SO Cam Firing Order

[nitroracer]

I was thinking about ways to get better mileage out of the Merk and I was thinking back to when she was stock, I could pull about 300 miles on every tank possibly 320-330 on a good week. So for my question, are they're any other cams with the same firing order as the SO box/t-birg cam? I still have my original injectors & computer but pretty much everything else is gone.

It is possible to run the E7's and the HO intake on the 14lb injectors but I think to get the mixture right Id need the SO cam & Computer. Right?

Or maybe I can swap in the 14lb injectors for a week and leave everything else alone...

The only part of the (possible) combinations Im missing is the orginal cam, and thats a bit more work but I could get it done in a day if I wanted.

[89LincolnTWNcar]

theres a guy on here that has a 1/2 HO conversion with just E7 heads, HO upper intake and throttle body and it runs fine. I had the same setup for a while and it ran fine also. The fuel mixture was fine, made decent power. But I like the full HO conversion better :slug:

[nitroracer]

I like it too, but for basically the cost of a few gaskets I could save some cash on gas. This summer is gonna be killer. I looked at it, and from when I get out of school to when I come back is going to be about $750 in gas alone if I buy a tank a week.

[88grandmarq]

You can run the stock, lo-po cam, stock ECM and 14lb injectors with the rest of the HO components. I ran my car like that for about a year it got great fuel mileage and made decent power. I still have all the parts I took off my car when I did the conversion.

there is still the whole theory that the ECM has an injector firing order, which I have not been able to prove or dis-prove yet. just for shits and giggles try swapping pin # 13-42 and 14-12 on the ECM wire harness, see if anything happens. this is whats printed in the instruction manual for the MAF conversion harness and according to the people at Interactive Systems and Technologies this will maintain the correct injector firing order.

http://www.mass-air.com/

[seneeb]

Yes, you can fool the PCM by swapping the wiring around. In the PCM however it still thinks it's on the same Firing order.

The rest of it doesnt really care much from what I understand of old systems

I really want to convert mine to current injection with coil on plug :P

[nitroracer]

The computer does have a set firing order. I ran the stock cam with HO parts elsewhere & a mustang computer and it ran but the mileage dropped to 150/tank. It gave four of the cylinders fuel too early in the cycle but was still able to combust, just without the best mixture.

I was trying to figure it out and going back to full stock specs I pulled down about 22-23mpg with my 3.08 rear. I wonder if it will jump back up that far keeping the E7 heads...

[88grandmarq]

my car is the same way, stock it would get 300-320 miles to ta tank of fuel. doing a full HO conversion dropped it to 275-280 a tank. after the new motor was installed with a Crane cam, the mileage dropped to about 200 miles to a tank. mileage was even worse after the MAF conversion. I took it back to SD and installed the HO cam, but I also found several vacuum leaks, so mileage is up to 240 to a tank now.
Think I might install a D9S ECM tonight and swap around those 2 pins, see if anything happens.

about the E7 heads, I would run the HO intake, exhaust and E7 Heads, they seem to be the most efficient. Running the stock cam, ECM and 14lb injectors isn't that bad, you could even install some 1.7 rockers to get more lift from the stock cam.

[nitroracer]

My full HO car cant seem to break 230-240 miles per tank, whether I drive with a light foot or a heavy one. I think my first try will be the HO with 14lb injectors, if thats a bad setup I'll look for a stock cam from someone who swapped over.


Let me know if switching those pins does anything for you.

[gadget73]

It will probabably run too lean with 14 lb injectors.

My gas mileage is also crap now. I used to get 17-18 consistantly, and once I did 21 mpg but now its like 15 mpg. I'm not going to get too concerned with it till after the exhaust is done and the broken O2 sensor is replaced. Once thats done, I'll see what I have. The intake vacuum is either really really friggin low, or my vac guage is shot too. It runs like 14" and it should be 17" or better. Not a leak that I can find either. I do notice my rockers rattling around a bit more than they used to, so I might pop the covers off and re-torque them just to make sure that its not simply a case of insufficcient valve action causing stupid crap. I ran it down the road and it cruises at 65 mph and like 8" of vacuum. Guage is rock steady, but I don't know how much stabilization effect that big intake gives for slight valve problems. I know with a carb, even a slight valve issue will show as a flutter on the guage, but I don't get that.

[Lincolnmania]

i've gone as far as 360 miles on a tank on my way to erics........the fillup took 16.5 gallons.......it's not as good lately, must be the fuel......and cant afford to fill it up lately i get gas 10 gallons at a time lol

[87mefull]

x2, The fuel quality is getting really bad lately and my gas mileage has been poor lately also 13-16mpg. I do need to do some work to my car, but even on a cool night on a flat strecth of deserted road maintaining 45-50mph the best I could get was 15.6 mpg. Before I filled it up from a half of tank 3 days ago, on the same strecth of road I was averaging 21.2mpg with bad wheel bearings and probably a bad tps.

[nitroracer]

My Dad was messing with the car and swapped in another set of 19lb injectors I found for free. The ones I was using were originals from an 86' mustang and I think more than one of them was going bad. I used to have a problem with valve noise under load and breaking up in the upper rpms, to the point where the timing had to be set back to about zero degrees. Now its up to 14* advanced with no pinging. Ill know how shes running tomorrow.

[Tiggie]

x2, The fuel quality is getting really bad lately and my gas mileage has been poor lately also 13-16mpg.

Thank the new ethanol mix in all gasoline now. EPA is forcing every company to eliminate the MTBE additive, replacing it with Ethanol. All gas is going to be around 10% ethanol/90% gasoline.

Yes, it eats some rubber seals. Yes, there is a shortage, so prices are higher. Yes, it doesn't produce as much energy, so you'll get worse MPG. It will also cause carb'd engines to run leaner without adjustments. EFI should compensate with extra fuel, again causing less MPG. On the good side, the 10/90 mix will raise octane about a point.

I think I'll build my next engine with 13:1 compression and run E85. E85 does have an octane rating of about 112!

[mrltd]

The ECU pinout is the same for the HO/lopos....I swapped the pins on my 87 and it ran like ASS. Put it back, great. There is something else wrong. I used to get 24 mpg with the HO...19 with the lopo..

I'd get the injectors professionally cleaned, check the sensors, etc...I am really wishing I never junked the 87. It should have been sent to Scott or Eric for dissection.

[88grandmarq]

I agree the pin outs are the same on both non-HO and HO and I dont really see how it makes a difference. theorectically, it doesnt matter when the injector sprays the fuel, the fuel will sit behind the intake valve until it opens anyway.
just for shits and giggles, I installed a D9S ECM and swapped pins 13-42 and 12-14. the car runs exactly the same.

Mike, which pins did you change to make it run so badly?