Setup:
8.3:1 B16, sc61
Walborro 255, Aeromotive FPR set to 43psi at idle, AEM fuel rail,
precision 780cc inj
MSD blaster coil.
HKS 40mm WG with 10psi spring
ITR distributer with new autozone rotor and cap

We first noticed this during a street tune, Car ran great at 7-8psi AFR was 11.1 the whole time. now 7-8psi on my Greddy spec II ebc is 20-21% on Lo boost mode. when we brought it up to 30 % it would hold steady at 9psi in 2nd gear and as soon as I reach 7k in 3rd it bucks like the spark got blown out.

Backed the EBC back down to low 20% and 3rd gear is fine. plug gap was .24 on NGK v power 8 heat range. I decided to just get new plugs and wires, I got NGK V power in the 7 heat range. gapped em to .20, then it bucks in 2nd gear so I gapped them .25, now I could run up to 37% without the bucking. but whats weird is my boost guage never moves past 9psi. so that makes me even more confused. but it definatly picked up way more power going up from 30-36%. even though it doesnt show on the guage.

but anyway what else can be causeing this bucking? I been reading thu old threads, and some people who had the MSD box removed it and it fixed their problem, I am only running the Blaster coil.

 

maybe because of stock map sensor?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RudeLude &raquo;</TD></TR><TR><TD CLASS="quote">maybe because of stock map sensor?</TD></TR></TABLE>

GM 3 bar

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostage &raquo;</TD></TR><TR><TD CLASS="quote"> I been reading thu old threads, and some people who had the MSD box removed it and it fixed their problem, I am only running the Blaster coil. </TD></TR></TABLE>

If it's not the fuel it HAS to be the ignition (aside from fuel cut settings or boost cut settings). I'd concentrate on the ignition portion and get the MSD outta there...no need anyway

 

ANY CEL's? Also did you check all your vacuum lines. I know thismight seem dumb and you've prob checked. I usually gap my 7's or 8's around .25/.26 usually when I have something a bit colder I take it down to .24.

Again just check everything small even timing again, fuel pressure under a load and so on. Are all the injectors working right. Just a few suggestions. Let us know what you find.

BTW its Steve "velocitytrends" I just opened this account to use for the business. Good luck man.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by velocitytrends.com &raquo;</TD></TR><TR><TD CLASS="quote">ANY CEL's? Also did you check all your vacuum lines. I know thismight seem dumb and you've prob checked. I usually gap my 7's or 8's around .25/.26 usually when I have something a bit colder I take it down to .24.

Again just check everything small even timing again, fuel pressure under a load and so on. Are all the injectors working right. Just a few suggestions. Let us know what you find.

BTW its Steve "velocitytrends" I just opened this account to use for the business. Good luck man.</TD></TR></TABLE>

Hey Steve no CEL's because I am running AEM EMS. Im going to try everything u suggested this week, I sure hope I get to the bottom of this soon.

 

make sure u disabled the boost cut in the program, my car did the same thing with hondata, cuz we forgot to disable the boost cut

 

tell who ever is tuning it to check the dwell settings...

 

Problem is fixed, it was a dip in the graph of I think the Boost calibration map or some **** like that, the dip was at 8psi, the previous guy must have did it by accident. once it was straighted up I had boost cut set to 16psi, car feels damn good now, and he even pulled some timing and my egt's are cooler in boost. I have to go back to him for a proper dyno tune next week. Marco at billetdesignes

 

you can also blow your boost out if your spark plugs arnt gapped right, like at 44 instead set them at 29-33

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2to5coupe &raquo;</TD></TR><TR><TD CLASS="quote">you can also blow your boost out if your spark plugs arnt gapped right, like at 44 instead set them at 29-33</TD></TR></TABLE>
Yeah they are at 31 now, my egts are no higher than 1300 degrees boosting 1 bar in 3rd gear. Im running 8 heat range plugs.

 

Forget about your EGT's, they aren't telling you anything usefull...

 

why are people so into EGTs. ******* tune your car to like mid 14s cruising and mid high 11s for air fuels, and call it a day

 

Good to hear you got it fixed!