1999 Mercury Marquis Car sputtering and stalling

REALITYCHEQUE

MEMBER
1999 MERCURY MARQUIS
15,500 MILES

Hello, I am having problems with sputtering on my 1999 Grand Marquis. This past Monday I had the intake manifold crack almost 3/4 of the way around, and I and my uncle in law replaced it with a good one with the metal housing for the thermostat from a junkyard and completed that on Thursday. Friday it ran well on a hot day and I assumed things were okay, but then yesterday it began to sputter after startup and while idling, and it does it more when the transmission is changing gears while accelerating on the main roads. The check engine light also turned off on Friday (the day it was running fine) and after driving it about 10 miles or so yesterday, (after it started sputtering) it came back on again. Any ideas on what may be causing this?

3 Replies

CARADIODOC

MECHANIC
33,873 POSTS

The Check Engine light means the Engine Computer detected a problem, set a diagnostic fault code, and turned the light on to tell you. Many auto parts stores will read those codes for you for free. They will indicate the circuit or system that needs further diagnosis.

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Sunday, July 21st, 2013 AT 10:56 AM

REALITYCHEQUE

MEMBER
2 POSTS

I took it to the local Advance Auto Parts where they hooked up the Actron Autoscanner Plus and received 5 codes (2 global, 3 ENG) total, which read as follows:

P1299
SOAE-Engine over temp. Condition NON-MIL

P0305
Cylinder 5 misfire detected-NON-MIL

P1285
Cylinder head over temp. Sensed NON-MIL

There were also the other two codes which were identical to the P1299 and P0305, with the only difference being that they said CONFIRMED instead of NON-MIL. I've read that I probably would need a thermostat and to replace that plug, since those are most likely the issues that are causing my problem since those could be the only things I can think of being a noob at this lol and just from helping taking the intake manifold out and putting it back in. Just wondering if this all makes sense or not!

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Sunday, July 21st, 2013 AT 12:20 PM

CARADIODOC

MECHANIC
33,873 POSTS

I'm confused with those codes. "MIL" is "malfunction indicator lamp", meaning the Check Engine light. In the U.S, any problem that is detected that could adversely affect emissions and sets a code must turn on the Check Engine light. I have never seen a scanner list a code with "non-mil", but regardless, a misfire will increase emissions if it is related to a loss of spark because you'll have raw fuel going out the tail pipe. That can also overheat the catalytic converter. I'd start with a set of spark plugs and wires. If you continue to get a code for misfire on cylinder 5, swap that injector with one of the other ones, erase the code, then see if a code sets for the cylinder you moved the suspect injector to.

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Sunday, July 21st, 2013 AT 12:51 PM