Thanks for the input guys.
I think we may have done something wrong during the install.The cam should work for the setup i have,according to Downs Ford.
I'm just gonna have to start all over...i'll tear it down and put it back together.Hopefully i see something that we put together wrong.
I'll keep you guys posted.

 

If you are gonna pull it apart, I'd get a better cam. Crane Cams has some sniffer legal ones with more LSA for idle. Hope that helps a tad more.

 

The reason they went to mass air was emissions.Thats why CA cars and trucks were mass air one year or so before the rest of the US.When you put your foot in the throttle your mass air system becomes a speed density set up.That is the pcm reverts to a wot fuel map.There's no way you can get feedback from sensors quick enough to make adjustments at wot.That being said mass air is more friendly to mods and keeping drivability.There are however some things with mass air you have to watch.Your MAF meter should be calibrated to the size injectors you are running.Even with mass air the pcm may need a chip to account for engine mods if you get too radical.Sometimes the position of the MAF meter can make a big difference.Try rotating the meter.Oil from a KN filter can contaminate and throw off the MAF reading.The TPS voltage should be adjusted to .95-.99 volts at idle.An adjustable fuelpressure regulator can help adjust the fuel trim.

Billy

 

So whats the biggest difference? I dont get it.. I have a SD set up on my 351 94 F150 and its got power out the ying yang and is as smooth as a babies ***.. Ive put bolt on mods on it so far (exhaust and intake and chip) and no probs... Just faster and smoother.....

Should I be thinking of converting to a MAF? Am I missing out? lol
Thanks

 

Naw your not missing out. The only time you really need a MAF is with head changes, and intake changes, and other major mods (injectors). The exhaust doesn't hurt make a difference. Something like a K&N you'll see more benefits from the MAF, but we're talking 2-3hp if that. There are lots of speed density cams available that will allow you to run heads, injectors, and intakes with speed density and a custom chip. If I ever did those mods, I'd stick to speed density, not sure why, thats just me.


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

Thats it for now, saving for a stang. Check out my Gallery for a look-see.


Justin

 

I agree, Stick with teh SD setup as long as you are sticking to basic mods. On a 1987 f150 I was fixing we ran true duals with no cats, headers, K&N, and the system worked fine. When we swaped to gt40 heads we ran into problems. It wouldn't idle, and ran lean. He installed a modified computer chip and still had problems. We decided to send the chip back and went with the Mass Air (only $200.00 more and you get a new mustang computer) we instantly gained power, and 2 miles per gallon. Is the Mass air system better? It's a toss up. But I will say that Sequential injection is much better than Bank Injecton. Timed injectors means more power, better mileage, and less emmissions!!!

Mass air will not give you any power by itself. However it will allow you to take full advantage of the upgrades that you have installed (even exhaust, and filter mods!)

 

>It can still be vacuum!! I wouldn't single that out! Check
>the vacuum and fuel pressure before you start throwing money
>at it! We'll figure this out!!!

Well guys,i think i found part of the problem.Vac leak...right where the heat spacer is between the plenum and lower intake,it sucked that gasket right in.You guys were right.
It's still alittle choppy at idle though.I was told i have to upgrade my mass air meter (stock 65mm the size that came with the mass air conversion kit)to run the 24lbs injectors i have.Someone told me put in a 75mm (calibrated for 24lbs injectors)from Pro-M.
Any advice guys?

Thanks again.
Jerry D.

 

That 65mm is plenty big. A 5.0 Mustang came with a 55mm if memory serves me...but a 75mm will equal more flow which inturn makes more power.

24's wouldn't hurt, but I'd still get an adjustable meter, makes life so much easier when tuning. You're probably going to need a bigger pump too. Walbro makes an inline that flows about the same as a 255in-tank.

 

I would stick with the 65mm and have it recalibrated for 24 lb injectors!! As far as Idle is concerned it could be the IAC. If you haven't cleaned it and the intake yet you may want to do so. Otherwise Maybe it's the cam itself causing the idle lope.

I'd like to say congrats on the problem!! It sure feels great to figure tough problems like these out!! ( and not spend a ton of money)

 

I just put a Pro-M 75 mm bullet MAM on order today....i think this might do the trick.

 

is it calibrated to your injector size? If so, and it fixes your problem tell us!!! I'd be interested for sure!

 

I just clicked on the link of your truck and may I say WOW. Thats probably the nicest 87-91 I have ever seen. I assume this is a show truck or do you actually drive it daily?

 

I'd have to say that is one huge truck! I'd run over all the ricers in my town with that.

 

[updated:LAST EDITED ON 02-Oct-02 AT 02:18 AM (EST)]Thanks guys!
It is my everyday driver. And man does it suck some gas.....thank god i work in the town i live in.

I should be getting my MAM next week and i hope it works.
Keep your fingers crossed.

 

UPDATE:
I just installed a Pro-M 75mm Bullet mass air meter,calibrated for 24lbs injectors.It works great.It took that chug/bog out of the lower rpm's.
I'm still having problems w/ the idle though.
Sometimes when i put it in DRIVE/REVERSE it stalls.I don't think it's the AIC valve,i just replaced it less than a year ago.
Any ideas?