CEL Code 23: How to Check Air Flow Sensor Voltage?

[elemgee]

A couple of times over the past 2 weeks my 94 SVX has stalled for no apparent reason. Just driving along and all of a sudden the engine will die; although I can restart it and continue on my way (although it may stall again). Other than that the it drives perfectly.

I checked the engine codes and it shows a code 23 - air flow sensor voltage. So my question is, how do I check the voltage (I have a voltmeter), and what should the normal voltage be?

Thanks.

Larry

[fasteract7]

Do a quick Search for the MAF and you'll find posts with the V readings for the 4 wires from the harness. I have tried the resolder the interior connectors on 3 MAFs w/o success. Right now I have been using a new, off eBay EJ22 Legacy MAF (very cheap compared to stock SVX one) for several months w/o a problem other than a rare intermittent CEL (will come on for a few seconds). The MAF from the legacy will reach full airflow readings 30% faster than the SVX one but no lean condition or real problem (checked plug color, MPG actually a bit better).

Pretty sure, unless your MAF wire harness has been badly stretched, that you are another bad MAF victim, awfully common problem.

[longassname]

You can get a re-manufactured mass air meter from any of the usual auto parts stores. Advance auto parts has some pretty decent discount codes if you order off their website.

[longassname]

I just did a quick search and found a discount code for advance for 35% off up to a max of $50 off (WD513 expires tomorrow.) With that code the right meter will set you back $169 either picked up from the store or shipped to your house.

[fasteract7]

http://www.ebay.com/itm/Mass-Air-Flow-Meter-Sensor-for-Subaru-Forester-Impreza-Legacy-2-5L-/310783314801?fits=Model%3ALegacy&hash=item485c210b71&vxp=mtr



This is the non-SVX unit..been using for 4+ months without apparent problems. The problem I noted with my testing intermittently faulty MAFs was the numbers were always in spec with car running obviously. Hard to document what the voltage was when it crapped out obviously.

The only down side to the cheaper replacement I've heard is that top end, 90 MPH or above, is limited. The other Forum has a pretty extensive discussion about this "fix" with Harvey, the Aussie guru, detailing why it isn't a dangerous replacement. At 20% of the cost, my cheap a** can live with it !! I noticed the plug in was a bit snugger than stock..a little dielectric grease eased that.

[elemgee]

Update - bought some MAF spray cleaner and sprayed the hell out of it. Put it back in after it dried. Took the car out for a drive later in the day and after about 5 miles it stalled (at a light). Took several tries to restart, but then ran fine.

So I ordered an MAF on ebay (from a 97 Outback, as suggested in other posts to this site. Per ebay, this is a NEW MAF. It looks exactly like the one in the SVX. Huge savings over "used" MAF's on ebay specifically for the SVX). Hopefully that will fix the problem. Will post an update after its received and installed.

[fasteract7]

I think you will be happy with this choice. As mentioned before, I have raRELY HAD THE "cel" IGNITE BUT GO OUT AFTER 20-30 SECONDS. Sorry about the CAp button. Notice that your MPG's should improve a bit...I got 75 miles per quarter tank, now 105 miles.

[trophy956]

I have used the 22680aa160 air flow sensor in my car for years

[fasteract7]

Good to hear..I posted elsewhere that my wideband O2 setup showed OK AFR's at WOT beside my plug chop color was on the money.

[longassname]

I've never had legacy injectors flow tested so I don't have the information I need to compare the scale of the legacy air flow meter to an SVX air flow meter but I extracted the vq table from the 96 uk legacy firmware and compared it to the SVX vq table and they have very similar shapes.

If their scale were exactly the same then using the legacy air flow meter without changing the vq table in the firmware would result in running leaner at higher air flows. A SVX with a stock ECU runs rich at high RPMs and full throttle so this afm would actually improve that--if the scale is identical to an SVX.

Has somebody bothered to flow test a legacy injector and an SVX injector at the same time so direct comparisons can be made and the scales of these air flow meters can be accurately compared?

http://www.subiechips.com/posts/vqComp.gif

[elemgee]

I installed the MAF sensor yesterday (the one for a 97 Legacy with the 2.5 liter engine I got off of ebay for under $40) and the car hasn't stalled out after driving around 25 miles over 2 days, so it looks like this fixed the problem.