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Thread: E36 M3: No power to secondary air pump

  1. #1
    Join Date
    May 2011
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    1988 BMW 325

    E36 M3: No power to secondary air pump

    Hey guys, just hoping someone could help me out here. I have to pass emissions in order to transfer the title on my car. Its a 1998 M3. The previous owner removed the secondary air pump, along with the bulb for the check engine light before the sale. He said he had a simulator wired in, I just didn't know any better at the time. I have since reinstalled the bulb and pump (and all related peripherals).

    Peake codes are f5 and f6 (secondary air flow too low on cylinders 1-3 as well as 4-6). No check engine light.

    If I manually apply 12V directly to my air pump it runs fine, but I can't get 12v through the actual connector in the engine bay. Multimeter reading was 10-13 mV (millivolts, not volts) when I actually tested it. I have been allowing the car to sit overnight between tests just to make sure I am starting with a completely cold engine each time.

    After triple checking the ETM for my exact year and model, I replaced the secondary air pump relay (K6304), no luck there. I've also checked all the fuses in the front power distribution box as well as the two under the drivers side kick panel. All of them look fine.
    Ground wire coming off the secondary air pump connector looked fine, but I sanded all the contacts clean and tried a different ground point just for the hell of it. Still no luck.

    At this point, I am completely stumped. The only thing left that I think might be causing this is an aftermarket chip that the PO installed. Is there any chance that an aftermarket chip could disable the SAP system by not sending it the required voltage when an unmodified DME normally would? Thats honestly the only thing I can think of, but I would rather avoid diagnosing by just throwing parts at my car (college budget).

    Anyways, thanks in advance guys, just let me know if there is anything else I should clarify


    1988 BMW 325 - S50B30US
    Instagram "Build Thread" - http://instagram.com/jfchiu

  2. #2
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    Your M3 should NOT have a chip. The MS41.1 dme does not use a removeable chip. If that car doesn't have the original dme then its a good bet that the replacement has SAP delete.

  3. #3
    Join Date
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    Quote Originally Posted by flyfishvt View Post
    Your M3 should NOT have a chip. The MS41.1 dme does not use a removeable chip. If that car doesn't have the original dme then its a good bet that the replacement has SAP delete.
    Thanks for the reply. Since my original post, I was able to dig up the original craigslist ad. The listing says the tune was done by TRM. I went on the website and looked, and there's no mention of a SAP delete for the standard performance software, but for the MS41 swap tune the listing says that "all unnecessary emissions equipment" is deleted.

    Thanks again, I was about to open up my DME to look at the chip. I'll give TRM a call as soon as I have some free time.


    1988 BMW 325 - S50B30US
    Instagram "Build Thread" - http://instagram.com/jfchiu

  4. #4
    Join Date
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    2001 740IL
    Any pics of the m3??



  5. #5
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    98 328IS 03 325xi
    I'm hoping you find the cause, a friend picked up a 97 328 that has the same problem along with numerous codes relating to emissions. His did have a new SAP installed by a shop but now doesn't run, I can't remember if the check valve was replaced too.

    Gave away my BMWs, driving a VW and an Audi now.

  6. #6
    Join Date
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    I currently do not have the Secondary Air Pump readiness monitor checked off and cannot get the monitor to check off despite many cold starts.

    The Secondary Air Pump (SAP) is powering on and positively displacing air and the vacuum operated valve responsible for allowing air from the SAP to the exhaust manifold is getting 8.315PSI vacuum. Is this sufficient amount of vacuum to open this valve? I don't have a spare gasket for the valve, otherwise I would uninstall it from the car and see the amount of vacuum required to open the valve.

    I suspicious that this valve may not be getting a sufficient amount of vacuum, since a previous owner of my car installed a S50 intake manifold on my S52 motor, while deleting several of the SAP system equipment. Vacuum is being provided to the valve via a hole drilled the underside of the S50 manifold with a piece of tube stuck in it. Long term, the missing equipment should be installed or the SAP system deleted out of the car. Since I'm registering the car in California, I'm concerned that deleting the SAP System will impact my ability to pass a smog check, since car could fail visual inspection for lack a Secondary Air Pump, assuming I remove the pump from the car instead of letting it sit dormant.

