PDA

View Full Version : no boost after burnout?



decipha
06-24-2008, 10:33 PM
i have a 90 sc 5spd, after a nice burnout leaving a gas station the car won't go into boost. This has been an ongoing problem since that night nearly 2 1/2 years ago. Before you ask, yes!, I have a check engine light, its throwing 3 codes, 22, 54, and 98. MAP, ACT, and passenger side o2. I don't think any of those codes are causing my problem though. For some reason when the car tries to go into boost it starts bucking, the tach drops to 0 and as soon as you let off the throttle its back to life again and tack works fine.

the harmonic balancer isin't warped and is spinning perfectly round
the cam sensor has been changed with a new unit
dis module has been changed as well
new plugs/wires
new fuel pump
new fuel filter
new adjustable ford fuel pressure regulator
swapped ecu's
swapped maf with a known working one
verified no vacuum leaks
no visible fuel leaks, but car does loose fuel pressure after an hour (40 to 10)
the sc belt isin't loose nor is the s/c slipping (no visible belt wear)
i've tried reseting the ecu and still have the same problem.


idle is high sits at about 1k. I haven't checked the tps yet but i will yet i don't think thats the problem.
the car seems to run as though its not getting enuff fuel but i can smell it big time. today i think fuel even came out the tail pipe. i'm thinking that maybe the fuel injectors are leaking and thats causing me to get terrible gas mileage along with the gas smell and causing it to run crappy -may explain the fuel coming out the tailpipe.

i can get the car to hit boost every once in a while, it doesn't do it often but sometimes it will. Even when it does hit boost it doesn't have any pull, seems as though its not getting enuff fuel.

also, the fuel pressure at idle is 39psi and jumps up to 50psi with a quick throttle pinch, i can't get it over 50psi no matter how hard i stomp it.


any ideas? I'm going to change out the injectors and replace the map, act, and o2s as well. if that doesn't do it i don't know what to do.

any ideas? anything i overlooked?

car is completely stock minus the aftermarket headers and egr delete.

rzibilske77
06-24-2008, 10:39 PM
like u mentioned u have codes...fix them and then go from there.....i bet your problem will be gone.

decipha
06-24-2008, 10:50 PM
rly u think? I hope so, I guess i'll have to get those sensors quicker than i thought. Maybe this friday when i get paid.

Mike8675309
06-24-2008, 11:02 PM
Sounds like you blew the line for the gauge off the manifold, or the vac line for the bypass valve. That would cut boost out.

The codes... I'd first check for vac leaks, then clear codes, and then see if they pop back up.

decipha
06-24-2008, 11:07 PM
gauge line is connected and boost gauge works perfect
valve has vac and is working as it should

i've verified no vac leaks, no pinched lines and pcv is working as it should

fturner
06-24-2008, 11:15 PM
The EEC will put the car into limp mode when it has picked up on sensor failures, which means the car will not like having boost and will choke on you, it will run pig rich and will be very down on power.

Replace the BAP sensor (we don't use MAP), and the ACT sensor before you do anything else to see if that gets rid of some of your problems.

Frit

decipha
06-25-2008, 12:06 AM
will do thanks for the heads up and the correction

Pablo94SC
06-25-2008, 12:58 AM
When the car is hot, it will pull timing. If the ACT is out of range or showing an excessively hot intake temp, it sure as hell will not let the car go into boost. You think Ford is going to just let the engine detonate? Fix yo ~~~~e, mang.

the-big-e
06-25-2008, 09:14 AM
You could have blown out the IC seals.....

After you check your sensors, get some IC gaskets and install them.....

decipha
06-25-2008, 07:27 PM
i have ic gaskets in there now, should i replace them?

i've heard many people prefer copper rtv... thats what i was thinking about doing when i change my injectors if the sensors don't do the trick

the-big-e
06-25-2008, 08:09 PM
Are they the thick gaskets that Wynn (aka Tbird 88) made.....

Or one of the thinner versions.....

Pablo94SC
06-25-2008, 09:13 PM
Dude... it's the ACT. Stop looking at IC tubes until you change your sensors out.

decipha
06-25-2008, 10:55 PM
im not sure if its the wynn version or not, i would think that its just the el cheapo crap you get at the local parts store.

i can take a pic and post it

yeah, i plan on changing my sensors out before i go any furthur.

decipha
07-26-2008, 08:09 PM
sensors are now fixed and check engine light is now off!

however, the car still doesn't want to go into boost, it sure as hell does run better though and now it has pull. I'm thinking it has an electrical problem though.

When I stop at a redlight with the clutch in and the car idling the tach will drop to 0 and go back up to 800 really fast. Doesn't do it everytime I stop but does do it quite often. Also today the car died on me altogether at a red light. It wouldn't restart until I turned the key off and back on again, started right up.

sounds like the dis to anyone? The dis was changed 2 years ago and the problem still remained. Maybe a short somewhere? How come it doesn't do it when I'm cruising at part throttle? Also could it be the coils? Perhaps there on there way out?

any ideas anyone?

Tech_Greek
07-27-2008, 02:55 AM
Sounds like you have a HUGE vacuum leak with the almost stall out sympton.

Your car will build boost if all the electrical components are screwed up if you can make enough pressure via throttle body (at least one the 94/95 without the solenoid)...

83GT460
07-27-2008, 09:45 AM
sensors are now fixed and check engine light is now off!

however, the car still doesn't want to go into boost, it sure as hell does run better though and now it has pull. I'm thinking it has an electrical problem though.

When I stop at a redlight with the clutch in and the car idling the tach will drop to 0 and go back up to 800 really fast. Doesn't do it everytime I stop but does do it quite often. Also today the car died on me altogether at a red light. It wouldn't restart until I turned the key off and back on again, started right up.

sounds like the dis to anyone? The dis was changed 2 years ago and the problem still remained. Maybe a short somewhere? How come it doesn't do it when I'm cruising at part throttle? Also could it be the coils? Perhaps there
on there way out?
any ideas anyone?


Do you have oil leaks? If the front seal leaks it can get oil on the crank sensor which will then cause dirt and crud to cover the sensor possibly causing your problem. My 95 would loose tach signal, the engine would die for a split second, and miss at higher rpm all because of a dirty crank sensor.

Charles

decipha
07-30-2008, 07:19 PM
BOOST LEAK FIXED!!!

probablem was the cam position sensor... i disconnected it and on the 3rd start attempt it fired up.. ran beautifully, idle was perfect, no surging, no bucking, and it now hits 11psi of boost WOT with absolutely no hesitation!

cam sensor is the culprit.. will be replaced real soon like

decipha
08-16-2008, 07:40 PM
well cam sensor wasn't the problem

damn crank bolt was snapped inside the crank shaft. stupid mechanic that put the new engine in cut corners and used a crappy bolt with 7 washers to put the balancer on.

found the problem today while i was taking the balancer off.