Under the current conditions: closed throttle, 625 rpm and 67 IAC counts the default airflow calculation should output: 4 gm/sec + (67 * 0.0820) + (0% tps * 0.6) = 9.494 gm/sec which is right in line with the actual maf signal shown, so introducing a MAF error won't help by itself. This info suggests that the min air adjustment is a bit high (IAC counts should be lower) but this is not your problem (yet).

Introducing some un-metered air should lean it out a bit, but it's already consuming PCV air, so pulling the pcv valve wont add any additional air. Suggest that you pull the vacuum line off of the brake booster to add additional un-metered air through the brake booster vacuum port. This should cause the IAC counts to drop to correct the idle speed and the MAF (metered airflow) should also drop accordingly with the reduced IAC counts. If the MAF flow remains high (~9 gm/sec) with reduced IAC counts, it suggests that the MAF is insensitive to airflow below 9 gm/sec and that it is likely over-reporting the actual airflow. If this is the case, introducing a MAF fault along with the extra un-metered should result in a reduced default airflow calculation which will lean it out further.

It seems to me that there is something else going on here as well (like high fuel pressure, or a regulator leaking fuel into the intake through the vacuum hose) because I don't think the MAF flow is high enough to produce all of the error. You could disconnect the regulator (which will raise the fuel pressure, but would eliminate a leaking regulator as a source of additional fuel). Another possibility is that it is somehow pulling fuel from the charcoal canister.

Good luck.

 

This is also what I'm thinking as well. Or oversized injector(s).

 

This is what (should) happen when you pull the brake booster vacuum hose: https://datazap.me/u/tequilaboy/inte...3189-3304-3342

Note: it may take awhile for the idle to settle back down due to the influence of the spark advance.

Also note the O2 signal behavior (it was consistently rich prior to pulling the hose): https://datazap.me/u/tequilaboy/inte...3189-3304-3342

Disregard the wacky tuning...this is a blower car with 63 lb/hr injectors operating down in the mud of injector limitations so the fuel, fuel trim and spark advance behavior is not typical (sometimes compromises must be made).

 

Hello everyone, so here is my latest update. So I unhooked the vacuum line that runs to the evap system.. yes I started to see the intergrater numbers go up…. Plug the line with my thumb and watched the numbers go right back down… the more lines I pulled like fuel regulator vacuum line the higher the numbers went up… I also put the fuel gauge on as well and did another leak down test…running the fuel pressure is at 34psi… running with vacuum line disconnected at the regulator is at 40psi… it took about 45 minutes to reach 15 psi after it was shut down… one thing I’m gonna do is change my fuel pump because I want reliability and that pump is probably the original one… but I don’t think that will fix my issue….. also another thing I played with was my MAF… as I said in my other posts I changed it last year and put a new one… I believe I had a code 34… after that service engine light stayed out all summer… until… the other day… I got a code 36.. MAF burn off… so I tapped one of the relays with my wrench.. it was the one further in behind the battery.. each time I would hit it I’d hear the engine stumble… so I changed both… put new ones… no more stumble when I tap them… however still had the code 36…. So I remembered that I didn’t have that code last year with the old MAF ….so I threw the old MAF back on to try… same thing.. however no code 34… but yes 36…. Then I started looking at connections connectors unplugged at relays and MAF… and then all of a sudden I tried it and the light went out and I cleared the code and has not come back on…so maybe loose connection somewhere…hopefully at a connector.. maybe put some kind of cleaner or dielectric grease…. So while playing with that I noticed something…. The intergrater numbers are different from the original MAF…. The new one with no vacuum lines disconnected I was getting 70 intergrater and 108 blocklearn… and with the original I’m getting 90 intergrater and 108 block learn… pretty soon I’m just gonna just drive it… someday will figure it out… but one thing I’m wondering is would a restricted exhaust cause this… I’m reading that these engines like to breathe… just a thought…. One more thing.. someone mentioned if my new MAF was a Delfi or not… it’s not… it’s a Spectra Premium…

 

I had one a long time back that ran rich and I never could figure out why. Till I took the heads off for upgrades:

 

Wow that looks like a washer jammed in there…it must of had a misfire ..no?

 

Yes and yes though the miss wasn't always that noticeable. Reminds me of the used corvette is like a box of chocolate saying.

 

Mass airflow came from these guys

A few weeks ago with new MAF and evap vacuum hose disconnected



I adjusted the tps to .54v couple days ago

This one is with the old MAF … and tps adjusted to .54 and no vacuum leak created

 

How much fuel is in the tank now? For a cheap experiment: adding 1 gallon of E85 for every 1 gallon of gas in the tank will lean it out by about 16% and should raise the BLM accordingly. I have to think that you're dealing with large injectors (like 36 lb/hr or even larger) and improper tuning.

1.3 ms is about the right ipw at idle for a 42 lb/hr injector: https://datazap.me/u/tequilaboy/feli...2027-1880-6284

You can tune it for what you have now, replace the injectors, or mix up a custom fuel blend that will run properly (something like E50). I run an E33 blend in one of my cars (not a C4).

I like this calculator: https://www.tunedbyzfgracing.com/ethanol-calculator

 

Good idea but measure the E you get it could be E50 to E90. My local station has been at E65 for the last year. I don't mind it's not E85 since I'm not boosted and it just returns mpg dollar value.