What's causing misfire at 1200-2100 when warm?

[Ande99SVT]

So I've been having an issue lately with a bit of a stutter/misfire/popping at 1200-2100 RPM's but the car runs strong when I bring it into high RPM's. I've read quite a bit about this problem and followed most of the steps for resolving it.

So far I've cleaned my IAC, checked my COP wiring, changed plugs, and cleaned my MAF. I also reloaded the tune just in case there may have been an issue there.

From what it sounds like now is that it may be my 02 Sensors, that seems to be the only other possibility.

Has anyone else had this issue and can chime in on it?

 

[Ande99SVT]

Well she finally threw some codes this morning driving to work with a quick stint of surging at a stop light.

P2196
P2198
P0172

I've new trying to read up on it and what I'm finding is since its throwing both 02 banks that its not the 02's but rather something else. Just cleaned my MAF last week but still had the miss when the car is warm. Ill be checking for vacuum leaks today after work and I will take another look at my MAF. Anyo other ideas?

 

[perry2k12]

Definitely check for vacuum leaks. The large rubber elbow on the back of the blower is notorious for going bad and leaking on the bottom. Check that thing out closely.

 

['88347coupe]

Yea I was gonna say that too. Def sounds like a vacuum leak.

 

[Ande99SVT]

Thanks guys, I will dive into her today to see what I can find and report back.

 

[Ande99SVT]

Hey guys, little bit of an update. Noticed all day today she was chugging fuel pretty well (Obviously due to the codes). Brought her home, checked all of my lines and elbows with no obvious sign of issues. I pulled my MAF and cleaned it (By the way, cleaned it a few days ago with CRC and now this problem has arisen). Checked what codes it was throwing and now it's only throwing the P0172. Going to put my MAF back on here shortly and see how it feels.

 

[Ande99SVT]

What's the best way to do a vacuum leak check?

 

[hotcobra03]

how many miles are on car?

what mods?

you are getting lean code 171/174 and rich codes 2196/2198

something says maf not clocked..

a smoke machine is used others is used to find vac leak..our vac system being so small i took mine off and found leak manualy...

my last leak was the elbow under supercharger...po171/174

 

[Ande99SVT]

how many miles are on car?

what mods?

you are getting lean code 171/174 and rich codes 2196/2198

something says maf not clocked..

a smoke machine is used others is used to find vac leak..our vac system being so small i took mine off and found leak manualy...

my last leak was the elbow under supercharger...po171/174

She has 61XXX with mods in signature, it actually started when I cleaned the MAF the first time. I cleaned it with CRC MAF Cleaner. I was getting 2196/2198 also but now I'm getting just 0172.

 

[BLU3VN0M]

She has 61XXX with mods in signature, it actually started when I cleaned the MAF the first time. I cleaned it with CRC MAF Cleaner. I was getting 2196/2198 also but now I'm getting just 0172.

Did you pull the negative battery cable and let the computer reset after you cleaned it? You need to do that in order for the computer to relearn

 

[Ande99SVT]

Did you pull the negative battery cable and let the computer reset after you cleaned it? You need to do that in order for the computer to relearn

I feel like an idiot. I just did this to my 99 also the same day and now I can't remember if I pulled the plug on my 03.

Ill do that, if that doesn't help I'll look into 02's. Would switching 02's duplicate the problem on bank 2? That way I could easily find out if my bank 1 is shot? My tuner told me that the tune the car had prior to me getting it was an A/F of 10.8 and said it was running stupid rich, which in turn could have wrecked my 02's. He did say they were a "little late" and that I should be looking at replacing them down the road, guess it won't hurt.

 

[BLU3VN0M]

I wouldnt think that your o2's would be the problem.. sounds like a MAF issue. im thinking once you reset it, it should be working fine.. try leaving the cable off for about 30 min.

 

[Ande99SVT]

Just pulled the negative, hopefully Ill see an improvement.

 

[hotcobra03]

She has 61XXX with mods in signature, it actually started when I cleaned the MAF the first time. I cleaned it with CRC MAF Cleaner. I was getting 2196/2198 also but now I'm getting just 0172.

have you done a compression test? base engine is a cause..see 1st note
H40 DTCs P1131, P1132, P1151, P1152, P2195, P2196, P2197 AND P2198: UPSTREAM HO2S NOT SWITCHING.

