Problems with TFS engine combo..wont idle right and sputters when you give it throttl

dashapht · 07-15-2001, 10:20 PM

I'm having a few problems with my 93 coupe. The combo is as follows: TFS twisted wedge heads, 1.6 ford roller rockers, tfs stage 1 cam, track heat intake, mac 70mm TB, 24 lb motorsport injectors (also swapped the sampling tube on my MAF meter for 24 lbers.), edelbrock water pump, be cool radiator (these items just installed), and i already had 73mm MAF sensor, exhaust, and a shifter. There are a few problems. The first problem is that when i start the car, it hunts for the idle like mad. I have it set to about 1000 rpm right now. If i set it any lower, the car dies because of the hunting idle. Being set to 1000 rpm just barely keeps it alive until it finally reaches idle. TPS voltage is set to .980 Is this ok? Any suggestions on resetting idle to make it work?
The second problem is that when at idle, the car is fine as far as running smooth, but once you give it a little gas or driev at part throttle, it sputters and backfires. The timing is set to 12 degrees. The fuel pump is stock. I have a BBK adjustable fuel pressure regulator, but the guage BBK sent me came with the wrong fitting so I have absolutely NO idea where the fuel pressure is. It was running EXTREMELY rough at idle and the we played with the regulator a little, which allowed us to at least drive it around the block. A friend that works at a Ford dealership is bringing me one to use to set until i get my in-line pressure guage. Can low/high fuel pressure cause this? I'm leaning toward that pretty heavily since we have gone through and re-adjusted the rockers (installed new lifters, and wanted to re-adjust them after they got filled with oil), double checked timing, checked for vacuum leaks, and double checked TPS voltage. I'm kind of at a loss here since this is my first 5.0 to heavily modify, but it seems that as many mustangs are owned and modified, it'll be pretty easy to figure out a solution. Thanks for any help/ideas you can give me.

95 King GT · 07-15-2001, 10:42 PM

It sounds like the MAF sensor, check for codes, reset computer. I hope this helps. or it could be an intake leak. spray carb cleaner around the upper intake amd check to see if it changes the idle, if so that could be it, well good luck

Nic92LXConv50 · 07-16-2001, 06:46 AM

The sputtering and backfiring is the nature of the stage 1 cam. I thought I had a problem as well until I did some research over at the fordmall.

As for the surging idle...how is your air filter connected to the MAF? Try letting your car idle through an open MAF to see if it helps any. I had my K&N attatched right to the MAF sensor and what was happening was the opening in the filter was restricting airflow to the sample tube. All I had to do was cut out a larger hole in the K&N to allow more air to go through the tube and it smoothed the idle right on out.

------------------
1989 LX 5.0 Coupe
13.30's @ 106.7 while doing the aod shuffle...needs gear and converter.
1992 LX 5.0 Convertible

Moderator SN95.com, Stangtec.com

dashapht · 07-16-2001, 07:43 AM

i have Mac fenderwell cold air. I know 3 people with a combo similar to mine, and they have no backfiring/sputtering problems. I seriously doubt it's cause of the cam, or else tfs would have done somethign about it.

07-16-2001, 11:52 AM

Sounds like you are running too lean. Give the FPR a few turns and try that out. I have close to the same combo, and when I first drove it, my autometer gauge was off and I was running around 24 fuel pressure. Needless to say it popped, backfired, and ran like garbage. It runs great now that I figured out the problem and upped the fuel pressure to 44. I also have the TFS cam and have not had problems with it.

