I did was just swap out the injectors for a spare set of stock injectors........did not help.

Also, this one idles ok....it just leans out at one point/load condition or something...but then clears up.....until you hit that load condition again....

I plan to check fuel pressure while driving....but I don't think that's it because the left bank seems to hang at 850-900mv while the right side is steadily leaning out until it starts misfiring.

 

Did you guys ever get anywhere on this?

You still didn't mention whether or not you checked the fuel pressure WHILE the car was running like crap? Pressure and flow volume are proportional for a given diameter tube, so if you have one, you have the other.

Because you said it is leaning only on one side of the engine, it sounds like fuel to that side of the engine. If it didn't run great when cold, I'd consider an obstruction in your fuel rails, reducing the amount of fuel which reaches the other bank of injectors.

Likely candidates are the injectors themselves, the wires between the ECU and the injectors, the wires between o2 sensor on the lean bank, and the ECU program. You said you replaced the ECU, yet you still seem to have some tune on it. Is there a reason you can't try the stock gm program? Do you have ported heads?

If it were a fauly o2 sensor though, the o2 would read lean, and the engine would do what it's doing, dumping in tons of fuel, and the car would actually run rich. Since you said you saw glowing headers, and you didn't indicate that you smelled unburnt fuel, I'm also going to assume the car actually is running lean, and cross this one out, too.

What's going on with the other side of the engine anyway? The side which isn't glowing red hot headers? I'm under the impression that it isn't running fine, judging by the way that you describe the car's performance...?

 

btw. how is your vacuum?

I'd like to see vacuum numbers under load before and during the crappy running, as well as fuel pressure numbers at the same points in time.

I don't think this is your problem, since it sounds like it's on one side only.. So, please confirm the lean condition on pass. side / whether or not drivers side is rich/lean/stoich? If ds is stoich, without crazy sterms/lterms don't bother checking vacuum or fp, because those would affect the whole engine not just one bank.

My guess:

I think that if one cyl is running lean enough, it will heat up all the headers on that side, since they're one piece of metal. If the other 3 cyls on that side are running too rich, to try to bring the o2 readings back into range, you'll end up flooding 3 cyls (no power), and leaning out the fourth, red headers. You might end up burning up a valve if you let this go on for too long. You wouldn't notice this in open loop, because the car wouldn't be trying to compensate for that lean cyl (which isn't really a power loss). After being in closed loop for a few minutes however, the STerms max out, and you flood those cyls, and your car runs like crap.

The exhaust pops because you aren't actually running LEAN as a whole, you're running rich. What happens is that after enough fuel builds up in the exhaust (flooded cyls), combined with enough heat, you get a some nice combustion going on in the exhaust. This problem would be compounded if you had a bad o2 sensor pass. side, or bad wires between o2 and ecu pass side. If this were the case, fixing the injector would only remove the bright red lean looking headers, but you'd still have a car that was running like crap a few mins after closed loop. So, check the injectors (prolly not the culprits) the wires between ECU and injectors (probably the culprit, I think you said #2 seemed bad), and the wires between ECU and pass. O2, and once again, pass O2, just for good measure, but don't replace it if it isn't bad. I bet it's just the wires.

Ok, its late and that post was longer and more repetative than it needed to be, but I hope you got the drift, and I hope you can figure it out, or at least update with more info so we can try to help. Good luck, let us know what happens either way.

 

One more thing that might cause this type of symptom, without the o2 sensors or their wires being fault at all.... if your AIR pump is stuck on for some reason, it would be making the o2 sensors think that the car was running lean, even if it were, mostly, running rich. The same problems would occur as a result (flooded cyls, backfiring, running like crap). If it were the AIR pump, both sides would read lean, yet be rich. If it were instead, both valves stuck open on one pass. side cyl, it'd give you your current symptoms.. but the chances that you have both a partly failing injector on one cyl and two valves stuck open on another, on the same side of the engine, at the same time.... are probably about as good as the odds of my mom fixing your car tonight while you sleep..

just a thought, which might be helpful to someone with a crazy air pump in the year 2012 or something, lol. :blah:

 

I'm going to guess that the rockers are too tight. Re-lash them. My car did the same thing after a rebuild.

 

good point, he did just rebuild the thing

 

ok, let me try to answer each one of your questions.

the air pump has been removed. So has the EGR. On the scanner it shows the quad driver that runs them to be bad. It's always been like that. PCMsforless said it's been removed, the SES light doesn't come on.

I took out the tune this past weekend and put in just the stock blue prom, on the 93's the tune goes between the ECU and that blue prom. It didn't make any difference.

The fuel pressure I did check with it running, it's right at 43psi regardless if its running bad or not. Thats what I thought was wrong with it orginally, after I replaced the ECU, because of how it was acting.

When I replaced the spark plug wires and swapped out the ignition module I re adjusted the rockers. Niether one made any difference.

Flyboy and I were talking about the exhaust glowing the other day. We checked it at night again when it was running bad and the headers didn't glow. Maybe I didn't try long enough, I don't know.

I haven't checked the vacuum. I will today.

The car never smells like gas from the exhaust, like it's running rich.

