I had a scan done on my friends car that we have a popping problem with.
If possible can anyone point me in the direction to look at into fixxing this problem?
Results are as follows.
engine Off\eng running open loop\engine closed loop\snap to 3670rpm
tpsvlts .56 .56 .88 2.50
blkLrn 128 150 136 136
plswth .0 3.0 2.7 7.0
idlerpm 3188 800 800 800
MAF 23gm 11gps 32 149
airflw 61gps 11gps 32 153
Vats yes
RPM 0 760 2150 3670
O2 0 130/280 852 102
exhaust reads lean lean lean
airflw lrned none yes no
coolant °'s 161° 170° 185°
MAT°'s 82° 82° 86°
Load 0 76 72 186
spk adv 0 26° 38° 30°
intgrte 0 0 130 128

This is 383,brodix head,10/1 comp ratio,cam 232@.050
Tpis Mini ram long tube headers,plugs are black rich reading

 

Well, based on the BLMs it's definitely running a bit lean, but not too bad. Try bumping up the fuel pressure by 4psi and see if the BLM numbers come down to 128.

If the pop is still there, I'd start looking at what was suggested in the the previous thread about this engine--cam being off a tooth and things like that.

Also, I'm assuming the "snap to 3670" was done in neutral? The 102mv O2 reading is way low... Would it be possible to do a WOT run with the scanner attached to see what the O2 sensor is reading under load? It should be around 900mv for WOT--if it stayed under that, that would be way, way too lean for WOT.

Finally, and I hope someone chimes in here because I'm just throwing out a suggestion without any first-hand knowledge on this (so I might be totally off): I thought I saw somewhere that ECM chip has a table that basically simulates the equivalent of an accelerator pump on a carb--basically dumps some extra gas in when the throttle is opened quickly. If this is indeed the case, does that table need to be "fattened up" because of the extra displacement and better airflow from the cam and heads?

Good luck!

Ben

 

What the tech told me was that its decreasing fuel as the throttle is opened,upping the fuel pressure has no effect on the pop have been as high as 50psi.
The car storms up to 6000 like a clock,the pop happens below 2200rpm cam is degreed in which means it's impossible to be a tooth off. thank you for the input though

 

ttt

 

ttt

 

What about an intake leak?


How bout in the distributor cap? I once had a pop and it turned out to
be the rotor was loose.

Good luck...

 

Don't you think the mass signal should be zero with the key on and engine off?
Should the O2 mv be higher at idle???