Throttle response problem after k&n install
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Throttle response problem after k&n install Alright guys .I have been cruising this forum since I got my LT1 2 years ago. I'm not very mechanically inclined but everything I've learned about my car, I've learned on here. Basics about the car is its a 94z A4. ~85k on the clock. Mostly stock except for a madhammer catback and more recently a k&n cai. Since the cai install I've been having a problem with extreme bogging at low throttle. Once i get on the throttle a little more it's like the car can breathe again. But if I drive for a while being heavy on the throttle when I come to a stop it bucks and shutters like it's gonna die (it hasn't bc I put it in neutral and rev it til the light changes) I've checked for leaks at the hose clamps on the whole system and best i can tell there are none. I took the maf sensor out and cleaned it with maf cleaner. Still having this problem. Anyone got any ideas? Apologies if this has been covered in another thread, I can't find anything anywhere .If it has been a link would be cool. Thanks y'all.
What you describe can mean a significant vacuum leak. Check the diodes on the MAF to ensure they are not damaged. Ensure throttle position sensor and idle air control sensors are plugged in. A notorious issue is not getting the underside of the bellows (90* rubber elbow or equiv that goes from MAF to throttle body) onto the throttle body correctly underneath where you really can't see if it's on or not causing a massive leak which causes a lean condition and you get more fuel than the engine needs. Do you hear a loud hiss after installation where there wasn't one? Also, a CAI will have a port for a ~ 3/4" hose for the AIR system. If you don't have the AIR system you need to block that port off. Make sure the air filter is not collapsing in on itself.
Any codes?
PS- If you are unfamiliar with any of the terminology, go here: www.shbox.com. The best reference site for the LT1.
Any codes?
PS- If you are unfamiliar with any of the terminology, go here: www.shbox.com. The best reference site for the LT1.
Last edited by SS RRR; Jan 28, 2019 at 11:43 AM.
Might also pull the MAF, and verify those tiny wires between the two bars are shiny silver. Those are heated, run red hot. People tend to over-oil K&N filters. The excess oil gets cooked onto those wires. The voltage required to maintain desired temp on those wires is used to calculate air flow. Insulate those wires with a coat of oil, less voltage needed, the PCM gives less foel, for the calculated lower air flow. If those wires are black, you can wash them off with Beryman's B12 Chemtool. Just shake out the access after washing them off, don't blow the MAF dry with compressed air, it's too easy to knock one end of those tiny wires loose with compressed air. Likely running lean now. Seen that many times in my shop. Skews the fuel trims as well.
A paper filter will run just as fast.
A paper filter will run just as fast.
When I mentioned needing the MAF turned around, several said "I thought that was supposed to point to the air filter." Really??
pointing the direction of air flow never occurred to you? Some people should just leave their vehicles alone.
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Thanks for the help guys. I think it’s my elbow. I looked on the underside and it’s folded up. Took it off and saw that it must have been that way for a while. Bc it’s like perma folded and has some tears at the creases. Must not have noticed until it had more air coming in. Got it on a little better and it helped some. Ordered a 1le elbow and that should fix it hopefully. If not I’ll try some more of talks suggestions. Thanks again y’all
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From: Euless, TX
Might also pull the MAF, and verify those tiny wires between the two bars are shiny silver. Those are heated, run red hot. People tend to over-oil K&N filters. The excess oil gets cooked onto those wires. The voltage required to maintain desired temp on those wires is used to calculate air flow. Insulate those wires with a coat of oil, less voltage needed, the PCM gives less foel, for the calculated lower air flow. If those wires are black, you can wash them off with Beryman's B12 Chemtool. Just shake out the access after washing them off, don't blow the MAF dry with compressed air, it's too easy to knock one end of those tiny wires loose with compressed air. Likely running lean now. Seen that many times in my shop. Skews the fuel trims as well.
A paper filter will run just as fast.
A paper filter will run just as fast.
In my own setup the K&N read higher airflow values and kept the MAP from dropping off as much at high rpm. FWIW, this was datalogged on a Vortec 350 application that uses the same filter. Picked up 3-4 KPA and 10-12 gms/sec between 4,000 and 5,200 rpm shift points. Stock heads, stock cam, stock vortec intake manifold, stock exhaust manifolds and stock 3" dual exhaust to the muffler with the only change at that time being a dual 3" in, single 4" out muffler and a 4" tailpipe as well as the TB lip removed.
