Still having idle issues--injectors??

[usinjin]

Hope everyone is having a nice November :)

My ZHP is still idling a little on the rough side. It's not a cold idle, it's usually after it warms up. Car starts fine, cold idle is fairly smooth, but once the revs drop to about 700 or so when it's warmer, it begins to stumble a little. I can feel it in the car and see it on the tach. Driving is fine, no noticeable loss of power or anything like that, but when I come to a stop, revs sometimes drop to about 500 and it again stumbles somewhat.

There are no codes.

Here is everything I've replaced:

CCV
Intake manifold gasket
Valve cover gaskets
Air filter
Fuel filter
Spark plugs
Brake booster vacuum valve
Camshaft sensor (intake)
Alternator
Battery

Rebuilt:
DISA (G.A.S. kit)
VANOS (seals)

Cleaned:
Idle control valve (cleaned it like 5 times by now!)
MAF sensor
Throttle body

Smoke test has been performed and leaks were fixed.

I'm wondering if I should replace my injectors. I tried getting readings using INPA but was having difficulty (all just module timeouts). In different software, I'm getting different values for "Average rough idle" across cylinders. Most read values of "15.xx" and others are "0". I'm not exactly sure what this is measuring though.

Any ideas/feedback would be appreciated, as always :)

[Fried_Chicken]

I just did my intake manifold removal cooling system replacement and everything that goes with it, including the oil sep system and cleaning the ICV valve.

I cleaned the throttle body and reset the adaptations. I’m also getting weird idling. My suspicion is the dual-mass flywheel. It doesn’t bother me tremendously, and usually a rev will clear things up.

[edit]

Actually you probably need to reset your adaptations (you never mentioned this), and then it’ll take a few days for it to smooth out.

[usinjin]

I just did my intake manifold removal cooling system replacement and everything that goes with it, including the oil sep system and cleaning the ICV valve.

I cleaned the throttle body and reset the adaptations. I’m also getting weird idling. My suspicion is the dual-mass flywheel. It doesn’t bother me tremendously, and usually a rev will clear things up.

[edit]

Actually you probably need to reset your adaptations (you never mentioned this), and then it’ll take a few days for it to smooth out.

My bad, you're right, totally forgot to mention, did reset all the adaptations (whoops, bucked like mad until I did the throttle reset!), and I've actually driven it about 500 miles--still a little rough. Before resetting the fuel trims were close to -10%, likely because of the leaks I'd fixed, but now it is back around 5%.

The thing is, it used to idle smoother, so I feel like it definitely /can/ idle smoother, but I'm running out of things to replace!

[Will]

My random guess: Oil filler cap?

[BMWCurves]

My random guess: Oil filler cap?

I've done that before...

[Fried_Chicken]

My bad, you're right, totally forgot to mention, did reset all the adaptations (whoops, bucked like mad until I did the throttle reset!), and I've actually driven it about 500 miles--still a little rough. Before resetting the fuel trims were close to -10%, likely because of the leaks I'd fixed, but now it is back around 5%.

The thing is, it used to idle smoother, so I feel like it definitely /can/ idle smoother, but I'm running out of things to replace!

Hhhmmm... my money is on something simple/stupid. I'd run another smoke test. Otherwise it could be the flywheel (mine rattles on occasion while idling).

[usinjin]

My random guess: Oil filler cap?

Been replaced as well, OEM cap and new gasket too.


Hhhmmm... my money is on something simple/stupid. I'd run another smoke test. Otherwise it could be the flywheel (mine rattles on occasion while idling).

Another smoke test it is. Did the rubber glove-over-the-upper-boot method and after filling it with smoke, it stayed inflated for several hours before I ended up removing it. Not sure what else I could replace. Every single rubber thing/hose that even looked warn has been replaced.

I feel like the flywheel is a bit more far-fetched...how could it be causing the revs to bounce up and down?

[Will]

Another random guess: the vacuum lines from the intake boot "F" connector down to the fuel pressure regulator (One at the F connector and one rubber vacuum line down by the fuel filter).

[usinjin]

Another random guess: the vacuum lines from the intake boot "F" connector down to the fuel pressure regulator (One at the F connector and one rubber vacuum line down by the fuel filter).

The f connector and the fuel vacuum line have been replaced too :|

[Fried_Chicken]

Truly a mystery, time to dig down.

What's the mileage of the car? Have you hooked up a computer to read codes that might be present but not throwing a CEL? At this point a proper diagnostics is in order - guessing and replacing parts will not do.

