JAKE

I'm posting this on a seperate topic because it MAY impact many of the problems that I've been reading about.

A couple of years ago, someone on another board offered to modify my PROM for me. I sent the PROM to him and he burned 89 Vette specs into it.

When I installed the PROM, the engine ran fine, but Diacom reported the BLM locked at 108 no matter which cell was being referenced, but the Integrator values remained at 128 (+/- 4) in closed loop. As I said, the engine ran fine and the plugs looked perfect so I didn't worry about it.

I assumed it was because the programming was too rich and figured I'd get around to addressing it after some other tuning matters were sorted out.

I recently got around to it and did a comparison between a Diacom trace I'd made with a stock type air fliter Vs a trace using a brand new K&N. I first noticed that the stock filter was showing more airflow at WOT than was the the K&N. Now, we all know how K&N's are touted to be super flowing filters, so that caused me to be more than a little confused.

I pulled the K&N out and examined it and it was a clean as a whistle, save the spray on oil which gives the filter medium a pink color.

So I decided to clean the oil off to see if there would be any difference in what Diacom reports. I used some gasoline and washed all the oil from the filter. I then used some spray carb cleaner to spray the MAF sensor wires just on the off-chance that some of the oil had been sucked off the filter medium and adhered to the MAF's sensor wires.

Let everything dry overnight and when reinstalled the next day, I took the car for a spin with Diacom running. Cold start up was raggedy and I thought, at first, that I'd made a bad move.

After running for a few minutes, magically, the BLM values were back where they belong, 128 +/- 4 in closed loop. At idle in gear, the values were dead on 128 and when driving they slowly cycled 4 above and below 128.

As each different cell was entered, I could see the BLM values increase from the low levels that had been previously 'learned' and new, higher values substituted.

So the only change made was the removal of the oil from the filter and the spray cleaning of the MAF wires. Interestingly, too, that the locked 108 BLM values were consistently locked at 108 even though I had installed three different MAF sensors. All of the MAFs gave the same 108 result and it wasn't until I washed off the filter oil that the BLMs began moving upwards (higher number) and returned to normal values.

There were no other changes made either other than the oil removal.

I was wondering if anyone else has had a similar experience.

Jake
_______

65Z01

I've never had any "funkey" BLM readings with the K&N in the Vette or in the IROC.

Maybe yours was over oiled.

JAKE

If so, that's how K&N shipped it because I took it out of the box, already pre-oiled, and installed it.

Jake

Lone Ranger

Somewhere deep within the bowels of the archived posts and threads of The Forum, there is a post where one of the guys that drag races a lot, I keep thinking it was Mr. Mojo, says in a debate over cut lid vs. stock air lid that he experimented: 1. cut lid + K&N; 2. stock lid + K&N; 3. stock lid and stock paper filter; 4. cut lid and stock paper filter. Or something like that. I believe he said his best time was achieved on the run with the cut lid and stock paper filter. If so, this would tend to confirm what you found.

Could it be that the cloth & oil filters are :bs ? :eek:

Lone Ranger

BTW, has any place ever flow tested paper filters vs. K&N and aFe "cloth 'n oil" type filters? Have any of us ever seen any real test data on air flow on either type of filter done by an unbiased facility?

Just wondering.

Mr Mojo

Hey Craig, Hot Rod magazine did an air filter test between paper,K&N and a few others. Not much difference except that the K&N and others tha were reusable flowed just as good dirty as a stock paper clean. The paper filter clean flowed just as good as the rest until it got dirty.

Tonight I'll be perfoming yet another test on the open vs closed lid.

I just put the open lid on my '93. We shall see if there is any difference from last week.

Lone Ranger

:cool: :cool: My filter is an aFe brand, basically a K&N clone where the filter material (oil makes it colored) is yellow instead of reddish pink. 4 months after having it in there I took the MAF sensor apart and noticed the top most diode on the left as you look from front to back had some very light greyish oily residue on it. The other two diodes were clean, don't know why. Cleaned it up just fine (q-tip with small amount of mineral spirits on it then dried with dry q-tip) but I think these filters at least when new (or cleaned and over-oiled) let some micro-particles of oil leech out into the filtered air blast.

