I'm seriously getting sick of my car. Ive had trouble with this car for years. I bought a maf because i thought mine was bad. It will run with the "bad maf" but every once and a while it'll stall or idle at 500 rpms and wont take gas. I bought a bosch maf and that made it worse. Now the car will barely run unless i stick my hand over 95% of the maf opening. Ive been getting codes 33 and 34. Also it runs great with the maf unplugged. 24mpg highway, plenty of power and everything. I've swapped relays also. It backfires through the intake with the maf plugged in. I'm at a complete loss. I read one post that said to adjust the tps voltage to .60 and that did nothing so i put it back to .54. Could it be where i siamesed the base intake and ported the heads to hell? It seems to run lean but i raised the fuel pressure up to 60psi with no change. I just dont know how it can run so good with it unplugged? What exactly does it do in limp mode? Maybe i need a custom tune? Any help/suggestions are welcome.

BTW it runs great with ported heads, siamesed intake and a cutout. I beat a stock STi from a stop with him only getting a fender on me then me pulling. It wont spin with so little backpressure. He was so pi$$ed, now it has a brand new 3" exhaust. Now it sounds like a 4cylinder running on only 3.

 

Wow, weird. Did you check the wires going to MAF, make sure the computer is putting out the correct voltage? It sounds like the computer is reading the MAF wrong and changing the timing all to hell for ya. You have checked the TPS and made sure that the voltage from the ECM is correct and that the idle and WOT voltage is correct and the the transfer from idle to WOT voltage is smooth and linear. I don't suppose you have a leak between the MAF and the throttle body or a vaccuum leak? There were only two times I have had this kind of crazy crap happen. One was an 87 TA that wouldn't run right at all and it didn't care what sensors were unplugged. Took forever until I pulled the ECM and found a Custom chip, swapped it with my stock one and the car was perfect. The other time the intake manifold was leaking between cylinders but not to the atmosphere, it backfired, ran lean did all sorts of crap. This is one of those things that is hard to solve via the internet, unless someone knows more than I.

 

Yeah i checked the voltages. I forget what they were now but it seemed normal. The Tps is set at .54 volts idle and 4.43 at WOT and its smooth and linear. No leaks in the intake piping but i know for a fact that my TB shaft seals leak bad. I'm not sure if it leaks anywhere else though. It holds 17" of vacuum at idle. The ecu, CTS, MAT, 24lb svo injectors, Maf burnoff and power relay, plugs, wires, coil, cap, ignition module are new but could still be bad i guess. I did notice one thing about the siamesed intake. It appears that #5 steals some of #7s fuel. #5s spark plug is black and #7 is tan/white looking. Anybody want to donate me an LS1 swap?

 

Just how far in did you siamese the runners? As long as there is about 3-4" of port separation before hte head/intake flange, there should be no trouble from that.

Before you burn a custom PROM, you'll have to gather some data on how it is running. That alone should help determine the problems.

 

Im not sure how far i went in since it was a while back. It seems like i went about halfway in or so. I remember reading about mike davis' intake and #7 going lean (turned out to not be the reason it blew), but i was worried about that so i didnt go as crazy on the 5/7 ports. I guess i need an aldl adapter so i can scan it.

 

Sounds like it's got bad relays I'd try swapping in another pair.

Also check the relay connectors, over time the insulation slides down exposing the bare copper wire, wrap any bare spots to make sure they are not contacting.