[Ian]

I have a '71 240Z w/a 280ZX Turbo motor. Here is a brief description: 3.0L block (87mm bore, 83mm stroke) 3 intake plumbing. 2 1/4 intercooler plumbing. Alpha United intercooler. 3 exhaust with an external wastegate from an '86 Audi 5000 CS Turbo. Garrett T3 from an SVO Mustang. Ported 280ZXT intake and exhaust manifolds. Ported P90 head. Stock turbo cam and valvetrain. Stock '81 ZXT F/I system. Ford Motorsport 30 lb/hr injectors. Custom billet aluminum fuel rail, paxton adj. press. reg. NOS high volume fuel pump. 1/2 tubing from fuel pump to reg. I also am using a Mallory unilite distributor and MSD 6 series ign w/boost timing retard. I could not get the factory computer to run the ign. (couldn't figure out the correct wiring).

Here is my problem: when I go WOT, my air/fuel ratio monitor says the mixture is dangerously lean for about 3 seconds. During this time when it's lean, the motor pings like crazy (7lbs boost). After flickering in the lean for three seconds or so, it goes full rich and runs great. I have tried to diagnose to the best of my ability without success. Is it because I am not running the ign. with the fact. computer? I would like to but when I hook it up the car runs like its on 3 cyl. Help!!! I want to turn up the boost but I need it to work correctly first! BTW, the car ran 13.76 @101.7 at Famoso pinging all the way down the strip. Maybe I'll just go to Accell DFI....

 

[Unknown User]

> I have a '71 240Z w/a 280ZX Turbo motor.
> Here is a brief description: 3.0L block
> (87mm bore, 83mm stroke) 3 intake
> plumbing. 2 1/4 intercooler plumbing.
> Alpha United intercooler. 3 exhaust
> with an external wastegate from an '86 Audi
> 5000 CS Turbo. Garrett T3 from an SVO
> Mustang. Ported 280ZXT intake and exhaust
> manifolds. Ported P90 head. Stock turbo cam
> and valvetrain. Stock '81 ZXT F/I system.
> Ford Motorsport 30 lb/hr injectors. Custom
> billet aluminum fuel rail, paxton adj.
> press. reg. NOS high volume fuel pump.
> 1/2 tubing from fuel pump to reg. I
> also am using a Mallory unilite distributor
> and MSD 6 series ign w/boost timing retard.
> I could not get the factory computer to run
> the ign. (couldn't figure out the correct
> wiring).

> Here is my problem: when I go WOT, my
> air/fuel ratio monitor says the mixture is
> dangerously lean for about 3 seconds. During
> this time when it's lean, the motor pings
> like crazy (7lbs boost). After flickering in
> the lean for three seconds or so, it goes
> full rich and runs great. I have tried to
> diagnose to the best of my ability without
> success. Is it because I am not running the
> ign. with the fact. computer? I would like
> to but when I hook it up the car runs like
> its on 3 cyl. Help!!! I want to turn up the
> boost but I need it to work correctly first!
> BTW, the car ran 13.76 @101.7 at Famoso
> pinging all the way down the strip. Maybe
> I'll just go to Accell DFI....

are you running the stock air flow meter? these things are very restrictive and slow to react to wot conditions. it may not be giving a max air flow signal to the computer right away. check its operation by moving the air flap with your finger, it should feel nice and smooth. you can also modify the spring tension inside the air flow meter, or you can find a less restrictive one. another thing to check is the throttle switch. this should signal the computer and wot also.