WallyGatorFL · 07-16-2001, 02:46 PM

Here is a tip for the Idle problem you have... I had the same thing happen to me. Unplug the idle control motor...(the thing attached to the throttle body) start the car and let it idle with the max a/c on. It will bounce around but adjust the throttle body screw until the idle is around 750 rpm. Shut the car off then plug the idler motor back in and set the tps sensor to .99 volts. That should do the trick.

dashapht · 07-16-2001, 05:22 PM

Ill try your guys' suggestions. Thanks a lot. I'll post when i do try them with their results. Any other suggestions are also greatly appreciated.

exgmguy · 07-16-2001, 06:03 PM

Try this. First a tip for resetting the TPS, computer etc... Disconnect the battery for 20 minutes to clear all computer memory. Reconnect the battery. Now disconnect the IAC motor and start the car. You may have to hold your foot on the gas to keep it running. turn the idle screw until the car idles by itself @ 700-750 RPM. Now adjust the TPS sensor to read about .95 volts. Shut the car off. Plug the IAC motor back in and let the car idle for 2 minutes with all accessories operating on high. Shut the car off for 2 minutes. Start the car again and let it idle for 2 minutes with no accessories on. This is the proper way to do it.
If you still have a hunting idle remove the smallest vacuum cap from the vacuum log at the firewall. My car will not idle without giving it the very slight vacuum leak.

remember to let us know if it works.

------------------
1988 Mustang GT
11.8 @ 123 (7/14/01)
1992 BadAzz Wrangler
1993 Explorer

dashapht · 07-17-2001, 12:23 AM

A few of my friends figured out the problem. Apparantly I was sold the srong sampling tube for my MAF meter. I got it on ebay as a 24 lb kit, but that it obviously was NOT. Pulled the mass air connector and revved it up. No more backfires, etc. Tried a MAF meter from a 97 cobra (they have 24 lb injectors) and it runs GREAT. So tomorrow I'll have a 24 lb sampling tube sent to me next day air. Thanks everyone for your replies.

07-15-2001, 10:20 PM	#1
dashapht Registered Member Join Date: Jan 2001 Location: nashville, tn Posts: 72	Problems with TFS engine combo..wont idle right and sputters when you give it throttl I'm having a few problems with my 93 coupe. The combo is as follows: TFS twisted wedge heads, 1.6 ford roller rockers, tfs stage 1 cam, track heat intake, mac 70mm TB, 24 lb motorsport injectors (also swapped the sampling tube on my MAF meter for 24 lbers.), edelbrock water pump, be cool radiator (these items just installed), and i already had 73mm MAF sensor, exhaust, and a shifter. There are a few problems. The first problem is that when i start the car, it hunts for the idle like mad. I have it set to about 1000 rpm right now. If i set it any lower, the car dies because of the hunting idle. Being set to 1000 rpm just barely keeps it alive until it finally reaches idle. TPS voltage is set to .980 Is this ok? Any suggestions on resetting idle to make it work? The second problem is that when at idle, the car is fine as far as running smooth, but once you give it a little gas or driev at part throttle, it sputters and backfires. The timing is set to 12 degrees. The fuel pump is stock. I have a BBK adjustable fuel pressure regulator, but the guage BBK sent me came with the wrong fitting so I have absolutely NO idea where the fuel pressure is. It was running EXTREMELY rough at idle and the we played with the regulator a little, which allowed us to at least drive it around the block. A friend that works at a Ford dealership is bringing me one to use to set until i get my in-line pressure guage. Can low/high fuel pressure cause this? I'm leaning toward that pretty heavily since we have gone through and re-adjusted the rockers (installed new lifters, and wanted to re-adjust them after they got filled with oil), double checked timing, checked for vacuum leaks, and double checked TPS voltage. I'm kind of at a loss here since this is my first 5.0 to heavily modify, but it seems that as many mustangs are owned and modified, it'll be pretty easy to figure out a solution. Thanks for any help/ideas you can give me.