• Note: It is necessary to address all Continuous Memory Ignition and Misfire DTCs, if received during Continuous Memory testing, before addressing any KOER HO2S DTCs.
  DTC/HO2S Reference List:
  • HO2S-11 = DTCs P1131, P1132, P2195 and P2196
  • HO2S-21 = DTCs P1151, P1152, P2197 and P2198
• Check intake air system for leaks, obstructions and damage.
• Check air cleaner element, air cleaner housing for blockage.
• Verify integrity of the PCV system.
• Check for vacuum leaks.

Were any concerns found during inspection?
Yes No REPAIR as necessary. GO to DC25 .
H41 DTCs P0171, P0172, P0174 AND P0175: FUEL SYSTEM AT THE CORRECTED FUEL TRIM

• Note: It is necessary to address all Continuous Memory Ignition and Misfire DTCs, if received during Continuous Memory testing, before addressing any Fuel Trim DTCs.
  Fuel System DTC Reference List:
  • Bank 1 = DTCs P0171 (lean) and P0172 (rich)
  • Bank 2 = DTCs P0174 (lean) and P0175 (rich)
• Check intake air system for leaks, obstructions and damage.
• Check air cleaner element, air cleaner housing for blockage.
• Verify integrity of the PCV system.
• Check fuel delivery system and filter for restriction.
• Check for vacuum leaks.

Were any concerns found during inspection?
Yes No REPAIR as necessary. COMPLETE KAM Reset. GO to DC25 .


DC25 DTC P0171, P0172, P0174, P0175, P1131, P1132, P1151, P1152, P1130, P1150, P2195, P2196, P2197, P2198 OR LEAN DRIVEABILITY CONCERNS: CHECK CONDITIONS RELATED TO MAF SENSOR

• Note: Most weather service reports are a local barometric pressure that has been corrected to sea level. However, the BARO PID reports the actual barometric pressure for the altitude the vehicle is being diagnosed in. Local weather conditions (high or low pressure areas) will change the local barometric pressure by several inches of mercury [+/- 3 Hz. (+/- 1 in.Hg.)].
• Verify the MAF sensor is connected. If not, repair as necessary.
• Key on, engine running.
• Access the BARO, LONGFT1, LONGFT2 and MAF V PIDs on fully warmed-up engine.
• Check that the BARO PID is approximately the same as the barometric pressure reading for the location, day and altitude the vehicle is being diagnosed at.
  • BARO PID values in Keep Alive Memory require updating at high throttle openings. If vehicle is driven down from higher altitudes for diagnosing, complete three or four heavy accelerations at greater than half-throttle to allow BARO PID to update.
  • BARO PID must be within +/- 6 Hz. (+/- 2 in.Hg.) of the altitude value in Barometric Pressure Reference Chart (at the beginning of this pinpoint test).
  • Make BARO PID comparisons to Barometric Pressure Reference Chart or daily airport barometric pressure reports, if available.
• Check that the LONGFT1 and LONGFT2 PIDS for all injector banks at idle is not more negative than -12%.
• Check that the MAF V PID at idle and neutral is not greater than 30% of the normal MAF V listed in Section 6 , Reference Values (or not greater than 1.1 volts).

Are two of the above three checks OK?
Yes No For DTC P0171, P0172, P0174, P0175, P1131, P1132, P1151, P1152, P1130, P1150, P2195, P2196, P2197 or P2198 : GO to H42 (or GO to HA42 for natural gas vehicles only). For driveability symptoms without DTCs : RETURN to Section 3 , Symptom Charts for further diagnosis. KEY OFF. GO to DC26 .
DC26 CHECK TO ISOLATE MAF SENSOR FROM LEAN DRIVEABILITY OCCURENCE

• Note: Due to increasingly stringent emission/OBD II requirements, a fuel system DTC on some vehicles will be generated without a noticeable driveability concern with or without the MAF sensor disconnected. Under these conditions, if the BARO, LONGFT1, LONGFT2 and MAF V PID indicates a MAF sensor concern, replace the MAF sensor.
• Disconnect the MAF sensor.
• Key on, engine running.
• Drive the vehicle.

