View Full Version : 1994 Deville 4.9 Engine Stalling

08-09-12, 09:24 PM
Hello, Need Some Tips Here Please, We Have Run Out Of Ideas, I Am Into This For Tons of money already, and cant afford much more. We are in bad shape and really need this car to get to work. Both of our cars decided to die on us this week.

The engine at idle, will just stall randomly , when driving it, it hesitates, and then starts going , or will stall out at a red light.

here are things we have done already:

Pretty much whole new ignition system, new ignition control module, new rotor cap, new distributor ..

new fuel filter

tested the fuel pump psi, not losing anything

only code we are pulling that is current is p062

The next step is a new ECM from autozone which is gonna run me another $80, any ideas on if this could be the problem as the mechanic is suggesting? or does anyone else have any ideas..

the recluse
08-09-12, 09:56 PM
P062 is telling you what the problem could be....vacuum solenoid problem...i.e. vacuum leak

more than likely you have a cracked or bad vacuum line at your cruise control unit or a bad diaphragm on the unit. If you don't need or use cruise control, pull the vacuum line to it and plug it with a screw...

To test for vacuum leak, spray the vacuum lines with WD40 or carb cleaner, just mist them...if the rpm's change you've found your leak...

08-09-12, 09:59 PM
do you happen to have a diagram of where the cruise control unit is, or what it looks like, i have never worked on these before...

08-09-12, 10:01 PM
If you are looking at the engine from the passenger's side fender, it's just to the left of the alternator - you'll be able to see a throttle cable running to it.

08-09-12, 10:02 PM
thank you so much gonna go try this now

the recluse
08-09-12, 10:14 PM
This is a diagram...parts marked "13"...usually big and black...back end is a diaphragm....


Any one of those vacuum lines around it could pose a problem for you...

08-09-12, 10:16 PM
i just found the bad hose, pulled it off and plugged up the t where the hose went with my finger, had someone else start it, and its still stalling out..

08-09-12, 10:25 PM
On a speed density management system such as this, a vacuum leak would probably make it idle fast rather than chug and die anyway. However, don't rule it out.

Other things to check for are a dirty throttle body, plugged EGR tubes (these are under the throttle plates - they need to be clear for proper EGR function), and also check for a leaking fuel pressure regulator (pull the vacuum hose off of it - there should be NO fuel present - if there is, replace the regulator).

08-09-12, 10:34 PM
no fuel in the regulator

08-09-12, 10:37 PM
what about map sensor?

08-09-12, 10:40 PM
Unlikely if there is no code for it.

Believe it or not, all engine management inputs (such as the MAP sensor) can be monitored through your dashboard display using the onboard diagnostics system. A search should bring up the details so that I don't have to type them out.

BTW, did you check those EGR tubes?

the recluse
08-09-12, 10:43 PM
If you push the throttle wide open and look down, you'll see the rods that Drew was talking about. Take a coat hanger and clean those out...

You can have problems with the MAP and never throw a code. Unplug the MAP sensor and run the car, it should go into a basic settings mode. If you don't have a problem, there you go...

MAP sensor is part marked "1"


08-09-12, 10:46 PM
yea all the tubing seems fine not clogged or leaking, my other mechanic is telling me it could be the map sensor if its biased and deceiving the computer ... whatever that means.. ive run out of ideas here...

08-09-12, 10:48 PM
Else, if unplugging it seems to help and you want some hard evidence - view MAP sensor data through the dashboard, it should return betwen 30-40kpa with the engine warm, at idle. If it's out of range, check the fuel block learn. If it's at 108 or 160 (it's limits), the MAP is a likely suspect.

EDIT: Just to be clear, those EGR tubes we are referring to are NOT the vacuum lines(couldn't tell if you understood this from your response) . These tubes are under the throttle body, in the intake manifold. Remove the air filter housing, open the throttle, look past the throttle blades and down into the intake manifold. There will be 2 tubes sticking out of the floor of the intake - they need to be clean - not plugged up (this is a relatively common problem that matches your symptoms).

