Lincoln vs Cadillac Forums

(This is the forums archive - If you want to get back to the main site simply click the banner above and you will be taken to our homepage.)

Lincoln vs Cadillac Forums is the Ultimate Online Resource for Owners and Enthusiasts of American Luxury Cars. Feel free to browse through our archive - but make sure you make it back to our main site - Lincoln vs Cadillac Forums

Cadillac XLR : Cadillac CTS : Cadillac : 2005 Cadillac STS : Cadillac Forums : 2000 Lincoln LS : Lincoln Mark VIII : Lincoln Mark VII : Car Wax
Lincoln Town Car : Lincoln Air Suspension : Lincoln Continental : Lemon Law : Do It Yourself Car Repair : Lincoln vs Cadillac Forums : Mesothelioma

Back to the Archive Main Page

Pages: 1

HELP! Pops and Backfire

(Click here to view the original thread with full colors/images)

Posted by: Joes Mark

I could use a little help from you guys.

For the past couple of weeks, the engine in my 90 LSC pops and backfires (thru the carb) when its first started.

It starts up fine and Idles great. But once you start giving it gas, it starts to hesitate, pop and backfire. Sometimes it wants to stall but does not. After the cars warms up about 10 minutes, everything seems fine.

Is there some valve that might need changing.

Hopefully somebody has an answer.

Posted by: NYC LS8

Put the fuel injection system back on it.

Posted by: Lincolnlov

Quote:

Originally Posted by Joes Mark

I could use a little help from you guys.

For the past couple of weeks, the engine in my 90 LSC pops and backfires (thru the carb) when its first started.

It starts up fine and Idles great. But once you start giving it gas, it starts to hesitate, pop and backfire. Sometimes it wants to stall but does not. After the cars warms up about 10 minutes, everything seems fine.

Is there some valve that might need changing.

Hopefully somebody has an answer.

Assuming that you don't have a carb but rather FI, and you haven't been working on the motor and gotten the plug wires crossed up, I'd start checking for a vacume leak! Sucking extra air will sometimes make it backfire. Otherwise you might have a look at the idle control valve which may be sticking.

Posted by: Joes Mark

Thanks for the reply. Motor is Fuel Injected and the backfire is in the motor. I have not done anything to the motor. Except for the battery, the alternator and changing the oil every 3000 miles everything else is original. The car only has 43,000 miles. I will check the idle control valve and replace it.

Posted by: Lincolnlov

Quote:

Originally Posted by Joes Mark

Thanks for the reply. Motor is Fuel Injected and the backfire is in the motor. I have not done anything to the motor. Except for the battery, the alternator and changing the oil every 3000 miles everything else is original. The car only has 43,000 miles. I will check the idle control valve and replace it.

Joe,
Another thought!
My 90 Mark VII with about 155K on it at the time did mysteriously start missing and would occasionally backfire under sudden acceleration. Problem = one plug of a set with less than 8,000 miles on them went bad and would only fire occasionally. Never happened before. What a PITA to discover without various testing equipment. Good luck!

Posted by: OldSchool1

You cannot rule out the plug wires unless you physically check the firing order between the dizzy and the plugs.

Even professionals switch the 1 and 2 at times.

Posted by: artbaileyjr

This is a classic symptom of a malfunctioning MAP sensor. (Manifold Absolute Pressure)

Black thing mounted on firewall, vehicle left. One vacuum hose and one elecrtical connector. Have someone hold throttle at an objectionable RPM and tap in the MAP sensor with a screwdriver handle. If nothing happens, pull the vacuum hose off and cover the hose with your finger. If there is no, or little change in the engine condition, replace the MAP sensor.

Art

Posted by: Lincolnlov

[quote=Joes Mark;315954]I could use a little help from you guys.

For the past couple of weeks, the engine in my 90 LSC pops and backfires (thru the carb) when its first started.

It starts up fine and Idles great. But once you start giving it gas, it starts to hesitate, pop and backfire. Sometimes it wants to stall but does not. After the cars warms up about 10 minutes, everything seems fine.

Is there some valve that might need changing.

hey Joe!
Did you solve the problem? What worked?

Posted by: Joes Mark

Still have the problem but not every day. I changed the cap and rotor. I plan on changing the plugs this weekend and see what happens. I will also check the MAP.

Thanks for all the help. I will let you when iis resolved.

Posted by: papa bear

might of jump timing..,plug wires crossed,...cats clogged,...improper plug gap...,bad valve,...cam rounded out a lobe,...pull the plugs and read them and replace and if you can do a compression test at least you will know how healthy your motor is if all else fails pull the vavle covers and turn the motor over and watch the rockers open and close

Posted by: Joes Mark

Well here is the latest, the plugs and wires were changes along with the fuel filter. STILL have the same problem! After the car warms up everytiong is fine.

I took it to a shop and after they did some tests, they determined that the intake manifold is all sludged up and some of the airways are clogged. They are suggesting that unit comes off and be boiled out. With a cost of $700-$900, I'm not so sure I want sink more $$$ into the car. The MAP checked out OK.

Any opinions regarding the manifold being the problem. The motor only has 43,000 miles on it.

Posted by: JoshMcMadMac

Pull codes. It's probably not the manifold, and if it is it's a simple job you can do as opposed to $700-$800. A can of Seafoam would probably clear most of it out anyway.

Posted by: Mulletoffury

Quote:

Originally Posted by JoshMcMadMac

Pull codes. It's probably not the manifold, and if it is it's a simple job you can do as opposed to $700-$800. A can of Seafoam would probably clear most of it out anyway.

how good does that sea foam work id really like to give it a try on my lincoln

Posted by: Lincolnlov

Quote:

Originally Posted by Mulletoffury

how good does that sea foam work id really like to give it a try on my lincoln

Worked pretty well on mine with 160k on it. Made it idle smooth again, Not bad for a $6 investment. Do it a night so the neighbors don't get upset with all the smoke that it creates.

Credit Card Consolidation:Car Accident Lawyer Los Angeles:Personal Loans:Remortgages:Loan