backfiring and popping under WOT and black smoke out the exhaust???

[Madmustard]

anybody know where I should start looking?Walbro pump new last year with 50 miles.Kirban regulator and gauge..aprox 46#s at idle.with vac line on or off pressure doesnt change?Flicking the throttle in park shows the gauge going down to 40#s..

Im lost...any help appreciated...I dont have an external gauge....tt chip and exhaust only real mods....

 

[1fast6]

afr might be bad. it should change when vac hose is removed. check your vac source for it.
who's chip are you using?
how much boost?
check plugs and report back.

 

[Madmustard]

16 to 18 ish pounds of boost..turbotweakchip.th downpipe. everything else stock except hot wire kit and k and n filter.walbro pump.

Was testing some different fuel pressures and at 52#s of pressure got the vac to drop to 46 with line on....is that ok?a lot less backfiring and can get to 3/4 throttle to 7/8 of WOT now without backfiring and popping..These cars are amazing!!!!(had one 6 to 8 years ago but forgot everything i did then)Also found a vacuum line off on drivers valve cover to a square black box on valve cover and re connected.

Had a couple good runs on the street and no popping last year---beat a newer black cobra mustang 3 times ...best $4k i ever spent!

I think its gonna be high 12's...I will check plugs but I need a detailed list of all exceptable scanmaster readings....have tps at .42 idle and wot is 4.8..

Whats AFR?Adjustable fuel regulator?its a new billet one...and thanks for your help

 

[kidglok]

erics chip calls for a starting fuel pressure of 43lbs at idle with the line off. it should drop with the line one...check what 1fast6 said about the vaccum source...does the pressure go up 1lb of fuel per 1lb of boost while driving?

 

[Daniel Jost]

Looking at what you have posted your base fuel pressure is through the roof! as stated it should be 43.5PSI base with Eric's chips. Also you show dropping 6 PSI now, so you should see it drop to ~37.5 PSI with the line on. Black smoke is a good indication of a rich condition or poor ignition.

,Dan

 

[Madmustard]

Switched to a new gauge...this new gauge reads 5to 6 pounds lower fuel pressure than the old one...I had this new in the packaging as I suspected a gauge problem last year...installed and adjusted to 46 and 52 with line off.I am a little higher than the 43 or 44#s as I was trying to figure out if a fuel starvation problem as I do not have a remote gauge on the cowl..

Car still has a bucking and popping and boost fluttering all over the place at wide open throttle...at 3/4 throttle everything ok..except when cold...the 1st time you get on it when around 160 sometimes no popping...after you get on it a few times pops every time no matter where in rpm range..

no apparant vacuum leaks or lines off...No codes on the scanmaster either..

Here are my scanmaster readings...af-04,lb27,sae-13.1-ine-128-bl-131-mph-0,cle-162,aes-107,r9-00,tps-.44,iac-00,cc-156 then 72 and all over the place,mal-0.Is my next step to buy a cowl mounted gauge to check fuel pressure while wot?

Wondering if this is the piece of **** new walbro pumps?have they solved the problem with these pumps yet????

any info appreciated.thanks!

also no more black smoke as a vac line was off on drivers valve cover to a square looking box near egr valve...

 

[GNDriven]

If you don't stop getting into the throttle and figure this out, you are going to here one last pop. Turn the boost down to 14lbs and start troubleshooting from there.
I did not see the 02counts.

 

[collins1]

I had a bad ignition module cause very similar problems

 

[ZNix]

At idle you should have 20-50 IAC iirc. That has nothing to do with the problems you are describing.. Just an observation. Listen to what these people tell you. Drop the FP to 43lbs LINE OFF. When you connect, it should be around 37ish. Then it should rise 1:1 with boost (at 16lbs: 58lbs of FP).