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2002 deville Northstar revs repeatedly at startup


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So...I get into my girl, turn her on and she begins to rev repeatedly, approximately 5-6 times, then dies. I repeat the performance...two more times. During the last time, I surveyed the dash for indications...none....I turn off the cruise control which was on, and after she dies, following the same amount of revs as before, I again try to start her. She starts perfectly and I drive away as I normally would. No residual actions of distress on her part.

This happened once before, with a SINGLE revs-up cycle. She immediatly started up that time and I discounted it as quirk, glitch, isolated incident. but now that it has done it again, I've got to delve deeper.

Any ideas?

 

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Is your air pump working? When the air pump comes on on startup it is supposed to rev a little higher til it kicks off. 

Doesnt explain the stalling but it is a start

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Post your codes.  This can be a lot of things from a dirty throttle body to a vacuum leak.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Yes, airline comes on shortly after startup and cycles off. I will get the codes as soon as I get the nerve to find out everything that my little girl is keeping from me....lol.

G

On 9/4/2016 at 8:46 PM, rockfangd said:

Is your air pump working? When the air pump comes on on startup it is supposed to rev a little higher til it kicks off. 

Doesnt explain the stalling but it is a start

 

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The cruise control should not engage when the car is stopped.  It can be "on" but it is locked out.

We do need the OBD trouble codes.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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googling these codes did not indicate anything that would cause my odd reving. HOWEVER...

...one gentleman suggested my battery may be going bad....I DO have a shaky battery which will not start the engine if I sit and listen to radio or play cassette/cd music, or accidentally leave light on, too....

A possibililty?

 

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Its always good to have a good battery.  The coils require a lot of current to drive them.  

I was hoping to see a lean code due to a leak in the rubber plenum between the throttle body and the intake, it can get a hole in the bottom and leak vacuum.

Have you cleaned your throttle body throat and plate?  Do not spray anything into the intake but use carb cleaner on a cloth and clean the throat walls and plate including the backside and edges.  It might be hanging open.

You should also check fuel pressure with a gauge to see if something is starving the engine like a filter or pump.  

Do you have a tach, specifically describe the problem, what does it rev to?, does it feel like its about to stall?  

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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It is so infrequent...a total of two times in the three month I have owned it. Wouldn't a throttle body plate sticking open cause this a lot more......conjecture, I know....

I think there is two probable systems that could cause this (looking for a yeah or nay here) electrical or fuel...and since the only other indication I have of malfunctions on either is a hinky battery, I will probably get a new battery and hope for the best. Need one anyway. Low voltages can cause havoc on electronics, I am aware..

The throttle body cleaning is a simple procedure so I'll include it, too...can't hurt.

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I can't think of much that would cause surging on cold startup that would not throw a code.  If you have a good OBD reader, you might look at the miss counts and other such, or hook it up before cold starts and check for latent codes when it acts up.

If the battery voltage drops below 9.0 Volts during startup, some of the modules won't function.  The car has default keep-running-for-safety modes that will kick in, and this may be what is happening.  If so, you will see low voltage HISTORY codes and such.

You might check out the IAC valve, which is a stepper motor and idle air control valve assembly.  There are two controls, A and B; the LT GRN/WHT and LT GRN/BLK wires are the A control, and the LT BLU/WHT and LT BLU/BLK wires are the B control.  The wires with the WHT stripe are the signal high lines; the wires with the BLK stripe are the signal low lines.

I'm assuming that all the EGR wires and plumbing are OK, because something there would throw a code.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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This is new info not preciously made clear, I got the impression it was frequent.   

It is so infrequent...a total of two times in the three month I have owned it. Wouldn't a throttle body plate sticking open cause this a lot more......conjecture, I know....

This could simply be an unmetered vacuum leak look for loose or cracked vacuum hoses.  Look at the throttle body for a loose  IAC.  Reset the IAC connector.  Has any work been done?, starter changed?

I would replace the battery asap.

The next time it happens, immediately check codes.  Problems will set codes.  

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I second the checking of the IAC. Those things can be very finicky and will not always throw a code. On startup the IAC will open slightly more for a short period of time during startup and a cold engine. If it sticks and is having trouble meeting the air requirements for the engine it can surge and stall. This problem can be magnified on an engine with a large cam and low idle vacuum too. Another thing to check would be the mass air meter. I have seen dirty air meters give people fits too. Especially if you are running a K&N or any washable oiled filter. Lots of times they get over oiled and that oil hits the air meter and screws up the voltage signal to the ECM. You can pull the meter and clean it with some electrical contact cleaner. 

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  • 2 months later...

Merry Christmas!

Just realized I should update my thread...

I replaced the battery last month when I noticed a substantial sale on Dell Gold batteries at a local GM dealership, and have not had any further revving up issues...or any other problems! At the same time I replaced the front brake pads. Very happy with the ease of replacement of them. 

Thanks for all your suggestions and help.

 

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