You mentioned spark plugs, but not coils. Coils tend to fail after ~100k miles, although if you didn't replace them, they shouldn't introduce a rough idle. You said you replaced the CCV, did you also replace all the hoses associated with it? These can get clogged along with the CCV, although if it didn't manifest before, it shouldn't manifest now.

As I'm writing this, I think the most suspicious item is the MAF. I don't like touching MAF sensors, they are super finnicky. If you did clean them, did you use the right type of spray? It's critically important you do. The wrong type of spray will leave oil residues, and permanently damage it. If you can quickly swap out another MAF, you can get your answer quickly. Alternatively, try spraying with the appropriate spray. You might have to again reset adaptations, although I don't think so.

[Will]

How many miles on your O2 sensors? They soft-fail around 100k miles.

[Dave1027]

Use OBD Fusion and an OBDII WiFi adaptor to view your short term fuel trims, MAF data and O2 sensor voltages. I had poor idle and that's how I tracked it down.

[usinjin]

Truly a mystery, time to dig down.

What's the mileage of the car? Have you hooked up a computer to read codes that might be present but not throwing a CEL? At this point a proper diagnostics is in order - guessing and replacing parts will not do.

You mentioned spark plugs, but not coils. Coils tend to fail after ~100k miles, although if you didn't replace them, they shouldn't introduce a rough idle. You said you replaced the CCV, did you also replace all the hoses associated with it? These can get clogged along with the CCV, although if it didn't manifest before, it shouldn't manifest now.

As I'm writing this, I think the most suspicious item is the MAF. I don't like touching MAF sensors, they are super finnicky. If you did clean them, did you use the right type of spray? It's critically important you do. The wrong type of spray will leave oil residues, and permanently damage it. If you can quickly swap out another MAF, you can get your answer quickly. Alternatively, try spraying with the appropriate spray. You might have to again reset adaptations, although I don't think so.

Car has 150,xxx miles. No codes whatsoever from ECU (except SAP, which has been coded out anyways).

Do coils soft fail at all? Not misfiring, so they didn't seem likely to me.

CCV was replaced, OEM unit and all hoses as well. When I pulled the intake off I inspected all the hoses again and they were good.

MAF was cleaned a couple of time with CRC mass airflow sensor cleaner. After spraying, it was left in a clean environment outside of the car overnight to dry. I've never touched any part of it besides the outer plastic housing. Don't have another MAF to test unfortunately.

[usinjin]

Use OBD Fusion and an OBDII WiFi adaptor to view your short term fuel trims, MAF data and O2 sensor voltages. I had poor idle and that's how I tracked it down.

Prior to an exhaust leak, I was seeing 7-12% on average for the fuel trims. After fixing, about -15%. After resetting adaptations and driving 500+ miles, they're at about 6%.

I hadn't realized I could actually diagnose using voltages. What is the range they should be in?

[Will]

BTW, as a side note: what did you find in regards to the wonky ride heights (link (http://www.zhpmafia.com/forums/showthread.php?23224-Koni-Sport-shocks-not-level))?

[Fried_Chicken]

Car has 150,xxx miles. No codes whatsoever from ECU (except SAP, which has been coded out anyways).

Do coils soft fail at all? Not misfiring, so they didn't seem likely to me.

CCV was replaced, OEM unit and all hoses as well. When I pulled the intake off I inspected all the hoses again and they were good.

MAF was cleaned a couple of time with CRC mass airflow sensor cleaner. After spraying, it was left in a clean environment outside of the car overnight to dry. I've never touched any part of it besides the outer plastic housing. Don't have another MAF to test unfortunately.

Did the rough idle start suddenly? Do you know when it started relative to any parts you replaced? If you do, that's the first place I would look.


I think it's a safe assumption that the intake is fine at this point. You say you reset the adaptations, have you had the car in an idle situation long enough? It might still be learning the adaptations (I assume it needs the engine under all conditions, so simply driving 500 miles wouldn't give it that). I had a rough-ish idle after doing the manifold out procedures (coolant lines, etc), cleaning the throttle body, and resetting the adaptations. It took a bit for my idle to normalize.

[Dave1027]

Prior to an exhaust leak, I was seeing 7-12% on average for the fuel trims. After fixing, about -15%. After resetting adaptations and driving 500+ miles, they're at about 6%.

I hadn't realized I could actually diagnose using voltages. What is the range they should be in?

The Pre-Cat O2 sensor voltages should be in the 1 volt range. They don't deviate much.

[usinjin]

BTW, as a side note: what did you find in regards to the wonky ride heights (link (http://www.zhpmafia.com/forums/showthread.php?23224-Koni-Sport-shocks-not-level))?