When watching the o2's, the passenger side always seems to run a little leaner than the driver, but not all the time. (I am sure that statement was helfpul) But when the engine starts running bad, both sides go lean, I mean down to 30-40 lean.

When it starts running bad the IAC motor runs all the way out to 160. I think I mentioned that before.

I put a noid light on a few of the injectors to see if it was getting a pulse. It is both when it's cold and when it's running bad. If you rev the motor the light gets brighter.

When it starts running bad, the engine temp goes up. ECT seems to be accurata.

I'm just trying to throw out some things I have checked, I know there has been a lot of info in this thread.

when it starts running bad, it will start missing at lets say 1500, if you give it more gas and get it above the point it misses its' fine. Then it starts getting worse, you will have to give it more and more gas to keep it going. then it gets to a point where you can have your foot to the floor and it won't go at all.

 

When you say that it runs lean on both sides when its running bad, but doesn't smell like gas, that starts to sound like fuel pump or fuel pressure regulator again. check that vacuum, if there's a leak, you could run lean, further, if the vacuum to the fpr is leaking, your fuel pressure could change as a result.

Then again, im suprised you could run it lean for that long and not burn something up...

Let us know about that vacuum check.

 

Yeah it runs lean, but it dosen't show it on the 02's until the car is running really bad. I checked the pressure and it's ok, stays at 43. I am afraid if i keep running it i am going to screw something up.

 

ttt. Would the opti make it do something like this? I drove it last week, and it was about 95 degrees out. Within 3 miles the car wouldn't pull itself.

 

My car does the exact same thing. For the first 10 minutes or so, it runs fine. Then, it will get a slight miss for about 10 minutes and then BAM, she bucks and sputters, backfires out of every orifice she has and you can barely make it down the road. I JUST got the car, so I have not had time to do any diagnostics on her yet, other than checking fuel pressure, which seemed to be fine when it started it 15 minute missing spree. I did not have it on there long enough for the full epileptic fit to take place, but, I figured if it was already starting to mis and the fuel did not fluctuate, then all was fine.

I am digging through all the posts I can fine to see whats up. My engine "supposidly" has 190k original miles on it, so, I am thinking of replacing the opti. I will keep informed as to what happens if I do and if it fixes its little problem. Keep us in tune if you get your problem fixed also, but, lets look at whats been done or checked so far.

coil
Air temp sensor
EGR - deleted
Plug wires
Ignition Module
O2 sensors
Pcm
Alternator - voltage checks
Spark Plugs

I dont think you are running lean, per say. I think the car acting up is making it run lean. I know it sounds silly what I said, but, a half stuck injector = running lean. A sensor or screwed timing = making the car run lean. I am erroring on that side of the fence, for now, but, my final conclusion, thus far, is that the timing is being thrown off somewhere. Even though the opti is giving you proper res's, I am wondering if there is a chip in there that is delaying the transmission of the res's to the computer when it gets hot. If it was another sensor, like you say, I would think you would just have really crappy performance and not the bucking and kicking like we get, or, at least as bad. A dropped injector would be like a pulled plug, I would assume, lacking in power and heating the headers to a nice pretty red, not backfiring.

Another small theory is that the valves are sticking or not closing. Could be weak or broken spring(s) or god forbid seized valves?? My car has 190k miles on it so I am sure (one would think) there is plenty of worn space for a valve NOT to seize, lol???

There is the ever so slight possobility of metal expansion and contraction of....... grounds or sensor plug prongs maybe?

Now, the only sensors we didnt go over, that I can think of off the top of my head that would have an effect, were the MAF (you do not have one?), MAP, TPS and coolant sensors. Have you tried plucking them off one by one and seeing what the results were?

Also, what is the timing like before the bucking and during?

P.S. On a side note, when I was driving it all around in the rain the first trip I ever took it on, it drove fine for 30 minutes, at least. Maybe the water and air temps was keeping something cool? There is no backed up confirmation on this so that is pure speculation as I have not been able to duplicate the "rain drive" to date.

 

Todays update: I was in traffic and when I got home 25/30 minutes later, she started acting up as useual. I plucked the MAP and MAF connectors off, individually, gave her a little gas and still the same results. I did not shut off the engine when I unplugged them, so, I do not know if that would have made a diffferance or not. Anyone else?

 

I posted awhile back that my car was exhibiting the same symptoms as you decribed.....well update for me is that I decided even though the optispark on the car only had about 5K on it I was going to pull it and check it out. Come to find out, the dowel pin on the cam was too long ( about 1/4 inch) and was putting pressure on the internals of the optispark to the point that when we cracked the case open the cap and rotor were actually cutting grooves into the plastic casing from being mashed so much.....I sanded down the dowel with a dremal and put a new opti on the car...problem solved!! car runs like a champ again......

 

Well ****, I am glad you got your car fixed, I wonder if I will be so lucky as I have the old opti in my 94 .

 

My car is doing the exact same thing: It has the following new parts with approx. 500 miles on them before it started acting up:

- GM Opti
- GM waterpump
- GM CTS
- MSD wires
- MSD coil
- MSD cap & rotor with vent retro-fit kit
- GM ICM
- coil cooling mod