    I found a SAP system troubleshooting guide on Bavarian Autosport that is particularly helpful.

    https://blog.bavauto.com/12072/bmw-secondary-air-system-fault-code-diagnosing-how-to-diy-obd-ii/

    I need to check off the SAP readiness monitor to he able to pass a smog check or find a smog station that will pass me without this readiness monitor checked off, which is technically legal, as long as it is the only readiness monitor not checked off.
    Last edited by Ratinoff; 12-17-2017 at 11:06 AM.

  7. #7
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    The fuse for the SAP is F50, but it's also the fuse for a half dozen other things that all work, so you can discount the fuse for now. Since the pump runs when you hardwire it, then the pump is good. The only remaining thing in the circuit, besides the wires, is the Secondary Air Pump Relay, located in the Front Power Distribution Box. Based upon other models, this should be salmon colored.

    Pin outs are,
    I have no information on Pins 1, 3 & 7. The schematic indicates 8 pins.

    Pin 2 is a RED wire that goes to the battery. (It occurs to me there should be a fuse, but none is shown.) When the relay is energized, this goes to Pin 6 and becomes a RED/YEL wire that goes to the SAP.
    Pin 4 is a BRN/GRN wire that is a Switched Ground to turn the relay on or off. The switching action comes from the ECU, Pin 35.
    Pin 5 is a BRN wire, and the RED/YEL wire (above) goes to it when the relay is de-energized. The SAP has two wires, the RED/YEL that is either powered or grounded depending upon the state of the relay, the other SAP wire is a ground (BRN wire) source for when the relay is energized.
    Pin 8 is a RED/WHT wire that goes to the output, Pin 2, of the Engine Control Module (ECM) Relay. There is a junction point after the ECM Relay that goes to the Fuel Pump Relay as well as the Secondary Air Pump Relay, so if you have a fuel pump, then the ECM Relay is good.

    So, the SAP Relay has a RED/WHT wire to power the coil, a BRN/GRN wire that is a switched ground for the coil of the relay. This completes the control circuit for the SAP relay.
    A RED wire from the battery sits on a contact, and a BRN wire sits on the other contact. There is a RED/YEL wire that goes back and forth between the relay contacts to turn the SAP on or off. This is the switched circuit of the SAP relay.

    My thoughts are that the contacts inside of the relay are toasted so that when it should be energized, no power flows from the RED wire to the RED/YEL wire.

  8. #8
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    Ratinoff what software are you using to check the status monitor. Do you have a CEL? are there any codes stored, I don't think you will have any trouble passing inspection if there are no codes and the system turns on.
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
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  9. #9
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    God damn it. This is like 4 years old.

    You can have one monitor still running and go for Smog in California. Call the BAR and tell them, "I had a Check Engine light and fixed it. Now I have a monitor that is still running, can I get smogged with one monitor running?"

    You may still fail, but the running monitor is not the reason why.

    Deleting equipment is a huge problem for the smog police in California. Indeed, with missing equipment, the tester should not even plug his machine into your car. The steps are, turn the car on, if no Check Engine light before Engine Start, fail. Look for the existence of system components, if any are missing, fail. Check that no monitors are running, if more than 1, fail. Test the car. If you have stuff missing, then it must be restored before the car can be tested.

  10. #10
    Join Date
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    Quote Originally Posted by JDStrickland View Post
    God damn it. This is like 4 years old.
    I don't give a single f*** that this thread this thread is 4 years old. If I have a question, I'm going to ask, because I think it's relevant.