Thanks for asking--you know, I'm convinced it was something like 20% my imagination, even though I did measure and there was a considerable difference in wheel well clearance on either side--I removed both shocks, replaced both rear shock mounts, wrestled springs around on both sides to make sure they were in the same place, everything else looked symmetrical. It still was a little wonky, and I gave it up for the time being.

Checked again recently, and the back was even again. I guess it needed time to settle?

[usinjin]

The Pre-Cat O2 sensor voltages should be in the 1 volt range. They don't deviate much.

Post-cat O2's are not present in the car (catless headers), they've also been coded out. Pre-cat voltages are fluxuating between 1.46v and 1.55v approximately.

[Will]

Thanks for asking--you know, I'm convinced it was something like 20% my imagination, even though I did measure and there was a considerable difference in wheel well clearance on either side--I removed both shocks, replaced both rear shock mounts, wrestled springs around on both sides to make sure they were in the same place, everything else looked symmetrical. It still was a little wonky, and I gave it up for the time being.

Checked again recently, and the back was even again. I guess it needed time to settle?

Nice, glad it's even. Might have been the uneven / sloping ground, I thought my m3 was off by 1/2"-3/4" in a corner but when I measured on flatter / less sloping ground it was about even (1/4").


Post-cat O2's are not present in the car (catless headers), they've also been coded out. Pre-cat voltages are fluxuating between 1.46v and 1.55v approximately.


How many miles on your O2 sensors? They soft-fail around 100k miles.

How old are those o2 sensors?

[usinjin]

How old are those o2 sensors?

As old as the car. 150,xxx. Indy thought they should be fine unless one or both totally failed, though perhaps "fine" means "running but running kinda rough"?

[racer2086]

I would have suggested MAF and coils also, unless those have been done. At 150k, it couldn't hurt to replace the O2 sensors if they've never been replaced before. Those 3 things are somewhat good preventive maintenance to do at that mileage anyway, but that's throwing parts at the problem.

1.5v seems high for the O2 sensors. Can anyone confirm? I think the higher the voltage, the richer the mixture. Which means something is wrong in terms of readings for the car to set the air/fuel mix OR an injector is leaking introducing extra fuel to the mix OR the fuel pressure regulator isn't working properly and your fuel pressure is too high.

The MAF would be a huge suspicion of mine, since that directly tells the car how much air is being introduced to the engine. The fuel mix will be adjusted based on that reading. What is the MAF reading? In INPA for example, it'll tell you what the air measurement is and if it is within the expected range.

[BMWCurves]

I wish I knew more so I could offer my $0.02, but other people will chime in, I'm sure.

[Vas]

If you can take a screenshot of your short and long term fuel trims that would be really helpful to diagnose the root of the problem



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[usinjin]

Here are screenshots from OBDFusion. Car idling after warming for about 15 minutes.37485374863748737488

Edit: Uh, not sure about those O2 sensor voltages. Different software put them around 1.5v.

Edit #2: MAF is stable at about 3.9 g/s.

[Fried_Chicken]

I have no idea how to read these values. What is "short term fuel trim" and "long term fuel trim"? What is ignition timing advance?

I do know what intake air temperature means, and 131F seems really high. I would expect it to be in and around atmospheric temperatures, no?

[usinjin]

I have no idea how to read these values. What is "short term fuel trim" and "long term fuel trim"? What is ignition timing advance?

I do know what intake air temperature means, and 131F seems really high. I would expect it to be in and around atmospheric temperatures, no?

For trims, notice 99.219 + 0.78 equals 100% (probably w/ rounding error). From a purely mathematical standpoint they appear to be the same thing just expressed differently. Usually they’re expressed as a percentage though so I’m inclined to only be concerned with 0.78%. Which seems pretty ideal to me.

Ignition timing advance has to do with the degree at which ignition occurs before top dead center (BTDC), I.e. the piston reaches its highest point of travel.

I’d expect the intake air temp to be higher than ambient, as the air has already been through the boots, throttle body, and into the intake manifold. I saw the sensor there when doing those pesky gaskets. If I have to remove the intake manifold a third time..*shudders*

[usinjin]

I did go ahead and throw some money at my problem and bought a new set of coils. My reasons are as follows: 1). When the last engine that was in it blew, I bought a few new coils to try and diagnose, and I think my last mechanic threw the same coils back in the replacement engine, so I've been running on a couple of newer coils and several much old ones, and 2). $150 really isn't bad at all for some preventative maintenance. Splurged on 1-day shipping :)

I'm still very much hoping to dig into these numbers and hopefully see for sure where the problem is definitively.

