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Be careful with LS air filter choice

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Jemo

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Discussion starter · #1 ·
Until now, I had a cobbled up set of pipes and a cone filter as an air intake on my car. It looks goofy and out of place on a '56 and would look more at home on a Honda Civic. So....last week I bought a air filter/MAF combo from S&P. It looks great under the hood but on the first drive, the car ran as usual (good) for the first 5 minutes then took a nose dive. It barely made it home, stalling each time I got to a stop sign and could barely hold idle.

I put the old MAF on but with the S&P filter - it runs much better but still has a stumble and 1 volt voltage drop when I come to a stop. I put a scanner on the car and it came up with no codes.

Puzzled, I posted on ls1tech and without saying the type of filter I put on the car, a guy asked if I installed an S&P filter/MAF on the car? He said they're unreliable and cannot be used because of the turbulence they cause. He said he's tried them on a dyno and will run it 5 times and get 5 different outcomes/readings.

Morale to the story: be careful what you buy. This piece was almost $300 and made my car run very poorly. Guess I'm back to the import looking filter.

Jeff
 
#3 ·
Jeff was the S&P MAF descreened???

If so it will read wrong. Some people removeth e screen to pickup extra HP but the gain is minal vs the reading problems with the MAF.

Also over oiling a K&N etc will mess up the MAF as well.
 
Discussion starter · #4 ·
Scott,

I don't think so. It had the mesh stuff on one side. It still doesn't run right with their S&P filter. I mailed the MAF back to S&P this morning but told them I'd keep the filter because I liked the look and now that I went back to a stock PS reservoir, the Honda part won't fit anymore anyways. After reading the post on ls1tech, I regret keeping the air filter because I guess it won't work either.

Now I'm in a bind and not sure what to put on for an air cleaner.

Jeff
 
Discussion starter · #6 ·
I looked on their site but can't find a link. Most of their stuff opens up in a pdf. It's just a square filter that connects directly to the throttle body. The filter has the MAF built into it so there is almost no separation between the filter, MAF, and TB.
 
#7 ·
Sorry to hear your having trouble with the S&P filter. I am running one on my 55. It's the only filter I have tried on it. I bought the one with thier deepest filter,about 4''. I went with it just for the fact it was an easy bolt on. I may try another MAF someday after reading your post.
 
#8 · (Edited)
I can see how a bad MAF would cause a problem, I have a tough time believing the filter itself is the culprit. Those rectangular filters have been around a long time, not just from S&P.

The main knock on the rectangular filters is they're going to pull air after it's gone through the radiator, not the coolest. Other than that, it's just a filter.

You can buy any shape or size you need here... http://www.sbfilters.com/

Charlie
 
Discussion starter · #9 ·
Hey guys, someone on ls1tech posted with what he found to be a solution for the S&P filter. I'm going to try this:

I'm using an S&P filter on my '79 Fox with LS2 conversion due to space constraints, what I did to fix the problem you are experiencing was to run a bead of silicone around the base and top of the air cleaner to make it seal to the filter element, I also put clamps on the hose which runs from the filter base fitting to the right hand valve cover. IMO the filter lid and base are poorly designed there should be a recess machined into them for the filter element to fit into to keep it from "squishing" out when its assembled, which causes the air leak which wreaks havoc with the PCM causing the lean code to be thrown. Hope this helps 79LS1FOX.
Click to expand...
 
#10 ·
Sound to me that you need to re-tune your computer. When you change the air intake to a free flow you need to compensate for it. Your getting a lean issue. Same thing that happen when guys put the cold air intake on and don't re-tune. They may run OK but there not right. Call S&P they will tell you the same thing I'm sure. Your getting more air faster and the computer is not calibrated for it.
 
#11 ·
I'm sorry, but I cannot agree with the statement that making a change to the air intake as Jemo has done, requires a PCM retune. Look at all the vehicles out there with an installed aftermarket cold air intake which run just fine w/o an aftermarket tune. The change in airflow is not significant enough to require a recalibration. The MAF will pick it up and make the change, some would argue the MAF/PCM even makes enough of a change to compensate, it normalizes it to be almost stock again. I'm speaking from a flow perspective alone, not temperature which is where the majority of the benefit comes from.

Charlie
 
#12 ·
CharlieC said:
I'm sorry, but I cannot agree with the statement that making a change to the air intake as Jemo has done, requires a PCM retune. Look at all the vehicles out there with an installed aftermarket cold air intake which run just fine w/o an aftermarket tune. The change in airflow is not significant enough to require a recalibration. The MAF will pick it up and make the change, some would argue the MAF/PCM even makes enough of a change to compensate, it normalizes it to be almost stock again. I'm speaking from a flow perspective alone, not temperature which is where the majority of the benefit comes from.

Charlie
Click to expand...
I never said they didn't run. They don't run to the full potential.
I don't see very many people adding just a filter to the front of the throttle body. Just as Jemo did.

Like i said call S&P and ask.
Or read tune 101

So in your theory if i take a 85mm throttle body off and install a 90mm I don't' need it re tuned do to more air? So the MAF will take care of it. It will run but not right and poorly at that.
 