07-15-2001, 10:42 PM	#2
95 King GT Registered Member Join Date: Jun 2001 Location: coweta OK USA Posts: 93	It sounds like the MAF sensor, check for codes, reset computer. I hope this helps. or it could be an intake leak. spray carb cleaner around the upper intake amd check to see if it changes the idle, if so that could be it, well good luck

07-16-2001, 06:46 AM	#3
Nic92LXConv50 Registered Member Join Date: Jun 2000 Location: Richmond, VA Posts: 78	The sputtering and backfiring is the nature of the stage 1 cam. I thought I had a problem as well until I did some research over at the fordmall. As for the surging idle...how is your air filter connected to the MAF? Try letting your car idle through an open MAF to see if it helps any. I had my K&N attatched right to the MAF sensor and what was happening was the opening in the filter was restricting airflow to the sample tube. All I had to do was cut out a larger hole in the K&N to allow more air to go through the tube and it smoothed the idle right on out. ------------------ 1989 LX 5.0 Coupe 13.30's @ 106.7 while doing the aod shuffle...needs gear and converter. 1992 LX 5.0 Convertible Moderator SN95.com, Stangtec.com

07-16-2001, 07:43 AM	#4
dashapht Registered Member Join Date: Jan 2001 Location: nashville, tn Posts: 72	i have Mac fenderwell cold air. I know 3 people with a combo similar to mine, and they have no backfiring/sputtering problems. I seriously doubt it's cause of the cam, or else tfs would have done somethign about it.

07-16-2001, 11:52 AM	#5
93 GT Guest Posts: n/a	Sounds like you are running too lean. Give the FPR a few turns and try that out. I have close to the same combo, and when I first drove it, my autometer gauge was off and I was running around 24 fuel pressure. Needless to say it popped, backfired, and ran like garbage. It runs great now that I figured out the problem and upped the fuel pressure to 44. I also have the TFS cam and have not had problems with it.

07-16-2001, 02:46 PM	#6
WallyGatorFL Registered Member Join Date: Jul 2001 Location: sarasota Posts: 2	Here is a tip for the Idle problem you have... I had the same thing happen to me. Unplug the idle control motor...(the thing attached to the throttle body) start the car and let it idle with the max a/c on. It will bounce around but adjust the throttle body screw until the idle is around 750 rpm. Shut the car off then plug the idler motor back in and set the tps sensor to .99 volts. That should do the trick.

07-16-2001, 05:22 PM	#7
dashapht Registered Member Join Date: Jan 2001 Location: nashville, tn Posts: 72	Ill try your guys' suggestions. Thanks a lot. I'll post when i do try them with their results. Any other suggestions are also greatly appreciated.

07-16-2001, 06:03 PM	#8
exgmguy Registered Member Join Date: Feb 1999 Location: Utica, Michigan Posts: 2,631	Try this. First a tip for resetting the TPS, computer etc... Disconnect the battery for 20 minutes to clear all computer memory. Reconnect the battery. Now disconnect the IAC motor and start the car. You may have to hold your foot on the gas to keep it running. turn the idle screw until the car idles by itself @ 700-750 RPM. Now adjust the TPS sensor to read about .95 volts. Shut the car off. Plug the IAC motor back in and let the car idle for 2 minutes with all accessories operating on high. Shut the car off for 2 minutes. Start the car again and let it idle for 2 minutes with no accessories on. This is the proper way to do it. If you still have a hunting idle remove the smallest vacuum cap from the vacuum log at the firewall. My car will not idle without giving it the very slight vacuum leak. remember to let us know if it works. ------------------ 1988 Mustang GT 11.8 @ 123 (7/14/01) 1992 BadAzz Wrangler 1993 Explorer

07-17-2001, 12:23 AM	#9
dashapht Registered Member Join Date: Jan 2001 Location: nashville, tn Posts: 72	A few of my friends figured out the problem. Apparantly I was sold the srong sampling tube for my MAF meter. I got it on ebay as a 24 lb kit, but that it obviously was NOT. Pulled the mass air connector and revved it up. No more backfires, etc. Tried a MAF meter from a 97 cobra (they have 24 lb injectors) and it runs GREAT. So tomorrow I'll have a 24 lb sampling tube sent to me next day air. Thanks everyone for your replies.