qwiketz

Hi all. The car is a vortech supercharged 383 lt4 that has been rebuilt about 15,000 miles ago. It's sat quite a bit over the past 7 years in my garage.

The car is running rich and I can't seem to figure it out. At this point, I'm wondering what else I should test. I've tested quite a bit and everything is checking out.

The car will start at about 12.5 to 1 on my wideband and the narrow band o2's seem to agree with that. As it gets warm, it richens up to about 11.5 to 1 and the o2's are up to the 800's at that point.

Here's what I have:
-good spark at the plugs (nice and white at even intervals on the tester)
-plugs have idle time on them. NGK iridiums gapped around 30
-opti was rebuilt/inspected by dynaspark
-relatively new iac (set to about 30-40 at idle
-idle vacuum is where it has always been at about 15"
-new ignition control module
-new air filter
-new oil filter
-fuel pressure at the rail is set to 42 where I usually had it
-fuel pump is next to new (340 lph aem)
-fuel pump is connected via racetronix harness
-plug wires appear okay and once again, spark at the plug looks good on all
-fresh 91 octane gas. Completely emptied and cleaned the tank out
-fresh grounds for the battery and chassis ground
-wideband o2 sensor is fresh and reads no diffeerent then the old one
-oil was changed recently and less than 2-3 street test miles ago
-pressure checked the exhaust system (3" b&b with cats). Readings were okay and within spec
-ecm was rebuilt (92 ecm has issues with the soldering going bad)

At this point, what else should i be checking? What could be causing my car to run rich like this? Are there any tests that I should do such as compression? I will check the oil and coolant to inspect (hopefully not a bad head gasket or anything like that).

Once I get beyond the mechanical, I will then turn to my tuner but the car ran perfectly before all of this started happening. I'd like to check the last few items since I've done so much but am almost out of ideas. I'm using tts datamaster to log and monitor the engine health. The engine fueling is in box 16 and 17 which I heard isn't good since those are the special boxes for adjustments.

pdxmotorhead

Since you said it sits a lot.. First random guess,, fouled injectors? They may be varnished up just enough to stick when they heat up and tolerances go tight?

ACE1252

Open loop or closed loop tune?

qwiketz

Hi all. thanks for the input.

If the injectors were a little gunked up, would a can of injector cleaner work being that I'm just running the thing idling for relatively short periods of time or would I need to just replace them or take them to a place to get serviced? Injectors are pretty cheap these days so maybe I could try swapping them out with a new set and seeing if that worked. If it does great, if not, I can sell them.

The tune is a custom tune that starts out in closed loop and then after a few minutes, I did verify that it went to open loop.

I have a question about narrow band o2's. I see that that close to when the car is fired up, the o2's read 453/595. A few minutes later when it goes to closed loop, they have worked their way up to around 500/635. The gap gets as big as 435/635. The left one responds quicker than the right one (on my program). I've heard that you can't expect them to be identical, but how much difference is acceptable? As the car heats up, the gap gets a little closer but is generally from about 100 to 150 higher on the right side.

The spark is about 18-20* at idle as a side note (not sure if this is reasonable/in the ballpark of where it should be).

Does all this sound reasonable?

ACE1252

Did you mean that the other way around? The car should always start in open loop and either go closed or stay open depending on the tune.

Do you have a data log of it running?

When you look at the logs, you need to look at the values in a graph type format. When in closed loop, the O2 values should be cycling high, low, high, low.....it will look like a sine wave when looking at the graph(some people call it histogram).

If in closed loop, they stay either high or low, you have a problem.

BALLSS

if car "sat a lot for 7 years"....injectors could be clogged some. You can try a can of injector cleaner in the tank to see if your rich condition improves. I have used www.cruzonperformance.com to service injectors if you want to send them out.

If your LTFT are high you need to find the "why". Un-metered air is often the "why". (exhaust leak pre 02, intake manifold leak, exhaust/header flange leak)

qwiketz

Thanks for the input. I'm taking a look at the datamaster scan of the car idling for about 5 minutes and the lt counds are at 128 on both. The short term counts are also 128. I ran through a bunch of positions in the run and it went to 129 on the st counts at one point on one side but that's about the only variation. I don't know how to read a lot of this stuff so I don't know if that is good or bad.

And yes, the tune went from open to closed loop. I think above I mentioned it backwards. I do have a datalog of the car running in datamaster if you'd like to take a look. I can either video the car running on youtube or email you the datamaster file. Hopefully I'll get some more data shortly of it running/idling over a longer time.

BALLSS

I am no tuner and don't have datamaster. I have a Actron scan tool that does have data read/log and the value for LT & STFT is+/- x.xx and you want them to be 0.00 +/- 1-3. not sure what value 128 or 129 is. IIRC MAX LTFT reading is 25 which is as much fuel as the PCM can add

You have a modified motor & SC so and assume larger injectors and bigger FP so the "tune" needs to be right as does the fuel pressure. First you need to confirm there is no "mechanical" issue and if none look at the tune

Maybe on data master the 128-129 "value" someone familiar with data log and tuning can advise

ACE1252

If the trims are locked around 128 and don't move, sounds like it may be some kind of open loop OBDI tune. Others may can chime in on what the tune might be....the percentage values didn't start until OBDII if I'm not mistaken.

