408 running like CRAP HELP!!

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May 30, 2007 | 11:18 PM

chrismcdaniel

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From: Kentucky

408 running like CRAP HELP!!

Ok, so I was driving my car the other day on a cruise. The car was running prfect, then like a flick of a switch, it started bogging and running like total ****.. couldnt keep it running with out giving it 50% throttle until i could get to the shoulder of the road.

best way to describe it is to take a SBC 350 and scramble up the plug wires.. it will run but only barely.. like it only has 20 hp or something.

so i get a tow home, and after finally getting it started, and babying the throttle until it would finally idle (sounding sick at best) i went to the front of the motor and heard a sucking noise comming from the air lid like i have never heard before.. sounded like a porta poty truck cleaning the **** house.. LOUD!

the Fuel presure guage was bouncing...almost viberating between 40 and 60 lbs.. not holding steady.. when i shut it off, it maintaind over 50 psi while just sitting.

I reverted back to a stock misfire table to scan misfires at RPMs above idle, and it did have a few misfires on the number one, but all cylinders where firing..

Any Ideas?

i have checked ALL the grounds
the racetronix wiring

May 30, 2007 | 11:32 PM

soulless

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From: searching for the perfect driving line

Have you tried to locate the source of the sucking noise, could just be a vacuum leak.

May 30, 2007 | 11:45 PM

Quik

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From: Pittsburgh!!!!!!!! Pa

it could be fouled out plugs. mine was popping and sputtering hte other day. i had 4 fouled plugs. changed them out runs good

May 30, 2007 | 11:46 PM

chrismcdaniel

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From: Kentucky

Quote:

Originally Posted by soulless

Have you tried to locate the source of the sucking noise, could just be a vacuum leak.

the throttle boddy.. when the idle drops below 1k rpm it tries to keep itself running and sucks in MASSIVE air

here is the codes i scanned just now.. looks like its definatly electrical

[PCM] P0200 - Injector Control Circuit (SES) (Pending) (Old) (History) (Current) (Immature)
[PCM] P0300 - Engine Misfire Detected (History) (Immature)
[PCM] P0443 - EVAP Purge Solenoid Valve 1 Control CKT (SES) (Pending) (Old) (History) (Current) (Immature)
[Brake] U1000 - Class 2 Communication Malfunction (History)
[Restraints] B1000 - ECU Malfunction (History) (Immature)
[Restraints] U1000 - Class 2 Communication Malfunction (History) (Immature)
[Restraints] U1301 - Class 2 Short to Battery (History) (Immature)
[Restraints] U1016 - Loss of Class 2 Communication with VCM (History) (Immature)
[Restraints] U1040 - Loss of Class 2 Communications with ABS (History) (Immature)

May 30, 2007 | 11:51 PM

Quik

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just curious where does the car idle at normally? my 408 idles around 800 without surgin

May 31, 2007 | 12:23 AM

chrismcdaniel

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From: Kentucky

about the same. like i said, it was running perfect before this, the motor only has 700 miles on it, and its is freshly tunned.

May 31, 2007 | 01:08 AM

chrismcdaniel

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From: Kentucky

number 1 plug

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May 31, 2007 | 01:08 PM

chrismcdaniel

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From: Kentucky

Quote:

Originally Posted by Joel_SS

Fix the vaccum leak.. You car will run like **** with a leak like that, and it if bad enough it will not run at all..

its not a vaccum leak, the motor is sucking LOUD/HARD through the normal intake track.. the motor is pulling in mass amounts of air.. through the TB/MAF/Air Lid

May 31, 2007 | 02:30 PM

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5.3LJimmy

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From: Napoleonville, LA

Quote:

Originally Posted by chrismcdaniel

This sounds like a shorted wire somewhere or possibly a bad PCM. Check to see if any of your fuses are blown this may help to isolate the problem.

May 31, 2007 | 10:13 PM

#11

jimmyblue

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From: East Central Florida

The sucking noise may just be the IAC jacked full open
trying to hold idle. What is the injector control circuit code
about? That's the oddball.

Jun 1, 2007 | 10:05 AM

#12

1BDHWK

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From: Joppa, MD

Cam Position Sensor possibly?

I know when I put my 408 in, we fought for 3 weeks trying to figure out why it was running like crap. Turned out, the CPS just crapped out.

Jun 1, 2007 | 10:43 AM

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santiago

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From: norcal

im jus gonna say its a broken valvespring. cuz that was what happen to me when my car started to run like ****.

Jun 2, 2007 | 05:38 PM

#14

chrismcdaniel

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From: Kentucky

not sure how to test the CPS, I guess its time to do some research.... ill pull the covers and check the springs today.. thanks for the input guys, keep it comming.

Jun 2, 2007 | 05:45 PM

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1fastTransAm

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From: Chitown-Jax NC-Jax FL-Honolulu-OKC, OK-NOW New Orleans Area

Sucks Chris esp after all the money that was spent. If you need my help give me a call and I will roll up there to the house k. Like I said before on PHFBA either something was grounded or shorted out somewhere. I hope its something cheap and simple. I am trying to remember about the CPS I will look it up when I get home. I have a few books to ponder through.
Best luck though bro

Jun 2, 2007 | 06:59 PM

#16

Asmodeus

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From: Naperville, IL

It sounds electrical. The very first thing I would check is the battery/alternator cables. If one came loose.. check them by the starter too. All that stuff was removed and put back on I'm sure during your 408 swap. If that was ok, I'd check the PCM plug as well as other plugs and make sure everything is tight. Swapping in a known good PCM would be something to consider.. not sure how much trouble it would have with the 408 but I'd think it would idle at least.