TWO A9Ls 1 good 1 bad Runs good on bad one? Is speed density better?

86gtriceeater · Aug 6, 2011

I got two A9L mass air computers as I converted my 86 gt to mass air. One seems to do what its supposed to as far as correct voltages at tps, priming fuel pump ect...the other one has the fuel pump running constantly (doesnt shut off once it primes) but it responds to throttle and runs way better. What to do??? Im tempted to just go back to speed density. I have the old computer. Also, I put an old rebuilt SROD tranny in that doesnt have the VSS on the tranny and didnt run those wires...Any suggestions? Oh and my motor is bored & stroked to a 347, voodoo lunati cam, trw flat tops, eagle rods ect.

JungleJoe · Aug 6, 2011

I wouls keep it MAF. You should hook the VSS up also, it does help the computer. I just got done fixing a SD mess, MAF is wayyyy better

stang&2Birds · Aug 6, 2011

86gtriceeater said:
Oh and my motor is bored & stroked to a 347, voodoo lunati cam, trw flat tops, eagle rods ect.

I was going to say go back to SD. Other than the ****ing hunting idle problem, IMHO, the SD setup is often better than MAF setup.

But.... not when "important" mods have been done to the engine ("most" heads, cam, etc).

With your setup, forget about SD! I guess you also don't have 19# injectors. IMHO, you need:

1) A good and proper MAF and setup. That is no ******ing cone filter in the engine bay! And, no low-end MAF, and don't even think about putting a POS C&L in there.

2) You need a VSS. Otherwise, the EEC will have problems with idle and low rpms.

3) You need custom chip or to do a tune yourself. Even a simple mail-order chip (check the classifieds) that has the correct engine size, MAF map, injectors, and maybe a few tweaks, will do wonders!

IMHO, you only other "decent" option that MAY OR MAY NOT work is to go to a 93 EEC, MAF and FULL MAF intake setup, with 24# injectors. That EEC, MAF, and injectors are the only OEM setup that comes "close" to being able to handle your setup.

Good Luck!
Four Eyes Rule!

stang&2Birds · Aug 6, 2011

JungleJoe said:
I wouls keep it MAF. You should hook the VSS up also, it does help the computer. I just got done fixing a SD mess, MAF is wayyyy better

???
If the SD setup didn't work for a stock setup, then a MAF setup has no chance in ****!

For a STOCK engine, the MAF setup gets better gas mileage, better idle, and less smog. But, the 55mm stock MAF is a restriction and will result in a HP loss and also reduce the throttle response!

redmustang83596 · Aug 7, 2011

Dont go back to SD, it will not like that cam. Sounds to me that both A9Ls are shot. Get a known good one and see if it helps your problem.

86gtriceeater · Aug 7, 2011

Im actually still running the 19# injectors. I thought they were good til like 500 horses or so? Its very silly but Im also running stock intakes & stock mass air. I need to update my signature, sorry. Any tricks to tuning you can think of? Im at 10 degrees for timing, 38# fuel pressure. Should I time it at like 14. Play with idle set screw or fuel pressure?

JungleJoe · Aug 7, 2011

stang&2Birds said:
???
If the SD setup didn't work for a stock setup, then a MAF setup has no chance in ****!

For a STOCK engine, the MAF setup gets better gas mileage, better idle, and less smog. But, the 55mm stock MAF is a restriction and will result in a HP loss and also reduce the throttle response!

His motor is far from stock. . .

tmoss · Aug 7, 2011

stock 19# inkectors are good to ~275-300 to the wheels. The stock fuel rail may be good to 500HP but not the injectors. See my sig - I'm still SD and that is about as far as you can go without serious diriveability problems.

Noobz347 · Aug 7, 2011

tmoss....

No luck on finding a reliable programmer for SD, huh?

TwEECer = TehLoze
Anderson PMS???

tmoss · Aug 7, 2011

TwEECer or Moates, just haven't been motivated yet as the car runs good.

Noobz347 · Aug 7, 2011

You're a better man than I, if you can make sense of that TwEECer mess.

86gtriceeater · Aug 7, 2011

Okay, it sounds like I need to upgrade injectors & intakes pretty quickly and I'll stay Mass Air but Im quite frustrated I cant get it run right. The SIGRTN for the map, tps, & egr is almost nonexistent. When I probe the orange wire (red lead on dvm) and the got to chassis ground I get 5v reference but if I check the black & orange wire on the tps, egr, or map I get like .12 volts. Is that a bad ground? Doesnt the computer ground that circuit?

tmoss · Aug 7, 2011

When guys convert to/from auto to T5, they can amke mistakes in the wiring that will cause the SigRtn trace on the board to burn off - you can open the EEC and look for that. It can be repaired by soldering in a piece of copper wire over the burned gap.

86gtriceeater · Aug 7, 2011

Can you tell me about where to look? I opened both of them when I got them but couldn't find anything burnt. There's lots of circuits though

HISSIN50 · Aug 8, 2011

You would probably throw a handful of codes if the sig-return burned.

Thanks to Joel for the picture - it gives an idea of what to look for if pursuing the burned trace idea:

http://www.stangnet.com/mustang-forums/7759761-post8.html

TWO A9Ls 1 good 1 bad Runs good on bad one? Is speed density better?

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