blackztpi

i look up the diagnosis for a code 33 and it says most likely a bad ground. i checked my ground to the map circuit with my fluke 87 and it said 28 ohms of resistance!! definately high. i don't have a factory spec on that but i was thinking .030-1ohm was about normal???? I plugged a jumper wire from my battery ground to my ground plug in the map plug, forcing ground to it. by doing this, i got it down to 8 ohms.

long story short.... computer cuts short term fuel down quickly in closed loop, until it stalls it. it wouldn't even idle in closed loop for long as the short term fuel in both bank 1 and 2 dropped from 128 down to 80 and then stalled. open loop operation is fine. it runs in open loop 80% of the time since the computer knows it can't tun properly in closed loop. i took care of some other issues and got all the rest of the codes gone. now, i'm down to code 33.

to continue, when i forced ground to the map circuit and it read 8 ohms, the car ran better and actually stayed idling in closed loop. bank 1 short term read about 120-128 varying back and forth a bit, and bank 2 dropped to 108and stayed there, also varying up and down a bit. So, i looked into this circuit (IAT, A/C pressure switch, MAP are all on the same circuit). and sitting still after a test drive the IAT was reading 180 some degrees. it was about 60 outside and the coolant temp was around 170 degrees. there's no way 180 was the real IAT, so I'm thinkin the whole circuit has a bas ground. very high resistance.
so, i'm thinking i have a bad ground on that whole circuit, or on something that effects that whole circuit. anyone have any thoughts or schematics on that circuit so i can trace the grounds??? better yet, anyone have a schematic for all grounds in the engine bay???? thanks

Injuneer

The code sets when the MAP reads above 68kPa with closed throttle. You can get tha condition with a huge cam, or a milder cam with a bad tune, incorrect valve adjustment, misfires, vacuum leak, throttle blades open too far, etc.

What does your MAP read it idle with the stock wiring? What does it read at idle with your improvised wiring?

What was the IAT with the engine running on the road? Heat soak can push the IAT up to 145* at idle, and probably even higher with the engine just shut down and all the heat under the hood.

blackztpi

well, my tb blades are open too far, and the car has a good size cam. bauer grind 230/236 with lots of lift, but more streetable than a cc306. i'm only making 10-12 in of vaccum, but i cannot find any leaks anywhere, even after the intake was decked and sealed again. valve adjustment is fine...i can check it again, but it's quiet. and the thing misfires like hell because the short term fuel trims are dropping like rocks in closed loop. it starves it of fuel and if you try and give it gas it usually backfires a tad (light pop). but i'm looking for answers and i think i'm on the right track with my grouns and all. after all, it straightened out a lot when i grounded it myself. i'll tryand get the rest of that info for you on tuesday