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Stumped!! Idle-1500rpm misfire/ hesitation. Help please !!v
So last week I was on my way to store the car and the engine light came on with code po442. I did research on the code itself. I retightened the gas cap and cleared the codes.. 20 more minutes of driving no light, (and no issues)
currently no codes still...
The car sat for a Couple days and I went to drive it and it has this misfire/ hesitation issue now. The car stumbles up to about 1500 rpm and then is fine, it will also backfire sometimes when driving.. Sounds like a typical misfire ..
So, I have checked all the plugs and they are in almost perfect shape.
All the wires are good also
I even went to the extent to check each Coil pack and they are all fine..
Could it be a dirty mas air sensor? Or something related to the fuel Evap system? Please help.
Most misfires are ignition related---Plugs are easy to see if they are bad--but not wires---The only way to check for a bad wire is with an OHM meter--Reading the OHM's to make sure they are all close to the same--However you should get a P0300 code for an ignition misfire
Other than that you can also get a misfire from a dirty or failing injector---If you suspect maybe a bad tank of gas or something that may have plugged an injector I would fill it up full with new fuel--and dump some Seafoam in the tank to clean the injectors--also check all the injector pigtails to make sure they are all good- Yoy would need to drive the car for about 100 miles for the Seafoam to do it's job
Most misfires are ignition related---Plugs are easy to see if they are bad--but not wires---The only way to check for a bad wire is with an OHM meter--Reading the OHM's to make sure they are all close to the same--However you should get a P0300 code for an ignition misfire
Other than that you can also get a misfire from a dirty or failing injector---If you suspect maybe a bad tank of gas or something that may have plugged an injector I would fill it up full with new fuel--and dump some Seafoam in the tank to clean the injectors--also check all the injector pigtails to make sure they are all good- Yoy would need to drive the car for about 100 miles for the Seafoam to do it's job
I think the last tank of gas I had in it was fine, it is low on gas though. Almost on E.. I'm sure the plugs, wires, and coil packs are all in good shape. I could try to put a little gas in it with some type of fuel treatment but, I can't drive it around a whole lot. Winter is here in Indiana and we are expecting snow this weekend .
I don't have any codes currently.. I almost wish I did.
The only code the car had recently was po442 for the fuel Evap system. I tightened the gas cap (most recommended) and cleared the codes. I drove 20-30 minutes after that no issues no codes.. It sat for a couple days and now currently has this problem .
The evap purge solenoid could be stuck open causing a vacuum leak which would explain the high idle.
Perhaps it only gives the code if the valve sticks shut?
Try this. Unplug the evap hose connector from the intake and put your finger over the tube where it connects to the intake while its running. If it runs normal after that, then the problem is the evap purge solenoid.
The evap purge solenoid could be stuck open causing a vacuum leak which would explain the high idle.
Perhaps it only gives the code if the valve sticks shut?
Try this. Unplug the evap hose connector from the intake and put your finger over the tube where it connects to the intake while its running. If it runs normal after that, then the problem is the evap purge solenoid.
It idles somewhat normal. It's just rough from idle (850ish rpm) up to 1500rpm when giving it gas. I will check the Evap vacuum lines, I'm not 100% sure which ones they are but I think they are a couple lines on the passenger side of the intake running from the throttle body to the back of the intake! Is that correct ?
that's right. the solenoid is about in the middle front to back. It hooks up to the intake just behind the throttle body, and there is a line running up the firewall that the other end attaches to.
that's right. the solenoid is about in the middle front to back. It hooks up to the intake just behind the throttle body, and there is a line running up the firewall that the other end attaches to.
Okay headed to the shop, got a few things to try and I will post back soon. Thanks!!!
Look for a vacuum leak on the PCV system OR an Air leak between the MAF and Throttle body ducting.
The PCV Manifold rubber fitting on the passengers side just behind the TB is well known to ROT and leak air.
The only way to check Spark Plug wires is:
1- Visual check for damaged boots, burnt wires/boots Poor connections, corroded contacts inside the boots.
2- Ohm Meter reading end to end. The OEM Wires read approx. 250 - 750 OHMS and most average approx. 350 ohms. If you are reading in the THOUSANDS ohm or Megohm rang,, there BAD!
If you have never cleaned the Throttle Blade OR the MAF, that would be something I would consider but, I do not think that's the primary issue.
