Injuneer

Check the fuel pressure with and without the vacuum compensation line connected. You want 43.5psi without the vac comp line (GM accepts 41-47psi as within range) and drop proportional to intake manifold vacuum when you reconnect the line. A stock cam might drop 8psi from the "no vacuum" pressure. With your cam, might only drop 5psi.

Keep in mind at 47psi (no vacuum) it would only be delivering about 4% extra fuel, and the long term fuel trims should account for that difference.

2QUIK6

48# with line off, 40# with it on at idle. Going to check it with another gauge to be sure but this has been a very accurate gauge in the past.

But, it did fire right up this morning no pedal action...so maybe the ICM was it. When I installed it, I also added a few washers on the back of the plate so the ICM mounting plate is not right up against the head causing additional heat transfer.

2QUIK6

The other gauge had similar readings.
Popped on a new fp reg, now the line off pressure is 42-43, and idle line on is 35# so this is definitely more like it should be.
I'll drive the car all this week, supposed to get alot colder around mid-week, that will be the true test. Going to put the MAF tables back to the way they were before I messed with them a few weeks ago to lean out idle some for emissions testing..... Now on it figure out the next issue...sounds like my power steering pump is about to bit the dust from the noise it makes upon start up

Injuneer

And it had a stock FPR when it was running at 48psi?

2QUIK6

Yes, it was the factory original, replaced with a non-adj factory replacement.
After loading the old tune in it, I drove it briefly today, idles smooth as ever and so far is starting right up. BLMs are right around 126-128 at idle.
Will drive it to work tomorrow and get more seat time....even got motivated and replaced the pass window motor today too

Injuneer

I reviewed the data log, even though you appear to have things straightened out. Seems to take a very long time to heat up, and keeps dropping out of closed loop as the O2 sensors go near static. The 140/136 BLM's in Cell 16 would seem to contradict the idea that it was running rich because of the 48psi fuel pressure.

2QUIK6

Keep in mind that the MAF1 table had been adj at that point. The adjustment was about 11% adjustment, which would coinside with a 5 psi increase in fp on a 43 psi basis. Not sure about it taking so long to heat up, thermostat seems to work ok, its a 160. Ive seen it go out of closed loop at idle when the BLMs get way off lean or rich which may be why it was doing it. Ive never noticed it to do that when actually driving it. After reflashing yesterday it does not appear to be going out of closed loop now that the BLMs are in check.
Started and drove fine this morning.

Injuneer

No. Going from 43.5psi to 48psi increases flow by only 5.0%. The flow is proportional to the square root of the pressure ratio. ( 48 / 43.5 )^0.50 = 1.0505

2QUIK6

Ok did not realize how the fp related to actual fuel increase. Maybe had something to do with the coul or ICM that i replaced as well as it did start easier after replacing them. A combination of both extra fuel and something wrong with the spark? I can swap the ICM and coil back next weekend to see if it makes a huge difference.

flyinZ

Keep us posted on your results. I have a similar problem.

2QUIK6

I haven't had time to swap the coil and ICM back out, but I will as I would like to know if I have good spares. I suspect the reason it seemed easier to start was because I had figured out exactly what to do to get it to start, have the pedal floored before cranking then let off while cranking.
I would say 85% of the issue was the fp regulator.

2QUIK6

The issue is back!!!!
Had to be towed in weekend before last, it just died at a stop sign after stumbling a few times driving down the block....thought it did not have spark, but it will spark if I close the test leads to about 1/2", will not spark at 1 inch.

I did all of the various coil tests and ICM and opti harness tests with the multi-meter, all checked out ok.
Fp is around 40# when key is turned on.
So I tried the pedal to the floor and start cranking like worked before, but nothing, would not even try to start.
After cranking it and fluttering the throttle, it would fire 1 or 2 cyclinders and puff a little smoke. Kept at it trying different methods, and it finally started tonight but smelled very rich.
Scanner shows it to be about ok on the BLMS, all were around 126-128 for the most part, until I put it in gear and power braked it some, then going back to idle would cause them to drop to 120-122 for just a bit before working back up to 126 or so.
FP at idle with vac line connected seemed low at 32# which I would think would cause the BLMs to lean out rather than be tilted towards the below 128 side periodically. Vac line off made fp at 40#, but it did seem to spike around sometimes when varying the throttle.
I turned it off and it would crank back up ok, once or twice it did crank a few secs though before firing.

I'm getting really frustrated with this car again, I may swap out the fp regulator again since the one I bought the last time is under warranty. I have also swapped out the coil and ICM back with the original that I had swapped before that turned out to not be the issue.

So, its does not appear to be the opti (its an AC Delco btw with about 400-500 miles on it)
Does not appear to be the ICM or coil.
If not the fp reg, I may look into the fp...don't suspect it would just stop and then start working again however the fp does seem a tad low with the vac line on. I had fp when it was cranking and nothing is why I'm reluctant to think there is anything wrong with the pump.

Injuneer

No.

32psi with the vacuum line connected is close to normal. The fuel pressure regulator is vacuum compensated to maintain the DIFFERENTIAL pressure between the inlet to the injector (rail pressure) and the outlet of the injector (manifold vacuum) as close to 43.5psi as possible. If you have 40psi at the rail (no vacuum) and 32psi with vacuum, the differential pressure is 40psi - a bit low, but not the same effect as the 32psi that you assumed. Fuel flow reduction at 40psi differential rather than 43.5psi is only 4.1%. That would cause the BLM to increase from 128 to 133.

The injector is an orifice. Fuel flow is proportional to the square root of the DIFFERENTIAL pressure (rail pressure minus manifold pressure), not the rail pressure alone.

The problem is not the 32psi with the vacuum line connected, it's the fact that you only have 40psi without the vacuum line, which is outside the GM specification tolerance.

2QUIK6

Thank you Fred for helping my sanity as none of what I was observing seemed to make sense. Ok, so I'm seeing an 8 psi difference with and w/o vac line. The LPE 211/219 cam does make slightly less vac than the stock cam, which you mentioned would cause an 8 psi drop, so I'm still thinking the 32# at idle is low as well as the vac line off being 40 is low as you point out.
And yes, I would have expected the BLMs to have jumped up a little rather than down.

So this morning I cranked it for a bit, nothing, mashed the pedal to the floor, cranked it for about 5 secs then slowly let off the pedal and it fired up...did the same thing this evening when I got home. So now it's acting exactly like it did before.....but right after it died last week I couldn't even get it to do that. I don't think this is a fuel pump issue as I had pressure when it died and let me stranded.
Someone mentioned earlier when I had this issue that their fuel pressure looked normal but the reg was still bad.
Since this is showing all the signs as it did before, the regulator is coming off tomorrow and being exchanged since it had a lifetime warranty.....I'll let you know how it behaves after that. Thanks again for the help.

2QUIK6

OK, put a new fp reg on today, it fired right up so I thought the problem was solved again. Let it cool down and went out a few hours later to start it again, same damn thing. Let it sit a few more hours, still no start unless you floor it and hold a few secs then flutter it backing off to start it. When its running at idle, it now has 36# with vac line, 44 without so the fp is definitely up now compared to the old fp reg. Maybe Autozone just has some bad regulators even though th epressure looks to be fine now. When the pump energizes with key on, it goes up to 42 or so pounds, then when the pump shuts off it pops to 38# pretty dramatically on the gauge.
It's going to a friends shop I think next week, then to the paint shop to touch up a few places then on to the for sale block at this point, I've spent way too much time on this car to the point I don't enjoy it any more