I have a problem that developed last Thursday that I have been trying to narrow down with my 97 Camaro SS. On my way to work (14 mile commute) about 2 minutes out of the neighborhood while cruising at ~50 mph in 6th gear there was a miss in the engine and the SES light came on for a brief moment and the car continued on like nothing was wrong.

Car sat at my work for 9 hours and then I go to drive home (95 degrees or so outside) and about 45 seconds down the road I get another miss and then 30 seconds later the car just died completely while stopped at a light. It took 3 attempts to restart it, cranked strong and sounded like it was right on the verge of starting before it ultimately did. I then got on the highway and drove for about 60 seconds before the car "died" again but this time the RPMs just dropped to zero but the engine/exhaust kept firing -- it just had no power and even max throttle would only barely sustain speed. It stayed like this for 2 or 3 seconds before the tach needle jumped back to normal position and throttle response returned. This happened again a minute later and then died completely during the third bogging forcing me to pull over.

I let it sit for a few minutes and then cranked it over three times until it started and then continued home with no additional trouble. Friday and Saturday were just about the same thing minus the bogging... now it just stumbles as a 30 second warning prior to stalling out either while driving or idling. I changed the fuel filter (looked old) and removed the SLP CAI and just left the (screened) MAF and intake elbow and took it for a short drive Sunday and the same thing happened. I put the CAI back on after cleaning the filters but longer drives confirm this only seems to happen in the first few minutes of operation.

Car drives fine other than that - maybe a bit low on power compared to what I feel it should be but I can't place why that is. One thing that may or may not be unusual is that during the first 10 minutes of running the car my oil pressure stays at just above 60 (according to dash gauge) regardless of engine speed before settling down to a low of 40ish some time later.

Some info about the car: 1997 Camaro SS M6, 112k miles, SLP CAI, pacesetter longtubes, 2.5" x-pipe into spiral flow bullets, car came with MSD plug wires and some kind of mild cam and PCM tune. I changed the plugs about 2000 miles ago with NGK TR55s properly gapped -- the old ones all had a light coating of oil on the threads.

I was originally thinking fuel pump or O2 sensors but now I'm thinking opti? I had an opti fail in the 97 SS I had years ago and it just went out and never came back but I'm not sure which death is "normal" for them. Thank you in advance for any advice, insight or suggestions!

 

I didn't see any where in your writeup that you scanned it for codes. Was the SES light solid, or flashing?

The loss of tach signal may point to loss or corruption of the cam position signal from the Optispark distributor. If that is the problem, it will set a trouble code. It can even be an intermittent problem, caused by corrosion or damage to the Opti harness.

Then you mention the oil pressure gauge acting up... maybe an engine ground problem.

But scan it - once the light comes on, the code is stored for a reasonably long period of time.

 

Haven't scanned it yet, I suppose that would certainly give me a good point to start from. The light is not on now but I see it blip on for an instant when it stumbles but I didn't really notice if it's on when the motor shuts down -- pretty much everything lights up like 'check gauges' and the like. I'll see if Autozone can scan it for me on the way home tomorrow. Thanks for the input so far, I'll update once I know more.

 

OK, a little more information and clarification as this issue is becoming more frequent and severe. She's now stalling in traffic randomly and taking several long cranking attempts to revive, hard starting after sitting long periods, and the engine is cutting out frequently at any throttle position. No longer seems to be confined to closed loop -- the behavior has surfaced on much longer drives now as well. The SES light is not on and only comes on when the engine dies completely (just as it would when you are Key On/Engine Off) and Autozone scan tool won't find anything if the light isn't on actively. I did borrow a Fuel Pressure Gauge from them and ran some tests:

Fuel pressure with engine cold/off is 9psi. Turning key I hear the pump prime and pressure rises slowly up to ~35psi after about 20 seconds. Starting the car it holds at ~35 psi with the vacuum line connected, and ~43 when disconnected. When sitting in the garage testing and I bring the RPMs up the fuel pressure drops by about 3 or 4 psi. When testing out on the road the pressure never gets above the 35-37 psi that I get at idle -- even holding as long as I can at WOT it never gets up to 40. It stalled twice while road testing and the pressure rose a few psi for a couple seconds right after the engine died and then fell at a rate of 1psi every second or so to a low of 10psi after about 2 minutes. I checked the vacuum line off the FPR and it's dry.

I searched and got all kinds of information but I'm still unsure of what I should do/check/test/replace now. Car is becoming scary to drive in traffic and when it's not acting up it feels like it's down on power across all RPMs (feels like it's running at 90% power if I had to put a number to it). I appreciate any information or advice offered.