I hit the MAF sensors on even stock cars with paper filters with CRC Maf Cleaner every filter change. Just driving on the rain soaked oily nasty roads often contaminate the sensor resistors.
I have also had a cheap crappy aftermarket paper filter "STP" cough get rain soaked and self destruct blocking one of the MAF sensors in a car I was driving.
Last edited by Fast355; Jan 31, 2019 at 12:16 AM.
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I dunno.... when it comes to small gains on the dyno I don't trust them. I've seen significant gains/losses on a chassis dyno due to engine temperature alone. BTW, there was also a whole lot of testimony on how an "airfoil" in the TB created power gains when in reality it was bullshit.
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IMHO I would take Ed's notes to the bank. He has seen WAY more dyno time with these LT1's than any of us.
Op had his elbow FU, as noted as a possibility by SS RRR. Likely Ray Charles could have seen that but OP figured it out. In addition to the FU intake elbow causing a significant vac leak and unmetered air entering motor.....a "new" K&N filter out of the box is typically "moist" with fluid which as Ed Wright noted gets on the fine wires of the MAF corrupting their sensing thus giving PCM false air reading which skews fueling. Careful cleaning of the MAF wires is required if contaminated with oil
Over oiling the filter element will cause MAF problems so take steps to eliminate that possibility....
Using compressed air through the oiled filter element (from inside) helps purge the excess oil from filter before use. If cleaning and then re-oiling a K&N, oil VERY sparingly and let dry overnight before install IMHO if you are using a oiled filter
Op had his elbow FU, as noted as a possibility by SS RRR. Likely Ray Charles could have seen that but OP figured it out. In addition to the FU intake elbow causing a significant vac leak and unmetered air entering motor.....a "new" K&N filter out of the box is typically "moist" with fluid which as Ed Wright noted gets on the fine wires of the MAF corrupting their sensing thus giving PCM false air reading which skews fueling. Careful cleaning of the MAF wires is required if contaminated with oil
Over oiling the filter element will cause MAF problems so take steps to eliminate that possibility....
Using compressed air through the oiled filter element (from inside) helps purge the excess oil from filter before use. If cleaning and then re-oiling a K&N, oil VERY sparingly and let dry overnight before install IMHO if you are using a oiled filter
TECH Resident
Joined: Oct 2006
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From: Euless, TX
IMHO I would take Ed's notes to the bank. He has seen WAY more dyno time with these LT1's than any of us.
Op had his elbow FU, as noted as a possibility by SS RRR. Likely Ray Charles could have seen that but OP figured it out. In addition to the FU intake elbow causing a significant vac leak and unmetered air entering motor.....a "new" K&N filter out of the box is typically "moist" with fluid which as Ed Wright noted gets on the fine wires of the MAF corrupting their sensing thus giving PCM false air reading which skews fueling. Careful cleaning of the MAF wires is required if contaminated with oil
Over oiling the filter element will cause MAF problems so take steps to eliminate that possibility....
Using compressed air through the oiled filter element (from inside) helps purge the excess oil from filter before use. If cleaning and then re-oiling a K&N, oil VERY sparingly and let dry overnight before install IMHO if you are using a oiled filter
Op had his elbow FU, as noted as a possibility by SS RRR. Likely Ray Charles could have seen that but OP figured it out. In addition to the FU intake elbow causing a significant vac leak and unmetered air entering motor.....a "new" K&N filter out of the box is typically "moist" with fluid which as Ed Wright noted gets on the fine wires of the MAF corrupting their sensing thus giving PCM false air reading which skews fueling. Careful cleaning of the MAF wires is required if contaminated with oil
Over oiling the filter element will cause MAF problems so take steps to eliminate that possibility....
Using compressed air through the oiled filter element (from inside) helps purge the excess oil from filter before use. If cleaning and then re-oiling a K&N, oil VERY sparingly and let dry overnight before install IMHO if you are using a oiled filter
He
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With that said if I could find a cone paper filter to replace the K&N, I would use that instead of a oiled filter