  11. #11
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    Quote Originally Posted by JDStrickland View Post
    You can have one monitor still running and go for Smog in California
    I had no check engine light and 7 of 8 readiness monitors checked off, with only Secondary Air Pump readiness monitor not checked off and was turned away from a smog check on the basis that the smog shop claims that if they pass cars with not all readiness monitors checked off, BAR will issue the shop a demerit. If a shop receives a sufficient number of demerits, they can be shut down. This necessitates calling a smog shop before hand and ask over the phone if they will administer a smog check to a car with one readiness monitor not checked off. This also necessitates calling a smog shop that will answer the phone, which usually is a tall order, since these shops are busy administering smog checks and not answering phones.

    You are correct though. As of May 2015, BAR permits at least one readiness monitor not be checked off while still allowing a smog check to be administered. This is unhelpful, if a smog shop is unwilling to administer a smog check for the reasons stated above.
    Last edited by Ratinoff; 12-18-2017 at 12:21 AM.

  12. #12
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    Quote Originally Posted by Eric93se View Post
    Ratinoff what software are you using to check the status monitor. Do you have a CEL? are there any codes stored, I don't think you will have any trouble passing inspection if there are no codes and the system turns on.
    I'm using a Actron CP9185 scan tool to check for emissions codes and to check for the status of the status of the readiness monitors. I cannot recommend this scan tool enough. It's the most useful scan tool I've ever used.

    I have no check engine light asserted. I have 7 of 8 readiness monitors checked off. The only readiness monitor not checked off is the Secondary Air Pump system.

    The scan tool I'm using is reporting no emissions related error codes.
    Last edited by Ratinoff; 12-18-2017 at 12:27 AM.

  13. #13
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    Do you have two post cat sensors? If not then that is probably the issue. If you do have both post-cat oxygen sensors then one is probably bad, use your scan tool to make sure both sensors are switching properly.
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
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  14. #14
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    Quote Originally Posted by Eric93se View Post
    Do you have two post cat sensors? If not then that is probably the issue. If you do have both post-cat oxygen sensors then one is probably bad, use your scan tool to make sure both sensors are switching properly.
    I recently replaced both post-cat O2 sensors and they're working correctly. I've heard that if the pre-cat O2 sensors are degraded, but not to the extent that they will trigger a check engine light (MIL), that they may not trigger the Secondary Air Injection System Monitoring test to run. This might be the issue I'm having.

    If the pre-cat O2 sensors were completely degraded, they would trigger a check engine light prompting replacement. Following the replacement of the O2 sensors and clearing the check engine light, the Secondary Air Injection System Monitoring test should run.
    Last edited by Ratinoff; 12-20-2017 at 02:30 AM.

  15. #15
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    When my Secondary Air Pump wouldn't come on, it was because the relay was bad. Have you changed the relay?

  16. #16
    Join Date
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    Quote Originally Posted by Twright View Post
    When my Secondary Air Pump wouldn't come on, it was because the relay was bad. Have you changed the relay?
    My Secondary Air Pump powers on, however I cannot get the Secondary Air Pump Readiness Monitor checked off, despite numerous engine cold starts.

  17. #17
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    Ratinoff, your right about replacing pre-cat sensors to solve other issues. I had this issue and fortunately read it in the forum years back, I had the code for catalyst below efficiency and replaced the pre-cat sensors instead of the post cat because they pre-cat are more important and the system compares the pre and post cat sensors to determine the cats efficiency. I'm confident that my post cat sensors are shot, but I don't get any codes.
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
    Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".

  18. #18
    Join Date
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    Quote Originally Posted by Eric93se View Post
    Ratinoff, your right about replacing pre-cat sensors to solve other issues. I had this issue and fortunately read it in the forum years back, I had the code for catalyst below efficiency and replaced the pre-cat sensors...
    I replaced both pre-catalytic converter oxygen sensors and within four engine starts, the Secondary Air Injection System Test was run and the associated readiness monitor was checked-off. Problem solved.

    Based on the markings on the pre-catalytic converter oxygen sensors removed from my car, they appeared to be original equipment and consequently had about 125k miles on them. They were most likely in a degraded state, which most likely inhibited the Secondary Air Injection System Test from running on engine start.
    Last edited by Ratinoff; 05-20-2018 at 02:42 AM.

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