Is the lean driveability symptom (lack of power, spark knock/detonation, buck/jerk or hesitation/surge on acceleration) gone?
Yes No REPLACE MAF sensor.

RESET Keep Alive random Access Memory (RAM) (REFER to Section 2, Powertrain Control Module (PCM) Reset ).

VERIFY a symptom no longer exists. For DTC P0171, P0172, P0174, P0175, P1131, P1132, P1151, P1152, P1130, P1150, P2195, P2196, P2197 or P2198 : GO to H42 (or GO to HA42 for natural gas vehicles only).

For lean driveability symptoms listed without DTCs : RETURN to Section 3 , Symptom Charts for further diagnosis.

Electrical:

• Short to VPWR in harness or HO2S
• Water in harness connector
• Open/Shorted HO2S circuit
• Corrosion or poor mating terminals and wiring
• Damaged HO2S
• Damaged PCM

Fuel System:

• Excessive fuel pressure
• Leaking/contaminated fuel injectors
• Leaking fuel pressure regulator
• Low fuel pressure or running out of fuel
• Vapor recovery system

Induction System:

• Air leaks after the MAF
• Vacuum Leaks
• PCV system
• Improperly seated engine oil dipstick

EGR System:

• Leaking gasket
• Stuck EGR valve
• Leaking diaphragm or EVR

Base Engine:

• Oil overfill
• Cam timing
• Cylinder compression
• Exhaust leaks before or near the HO2S(s

 

[Ande99SVT]

Well pulled the negative before I left work and the 25 mile drive back home was great. CEL went away, fuel wasn't being sucked down in mach speed and overall driveability improved.

hotcobra03: I got a compression test about two weeks ago or so and it was good across the board. I believe it was me not allowing the PCM to relearn the cleaned MAF and the MAF may have been bringing in a little bit more air than what the car was used to.

Thanks again guys, I really appreciate it!

 

[BLU3VN0M]

Well pulled the negative before I left work and the 25 mile drive back home was great. CEL went away, fuel wasn't being sucked down in mach speed and overall driveability improved.

hotcobra03: I got a compression test about two weeks ago or so and it was good across the board. I believe it was me not allowing the PCM to relearn the cleaned MAF and the MAF may have been bringing in a little bit more air than what the car was used to.

Thanks again guys, I really appreciate it!

Great to know! give it about 100 miles and if the CEL doesn't come back on you're good to go!

 

[Ande99SVT]

Great to know! give it about 100 miles and if the CEL doesn't come back on you're good to go!

Will do man. I still have the misfire around the same RPM range and I'm still looking into it, but the codes are gone and the car runs fine, thanks again man.

 

[Bdubbs]

Will do man. I still have the misfire around the same RPM range and I'm still looking into it, but the codes are gone and the car runs fine, thanks again man.

Can you describe the misfire feeling? Is it more like a hesitation feeling? Spark plugs can act differently than others creating this "hesitation" feel at lower mph speeds. Does this misfire happen on the highway in 6th gear at 60 mph? The NGK TR6 is known for this in some terminators. I had that problem, went to tr6ix and problem almost went away. Then recently I tried another set of tr6's and it's much much less than the first ones I tried.

 

[Ande99SVT]

Can you describe the misfire feeling? Is it more like a hesitation feeling? Spark plugs can act differently than others creating this "hesitation" feel at lower mph speeds. Does this misfire happen on the highway in 6th gear at 60 mph? The NGK TR6 is known for this in some terminators. I had that problem, went to tr6ix and problem almost went away. Then recently I tried another set of tr6's and it's much much less than the first ones I tried.

It's got a slight miss inbetween that RPM range but runs strong up top without any miss, even between shifts at 5-6k. Decel does a slight stutter/backfire also that more or less sounds like a low pop. This is the second set of TR6's I've ran in less than a month, what's the big difference between te TR6 and TR6IX?

 

[03cobra#694]

The IX's are iridium and have been known to idle better. Might be worth a shot. What is the gap on your current plugs?