[Fried_Chicken]

I’d expect the intake air temp to be higher than ambient, as the air has already been through the boots, throttle body, and into the intake manifold. I saw the sensor there when doing those pesky gaskets. If I have to remove the intake manifold a third time..*shudders*

Don't reason with wishful thinking. 131°F seems way too high, unless you don't have your air filter installed, or have some aftermarket air filter installed. Do you have a "warm air intake" installed by any chance?

[usinjin]

Wishful thinking?? Not exactly sure where you got that. These are my reasonings I’ve come to after discussing issues with my mechanic and internet research. Of course I could be wrong, which is another story altogether. If anyone can correct anything I’m coming up with, that would be appreciated, as it’ll help me learn and better understand.

No aftermarket intakes/boots/filters of any kind.

130F seemed more or less normal to me, after reading comments of ~150F AIT on similarly specced e46 models across various forums, and reassurances that that range was probably okay. Especially after running the car hard and then allowing it to idle again, perhaps heat-soak played a part. Perhaps the tune it’s running plays a role.

Again, I could definitely be wrong.

[Fried_Chicken]

Wishful thinking?? Not exactly sure where you got that. These are my reasonings I’ve come to after discussing issues with my mechanic and internet research. Of course I could be wrong, which is another story altogether. If anyone can correct anything I’m coming up with, that would be appreciated, as it’ll help me learn and better understand.

No aftermarket intakes/boots/filters of any kind.

130F seemed more or less normal to me, after reading comments of ~150F AIT on similarly specced e46 models across various forums, and reassurances that that range was probably okay. Especially after running the car hard and then allowing it to idle again, perhaps heat-soak played a part. Perhaps the tune it’s running plays a role.

Again, I could definitely be wrong.

Wishful thinking being afraid to remove the intake manifold again, but sorry, I was being insensitive.

131F seems high, but if others are reporting it, I could believe it. It would cause wonky idling. How bad is this wonky idling exactly?
Have you let your car do a lot of idling? I think after an adaptations reset the car needs a while to get itself in shape, in all different running conditions. Mine didn't idle nicely for a bit after doing all the work.

[usinjin]

Wishful thinking being afraid to remove the intake manifold again, but sorry, I was being insensitive.

131F seems high, but if others are reporting it, I could believe it. It would cause wonky idling. How bad is this wonky idling exactly?
Have you let your car do a lot of idling? I think after an adaptations reset the car needs a while to get itself in shape, in all different running conditions. Mine didn't idle nicely for a bit after doing all the work.

That’s my bad, I made a bit of a dumb joke. If the sensor was indeed bad, I’d happily pull the intake again. I feel like a pro by now!

It may just need more time, I agree there. It’s been about 600 miles since I rest the adaptations, driven slow, moderate, WOT and idled (probably idled for 3-4 hours since then).

It’s not terrible idling—it’s more like inconsistently-okay idling. Sometimes it’s okay, not terribly smooth (but then again it is 16 years old)...but other times it’s fairly rough. Like, the car shakes a bit and the tach bounces. This usually happens after I’ve been driving and then come to a stop. The idle drops to about 500 revs and stutters somewhat.

[Fried_Chicken]

That's plenty to reset the adaptations. Do you have the OEM air intake installed? After running and coming to a stop, hot air could cause issues.

[usinjin]

That's plenty to reset the adaptations. Do you have the OEM air intake installed? After running and coming to a stop, hot air could cause issues.The stock intake is pretty good, I'm doubting it's the thing causing a poor idle.

[Vas]

Are the short term fuel trims always that far apart? Both banks should be closer together but your bank 1 is not close to bank 2. The dme is pulling alot of fuel from bank 1.

Keep in mind that long term fuel trims are driven by short term trims. They also should be measured at idle, 1500 rpm and 2500 rpm.

Also your idle value is out of spec. Target range is 650 rpm.

At the mileage your car is at I would replace the primary oxygen sensors ( they are 100k mileage maintenance item ).

Also disconnect the maf sensor and see what your scanner puts out and how the car runs. My hunch is that your maf is also kaput.



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[usinjin]

Are the short term fuel trims always that far apart? Both banks should be closer together but your bank 1 is not close to bank 2. The dme is pulling alot of fuel from bank 1.

Keep in mind that long term fuel trims are driven by short term trims. They also should be measured at idle, 1500 rpm and 2500 rpm.

Also your idle value is out of spec. Target range is 650 rpm.

At the mileage your car is at I would replace the primary oxygen sensors ( they are 100k mileage maintenance item ).

Also disconnect the maf sensor and see what your scanner puts out and how the car runs. My hunch is that your maf is also kaput.



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The STFTs are not consistent with each other. I might have an exhaust leak as well still.