JAKE

I was hoping that someone else had done a back to back like I did to see if their airflow increased with the stock type filter element vs the oiled K&N using Diacom to record the results.

I may be wrong about this, but I can't think of anything else that could have caused this result in my setup. It may be exactly like Lone Ranger said, that the oil from the filter medium is contaminating the MAF sensor wire(s).

Jake

Blue 92

I thought that the MAF sensor wires heat up after shut down to burn off impurities? :confused:

Lone Ranger

1st time I've heard of that. Besides, if oil residue was burned off it would still leave fouling on the wires/diodes.

In my opinion, anyone who's had one of the gauze and oil re usable air filters installed for awhile would benefit from taking apart the MAF and inspecting the wires/diodes for build-up, and cleaning as needed.

Just my $0.02 worth

No Go

I believe you are correct...it can be called a burnoff relay or something to that effect.

I have come across a carbureted chassis dyno test that swapped from a paper to a K+N (14 in diameter by 3 in tall)...gained 8 RWHP.

:)

Lone Ranger

260RWHP stock on an LT4 :confused:

ZylaRace

On the L98, there are 2 MAF relay's. One to apply sensor power when the engine is on, the other is on a timer to cook the sensor wire for a short time at engine-off. i.e. This cleans (burns off) any junk that may have deposited on the wire during the engine operation. I'm not sure if the wire glow's red or not,... I tend to think not, but I remember someone commenting it did.

vettmech

The MAF does glow red hot on my 85 after it's shut down. A note on my K&N filt ......when I service my filter , the first time I start the engine afterwords it runs rough for a min or so ..........it seems like it may suck some oil through but it clears right up and runs dine afterwards

Crispyc21

What type of spray did you use to clean the MAF sensor wires. I've had some issues after installing my K&N and would like to give that a try. Also do you just spray it on and let it dry or do you run the engine?

JAKE

I think we're on to something here.

I suspect the oil doesn't effect a carbed engine because there are no sensor wires to contaminate. Since the MAF sensor wires are critical to the ECM getting correct airflow data, even a slight buildup of residue will effect what the ECM "thinks" the airflow is. Fuel flow is effected accordingly. IU guess that's why GM included the burn-off cycle.

I suspect, too, like someone else said, that burning off oil leaves a residue which, over time, can buildup and effect the data the ECM receives from the MAF sensor wires.

Here's how I did mine.

I removed the MAF, then held it upside down with the flat part facing upward and I kept one end of the MAF angled downward so the fluid would run out as I sprayed.

I did this to keep any Gumout carb cleaner fluid from running down between the heat sinks and possibly entering the area where the electricals are. So when I sprayed, using the red plastic tube that came with the Gumout carb cleaner, all the fluid, and residue would drop on the inside of the MAF and run out one end.

I then used a paper towel to wipe the interior surface of the MAF and continually checked the towel for discoloration. When the towel remained clean, I knew I'd removed all the residue.

Hope this helps.

Jake

Lone Ranger

I didn't use a spray, instead I completely disassembled the MAF. My MAF doesn't have the heat sinks sticking up and once you have the unit completely removed from the rubber accordian air ducts and gthen remove the 4 torx bolts holding the MAF sensor unit together you can easily get to the wires with a q-tip. I used a q-tip soaked in mineral spirits (paint thinner) and gently wiped and dried (with a dry q-tip) the diodes several times. This method seemed to work okay. As long as a spray cleaner leaves zero residue behind, it should work good I would think, but the trick would be to find a TB cleaner spray that leaves nothing behind.


[Modified by Lone Ranger, 8:19 AM 7/23/2002]

ConeKLR

Also keep in mind there is Gumout CARB and Gumout THROTLLE BODY cleaners. The carb cleaner will strip away the coating on the throttle bodys. Not sure if the MAF will have this same coating.

Sure hope you at least rinse the air filter with mild soap and water after cleaning it with gasoline. Gas fumes go Kaboom! :lol:

Red91Vette

Well since I don't have a MAF should it effect me still at all? I have a K&N, its been in my cut air lid for about 2 months now. When I raced at the track, I ran quicker. But next time I go down, im gonna take a clean brand new paper filter and my K&N and see what happens.

JAKE

[SNIP]

No, with a carb you won't see any problem.

Jake