Discussion starter · #13 ·
Darrin,

I didn't just put a filter on a throttle body. The S&P filter has a MAF built into it. The MAF sent to me was bad so I attached my old MAF to the S&P filter. The only thing I've changed is the filter. A tuner on ls1tech said these cause too much turbulence, I guess because the filter is side by side with the MAF? The quote I pasted above says he spread silicone around the filter housing which I wouldn't expect on a part that costs almost $400. I'm willing to try it though.

Yep, I sent the PCM back to the tuner this morning. Maybe there is something he can do to raise the idle when the car comes to a stop but I don't think changing just a filter would cause this much trouble - something here is defective and it's the only change I made. No other engine codes being shown.

Jeff
 
#14 ·
I have to disagree with Darrin - first thing is that's not a freer flowing filter. And that shouldn't make a spitting bit of difference at idle either.

And Jemo, the same goes for the "turbulence". It isn't happening at idle.

All this might be true if it was a high speed problem.

I think I'd get S&P to send you another set of parts and have a go at it that way.

Another thing that could be going on is that all the air isn't flowing through the MAF. In other words a leak between it and the manifold.
 
#16 ·
Running the same set up on mine it runs great only problem pulls hot air off top of radiator. Did have problem with idle and stumble off idle it was bad spot on TPI not reading smooth when opening throttle changed out TPI everything OK.
 
#17 ·
The S&P unit may have a "non stock" maf in it...If that's the case, then the maf calibration map may need some correction. Done in grams/sec vs rpm. starting at 1500 rpm.

For those not familiar w/ the enormous amt of control in the pcm>>>> Try a visit to www.efilive.com, and d/l the program. It's free.
 
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#18 ·
Darrin's55 said:
I never said they didn't run. They don't run to the full potential.
I don't see very many people adding just a filter to the front of the throttle body. Just as Jemo did.
Click to expand...
Most of the LS/LT transplants out there, have the same style of rectangular air filter at the front as Jemo tried, since it's the easiest thing to install after going through a sometimes tough engine transplant, so it's very common.

... or read tune 101.
Click to expand...
I didn't read Tune 101, but in Remedial Tuning 90 there's a section that tells you there is no need to retune just because you install a CAI kit or some other filter replacement.

So in your theory if i take a 85mm throttle body off and install a 90mm I don't' need it re tuned do to more air? So the MAF will take care of it. It will run but not right and poorly at that.
Click to expand...
Disagree again on the car not running right or even poorly if that's the only thing being done and it's installed correctly. What possible tuning change would be made if the only mod was increasing the TB size 5%, or alternatively, how much of a change do you expect that mod alone to deliver to the motor? You can tweak a stock tune, with no mods and squeeze more of a HP gain than you would increasing TB size 5% only. Most of the time if someone is increasing their TB size, they are also changing manifolds as well. Then yes, I would agree some tuning would help.

Jeff is running a stock throttle body with an aftermarket tune. His car should not run like crap due to changing the filter only, and changing the filter only does not require a tuning change.

Charlie
 
#19 ·
It would be helpful if you were able to pull some information off the ECU - can you get this? Somehow the reading from the MAF are not what the ECU is programed to use. Could be bad wire, air leak, tune, MAF, MAF location, dirty MAF sensor, increased air turbulence, etc.

Can you provide some information on your set-up: Engine type, ECU, throttle body type, MAF pin type and any modification to the fuel system.

Let's try to figure out why with the old MAF and new air filter the car seems to stumble at temperature (I think that is the problem you described - clarify if it is not). Getting some readings from the ECU will help isolate the problem (air temp, air pressure, engine temp).

Thanks,
 
Discussion starter · #20 ·
Thanks for all the ideas and suggestions. The guy that originally tuned my car is MIA. I've called, sent emails, and texts and but haven't heard back. So, I packaged up my PCM and sent it to one of the tuners recommended on ls1tech: "Tuning by Frost" Seems like he really knows his stuff but it's still a mail order tune.

Unfortunately, I don't have a way to log running data on the car. If there is a cheap way to do it without taking it to another tuner, I'd love to know. This weekend though I did silicone the MAF and air filter assembly. I do see some gaps so maybe that is part of the problem. Since it ran great before the change though, I'm thinking it isn't a bad wire or MAF? I don't really know though.

The engine is a bone stock 5.3L with a *411 PCM, 85 mm TB, 5-pin MAF. The fuel system has an internal pump using a Corvette FPR.

The car doesn't seem to mind the temp, it just stumbles when I'm coming to a stop. The rest of the time it appears to run and respond to throttle fine.

I'd sure like to learn of a cheap way to getting some readings from the ECU to isolate the problem.

Here is how it looks now with the S&P filter and my MAF:

Image


Image


Here is what it looked like before the change and ran fine:

Image


Besides not looking the look of that large air filter, the primary reason for changing to the S&P piece is I was using a remove PS reservoir that had a bad leaking problem, which leaked on the brakes, which caused the car to pull hard right. I switched to an OEM reservoir and the problem is gone but it sits where the import looking filter used to route. You might be able to see the new reservoir in the photos. Switching to a third PS reservoir so I can go back to the old way isn't a desirable option at all. :)

Jeff
 
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Jemo
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