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Misfires
vza - 6 months ago
Hi All, Here is a quick overview of work I have done. Had a CEL for solenoid in Bank 2. Pulled Cams and replaced Solenoid Bank 2 and replaced Variocam Ramps for both Banks. New IMS,RMS,Case Bolts,AOS,Plugs(IRIDIUMS). Buttoned everything up and had nasty Tap/Tick. Thought it was lifters not pumping up. Ran the car cumulatively for about an hour(not all at once...idle w some revs.) to pump up lifters. Found out Bank 1 lost timing(ugh) Re-timed and tap went away, car sounded good. Then got Blinking CEL. then went solid and got misfire codes for Bank 2 Cyl# 4-5-6. Re-timed Bank 2(was nominal adjustment) checked plugs and looked as though 1 plug on Bank 2 was pristine no carbon (maybe cylinder wasn't firing??) Replaced plugs w OEM NGK(prior plugs were IRIDIUM's) ....now I'm still getting a ruff idle at start with some stalls then car sounds ok after few min warm up but still throwing pending misfires codes on 2 cylinders and precat o2 codes for both banks. Car does run better w MAF dis-connected. I also found a few leaks in the exhaust. One clamp needed to be tightened down on Bank 1 and put muffler repair dope on a small hole in Cat on Bank 2. Waiting for dope to cure will restart in a few days. Any thoughts....my 1st Porsche and would love to actually drive it some day!! I was mainly concerned that I bent up the valves by running the engine with lost timing on Bank 1 but now I'm getting misfire codes for the other Bank so I'm hoping this is a different issue and I didn't do any damage. Compression test results Bank 1 145/150/150 Bank 2 195/195/180...I did not step on accelerator while doing this cause I was alone.Any help appreciated....I'm also waiting for new MAF to come as well. Thanks V



Edited 2 time(s). Last edit at 12/24/2018 12:32PM by vza. (view changes)
Re: Misfires
vza - 5 months ago
Well....Got rid of exhaust leaks,Installed new MAF ...no stalls at start up....no misfires on 4-5 or 6 anymore....no o2 codes. NOW I'm getting misfires on 1-2 and 3 which I never got before.Codes are as follows:
P1319
P1313
P1314
P1315
Misfires on 1-2 and 3 Emission relevant. Can I drive to a mechanic or should I flatbed it?? Fuel trim bouncing around Bank 1 -0.8 to -1.6 Bank 2 0.08 to 1.6 that was using Torque Light. Got some other strange Codes with torque light Cam Shaft Pos A plausable BMW. Don't know what the Fuel trim should be....does this mean one bank is rich and the other lean?? Any good indies in Northern Bergen County NJ?? Thanks V
Re: Misfires
MarcW - 5 months ago
Quote
vza
Well....Got rid of exhaust leaks,Installed new MAF ...no stalls at start up....no misfires on 4-5 or 6 anymore....no o2 codes. NOW I'm getting misfires on 1-2 and 3 which I never got before.Codes are as follows:
P1319
P1313
P1314
P1315
Misfires on 1-2 and 3 Emission relevant. Can I drive to a mechanic or should I flatbed it?? Fuel trim bouncing around Bank 1 -0.8 to -1.6 Bank 2 0.08 to 1.6 that was using Torque Light. Got some other strange Codes with torque light Cam Shaft Pos A plausable BMW. Don't know what the Fuel trim should be....does this mean one bank is rich and the other lean?? Any good indies in Northern Bergen County NJ?? Thanks V

In the event the CEL comes on if the engine is not manifesting any untoward behavior, was running OK before the CEL came on, I have been known to drive my cars to the shop. But I'm always on high alert if the engine's condition suddenly gets worse to shut off the engine and arrange for a flat bed.

But I hate to do this on the side of the road. So if there is any question in my mind I'll just err on the side of caution and have the car flat bedded to the shop. At least I can wait at my house and then follow the flat bed to the shop in my other car and be there when the car is dropped off.

Emissions relevant misfires are I believe rich misfires. Is the CEL flashing? If they are rich misfires cylinders are being fed too much fuel which can affect cylinder wall/ring/piston lubrication and possibly damage the converters. (The excess fuel is burned in the converter which overheats it and this can ruin a converter in very little time.)

Do not know anything about the Torque Light scan tool. If the camshaft position A [im]plausible that could be from a bad Variocam solenoid and actuator to just a camshaft not in proper time or possibly a bad camshaft position sensor, bad wiring, or maybe even a bad DME.

My experience with fuel trim readings is in percentage. In percentage I do know as fuel trims get close to +/- 10% this is getting into CEL territory. I do not know how the Torque Light readings of -0.8 to -1.6 and 0.08 to 1.6 map to percentage.