Make SURE that you are pulling the DTCs PRIOR to turning off the ignition switch. Some DTCS don't reappear after the switch is turned off. P-0300 is one of them.
BC
Last edited by Bill Curlee; 11-19-2015 at 03:40 PM.
Look for a vacuum leak on the PCV system OR an Air leak between the MAF and Throttle body ducting.
The PCV Manifold rubber fitting on the passengers side just behind the TB is well known to ROT and leak air.
The only way to check Spark Plug wires is:
1- Visual check for damaged boots, burnt wires/boots Poor connections, corroded contacts inside the boots.
2- Ohm Meter reading end to end. The OEM Wires read approx. 250 - 750 OHMS and most average approx. 350 ohms. If you are reading in the THOUSANDS ohm or Megohm rang,, there BAD!
If you have never cleaned the Throttle Blade OR the MAF, that would be something I would consider but, I do not think that's the primary issue.
Make SURE that you are pulling the DTCs PRIOR to turning off the ignition switch. Some DTCS don't reappear after the switch is turned off. P-0300 is one of them.
BC
The pcv hoses and Evap hoses all appear fine... The plugs and wires only have 4,000 miles on them. Lg g2 wires and ngk tr55 plugs all appear great. I'm gonna try clean the maf and see what happens .
The pcv hoses and Evap hoses all appear fine... The plugs and wires only have 4,000 miles on them. Lg g2 wires and ngk tr55 plugs all appear great. I'm gonna try clean the maf and see what happens .
Well I added some fresh gas, cleaned the mas air sensor and air filter. No luck. Still searching for the answer to this . I'm not so sure I should've described it as a misfire. It's more of a rough idle and the car will sputter and hesitate until about 1500 rpm then it clears up.
The pcv hoses and Evap hoses all appear fine... The plugs and wires only have 4,000 miles on them. Lg g2 wires and ngk tr55 plugs all appear great. I'm gonna try clean the maf and see what happens .
When checking for Vacuum Leaks, it can be difficult to verify where the leaks maybe occurring with a visual inspection. I find it very helpful to use a can of spray carb cleaner.
Start the engine and let it idle. using the can of spray carb cleaner, lightly spray (bursts of spray) the area of the intake where it meets the heads, spray in bursts, the complete PVC system hose (not just connections). Spray the area where the throttle body mates to the intake. If there is a Vac Leak, the mist from the Carb Cleaner will be ingested into the engine and you should hear a very noticeable engine RPM change.
From you Profile Mod list, you indicate the LS6 Intake manifold is installed>>>Also use the carb cleaner and spray the back side of the manifold by the fire wall.
From the electrical side>> remove the left and right coil covers and inspect every inch of wiring from the coils and injectors paying attention to the areas where the wire harness can chaff on the brackets mounted on the heads near the fire wall.
i had this same problem even thing looked fine i searched and checked every thing! could not find a problem UNTIL as 69 stated I sprayed MAF cleaner around and every time i sprayed under the intake manifold the idle changed! pulled the intake off and found a crack in the bottom
same weird hunting idle or idle would hang around 1500rpms or so then drop after a little while, so it sounds like you have un-metered air getting in also not saying you have a crack like i did but maybe a vacuum line crack or off? bad intake manifold seals?
spraying around the engine will tell you if you have an air leak
i had this same problem even thing looked fine i searched and checked every thing! could not find a problem UNTIL as 69 stated I sprayed MAF cleaner around and every time i sprayed under the intake manifold the idle changed! pulled the intake off and found a crack in the bottom
same weird hunting idle or idle would hang around 1500rpms or so then drop after a little while, so it sounds like you have un-metered air getting in also not saying you have a crack like i did but maybe a vacuum line crack or off? bad intake manifold seals?
spraying around the engine will tell you if you have an air leak
I'll give it a shot but it doesn't act like a normal vacuum leak. The idle doesn't surge it stay around 900. It just idles rough and it will stumble and cut out when driving. I'm almost thinking it's more of a fuel issue. I will try checking for air leaks . I also got a fuel filter to try and change (hoping the old ones plugged) and some sea foam to put in with fresh gas . Hopefully it clears up
11-18-2015, 04:22 PM
Stumped!! Idle-1500rpm misfire/ hesitation. Help please !!v
