Thread: issues today on the dyno! please help!

Ok well when I got to the dyno it was breaking up bad on the first pull due to it running pig rich, adjusted the air fuel and started making some decent power (265 on a low reading mustang dyno. Would be around 300whp on a dyno jet) and started gettin a little spark blow out. Nothin to big though, so we pulled the plugs and gapped them closer (104s gapped at .035 just to see what would happen) and the car started missing and breaking up pretty bad at wot, so then I put in new 104s gapped at .055. Did another pull and the same thing, still missing and cutting out at wot, so put new plug wires in, and still the same outcome......I just don't get it, I was starting to make some good power and as soon as I touched the plugs, everything went down hill.....only other guess would be the coil packs or maybe the fuel filter is clogged from the e85 cleaning everything out.......

Current mods


9" cone filter, a104s gapped at .055, drilled 180tstat, speed daddy headers, wrapped crossover pipe, xp cam, crower 105lb springs, viton valve seals, modded steel retainers, flipped mounts, gen v, ported inlet, 3.0,3.4 intense mps, no cat, no res, stock mufflers, 3" exhaust cutout, 65lb inhectors, zzp stage 1 volt booster, Racetronix fuel pump rewire, e85, hp tuned.

Hope everything is resolved chris. Have you tuned yet for the E85?

Yes that's what I was doing today and why I was at the dyno...only two things I can think of is fuel filter or coils

i think the issue is that im out of maf and need a mini afc, when i closed my cutout it doesnt do it nearly as bad i took some vids today, i also changed the fuel filter as well..

first run after closing the cutout and changing the fuel filter, didnt give me any issue until right at redline.
YouTube - ‪Impala ss breaking up‬‏

this was after doing another pull letting the car downshift to first. it started breaking up and you van clearly see and hear it

YouTube - ‪Impala ss 2nd pull breaking up‬‏

and this was the last pull, i put it in first maually and again same thing started breaking up especially in 2nd gear around 3k+ rpms

YouTube - ‪Impala ss third pull braking up‬‏

Did you try putting your old plugs back in?

What codes are you pulling? i see your SES light is illuminated.

air fuel is fine i think the issue is i am out of maf, and no i did not put the old plugs back in i got new ones and gapped them at the same gap as the old ones .055, ses is p0300 from the xp cam .

Did a scan tonight and my maff levels where around 8500 when it was cutting out air fuel is in the mid to high 11, it seems to be doing the problem worse and even at 1/2 and 3/4 throttle ...during on of the pulls the car actually died, I cranked it back over and gave it a quick rev and it died again and took a good amount of cranking to get it started. Im beyond frustrated, that and my misfire code seemed to disappeared

ok so here are a few vids of the scans

scan one (read description in the video)

‪Impala ss scan 1‬‏ - YouTube

second scan which actually resulted in the car stalling out and dieing, after i started it up i gave it a quick rev in neutral and it died again, and took a good bit of cranking to get it started again...any thoughts..im at a loss

‪Impala ss scan 2‬‏ - YouTube

Anybody?...I'm thinking it may either be the fuel pump a clogged filter or maybe a crank sensor..? Only code I'm seeing is the p0300 code from the xp cam, also I swapped coils and icm and nothing...

Ok so status on the car...checked 02 voltage while the car was wot and cutting out. Read 930-940 range on both sensors and maff read around 9300-9500... and I also checked fuel pressure at on position and was around 45 psi and 52 while running, so that pretty much eliminates the pump and filter, I also pulled the supercharger belt off and it still does it but not nearly as bad ...any ideas...only things left to check is cam and crank sensors and maybe try a different maff, and only code is p0300 from the cam

Yea only cel im getting is from the cam at idle which is p0300. And the car doesn't miss fire till the problem happens, and sometimes the tach is erratic when it does it jumping back and fourth from 4k to 3k rpms...but no specific cylinder miss fire....also not sure if this has to do with anything but sometimes when I drive the car my gauges will cut out then come back on with a battery light while driving or at idle....and since the car does the cutting out up top still without the supercharger belt on I'm guessing it still has to be sensor related

The tach jumping...however IS a sign that the crank sensor is bad...which would make me lean towards that.

Yea only does it sometimes also checked fuel pressure at wot when it cuts out its right around 60-62. And when the car cuts out the gauge flutters and jumps a little but doesn't seem to go under 60

Ok so I replaced the crank position sensor and cam sensor, and now the car barly does it just feels like it is breaking up a little than actually cutting out, and I can go all the way to redline, I'm thinking I just need to regap my plugs now