That one bank has negative readings and the other positive readings suggests the bank with the negative readings is having fuel removed while the bank with the positive readings is having fuel added. It is not a good sign when the two banks differ by very much but as I mentioned I don't know how these readings map to units of trim I'm more familiar with.

OTOH, I do know some seemingly wide swings of fuel trim can be "normal" as the DME attempts to relearn fueling such is the case after the error codes are erased which also clears away learned fuel trims, resets these to their factory defaults.

However, I sort of suspect given the presence of the error codes the differences in readings between the two banks is significant.

Can't help you with any indy Porsche shops in your area. You might check out a copy of Excellence and look at the ads to see if any shop in your area advertises in Excellence.

Or perhaps use Google to search for a Porsche indy shop near your ZIP code.
Re: Misfires
vza - 5 months ago
Thanks for the response...had flashing CEL a while back but went solid. Odd thing I had misfires on Bank 2 with O2 codes and stalling.. replaced MAF.. all misfires
O2 and stalling gone Now misfires on Bank 1...computers all over the place. DME?
Re: Misfires
MarcW - 5 months ago
Quote
vza
Thanks for the response...had flashing CEL a while back but went solid. Odd thing I had misfires on Bank 2 with O2 codes and stalling.. replaced MAF.. all misfires
O2 and stalling gone Now misfires on Bank 1...computers all over the place. DME?

If the misfires are spurious, spurious misfires are not a bad DME symptom. The DME processes a signal from a knock sensor, make that 2 knock sensors, one per bank. If the DME was bad -- at least at one of the 2 pins that receive the signal from the knock sensor the failure would there would be no input. The input would either be 0V or 5V. There would be a different error code.

There have been reports of misfires (or other error codes) caused by a knock sensor that was not right. Loose or even disconnected. You want to check the knock sensor of that bank that is misfiring is properly secured to the engine and the wiring connection is good and the wiring ok.

Not sure what you mean by "computers all over the place". Assuming you are referring to the fuel trim of at least one bank this suggests an air/fuel mixture problem or a mechanical problem that cause an air/fuel mixture problem.

An intake leak, or possibly an exhaust leak. Low fuel pressure or supply to the bank can also be possible. You have to be sure in all the working on the engine (by you or someone before you) the fuel rail on the bad bank is ok the fuel supply line to it ok, not pinched, crimped.

But another possible explanation of the sudden appearance of the misfires and limited to one bank is the camshaft timing for that bank is out of whack. If you have a way of monitoring cam timing via say a Durametric tool doing so while the misfires are active or when you suspect they'll become active when you believe the CEL will come on you can (perhaps) eliminate cam timing as a possible explanation.
Re: Misfires
vza - 5 months ago
I timed the cams and certain they're good. I had misfires on bank 2 and stalls ......ruff idle, O2 codes then changed the MAF and it all went away BUT now have misfires on Bank 1 INSTEAD of Bank 2 that's what I meant by 'computer's all over the place' finding errors willy nilly. I guess I can check knock sensors...read some where low voltage can cause this as well. My Batt is weak and needs to be constantly recharged for it to turn the engine over but once its started the voltage is coming from the alternator anyway.....correct? thanks for getting back....happy new year
Re: Misfires
MarcW - 5 months ago
Quote
vza
I timed the cams and certain they're good. I had misfires on bank 2 and stalls ......ruff idle, O2 codes then changed the MAF and it all went away BUT now have misfires on Bank 1 INSTEAD of Bank 2 that's what I meant by 'computer's all over the place' finding errors willy nilly. I guess I can check knock sensors...read some where low voltage can cause this as well. My Batt is weak and needs to be constantly recharged for it to turn the engine over but once its started the voltage is coming from the alternator anyway.....correct? thanks for getting back....happy new year

Normally yes the electrical power to operate the car after engine start comes from the alternator. However a bad battery can suck up electrical power or even if the battery is healthy the alternator's output can be down due to a problem with the alternator/voltage regulator/or wiring

It is imperative that the battery be in good condition. It doesn't read like it is if you have to constantly recharge it. If the battery is not in good condition then after engine start the bad battery can represent a large electrical load the alternator is unable to satisfy and still satisfy the electrical needs of the rest of the car, including the engine.

If this is happening this can result in all sorts of weird problems.
Re: Misfires
vza - 5 months ago
Hmm..would be something if it were just the batt. Yeah they (seller) had to jump the car every time I went to test drive it.and if I don't start it for a few days it'll be dead.Was just holding off so I wouldn't have a new batt sitting in a cold garage for the winter. So your saying the batt can be taxing the alternator therefore not supplying the car w enough voltage. ? I'll buy a new batt this week.thanks v
Re: Misfires
MarcW - 5 months ago
Quote
vza
Hmm..would be something if it were just the batt. Yeah they (seller) had to jump the car every time I went to test drive it.and if I don't start it for a few days it'll be dead.Was just holding off so I wouldn't have a new batt sitting in a cold garage for the winter. So your saying the batt can be taxing the alternator therefore not supplying the car w enough voltage. ? I'll buy a new batt this week.thanks v

A lead/acid battery does not like to be fully discharged. It harms the battery in a way that can't be undone. A bad battery, and in this context bad can be any one of a number of ways a lead/acid battery can end up not performing properly, can when the engine is running tax the alternator and its ability to supply enough electrical power to replenish the battery and supply the rest of the car's electrical needs.

