Thread: So the new ICM helped but not much could it be my CPS

Lately I've seen a couple instances where these symptoms are caused by a vacuum leak at the check valve for the break booster or the booster itself.

im with rico. ^^^^ the booster kinda dumps the vac pressure and the engine starves for a moment.

Rico i`ll check it but about a week ago I sprayed brake cleaner around my whole vacuum harness, including the brake booster line started around the booster cap ended by the booster in the firewall no change in rpms nothing. I think its my CPS because I was having a trans slip out of gear issue do to starvation in left hand turns the problem is gone but if i turn the wheel completley to the left it`ll still slip EX: in a 90* left hand turn. So I think my CPS is dirty because the car has its power but seems to be holding back some power its a ratio of 85-90% power all the time i`ll say, but it feels somethings off like extra timing so its not pushing its potential. I can drive it and it revs, shifts under light and heavy throttle smooth and i`m not lieing but yes it feels almost fine to me but I can feel like 10% or 15% of the power not there when I need want it EX: if i calmly come up to 30mph after the shift when it drops an smooths I punch the gas WOT it`ll hit 6.5lbs-6.9lbs and 8lbs at the shift it`ll get up to 70mph holding WOT no problem supercharger whining etc sounds perfect no misfires on aeroforce etc no kr seen. Another WOT senario rolling around 60mph after I feel the computer pull the timing and compensate itself and feel the throttle get stiffer i`ll finally punch the throttle and hold WOT to 90mh and it seems fine no misfires it seems to just go without a problem no bogging it gets up an goes like the 2nd gear pull I describe before this the car pulls strong but seems like its holding back. Another thing I`m stock l67 tuned, no tuning done besides rear 02 delete with the HPTuners. But in the morning or the first crank of the day it turns over no problem but seems to fire up slow and all the other starts for the rest of the day are awesome. So I think it maybe my CPS because longer crank run, lack of power or power loss, hard or not perfect starts (though its only once a day never again always on the first crank of the day), timing seems off, my rpms dropping then settle under heavy braking, these seem like CPS symptoms. If I brake hard an the rpms drop and it feels like the engines (dies/stalls) but it doenst I can hear it still running, if I try to give it throttle it`ll slip like I was trying to take a sharp left hand turn coming up to speed which already happens these all feel like CPS problems to me since my engine was just rebuilt and runs, idles, boost/pulls strong, and also oil pressure an fuel pressure are fine along with spark and not a vacuum leak or a exhaust leak in site. My mods are PLOG, rear pem, 3'catless dp, ZZP stage 2 p&p heads 105lb springs, stock 3.8 sc pulley, FWI, ZZP oil pressure spring, comp cams pushrods yes factory length, AL 606 gapped at .60 could it be the HEADS???

yes the big round thing the master cylinder is bolted to.

how are your brakes feeling? does the pedal get hard when this stutter happens at a hard stop?

describe that better if you can.

example: like is the pedal normal feeling at first, then as you come to a stop its gets harder to push and harder to stop.

Seems like it's dumping a lot of unmetered air into the engine when you press the brakes.

when the pedal gets hard you have lost vacuum to the booster. then the engine will almost stall due to that loss of vacuum.

chances are your booster is going bad.

if you feel the brake pedal and the front end pulsating and in the steering wheel, your rotors are warped. but that wont make you lose vac pressure.

or a crack in the booster vac hose.

under the dash follow the brake pedal up, you will see a rod connected to the brake. take that off. then under the hood, take the master off, then the 4 bolts that hold the booster to the fire wall, and the vac hose, and its off.

its kinda easy.

id check the hose over first, when we brake the engine moves and that could be when a small crack opens up or something dumb like that.

the fact that they work and then fade out, with a hard pedal says its got vac but then it losses it.

if you pull that hose off the booster when the car is running the tube should have quite a bit of suction, the car will stumble, put your finger over the end of the tube and the car should run fine instantly.

this stumble in the idle when you pull this hose should in some way feel like what your feeling when stopping.