Last week I had my wot tables dialed in perfectly so my a/f was between 11.8 and 12.0 across the board. This week I cleaned my maf and made some changes to the throttle follower and closed throttle timing tables and my a/f made a huge jump to 14.3!!! Good thing I had the wideband hooked up or I could have had a broken car right now... What gives? How could this happen? The things I changed should have no effect on WOT.

Another weird thing is that to get my a/f to 12.0 I had to cut my WOT tables down pretty hard. Here is my current rpm vs. fuel % at WOT table pasted from tunercat:

400 0.0
800 0.8
1200 0.4
1600 0.8
2000 0.8
2400 0.8
2800 1.6
3200 2.0
3600 2.3
4000 2.0
4400 2.0
4800 2.3
5200 3.9
5600 3.9
6000 4.3
6400 4.3
6800 4.3

The table I originally had from PCM forless was about 4 times as much as this one across the board and my A/F was between 10.9 and 11.8 (rich). When I entered this new table based on my wideband readings and the WOT spreadsheet thing my A/F was perfect. Now, a week later, with no changes, my A/F is way to lean. I think there was some kind of fluke last week because the table above has less power enrichment than the stock table...

Anybody have a theory as to how this happened?

 

Your minor change of Cleaning the MAF was a huge change! put the file brian wrote for you back in the car and I bet your air/fuel is dead on.

 

I know that it was a huge change BUT, in PE mode isn't the MAF ignored??? Could it have some unforseen effect?

 

no your maf is used and the numbers in the pe table are used as a multiplier for the airfuel ratio.

that came off a lil harsh huh sorry about that.

 

I have an OBDI pcm. Is the MAF still used?

I believe you man, I just always thought that PE mode = no MAF (or o2 sensors)

 

Yes, the MAF sensor is used all the time. That's how the PCM knows the mass air flow.

 

Dalai Fred Lama has spoken. No really, thanks to both of for that clarification. I can't wait to get some time to get the WOT tune right with the MAF working. The car ran so much smoother everywhere else.

Since I know that you will most likely glance over this thread again... what do you think about using alcohol (water/isopropyl mix) on a q-trip to clean the maf resisitors? I figured that would be the way to go because it dissolves oil and evaporates quickly and cleanly. I searched but everybody mostly says to use electrical parts cleaner. I wonder if there is really a need to actually buy a bottle of some stuff. BTW CRC electrical parts cleaner is comprised of carbon dioxide and isohexanes... don't see how that works to clean electrical parts but I guess it does.

 

I use carb cleaner and just blast the thermistors for a moment or two- it's probably a good deal stronger than isopropyl. In the CRC cleaner, CO2 is an environmentally safe propellant and the isohexanes are the cleansing solvents.

 

Right I knew that... I am a biochemistry major so I have a pretty good idea of the chemistry, I am probably just overthinking this as I usually do. I'll get the electrical parts cleaner although the alcohol would probably be just as good.

I can't believe this MAF... I remember a few years back some guy made a post saying that the MAF was a scam and I argued with him. Now I'm starting to believe it is a scam. How can something which obviously must be cleaned regularly to get an accurate reading not be part of regular maintenance? I'm sure that many people have spent lots of money fixing problems that could have been solved with 10 minutes and a can of electrical parts cleaner.

 

Check your TPS! Hook up datamaster and hold the throttle wide open to verify 100%in Datamaster. It is very possible to over drive the TPS and at WOT the TPS reads 0%. This will cause the PCM to not know it's in PE mode and the BLMs will try to correct down to 14.7AFR. This exact scenerio happened to me when I put on a Holley 58MM throttle body. 0% TPS reading with the blades wide open is a recipie for disaster. I had to slot my TPS to get some adjustment to keep it from being overdriven by the throttlebody shaft.

Good Luck,

Steve

 

Do you have a K&N filter? The only time I really hear/read about dirty MAFs is when filter oil collects on them. OEM filters are unoiled, so I can't imagine it being a problem with an OEM unless you frequently drive through McDonalds kitchens or something.

 

lol. I have a K&N but I only oil it once in a while because the car doesn't get driven too much. I think the oil is probably coming from the blower... methinks at least. Could be K&N... is there any way to put some kind of filter or baffle or something of the sort to catch the oil before it hits the MAF with sacrificing the reading or airflow?

 

How is your PCV valve connected? Has it been rerouted to the suction side of the blower? If so, does it have an oil sperator in the line from the PCV valve to the blower suction?

 

The vent tube on the passenger valve cover is routed through a long tube to the suction side of the blower. And no, I don't have an oil separator... you make a really good point fred I never thought about this. I have a filter on my eclipse, never thought to put one on the t/a. What should I use? Do I need a catch can or can I just use a fuel filter or what?

 

Fred I got a kick out of this thread...

http://web.camaross.com/forums/showt...&highlight=pcv

That just made my day. Fred dealing with a bunch of immature brainless fools.

Do you think one of those inline filters that plug right onto the valve cover and fit the stock tube will be okay with the blower?