Direct current from the battery is routed to the field coil. The amount of current is adjusted to produce a sufficiently strong magnetic field that as this spins inside the stator electricity is generated. If the battery is sick it may not be able to supply sufficient power and the alternator's output can suffer.

An engine -- I'll ignore the rest of the car's electrical system -- requires enough power to operate the injectors, the coils, and the various sensors. Primarily -- at least this was the case with older engines -- when power dropped too low the coils were unable to generate a spark and the engine would not run.

Once running and then under low electrical power levels the coils can enter an intermediate or twilight zone and can due to differences in construction that at other times would not matter behave differently. A weak spark or an intermittent spark can be the result. Misfires.

Also, if the injectors are not receiving sufficient power they may not produce a consistent pulse width. They may be slower to open/quicker to close. The result? Misfires.

The MAF may not receive a stable supply of electrical power and its reference may be upset so it has a tougher time in determining the amount of air the engine is using. The lousy info the engine controller receives can have the short term fuel trims swinging about as a result.

The O2 sensors may not receive the power necessary to operate properly. If the heater is not supplied with the right amount of electrical power the sensor runs cold and the sensor may not work properly due to being cold. The voltage signal to the engine controller can be affected and the engine controller has another input that is causing it to mis fuel the engine.

A stable supply of electrical power of a certain voltage level is critical for proper engine operation.

Will replacing the battery be the magic bullet that eliminates all the behavior you are seeing? I hope so but I would not count on it. Still you must eliminate all other factors that can contribute to a sick engine.

As for the new battery sitting in the cold garage if you can use a battery maintainer as long as the battery is kept topped up with charge cold doesn't really bother it.

For addressing the cold garage what I have done when I had a garage, unheated, was to get a couple of oil filled electric radiant heaters. These had no exposed flame or electrical heating element, no fan. As a matter of habit I made sure they were positioned a few inches away from the wall and were no located near anything flammable. This was not hard as the garage was empty save for an air compressor and the Boxster. I experimented with the temperature control to find a setting that while it didn't have the garage toasty kept it from reaching arctic levels of cold.

(When I moved I gave these away to a buddy who had a farm. He put them in the barn where his few head of cattle would spend the night. He said after he put the heaters in the barn the cows would race to get to the barn where before they'd hang back.)
Re: Misfires
vza - 5 months ago
Thanks...I did remember getting a code having to do with insufficient heat for the O2's...gona hope for the battery....do you think if I did head damage by running the engine while bank 1 was untimed I would get misfires on bank 2 then flip flop and get them on bank 1....or is this a completely different issue.?
Re: Misfires
MarcW - 5 months ago
Quote
vza
Thanks...I did remember getting a code having to do with insufficient heat for the O2's...gona hope for the battery....do you think if I did head damage by running the engine while bank 1 was untimed I would get misfires on bank 2 then flip flop and get them on bank 1....or is this a completely different issue.?

In the event there was damage to the head (valves primarily) from running the engine improperly timed my belief is the resulting error codes would not flip flop from one bank to the other bank.The damage of course would remain and thus any resulting error codes would/could only arise from that.

There is a possibility -- just sayin' -- that the other bank's timing was off or went off -- and the other bank suffered from similar damage but only some time after the 1st bank suffered damage. The error codes appearing at bank 2 then are due to that bank having suffered real damage similar to what the 1st bank suffered.

However, while this is a possibility, it is just a possibility. I doubt this has happened.

Replace the bad battery with a good battery of proper physical size and AHs and CCAs. Be sure the battery is secure in the battery box, the vent tube is connected properly, routed properly and the battery's electrical connections are good.

Review other electrical connections. Do not skip the ground connections. These are often out of the way and as a result receive no attention but they can become marginal and cause problems.

Be sure the engine/car receives the correct amount of power at engine start and afterwards.

Then if any errors or signs of trouble appear deal with those as they need to be dealt with.
Re: Misfires
vza - 5 months ago
Thanks ...That's what I was thinking (why would the errors be going back and forth from bank to bank) I did re-time Bank 2 just to be sure but it was such a minimal adjustment I don't think that it could have done any damage on that bank(engine was running quiet) well.... just anxious to see what the batt does. V
Re: Misfires
vza - 5 months ago
WOW...I replaced my weak battery. Engine ran good...changed coolant and had to rev to 5000 RPMS to 'burp" the engine.....no CEL....NO CEL... Could it have really been the battery!!!