I've borrowed a picture to illustrate. This is what you will be looking at. Note that in this example, the tubes are completely clogged. If yours look like this, clean them out.

http://img820.imageshack.us/img820/7942/cimg0599j.jpg (http://imageshack.us/photo/my-images/820/cimg0599j.jpg/)

the recluse
08-09-12, 10:51 PM
I've had 2 MAP's go bad and never throw a code, try unplugging it...

EDIT: Sorry Drew, we keep posting in between answers...I don't want to sound argumentative...

08-09-12, 10:58 PM
EDIT: Sorry Drew, we keep posting in between answers...I don't want to sound argumentative...


08-09-12, 11:05 PM
unplugged map sensor, but unfortunatly i cant get an accurate test because i broke the fuel pressure regulator hose, and need to head up the autozone and grab new hose.. but with that hose off, and it unplugged its still stalling.. i will double check those tubes again..

the recluse
08-09-12, 11:24 PM
I know this is going to sound REALLY stupid, but, when was the last time you changed the fuel filter?

EDIT: scratch that, went back and read you changed it...

the recluse
08-09-12, 11:35 PM
I gather you're not familiar with how to run diagnostics on the DIC, so we need a more pragmatic approach to weed out electronic or mechanical. If you broke the hose to the FPR, but didn't see a noted difference, it might just be the FPR after all...it's mechanical...

Once you fix the vacuum line problems to the FPR; disconnect the battery for a minute or so, reconnect and leave the MAP unplugged (but plug the vacuum line to it so it doesn't leak). Restart car and see if there is any change. Disconnecting the battery should clear the codes and reset the computer...

the recluse
08-09-12, 11:45 PM
From here, though, it's getting late....check tubes, check MAP... there are a few other items to look into, but one thing at a time...will check in tomorrow...good luck...

08-10-12, 02:02 AM
ok guys, i really appreciate you guys giving me a hand with this... ive been at this for so long... im ready to give up.

i managed to get new hoses on the cruise control and the fuel pressure regulator, still having the same problem

i also cleaned out those egr tubes in the throttle bottle really well with a hanger and i tried running it with the map sensor unplugged, still same problem.

i also unplugged the battery the whole time while i was cleaning out the throttle to reset the codes, but as soon as i plugged it back in, i got map sensor code, as well as the same cruise control vacuum solenoid code...

08-10-12, 07:33 AM
Well you finally got the MAP code. Mine acted up for a few weeks before i got the code. The biggest symptom for me was the near stalling at red lights. It could just be low vacuum too, since the cruise is also affected, and that would be easier to check if you had access to a gauge.

08-10-12, 01:45 PM
no, i had the map sensor unplugged which is why i had the code, i plugged it back in and code went away..

08-10-12, 06:37 PM
This might be a long shot, but when your engine is idling. Reach under the EGR valve and lift up the diaphragm. If the idle does not change, then you have a bad EGR. That code you keep getting, you might look under the dash at your brake switches, one of them has a hose connected to it, that is the vacuum hose that releases the Cruise when you step on the brake pedal. Also look at the wiring on that switch, it sends a signal to your PCM which in turns communicates with the cruise solenoid.

08-10-12, 07:03 PM
just retested fuel pressure, getting 38-40 with key on, fluctuating from 34-40+ when car is started

the recluse
08-10-12, 07:22 PM
Have you addressed the EVAP system? The purge valve could also be giving you a fit....if you drive/run it and pop the gas cap and get a "whoosh", you may have problems there too...EVAP problems can stifle good fuel flow...

08-12-12, 12:59 AM
just wanted to give you guys a heads up.. we plugged the vacuum line from the throttle body to the fpr and the car is now running with no issues! before we plugged it, the fuel pressure was dropping down to 36-38, we plugged it and it stays at a nice 45psi now. thanks everyone for your help

the recluse
08-12-12, 09:18 AM
Good show, happy motoring...

08-12-12, 09:48 AM
I don't think disabling the fpr is a fix but it sounds like you are getting warmer.

the recluse
08-12-12, 01:42 PM
I don't think disabling the fpr is a fix but it sounds like you are getting warmer.


I agree, but I suspected he'd get a hold of us when the next problem showed up....:2thumbs:

08-12-12, 08:43 PM
Hate to say this but taking that vacuum line off the pressure regulator isn't the true fix... They put it on there for a reason.