misfiring and p1131

[dSVTj]

ok so i have a 98 svt and it has some issues. i bought it knowing it had a misfire from another ceg'er. it does misfire occasionally (generally cylinder 3) but not all that often. i went to autozone yesterday to have the codes read and i had a p1131 along with a cylinder 3 misfire. the car is sluggish until the secondaries open at which point it takes off considerably. i once told my mechanic about the misfire and he said there was a chance coolant was leaking in there. does that make sense? just recently my coolant light has been coming on. my mechanics kind of a dumbass so i was wondering if anyone knows what i should do?

thanks for any help

 

[Tony2005]

What was the exact CEL code for the cylinder 3 misfire?

A misfire could be due to 1) SP, 2) SP gap, 3) coilpack, 4) SP wires, 5) others. Check those first.

Of course, the misfire could also be the cause of the P1131.

Per TSB, some reasons are
P1131 - Lack of HO2S-11 Switch, Indicates Lean When an HO2S sensor indicates lean at the end of a test, the system is trying to correct for an over-lean condition. The code is set when the fuel control system no longer detects switching for a calibrated amount of time.

Electrical:
· Short to VPWR or VREF in harness or HO2S
· HO2S circuit shorted to Ground
· Water in harness connector
· Open circuit
· Corrosion or poor mating terminals and wiring
· Damaged HO2S
· Damaged PCM (other DTCs should be present)

Fuel System:
· Excessive fuel pressure (stuck fuel pressure regulator, restricted fuel return lines, etc.)
· Leaking/contaminated fuel injectors or fuel pressure regulator
· Low fuel pressure or running out of fuel (fuel pump concern, fuel supply line restrictions, low fuel level, etc.)
· Vapor recovery system (stuck VMV, etc.)

Induction System:
· MAF contamination
· Air leaks between MAF and throttle plate
· PCV system / Other vacuum leaks
· Improperly seated engine oil dipstick

EGR System:
· Leaking gasket
· Stuck EGR valve / Leaking diaphragm or EVR

Base Engine:
· Oil overfill
· Incorrect cylinder compression
· Exhaust leaks before or near the HO2S
· Secondary air stuck on

 

[mikeswartz]

also are you losing coolant?, it is well docummented that you have to keep the coolant reservior 1/2 inch or more over the full line as the coolant level sensors are very sensitive on those models. so you may have two different things going on. the other thing is as tony says, check spark plugs, if coolant is getting in #3 it will look different from the rest.

 

[dSVTj]

i did fill the coolant 1/2 an inch above, but that was in january. i havent had the light since, but it recently came on....

 

[dSVTj]

the plugs, the coilpack and the wires have all been changed to no avail

 

[SVTGT350]

Check compression. Low compression will cause a misfire condition.

 

[code510]

i worked for ford for years and owned a 99 myself. the fuel pumps are notorious for failing, however it my not be failing but it may not have the pressure it requires. i lost mine at 30k.... a great car but with its quirks.

 

[Tony2005]

i worked for ford for years and owned a 99 myself. the fuel pumps are notorious for failing, however it my not be failing but it may not have the pressure it requires. i lost mine at 30k.... a great car but with its quirks.

Welcome, code510. Thanks for posting.