Does any one know what the fuel trim should be at idle. I'm using Torque Lite and looking at fuel trim for banks 1 and 2 sensor 1.

Mine both read -24% at idle and went toward 0% when revved. Thanks....very happy so far with the outcome ....hope it stays that way. V

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Re: Misfires
MarcW - 5 months ago
Quote
vza
WOW...I replaced my weak battery. Engine ran good...changed coolant and had to rev to 5000 RPMS to 'burp" the engine.....no CEL....NO CEL... Could it have really been the battery!!!

Does any one know what the fuel trim should be at idle. I'm using Torque Lite and looking at fuel trim for banks 1 and 2 sensor 1.

Mine both read -24% at idle and went toward 0% when revved. Thanks....very happy so far with the outcome ....hope it stays that way. V

vza is online now Report Post

A weak battery, which in some way results in an insufficient supply of electricity to the car, and especially the engine, can cause all sorts of issues.

If the wandering CEL stays away then it was the battery.

Short term fuel trims can vary quite a bit but should settle down to just a percent or two on either side of 0%.

Best advice I can offer is to clear the error codes -- even if there aren't any -- which among other things also sets the trims back to their factory defaults. What can happen is the fuel trims get out of whack do to a problem like a bad MAF or an air leak or something. If this out of whack condition is not reset upon engine start and as it runs the short term fuel trims can be all over the map as the engine controller works to find short term fuel trims that work best.

But if you clear the codes first, reset the fuel trims to their defaults, then when you start the engine and as it idles, warms up, and as you drive the car normally, and while the engine controller relearn the fuel trims the engine needs and while the swings in trim values can be rather high -- I've observed around +/- 5% or thereabouts -- the swings will become less severe as the engine runs.

But even after the engine controller has relearned short term and long term fuel trims, short term fuel trims are as I mentioned above dynamic in that the engine controller is constantly varying the short term fuel trim to account for varying engine loads and really anything that affects the amount of air the engine is consuming. Additionally the engine controller varies the short term fuel trims at idle about once per second from just under stoichiometric (nominally around 14.7:1 for it is at this air to fuel ratio a healthy engine will produce exhaust gases that can most completely be processed by the exhaust converters) to just over stoichiometric.

If the engine controller is finding it has to make big adjustments to the short term fuel trims this adjustment will get moved to the long term fuel trims which tends to keep the short term fuel trims hovering around 0%.

This very slight variation in fueling is so the engine controller can know it has control of the fueling. It also during those times the fueling is a bit lean that extra oxygen is supplied to the converters which should capture this oxygen. Then when the fueling is a bit rich -- has less oxygen -- the converter "gives up" this captured oxygen as it processes the exhaust gases.

The #2 sensors detect the amount of oxygen in the exhaust gases from the converters and the engine controller from these readings can know the converter is operating ok, or not, as the case may be.
Ideas
Boxsterra - 5 months ago
Double-check that the plugs you used are correct. There are a lot of variations.
Could you have an intake leak? Misfires on all three cylinders of a single bank would cause this.
Re: Ideas
vza - 5 months ago
Well ...now you got me thinking...had no misfires before I changed plugs. Replaced the ngk's that were there with the same ngk which are correct. Pre-gapped to.81mm. Now both Autozone and NGK said they SHOULD be pre-gapped(what ever that means) these are dual electrode plugs and not too sure how to check anyway! Any thoughts?
Re: Ideas
MarcW - 5 months ago
Quote
vza
Well ...now you got me thinking...had no misfires before I changed plugs. Replaced the ngk's that were there with the same ngk which are correct. Pre-gapped to.81mm. Now both Autozone and NGK said they SHOULD be pre-gapped(what ever that means) these are dual electrode plugs and not too sure how to check anyway! Any thoughts?

My 2002 Boxster used Beru plugs. I don't recall the number. There were 4 ground electrodes and based on pics I took of the old plugs vs the new plugs I do not believe the plug gap was really adjustable.
Re: Ideas
vza - 5 months ago
Thanks..cleared pending codes and looking at fuel trims. What would be good numbers...should both banks be close or the same. The pending codes were for misfires and cam position. uh oh...its not throwing a CEL yet so still feeling ok about it. v
Not to nitpick but
Boxsterra - 5 months ago
Are you sure that the plugs are exactly the same #s?

I would start by double-checking the ignition coil plugs on the failing side. Not likely that all 3 aren't clipped properly but easy to check.
Re: Not to nitpick but
vza - 5 months ago
Same #'s ...coil plugs are good. Misfires are roaming from bank to bank...that's the issue.
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