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AFM Adjustment bucking and running rich

Old 11-24-2012, 09:06 PM
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AFM Adjustment bucking and running rich

I know I'm posting a lot but well, I'm doing a lot. The car has been on stands 2 months without water while I installed new headers, weber bb throttle body, palnet rail, new tps.

Upon starting today, the car was running very rough and smoking white. Before, the tps was never hooked up because it wasn't there, but now a new one is on and works properly. I figured the afm needed adjustment because it was running rich. I had cleaned and ohmed it out before, but didn't adjusted it. I ended up having to turn it 10 clicks CW. Would that be normal? I figured it might since I'm taking in more air on the motor side of the afm.

I adjusted to where it ran ok and the smoking was minimal, but when I got in second and hit 2500 rpm, the car started bucking like crazy and wouldn't accelerate. Then the car died at idle, and wouldn't start unless wot, and bucked all the way back to the house from start to finish. The plugs were carbon fouled, the pistons were dry. I have to clean the plugs just to get it to idle enough to mess with the afm. I just don't get it, has anyone had any issues like this? Haven't ran a compression test yet.
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Old 11-24-2012, 10:14 PM
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Let me guess,do have a 75-83 N/A Z?!
More info will really help,what year model and what kind a set up do you have!!!???
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Old 11-24-2012, 10:33 PM
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Haha yeah I guess that's pertinent info huh? 78 280z. Manual 5 speed. Deleted egr, aar, csv. Palnet fuel rail, stock fuel pump. Fuel pressure 34. Stock injectors that i recently cleaned (they're all clicking). 6 to 1 headers. 60mm weber big bore throttle body, bored out intake manifold and new tps. Breather on the valve cover. New pcv valve and hose. Dizzy vacuum good. No ac or heat. Still running the carbon canister. The water pump looks to have been replaced. Motors got 187k on it. That's all I can think of. It was running well before I put it up on the stands although it had a rough idle and no tps.

Last edited by Turbo Biscuit; 11-24-2012 at 10:51 PM.
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Old 11-25-2012, 07:47 AM
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You need an a/f ratio gauge to tune the afm properly.
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Old 11-25-2012, 08:15 AM
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Originally Posted by NismoPick View Post
You need an a/f ratio gauge to tune the afm properly.
The MSA 6-1 headers don't have a bung for an o2 sensor. Would you recommend getting it tapped on one leg or where they all converge?
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Old 11-25-2012, 08:55 AM
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cut one weld it in where they all meet up.
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Old 11-25-2012, 01:32 PM
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A few things.

1. Let it be known far and wide that the car does not like running with the thermotime wires hooked up to the temp sensor...

2. Even after I remedied the main problem, the car was still bucking and refusing to accelerate in 1st at 3k and in 2nd at 2.5k. Obviously it was the TPS, so I disconected it and the car runs fine now. I would like to incorporate the new TPS, but if it's going to cause problems then I guess I'll just paint flames on it and call it "decoration".

I also backed the AFM up 5 teeth, so now it's only 5 teeth CW. Thanks for all the input and not flaming me as this is still a learning experience.
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