Tuning

Mountain Main · 06-01-2003, 11:53 PM

I have an 89 5.0 LX. I have swapped out my AOD to a t-5. I have Mac headers, Off road X pipe, Mufflers and tail pipes. I have a March Ram Air Kit and a hyper tech chip and fuel pressure regulator. I have by passed my smog pump. Every thing else is stock including the fuel pump. My understanding is stock 302 runs better lean.

What should I set my fuel pressure at on WOT. I believe that you set WOT when you take the hose off the fuel pressure regulator and plug it with your thumb.

What should I set the timing to with these small modifications.

jimberg · 06-02-2003, 07:21 AM

Your hypertech chip should be programmed to set your A/F ratio to the leaner end. Otherwise, set your fuel pressure about 10 psi higher than it is now, then after a week, set it back to normal. That should put it on the lean side of the window. I personally believe that our engines run better on the rich side, though.

You can set your fuel pressure without even starting the engine. You just need to ground your fuel pump test connector while the key is in the on position. This will force your fuel pump to run. You also don't have to worry about the vacuum line doing it this way. The fuel pump test connector is on your EEC IV test connector. I posted a picture below.

The best way to set your timing is to take it to a dyno and experiment. If you can't do that, you can probably set it to 14 and be safe. Just make sure that you use at least 92 octane gas and listen for pinging. If you hear it ping, drop it 1 degree at a time until the pinging goes away.

Mountain Main · 06-02-2003, 10:18 PM

So if you give me directions for faking the computer to run lean. Then how do you set if to run rich? If that is what you recommend? I plan on experimenting between the two and posting my thoughts. Of course I would let the car cool down between both experiments.

Thanks,

Mountain Main

jimberg · 06-02-2003, 10:26 PM

Just raise the fuel pressure 10 psi and the computer will remove that extra fuel until it hits the rich side of the normal range. It takes time for that to happen, though. You need to drive for 50 or so miles. You can raise or lower your fuel pressure and get immediate changes in the air/fuel ratio, but those changes will eventually be erased by the adaptive strategy. Just keep that in mind if you're tuning on a dyno.

Mountain Main · 06-02-2003, 10:52 PM

I assume that since a stock 5.0 primes at 39 and the goes down to 36 at WOT. I would jump it up to 46 and then a week later move it back down to 36. This of course would be the test to run the engine lean.

Right now I have the car at 35 WOT and 30 at idle.

What does every body think their car runs best?

Rich or Lean?

Please any one reply. Thoughts, ideas and opinions.

Mountain Main · 06-03-2003, 01:42 AM

This explains alot of my questions I asked. But what does a stock MAF fuel pressure readings?

jimberg · 06-03-2003, 07:00 AM

With the engine off and running the fuel pump like I described above, you should normally have your fuel pressure set to 39 psi. Fuel pressure should go down as vacuum increases and go up as vacuum decreases. Vacuum should go to 0 at WOT so you should have 39 psi at WOT.

Mountain Main · 06-03-2003, 08:03 AM

I will first set my car to WOT 39 PSI for right now untill I get my ignition problems all sorted out. Thankx for all the helpful information. You are a very knowledgeable in the 302 TFI Mass air flow cars.

I still plan on doing the lean and rich trials. This will be fun to check out. I now know that adjusting the regulator will not work for that long due to the strategy of the computer compensation. The grounding of the fuel pump on the STO is also very helpful.

Sincerely

Mountain Main

06-01-2003, 11:53 PM	#1
Mountain Main Registered Member Join Date: Feb 2003 Location: Minturn, CO 81645 Posts: 109	Tuning I have an 89 5.0 LX. I have swapped out my AOD to a t-5. I have Mac headers, Off road X pipe, Mufflers and tail pipes. I have a March Ram Air Kit and a hyper tech chip and fuel pressure regulator. I have by passed my smog pump. Every thing else is stock including the fuel pump. My understanding is stock 302 runs better lean. What should I set my fuel pressure at on WOT. I believe that you set WOT when you take the hose off the fuel pressure regulator and plug it with your thumb. What should I set the timing to with these small modifications.

06-02-2003, 07:21 AM	#2
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	Your hypertech chip should be programmed to set your A/F ratio to the leaner end. Otherwise, set your fuel pressure about 10 psi higher than it is now, then after a week, set it back to normal. That should put it on the lean side of the window. I personally believe that our engines run better on the rich side, though. You can set your fuel pressure without even starting the engine. You just need to ground your fuel pump test connector while the key is in the on position. This will force your fuel pump to run. You also don't have to worry about the vacuum line doing it this way. The fuel pump test connector is on your EEC IV test connector. I posted a picture below. The best way to set your timing is to take it to a dyno and experiment. If you can't do that, you can probably set it to 14 and be safe. Just make sure that you use at least 92 octane gas and listen for pinging. If you hear it ping, drop it 1 degree at a time until the pinging goes away. __________________ 351W 89 Mustang GT Convertible

06-02-2003, 10:18 PM	#3
Mountain Main Registered Member Join Date: Feb 2003 Location: Minturn, CO 81645 Posts: 109	Running rich. So if you give me directions for faking the computer to run lean. Then how do you set if to run rich? If that is what you recommend? I plan on experimenting between the two and posting my thoughts. Of course I would let the car cool down between both experiments. Thanks, Mountain Main

06-02-2003, 10:26 PM	#4
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	Just raise the fuel pressure 10 psi and the computer will remove that extra fuel until it hits the rich side of the normal range. It takes time for that to happen, though. You need to drive for 50 or so miles. You can raise or lower your fuel pressure and get immediate changes in the air/fuel ratio, but those changes will eventually be erased by the adaptive strategy. Just keep that in mind if you're tuning on a dyno. __________________ 351W 89 Mustang GT Convertible

06-02-2003, 10:52 PM	#5
Mountain Main Registered Member Join Date: Feb 2003 Location: Minturn, CO 81645 Posts: 109	PS I assume that since a stock 5.0 primes at 39 and the goes down to 36 at WOT. I would jump it up to 46 and then a week later move it back down to 36. This of course would be the test to run the engine lean. Right now I have the car at 35 WOT and 30 at idle. What does every body think their car runs best? Rich or Lean? Please any one reply. Thoughts, ideas and opinions.

06-03-2003, 01:42 AM	#6
Mountain Main Registered Member Join Date: Feb 2003 Location: Minturn, CO 81645 Posts: 109	I reread the dyno post tips. This explains alot of my questions I asked. But what does a stock MAF fuel pressure readings?

06-03-2003, 07:00 AM	#7
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	With the engine off and running the fuel pump like I described above, you should normally have your fuel pressure set to 39 psi. Fuel pressure should go down as vacuum increases and go up as vacuum decreases. Vacuum should go to 0 at WOT so you should have 39 psi at WOT. __________________ 351W 89 Mustang GT Convertible Last edited by jimberg; 06-03-2003 at 07:23 AM..

06-03-2003, 08:03 AM	#8
Mountain Main Registered Member Join Date: Feb 2003 Location: Minturn, CO 81645 Posts: 109	Thankx I will first set my car to WOT 39 PSI for right now untill I get my ignition problems all sorted out. Thankx for all the helpful information. You are a very knowledgeable in the 302 TFI Mass air flow cars. I still plan on doing the lean and rich trials. This will be fun to check out. I now know that adjusting the regulator will not work for that long due to the strategy of the computer compensation. The grounding of the fuel pump on the STO is also very helpful. Sincerely Mountain Main

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