Replace air pump or go simulator route?

[igeak691]

I've got a busted secondary air pump which causes a CEL to come on within a few days of clearing it. The cheapest I could find a secondary air pump was $250 (used) or $350 (new). I've read many issues with the secondary air pump, with all the pieces that can go wrong. First, the relay. Next, the valve. Also, the hoses. And finally the pump itself. Each of these are pretty prone to failure so my question is should I just go with a secondary air pump simulator and delete the secondary air pump? This would mean no more CEL's for this. I'm worried about inspections, and whether garages will catch onto this sort of stuff. Since it only gets turned on for a minute or so after a cold start (or all starts? please clarify if you know), I feel like the very little extra emissions is worth it than to replace the pump and then have either it, or another part, fail further down the line. Added bonus would be saving about 8lbs

 

[bcworkz]

The pump runs for up to around 90 sec on start up if the engine temperature is below 60C (140F), so it runs pretty much for all starts where the engine sits for more than just a few minutes.

I doubt many garages would notice a missing pump, since some BMW engines do not have them. OTOH, they probably see a lot of M54s and might actually have a clue about BMWs. You could always leave it in place but non operational.

If you care at all about emissions, it helps much more than you realize. A LOT of a modern car's emissions happen when the engine is cold. The pump allows the cats to heat up quickly so they can do their job much sooner (they don't work at all cold). I don't know if this is an issue, but I'd be concerned the lack of a functional pump might shorten the cat life. The air helps burn unburnt and partially burnt fuel. Raw fuel reaching the cats is really bad for them.

$350 isn't really that bad for a BMW part, and I suspect there are few easier part swaps on the car. Yes, there are problems with the air system. But also cooling, electrics, intake, roof, blah blah. The list is long. If you took out all unreliable parts there wouldn't be much left. Honestly, if reliability is your prime concern, you bought the wrong car. There is still a reasonable chance you will not have any more related problems.

I'd just fix it then not worry about it any more, it'll probably be fine.

 

[igeak691]

Very good point, I appreciate the honest opinion. I took a look at old service records and saw that the pump was replaced before, but knowing how mechanics work here in the United States, I really wouldn't be surprised if all they did was clear the check engine light. A couple cold starts later, the check engine light comes back on, but after the customer realizes they've been dooped, take it back and the garage will then place another thing being the issue and try to pry more money from the customer. I hope this is the case, that the pump wasn't working, and was just never replaced, rather than if a new one was really put in and has stopped working again in less than two years.

I noticed though that the power connector connecting to the pump wasn't getting any power when I turned on the engine. I'm not sure if the engine was cold enough though, but the next time I leave the car overnight I will see if the pump is getting power on cold starts. I have checked the relay and have tested its functionality. Is there anything between the relay and the power plug that might go wrong? As far as I know the order to check is relay --> power to air pump --> air pump turns on or not --> air pump valve opens and closes properly. Short of those things, I'm not sure right now if its only the air pump that needs to be replaced or if power isn't getting to the air pump for some reason other than the relay.

 

[igeak691]

Being new to the zed world I'm getting a glimpse into common issues with these cars. Of course the roof motor is the number one issue, followed by must have mods such as non-RFT's because of how terrible the stock bridgestones run. Seems the secondary air pump issue is something that plagues not only z4's but many other BMW's as well. The fixing of it can be extensive and cost a lot of money, whereas the simulator route will be a one time fix. Also, older BMW's never had this secondary air pump and the catalytic converters never had any issues with premature lifespan. Is there any other reason I would consider keeping the secondary air pump other than that?

 

[bcworkz]

While there is no doubt a slew of sleazy American mechanics, I doubt they simply reset the light and charged the customer for a pump replacement, though it's possible. I think more likely they sourced a junk yard part, possibly older than your car, and charged the customer for a new part. There's plenty of BMWs with air pumps. M54 engines were available on nearly every BMW from 2000 to 2006, and there's likely other engines with pumps besides the M54. So there are millions of these things about. Sure there is a larger than normal share of problems, but there are still a lot of pumps that are not giving people problems.

The only real reason to keep it is if you care at all about emissions. It's easy to complain about pollution when someone else needs to pay to fix it. It's a lot harder to do the right thing when it's coming directly out of one's own pay check. I get the sense I'm not telling you what you want to hear. I'm not trying to talk you out of a simulator. Do what you want, it doesn't matter to me. But my opinion is what it is.

Exactly if and when the pump comes on, and for how long, varies by several factors, so you will need to monitor the power to the pump for a while to ensure it's really getting power or not. It's a very simple circuit. The DME/ECU controls a relay that connects the pump motor to power and it runs. The valve is basically just a spring loaded check valve, it has no electrical control. The DME uses the O2 sensors to verify the pump is working, so if that system is not operating correctly, it could throw misleading error codes.

 

[igeak691]

I'd much rather get a replacement pump and follow emissions just for peace of mind about pollution as well as when inspection time comes around. When looking for Z4 parts, prices vary so widely. I replaced my expansion tank with a $30 one that was for a 325i, when had I bought the one specifically for the z4, it would've costed me $90. Now that I'm looking at pumps, the cheapest I found was $350 new, which pushes me towards simulator route. But now that you've reminded me how m54 engines were so popular I did more research and have found some pumps for other models for less than $100 used. I will probably go this route so that it is as stock as possible. Now when I look for a pump, will any pump for any m54 engine work? Or do I have to look specifically for the same engine as mine? I know I have the M54B30.

 

[bcworkz]

Hmm, good question. I checked the part number application search at realoem.com and expected a long list of all BMWs with M54 engines. To my surprise, only Z4 E85 & 6 and X3 E83 came up! WTF?? While it did indicate the pump from a 2.5L would work, the lack of other models is perplexing. The site is usually pretty reliable, yet I find this hard to believe.

I think if I were in your situation, I'd take some pictures of my pump, then go to a junk yard and compare it with other models with the M54. If there's no obvious physical difference, it may be worth a chance there is no internal difference either. How much of a chance would depend on the price spread between any M54 and Z4 specific. If not too huge, it's probably worth being safe. For a big spread, how lucky do you feel?

 

[tgurske]

I hate to introduce some common sense into this thread, but nothing you regarding that pump will make any difference to anything. Please consider that there are millions of cars worldwide with no functional exhausts, and that there are many active volcanoes that in a billionth of a second pump out more horrid fumes than you could create in a lifetime. At the end of the day, what you do will not make any difference to anything. Sorry.

If you want to feel like you are helping the environment, sell your sports car and buy a 60mpg diesel and drive it like an old lady. If you want to help the world, give that $350 to a charity that will feed a starving child.