hahaha....figure this ridiculous sh1t out......**UPDATE**
09-15-2011, 04:07 PM
#21
TECH Senior Member
What you guys described possibly sounds like a leak in the EVAP system...
during the first few minutes of engine running the PCM opens the purge solenoid/valve to pull residual gas fumes out of the charcol canister and into the intake manifold... if there is a leak between the purge valve and the canister, then this is a fairly large vacuum leak (un-metered extra air during open loop, engine runs lean, causes misfires), this continues until the purge valve is closed a few minutes later (vacuum leak stops, engine now runs good).
during the first few minutes of engine running the PCM opens the purge solenoid/valve to pull residual gas fumes out of the charcol canister and into the intake manifold... if there is a leak between the purge valve and the canister, then this is a fairly large vacuum leak (un-metered extra air during open loop, engine runs lean, causes misfires), this continues until the purge valve is closed a few minutes later (vacuum leak stops, engine now runs good).
Last edited by joecar; 09-16-2011 at 04:50 PM.
09-15-2011, 04:23 PM
#22
I would bet it's too lean when you first start it, and after it runs for a bit, it goes into closed loop, adds a bunch of fuel and BAM starts running good once it has enough fuel.
Then, even once it's warmed and in closed loop, and running good, your fuel trims are maxed. When your fuel trims are maxed, alot of times they'll reset to zero, and start over. That's your intermittent rough running even when it's warm.
The fuel trims being maxed are part of the lean code.
Root cause will be the tune is off pretty bad, or a contaminated MAF sensor.
PS, you need to check you plugs and plug wires real good too.
Then, even once it's warmed and in closed loop, and running good, your fuel trims are maxed. When your fuel trims are maxed, alot of times they'll reset to zero, and start over. That's your intermittent rough running even when it's warm.
The fuel trims being maxed are part of the lean code.
Root cause will be the tune is off pretty bad, or a contaminated MAF sensor.
PS, you need to check you plugs and plug wires real good too.
I cleaned the MAF about 1 month ago, but I can do that again today.
My tune was done in 2002, and when I got a new PCM a year ago that same tune was downloaded to it and it's been perfect since.
I put a new fuel purge valve on last week (the one on the intake) that has been disconnected for about 6 months with a cap over the intake port. I put the new one on and the code P0443) went away.
Maybe its causing an issue.......can it make this issue happen???
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09-15-2011, 04:26 PM
#23
What you guys described possibly sounds like a leak in the EVAP system...
during the first few minutes of engine running the PCM opens the purge solenoid/valve to pull residual gas fumes out of the charcol canister and into the intake manifold... if there is a leak between the purge valve and the canister, then this is a fairly large vacuum leak (un-metered extra air during open loop, engine runs lean, causes misfires), this continues until the purge valve is closed a few minutes later (vacuum stops, engine now runs good).
during the first few minutes of engine running the PCM opens the purge solenoid/valve to pull residual gas fumes out of the charcol canister and into the intake manifold... if there is a leak between the purge valve and the canister, then this is a fairly large vacuum leak (un-metered extra air during open loop, engine runs lean, causes misfires), this continues until the purge valve is closed a few minutes later (vacuum stops, engine now runs good).
Huh....I just replaced that purge valve (on the intake) last week.
I'm gonna go outside now and unhook it again, cap that intake port and go for a drive.....see if the missing DOES NOT happen.....
Be right back......
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09-15-2011, 05:00 PM
#24
Unplugged that purge valve on the intake and disconnected the fuel line to the intake and capped off that port like its been for 6 months and has run perfectly fine.
Sprayed the hell outta the MAF with cleaner and the IAT sensor in the lid........
Same ****........missing/stumbling for a few minutes, then it clears up. It also came back for a few seconds after it had cleared up, then cleared again, then came back for a few seconds and cleared again. It would clear for like 6-7 seconds, then come back for 6-7 seconds, and so on........then it went away and stayed away all the way back to the house.
I also tried unplugging the MAF....it was hard to start. Turned over for like 3-4 full seconds before it started, then idled up and down. A key bump is all it ever takes to start it, so I guess the MAF is good.
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Sprayed the hell outta the MAF with cleaner and the IAT sensor in the lid........
Same ****........missing/stumbling for a few minutes, then it clears up. It also came back for a few seconds after it had cleared up, then cleared again, then came back for a few seconds and cleared again. It would clear for like 6-7 seconds, then come back for 6-7 seconds, and so on........then it went away and stayed away all the way back to the house.
I also tried unplugging the MAF....it was hard to start. Turned over for like 3-4 full seconds before it started, then idled up and down. A key bump is all it ever takes to start it, so I guess the MAF is good.
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09-16-2011, 01:30 PM
#26
BUT...listen to this craziness......
Today I get in my car, start it up and leave right away. I drive for about 2 minutes with zero missing. Then it starts.......it lasted for about 6 seconds and never came back all day, I drove for about 30 minutes total today so far, shutting the car off once inbetween for 25 minutes. After that 25 minute stop I started it up and drove home with no missing.
It's like its fixing itself of the missing/stumbling.
BUT.......
Now I accelerated kind of hard one time from a traffic light on the way home, maybe 70% throttle, nothing crazy. I lost zero traction.......but the damn TCS activated and the light came on and the pedal dropped away from my foot like it does when you really lose traction. So, I stopped and tried it again, I accelerated kind of hard and TCS activated again.............what the hell...........OH...I left the purge valve on the intake disconnected and the intake vacuum port capped since yesterday.......so.....
