This one turned out to be not so easy to search for. Testing data connection on 165 ecm(not running, key in run position), noticed the airflow showing 5888. This is on TunerPro RT. Was thinking that it should change if I actually get some air moving through it, but no change. Actual airflow numbers can't be that high, so I am thinking problem with configuration or ecm. Other items appeared to show correctly. Wondering if there are any ideas on why it is showing 5888

 

Data values with the engine not running are often wacky like that. It means nothing. The ECM doesn't use the MAF for startup.

If if were a newer OBD-II car then we would be concerned. But it is very common to see things like this on OBD-I and the ECM isn't even looking at it durring cranking and startup.

GD

 

With ign on and engine off, the MAF signal will be pulled high, but it will also be limited to the max maf vs rpm table....typically 23 gm/sec at 0-400 rpm, but maybe less for a 305 bin. The unlimited airflow signal should show about 254 gm/sec. 5888 value does not make any sense.

Which datastream are you trying to log (160 baud or 8192 baud)? 10k resistor switch on/off? Suspect bad or incorrect *.adx file.

Can you attach a log file and adx file here?

 

While cranking the number goes down. Using default 160 baud adx. 165 ecm running hypertech 87 tpi chip. Did not try disconnecting the 10k resistor after acquisition started yet.
Uploaded log and data stream definition.

 

Wanted to get logs as it is not able to idle and has very poor throttle response after a cam change.(It is a very large cam with stealth ram, but still seem to run worse than expected without a tune) Wanted to make sure it is just in need of a tune and not some other items affecting it before paying a tuner to come out..
Edit.
uploading another log file with a short run. Values for airflow tend to stay in 1000-6000 range while running.

 

I see airflow ranging from about 4 gm/sec to 26 gm/sec in your log. It is also being limited to 23 gm/sec with engine off as expected.

Here's a 160 baud adx file that I had on hand, but really need to step it up to 8192 baud with appropriate adx and 10k resistor.

 

Thank you, it is showing reasonable numbers using your adx file. Now, I will try to get it to switch to 8192 baud rate. It will barely idle with throttle partially open and then will start clearing up. But when it is starting to clear up, have to close the throttle as it will rev to 5k rpm as soon as it clears up.

 

You're going to have a heck of a time with a MAF system and a really big camshaft. At idle the reversion into the intake causes rapid and unpredictable airflow variations across the sensor basically rendering it useless. One of the limitations of this type of fuel injection. It needs a nice smooth (ideally) airflow through the intake or the sensor can't do it's job.

You may have to go to a speed density setup like EBL that can do n-alpha blending to mask some of the idle reversion problems.

GD

 

I went ahead and ordered hardware to be able to burn a chip. Was going to try starting from a base $6e bin.
Cam is 290H-R12(Duration at 050 inch Lift: 230 int./244 exh.). Do you have any suggestions on steps to take towards making it run at a more acceptable manner with a maf? Changing to a SD setup is still an option if required but was trying to stay with maf if can make it to work.

 

I have a fairly gnarly cam in my 89 maf and it's just fine with a stock tune. (Yes I know it'll be a s-ton better with a proper tune)

 

What cam are you running?

 

Generally speaking, you need to run speed density for cam's larger than 224 @ .050" duration. And the more overlap in the profile, the harder it will be to tune. The reversion into the intake makes the airflow across the sensor very unstable. I don't know what you think your going to do about that since the 165 ECM will not run without a MAF. Without a stable MAF reading, the ECM can't calculate fuel.

GD

 

I am open to going SD if 165 ecm can't handle it, but if it can work to keep idle in 900rpm range with 100rpm swing and work fine higher up then 165 ecm can stay. So far I have not been able to find a definite line of where 165 ecm can't run it at all. Your statement of needing SD on cams larger than 224 duration would make sense as currently the motor can only run 3k rpm and above and otherwise will surge 600-1600rpm with constant throttle adjustment. But I wanted to verify that it is ecm and not the tune that is the reason for it running the way it is before changing to SD via 91-92 ecm or EBL.

 

All you have to do is graph the MAF sensor data. If it's too violent of a swing in the data then the ECM will just yo-yo back and forth with the fueling and there's not really any way to stop it from doing that.

GD

 

Solid roller in the .700 lift range but can't recall exact duration an lobe sep. I'd have to look it up. But it's decent though. Have driven it all over and still get 20ish mpg (highway) with stock tune.

 

It's not the lift that's the problem. It's the idle characteristics. If you have smooth idling camshaft then chances are you don't have the intake reversion so the MAF sensor reading is stable. MAF systems are relatively good at compensating for engine upgrades (better than SD systems by far), but they can't cope with a really ratty camshaft at idle. The airflow sensor fundamentally isn't compatible with this type of camshaft.

GD

 

Lol you can go alot bigger than a 224 on a 165


230/245 on a 109 with some spray lol

 

Nice. What do you do about the MAF readings at idle?

GD

 

Yes, the duration and lob separation are on the nutty side like the lift. (for a sbc street car) It's a snotty idle that doesn't "clean up" till 3500-3700rpm or so. Have no real problems with brakes or anything even with the mini-ram. Surprisingly very drivable all things considered.

 

Nothing. They had no issues. It idled higher than stock maf readings as expected since it idled higher and was demanding alot more air. I even made a 3.5” maf withstock guts and just rescaled every thing. No difference inpower it seemed

ran a 230/236 xfi 113 on a 350” bored .060, stock crank, budget rods and pistons. Afr 190’s. Also maf. Ran great at 750-800 rpm idle.
Chad speier on here has a very similar setup but with miniram and his maf runs great

there may be a point it becomes an issue but that have to be a giant cam most guys dont wanna play with. A 230 lobe with good induction can go to 6500+ rpm. How much more does a hyd roller street driver need?

 

It is not far off from a cam that I am trying to run. I am going to try and see how it goes with ARAP bin with couple of changes. Do you happen to have a bin file from your tune that I could possibly use to compare and see what things has been changed? I am sure it would not be correct for my motor combo but would be interested in getting an idea on what tables are to work with.

 

Yeah i should. The milder motor with the xfi cam was arap based. The old 190 heads are similar to L98’s 113’s

my 383 was aujl based i believe. Much less timing due to better head chambers on afr 195 eliminators

 

I looked at my cam card while in garage last night.. Dur is High 250s and low 260s ex @.050 on a 106