 

As far as the tach dropping out, it seems that's related to the engine cutting out - it's pretty much stalling while in gear and then restarting itself. Sometimes the duration is like 1 second (feels like a miss) and sometimes it's 3; the engine only feels like it's running because the wheels/transmission are turning the internals and if it doesn't "catch" and start itself back up then I just coast to a stalled stop.

I'm growing more concerned about the oil pressure hanging out at 60psi pretty much all the time but I'm not sure what the significance of that is. It's rare that I see it below 60 anymore but haven't spotted it below 45 under any operating condition in recent memory.

 

theres a problem with 3 or 4 psi should never get that low.you need to scan for codes before you waste any more time.

 

Doesn't sound right at all. A code scanner pulls both active and stored codes, whether the SES light is on or not. There are codes, like the ones for the cam position signals from the Opti that do not turn on the SES light, but will shut down the engine.

You need to get it scanned by someone who has the correct tool, and knows what they are doing.

 

I agree and told the person there that the car has stored codes that can be pulled up and he refused to scan it because "it won't find anything if the light isn't on". I went to a second Autozone and the guy there came out to the car and said "oh the light's not on? this won't work" and told me to come back when it's on and leave it running. I don't know if they are just populated with idiots or if this really is a limitation of their device as neither of them would even attempt to scan even when I specifically told them there are likely stored codes (first guy told me the car doesn't store them and that's when I just walked out).

 

Sorry, that was my fault with the wording. I meant that it drops BY 3 or 4 psi -- while running it hasn't dropped below 30 at any given time.

 

I have a snap-on scanner that will help. It can retrieve and clear the codes as well as do some runnability testing. I live in florida and can stop by sometime.

I do have a few questions..

Were you really driving at 50 mph in 6th gear? A low engine speed yields low oil pressure just at a time when you need all the help you can get. Don't lug the engine..

What does properly gapped mean? I recommend you pull the plugs and take a look and then,if you choose to reinstall them, gap 'em to 0.035"

When I first read this I immediately thought ignition. Most things won't be intermittant so I'd focus on the ICM, coil and OPTI......after you get the scan done.

 

Thanks very much for the offer -- I'd be most grateful for the opportunity to meet you and see what we can determine from the scan. I'll take that to PM with you.

I don't lug the engine but the exhaust setup on the car is pretty loud and resonates quite a bit at those speeds so 6th gear lets me use light throttle and provides a quiet(er) exhaust tone. The engine doesn't feel labored at all; RPMs hang out around 1500ish but the oil pressure is never low - in fact it always seems to be just above 60 psi while driving. Only in neutral at stoplights does it ever go down to a low of 45ish but never lower. Might be nothing though, but seems unusual.

As for properly gapped -- I set the gap on the new NGK TR55s to whatever the recommended gap is for the LT1 when I researched it at the time... I don't remember exactly what value that is off the top of my head though. I'll pull one out when I get home and see where it's at but I recall having to widen the gap a tiny fraction from the out-of-the-box gap (0.04" sounds familiar though). This trouble didn't develop until a month or so after the plugs were changed as routine maintenance so I didn't really suspect them as part of the problem.

 

The one possibility that might erase the codes.... loss of the battery ground or power connections. When the tach goes to "0" and the engine stumbles, does the volt meter drop to "0".

 

I'm not 100% sure if the volts drop too, I've been so focused on the tach. When it stumbled today on the way home (which happened about 5 times) I found that if I popped the clutch in and out like I was push-starting the car it would start the engine again. Not sure if that is helpful information or not.

In regards to the plugs, I pulled one out and found a couple things - 1st it's an NGK TR5GP, it's gapped to 0.045" and looks like it's not doing so well ... the threads are blackened with a sooty substance and the side electrode looks oxidized. There are very few miles on these... would it be worth swapping them out with a different type of plug and set the new ones to a smaller gap (like 0.035")?

 

I put the plug back in and took the car for a drive up to Autozone to return to fuel pressure gauge and it stumbled on me on the return trip. I took note of the gauges and the volt meter stays at its current reading, it doesn't drop to zero.

I picked up some TR55s since they're cheap and start swapping them in once the headers cool off a bit. Maybe the problem is just now occurring as it took some time/miles for junk to accumulate on the old plugs? We'll see if the new ones give me any different results.

 

Just as a heads-up - I replaced the plugs with the new TR55s gapped to 0.037" and the same trouble persists. It started up after 3 seconds of cranking, ran for 3 seconds and died. Took 8 attempts to start again and on the test drive she still cuts out randomly.