What AFR is it showing running down the highway? If you go wide open throttle for a short, hard, acceleration run, what does the AFR show?

Is it running badly? Does it smell rich? Can you post up a data log of what it's doing? Is the fuel pressure regulator vacuum compensated?

Sticking injectors could be a real possibility sitting that long...or some kind of intermittent misfire or ignition issue.

I was wondering about dry rotted hoses causing a vacuum leak, but I think that would cause a lean condition.

I'm assuming it ran fine on the AFR before storage.

Camaro_freak

iTrader: (1)

Not sure if this could be your issue, but I had issues with my engine going rich many years ago after driving for awhile. It ended up being cat overtemp protection kicking in, which runs the engine rich to cool down the cats. I disabled that "feature" in my tune and it stays in closed loop now.

mr.beachcomber

We all tend to make mistakes once in a while. When you said that the fuel pressure was set to 42 psi, that was with no vacuum to the fuel pressure regulator right? Otherwise, your fuel pressure is going to be around 50 psi a WOT. Just checking...

qwiketz

Thanks for the input. The day before it sat for an extended amount of time due to burnt up transmission bands, it was running perfect. Drove it to work in stop and go traffic, ran it hard at wot and it was perfect. Car sat and I eventually replaced the trans and it ran like crap as I limped it over to my new neighborhood. It probably sat for about 18 months at that point.

Fixed the trans and it's mostly sat the past 4 1/2 years since it wasn't running right and I didn't have the time to work on it.

The vacuum guage reads normally. I did have a small vacuum leak from routing the vented opti line wrong but I caught that (12" to 15" which is about where it usually was at idle).

The fuel pressure regulator is a vacuum/boost referenced aeromotive. AFR at idle starts at 12.5 to 1 and richen up over time to the mid 11's at idle or light throttle(I have a wide band and the narrow 02's are in line with the wideband). I haven't really put much load on the car because it's not running right. The most that I've done is drive it around the neighborhood at low speeds.

I checked spark at the plugs and it looks good. The plugs are newer but who knows, maybe I messed up an electrode gapping them.

I believe I adjusted the fuel pressure to 42 with the vacuum line connected and with the car running. Should I be reviewing how to do this again? I'm not familiar with the process.

Fuel injectors are something that seems logical. Maybe I'll run some injector cleaner through them this weekend. At least it won't cost much and it's probably good for the whole fuel system anyhow.

qwiketz

You might be onto something here. However, I'm mostly just talking about the car running at idle and part throttle.

It is a boost referenced regulator, so I'm assuming that under boost, it will just increase linearly.

But, if back to the regulator setup. If I'm seeing approximately the right fuel pressure at idle on a gauge on the rail, isn't that the main thing or am I missing something here? I relied on the stock one for quite a while so I don't even know if I setup this one incorrectly.

BALLSS

you should have the vacuum line disconnected and plugged (the vac nipple that attaches to FPR) when setting fuel pressure. It should be 43.5 without vacuum. When you connect the vac line it should drop to around 37

sounds like your FP is to high if you adjusted it with the vac line connected. I am assuming your Aeromotive is a adjustable FPR.

Heatmaker

The LT1's PCM just doesn't like working with the Aeromotive.

Everyone kind of warned you about using them before and the problems they bring.

https://ls1tech.com/forums/lt1-lt4-m...regulator.html

I ran 30 pounders, Walbro High Flow and the Aeromotive FPR and it gave me all kinds of rich conditions. Even went so far as to install a FP gauge in my car. The Aeromotive would give all all kinds of wonky numbers. Even wasted money going through a few sets of injectors and having the tune inspected till I finally swapped out the Aeromotive for a Metco and the problem was fixed. Like I said in your other post running rich with a Aeromotive has always been a problem with that FPR.

ACE1252

That will certainly cause it to run rich. As the others mentioned, needs to be 43.5 with the vacuum compensation removed from the regulator.

I've read of all kinds of problems with the Aeromotive FPR as well.

qwiketz

Once again, the rich condition was already present prior to me going to the aeromotive. The issues started in late 2012 and the post on the regulator was from 2014. There were definately some complaints and there were a few that it worked for.

With that being said, I'm reading up and not ruling it out. I just checked the metco site and I'm not seeing the regulator listed on there anymore. I'll try emailing them.

In the meantime though, it sounds like I may not have setup my current fuel pressure regulator correct to begin with. I'll start there.

BALLSS

1. correct your FP using the method I and others note
2. if problem persists after FP is adjusted correctly, dump that Aeromotive. I am one who had zero luck with Aeromotive, DOA.

If you get another FPR the BWD ( Borg Warner) # 23065. I got mine at O'Riely's auto parts. Just like the Metco one I had before. Adjustable

https://www.oreillyauto.com/detail/b...evrolet/impala

qwiketz

awesome. Thanks for the suggestion. Got one of the o'reillies right down the hill.

qwiketz

setup the fuel pressure regulator correctly. Set it to 42-43 psi with no vacuum which brings it down to 39 with vacuum. I'll have to check it on the wide band but little by little I'm getting this thing straightened out. If I can get it close mechanically, then we can play with the tune.

ran it a bit longer and checked for exhaust pressure and that was fine. No problems with clogged cats.