The idle is also not consistent. It will be as high as 800 or as low as 500.

Will also test MAF as requested, results soon.

[Fried_Chicken]

The stock intake is pretty good, I'm doubting it's the thing causing a poor idle.

It is. People that install aftermarket intakes are idiots - they suck warm air from the engine compartment.

[Vas]

The STFTs are not consistent with each other. I might have an exhaust leak as well still.

The idle is also not consistent. It will be as high as 800 or as low as 500.

Will also test MAF as requested, results soon.The numbers should be no greater then 10% and the total fuel trim numbers should be no more then 10% when they are added. The fuel trims should be monitored at idle, 1500 rpm and 2500 rpm. The image attached is at 2500 rpm

If the numbers are greater then 10% in the positive or negative direction, the DME is compensating for more then just normal wear and tear on the engine.

Also something to consider is that when the numbers reach 25% in either direction the check engine light will come on for either system too lean or rich.

After replacing the primary o2 sensors and a new maf car is running great. https://uploads.tapatalk-cdn.com/20201124/84661d2d6ed47b21828b931afb0ac076.jpg

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[usinjin]

Unplugging the MAF, the engine doesn’t run that much rougher, only slightly more so.

MAF reinstalled, at 2500 rpm, the fuel trims are as follows:

STFT bank 1: -7.03%
LTFT bank 1: 5.47%

STFT bank 2: -6.25%
LTFT bank 2: 5.47%

I have questions as to “why”, but I’m in agreement that a new MAF + O2s are in order. I’m not sure why I thought MAFs were super expensive; they’re actually not as bad as I was thinking.

Edit: Is there a quality difference between the Bremi and the VDO branded MAFs?

[Fried_Chicken]

Unplugging the MAF, the engine doesn’t run that much rougher, only slightly more so.

MAF reinstalled, at 2500 rpm, the fuel trims are as follows:

STFT bank 1: -7.03%
LTFT bank 1: 5.47%

STFT bank 2: -6.25%
LTFT bank 2: 5.47%

I have questions as to “why”, but I’m in agreement that a new MAF + O2s are in order. I’m not sure why I thought MAFs were super expensive; they’re actually not as bad as I was thinking.

Edit: Is there a quality difference between the Bremi and the VDO branded MAFs?

Both are German. I would caution against throwing money at problems. If you're looking to do O2 sensors and want to save money, I'd recommend getting these (https://www.amazon.com/Bosch-15733-Oxygen-Universal-Fitment/dp/B000BZG8ZU/ref=sxts_sxwds-bia-wc-nc-drs1_0?cv_ct_cx=bosch+oxygen+sensor&dchild=1&keywords=bosch+oxygen+sensor&pd_rd_i=B000BZG8ZU&pd_rd_r=8371986e-3051-4ffd-97c2-7e3db3d85900&pd_rd_w=lYUrP&pd_rd_wg=nfavf&pf_rd_p=84ce0865-d9ca-42e3-87ed-168be8f93162&pf_rd_r=ZA9PMM841QWFQ3MX8QPD&psc=1&qid=1606283947&sr=1-1-88388c6d-14b8-4f70-90f6-05ac39e80cc0) "used" from the Amazon Warehouse for $25 each.

I installed 8 of them on two cars and saved a fortune.

[usinjin]

Both are German. I would caution against throwing money at problems. If you're looking to do O2 sensors and want to save money, I'd recommend getting [url=https://www.amazon.com/Bosch-15733-Oxygen-Universal-Fitment/dp/B000BZG8ZU/ref=sxts_sxwds-bia-wc-nc-drs1_0?cv_ct_cx=bosch+oxygen+sensor&dchild=1&keywords=bosch+oxygen+sensor&pd_rd_i=B000BZG8ZU&pd_rd_r=8371986e-3051-4ffd-97c2-7e3db3d85900&pd_rd_w=lYUrP&pd_rd_wg=nfavf&pf_rd_p=84ce0865-d9ca-42e3-87ed-168be8f93162&pf_rd_r=ZA9PMM841QWFQ3MX8QPD&psc=1&qid=1606283947&sr=1-1-88388c6d-14b8-4f70-90f6-05ac39e80cc0[/url] "used" from the Amazon Warehouse for $25 each.

I installed 8 of them on two cars and saved a fortune.

Yeah, but if I throw no money at it, it'll never be fixed. :)

I'm aware that the coils probably won't have a big effect. But, these are the new design, and the current set is mis-matched and high mileage anyways. So I feel good about replacing them.

Thanks to everyone for the input.

[Fried_Chicken]

Let us know if this solves the problem

[Fried_Chicken]

Any update?