SCTw/ JLT-hanging rpm's - 2003-04 Mach 1 Registry Owners Club

tractor · 04-20-2006, 09:15 AM

Hello I ve had my mach a month today actually and just recently put in the jlt rai and the sct tune from paul's high performance-hand held. When I put the jlt in I started the maf at the stock position which in mine was at 12 oclock. The rpms would hang after letting off the gas like described in the hanging rpm post. Being new to efi and programmers I didnt know if this might go away once the computer learned the new program. I read around the forum and the instructions for the jlt and put the maf at 11. It did help the rpm hang a bit and the car felt alot stronger. I put about 100 miles on the car last night. My question is should I wait to see if the hanging rpms go away with more time for the computer to learn or should i move the maf to 10 oclock and see or should I try to restrict the airflow to the IAC? I think that s what it called. The hanging rpm was there a bit stock but worse since I put on the jlt and sct in. I checked the jlt for any air leaks and all seems well. Overall real happy with the car. But I did think that the mods would net me a little more. thanks

ThatsBAD06 · 04-20-2006, 11:47 AM

Yeah maybe the only thing you need to solve the problem is an IAC valve.

Gunny · 04-20-2006, 08:05 PM

ya i have the hanging idle too. not to mention ever since i installed
my JLT RAI i hear this hissing sound when i hit the gas.

tractor · 04-20-2006, 11:56 PM

No hissing sound here I'm gonna order a plate off ebay tommorrow and get some gaskets too. So next week I should be able to play with it. Drove the car again tonight and seems to be a little better.

wigsite · 04-21-2006, 09:49 AM

I just out a JLT RAI on my car about a week ago. I already have an IAC restrictor plate. I have noticed that my rpm's are hanging more since the CAI install. It is not as bad as stock without the IAC plate. I think the CAI introduces more air and therefore the rpm's hang more.

Gunny, the hissing sound is air being sucked into the filter. I love that sucking noise when you blip the htrottle with a CAI installed.

Mach1Canuck · 04-21-2006, 10:39 AM

The hissing noise could also be an air leak.
I think a few of the stalling problem people are having are due to the system not being sealed up properly.

04-20-2006, 09:15 AM	#1
tractor Registered User Join Date: Jun 2005 Location: Michigan Posts: 57	SCTw/ JLT-hanging rpm's Hello I ve had my mach a month today actually and just recently put in the jlt rai and the sct tune from paul's high performance-hand held. When I put the jlt in I started the maf at the stock position which in mine was at 12 oclock. The rpms would hang after letting off the gas like described in the hanging rpm post. Being new to efi and programmers I didnt know if this might go away once the computer learned the new program. I read around the forum and the instructions for the jlt and put the maf at 11. It did help the rpm hang a bit and the car felt alot stronger. I put about 100 miles on the car last night. My question is should I wait to see if the hanging rpms go away with more time for the computer to learn or should i move the maf to 10 oclock and see or should I try to restrict the airflow to the IAC? I think that s what it called. The hanging rpm was there a bit stock but worse since I put on the jlt and sct in. I checked the jlt for any air leaks and all seems well. Overall real happy with the car. But I did think that the mods would net me a little more. thanks __________________ bbk x pipe 40 series flows php spacer jlt rai sct x cal2 from php fiore quadrant/cable adjuster mgw shifter Last edited by tractor; 04-20-2006 at 02:30 PM.

04-20-2006, 11:47 AM	#2
ThatsBAD06 The Thread Killer Join Date: Jan 2004 Location: Burke,VA Posts: 814	Re: SCTw/ JLT-hanging rpm's Yeah maybe the only thing you need to solve the problem is an IAC valve. __________________ 2004 Black Mach 1 297.77 RWHP & 320.27 RWTQ 1/4 mile: 13.230 @ 106.43, 1.979 60' 1/8 mile: 8.568 @ 84.54, 1.979 60' -MAC Catted Prochamber w/ Magnaflow MagnaPacks -Ported/Polished Intake & PHP Intake Spacer -K&N Drop In Air Filter w/ snorkel & maf screen removed -MGW Short Throw Shifter (Blue) -FRPP 4.10's & Aluminum Driveshaft -Moser 31 splines w/ Detroit Truetrac posi -Black Bullitts(17x9,10.5) wrapped in GSD3's (255x40x17 F 285x40x17 R)

04-20-2006, 11:56 PM	#4
tractor Registered User Join Date: Jun 2005 Location: Michigan Posts: 57	Re: SCTw/ JLT-hanging rpm's No hissing sound here I'm gonna order a plate off ebay tommorrow and get some gaskets too. So next week I should be able to play with it. Drove the car again tonight and seems to be a little better. __________________ bbk x pipe 40 series flows php spacer jlt rai sct x cal2 from php fiore quadrant/cable adjuster mgw shifter

04-21-2006, 09:49 AM	#5
wigsite Registered User Join Date: Jul 2004 Location: Delaware, Ohio Posts: 1,504	Re: SCTw/ JLT-hanging rpm's I just out a JLT RAI on my car about a week ago. I already have an IAC restrictor plate. I have noticed that my rpm's are hanging more since the CAI install. It is not as bad as stock without the IAC plate. I think the CAI introduces more air and therefore the rpm's hang more. Gunny, the hissing sound is air being sucked into the filter. I love that sucking noise when you blip the htrottle with a CAI installed. __________________ Borla catback BBK LT's/ catted mid JLT RAI..4.10..Moser 28 spline..UPR u/l Dyno tuned by CRT Performance Pro 5.0 Power Tower shifter best 1/4 12.62 @ 108.05 mph 313 RWHP..330 TQ

04-21-2006, 10:39 AM	#6
Mach1Canuck Registered User Join Date: Feb 2003 Location: Victoria, BC Posts: 270	Re: SCTw/ JLT-hanging rpm's The hissing noise could also be an air leak. I think a few of the stalling problem people are having are due to the system not being sealed up properly. __________________ 2003 Mustang Mach 1 Torch Red, 5-Speed w/ IUP Steeda Tri-Ax Steeda Sport Springs UPR Adjustable LCA's Offset Urethane Rack Bushings Maximum Motorsports Full Length SFC's Ford Racing 4.10 Ring/Pinion JLT CAI Ported/Polished TB/Upper Intake PHP Intake Spacer NGK TR6 Plugs, Gapped @ .050 MAC O/R Prochamber Borla Stinger Exhaust SCT Custom Tune

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