I'll post up the codes later.
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09-16-2011, 05:24 PM
#28
Maybe it was that purge valve because I haven;t connected it back yet......and the intake vacuum port is still capped.
Weird ****....eh!
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09-16-2011, 08:03 PM
#29
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What are the fuel trims doin when its miss also injector pulse width u could have leaking intake gaskets when cold causing a lean missfire and when it warms up the seals swell enough to seal and get rid of the lean condition or it going into closed loop and adding a bunch of fuel try spraying around the intake ports with carb cleaner while its missing and see if it goes away or smoke out the intake and look for vaccum leaks
09-16-2011, 09:48 PM
#30
What are the fuel trims doin when its miss also injector pulse width u could have leaking intake gaskets when cold causing a lean missfire and when it warms up the seals swell enough to seal and get rid of the lean condition or it going into closed loop and adding a bunch of fuel try spraying around the intake ports with carb cleaner while its missing and see if it goes away or smoke out the intake and look for vaccum leaks
Also....just about 1 hour ago I went to the gym........engine was cold. I drive off and it was perfect, about 2 minutes into the drive it started to stumble under steady throttle doing 45mph. I left my foot where it was and it cleared up in about 15 seconds. Went into the gym for about 30 minutes...came out and started it up and left to go home...it immediately stumbled for about the first 3 minutes, then came alive and smoothed right out the rest of the way home, about 5 minutes.
Can bad intake gaskets really cause that.....if so, I'll change them. Easy job.
Maybe I can spray that carb cleaner around the intake when its dead cold.....will that show an increase in rpm if the carb cleaner gets sucked in.??
Sucks...because once it clears up the engine runs like new.......as it always has.
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09-17-2011, 02:24 PM
#31
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Ya intake gaskets can def. Do that espeacially being that old they get hard and brittle from heat cycling and fuel fumes its a easy and cheap enough option to rule it out keep us posted on what u find gd luck
09-17-2011, 04:37 PM
#32
I was able to turn the bolts 2-3 full turns to tighten them. Other side too. But it still has the stumbling/missing AFTER the engine has been running for about 2 minutes while driving. Then after it stumbles/misses for about 10 seconds it cleared up for about 1 0seconds, then came back for about 10 seconds....and that was it, it stayed good till I shut down later on.
If I spray carb cleaner at each runner where the gaskets are while I'm idling with a cold engine, if there is a leaky gasket....what will happen? Engine rpm increase.....???
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09-17-2011, 06:40 PM
#33
I hate intermittent problems. An intake gasket leaking bad enough to make it act like that wouldnt heal itself and then be normal for awhile. Since you say it only does it when driving, Problem sounds mechanically actuated. How much does your engine torque back and fourth when you rev it in neutral? It will move more than that with a load. Also any thing touching your steering components? Check all your sensor connections.. undo them and look at the prongs inside the connector and make sure none got pushed back.,...especially on those that the code pops up on.
09-18-2011, 11:32 PM
#35
I hate intermittent problems. An intake gasket leaking bad enough to make it act like that wouldnt heal itself and then be normal for awhile. Since you say it only does it when driving, Problem sounds mechanically actuated. How much does your engine torque back and fourth when you rev it in neutral? It will move more than that with a load. Also any thing touching your steering components? Check all your sensor connections.. undo them and look at the prongs inside the connector and make sure none got pushed back.,...especially on those that the code pops up on.
Weird thing about this is how its "time" related. It will miss/stumble for 6-10 seconds, then go away for 6-10 seconds, and so on. Till it decides to stay away and it runs perfect.
How many things on our engines can actually think like that...............PCM for sure can make its own changes. So its either a bad PCM of its getting weird signals from a sensor(s) making the PCM go through those changes.
I already unplugged and swapped the 02 sensors. I only have the front two.
I unplugged and checked MAF, TPS, IAC. PCV is the same as its always been.
I'm almost just tired of worrying about it. It clears up in 2-3 minutes, so I can live with it till my new set-up goes in. Hopefully in a couple months I can get it started.
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09-26-2011, 01:08 AM
#38
The issue with the missing/stumbling can't be the 98 PCM......its been great for 9 1/2 years. I think its some shorting wires somewhere because the car is almost 14 years old. I gave up looking for it. I just sit out the 20-30 seconds of missing, I drive it very easy during that time...then it clears up and I'm good to go all day.
I'd still like to come by and put it up on the dyno to see what Josh see's because of the black soot in the pipes that Ollie saw. I'll try this next week sometime. I had to leave town last week for two days.
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I'd still like to come by and put it up on the dyno to see what Josh see's because of the black soot in the pipes that Ollie saw. I'll try this next week sometime. I had to leave town last week for two days.
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09-26-2011, 10:38 AM
#39
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Can you pin point the cylinder or cylinders that are missing? A temp gun on the header tubes. The misfire will be colder. Maybe a bad injector sticking? Find the cold one and switch it out.
09-26-2011, 05:43 PM
#40
When it misses/stumbles its all cylinders doing it evenly.
He watched it today and said Bank 2 was switching but the numbers were literally 3-4 up to like 8-9, sometimes read 0. Bank 1 was switching from the 400's up to the 800's.
He gave me a schematic and told me where to check 3 different grounds that are associated with the 02 sensors getting their power.
Do you know exactly where on the Drivers side head ground wire G112 is attached.....I need to check that to make sure its tight. But I'll just be reaching back there blind with my hand.
The other 2 are splices.....S104 and S108.......6 and 3 inches from the PCM, respectively.
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