Millenia S stalls after gassing up

[OldMazzies]

Hi Millenia aficionados. I got my diagnostic codes read today as I'm again hopefully going to have some time to get to the bottom of some problems with my Millenia S. I had thought I had a persistent P0400 and P0421, as I had erased them twice and those two came back. It's been a few months since the last reset and today they were different: P0400 (EGR system) and P0505 (Idle-air Control circuit malfunction). About a year ago when the P0400 was checked out a little bit, a test of the EGR valve indicated the diaphragm was at least holding its seal (at least if I understood what they did), nor was there abnormal exhaust back-pressure, so I didn't worry about it much. I'm in an area that doesn't require emissions testing and I haven't had it on a machine to know how the combustion products look, but gas mileage was very close to the EPA ratings for this car (if I recall I got about 26 hwy and 16 around town) so I figured it must be burning fuel about right. Since then gas mileage does seem to have dropped a bit (2 or 3 mpg) I think something has changed, and maybe it will be easier to find the problem now. Really there is almost nothing beside the DTCs to convince me there is something wrong - it starts easy, accelerates and drives fine.

This new DTC and the only unexplained odd behavior I’ve noticed I’m hoping may be a clue to my problem. Right from the beginning (after the engine was rebuilt about a year ago – I bought the car with a bad engine), whenever it is filled up with gas, the first time starting it (to drive away from the pump) the engine starts then quickly stalls and becomes hard to start. After a few tries it starts and runs fine until the next time the tank is filled. Lately I’ve gotten better at keeping it rev’d up after it initially catches and preventing it from stalling. This does not happen if I put just a few gallons in.

I don’t hear any sounds that sound to me like leaks of intake air, nor have I seen any obviously bad vacuum hoses (though most of them I can't see very well, the engine is so crowded!). They were visually inspected or replaced when the engine was rebuilt and so bad vaccuum hoses seem unlikely to me, although an error such as not having one or both of the vaccuum hoses that have a one-way valve molded into them could be more likely (I read about their existence somewhere on this site and I figure one or both of them could have gotten swapped out after the rebuild), or one or both of could be installed backwards if the arrows were not noticed. Based on exhaust flow and sound of the engine, it doesn’t seem to me like exhaust flow is impeded at all, which is listed a possible cause of both of the DTCs. Haven't looked at the air filter recently, but it seems unlikely (replaced 1 yr/~7000 miles ago). The stall after gas-up problem was there when the filter was new. I always fill with 91 octane and top it off. Anybody have a guess at what is wrong, or a recommendation? Thanks.

[bigb]

so your IAC motor sounds toast. Probably causing poor mixture and you probably clogged the rear cat or at the very lest made everything sooty which could have choked up the EGR. 421 also indicates the rear bank effeciency is low but it is also where the EGR is connected so at least the codes are consistent. maybe there is a leak there or something...

I'd first fix the IAC valve and drive it 2-3 tanks and see if the other codes sort themselves out.

if you need parts, i have an IAC valve.

[OldMazzies]

Is there some test of it I can do like powering its motor off a separate battery to see if there is a noise? It looks like there are just two wires and it must be powered with 12V. But the valve does look very crowded by other parts. Is this something the hobby mechanic can change? Are there any special tools, sealants, etc., required?

As for the carbon deposits, I just learned you can put Sea Foam directly into an intake manifold and do a much better cleaning job than running Sea Foam in the gas (at least on some cars - winter starts really improved on my Astro van after having this done). With the MCE engine is there a vaccuum going into the intake manifold, or is it positive pressure there due to the supercharger? What is the most convenient way (a particular vaccuum hose, perhaps) for inserting some Sea Foam, assuming it is possible?

[bigb]

for the IAC valve, it uses a PWM signal so unless you have a proper signal generator or power supply, I doubt you will be able to test it. Not sure what putting 12V on there would do but that is one piece of the car I would not mess around with unless you have the proper equipment.

as for seafoam. I have used it in the past, and personally I dont think it does jack ****. my car is in good shape and the whole "smoking" thing where people think it's doing something is just a load of BS. smoke does not mean it's cleaning anything... it's just vaporized chemical. snake oil in a can unless you intake is so drown in crud that this isn't really going to help you anyways

Instead use a good methanol free gas line antifreeze treatment every other tank for a few months. that will do what you want gradually, and cheaply. I dont recommend using seafoam in the gas tank either as it is basically like dumping varsol in the tank. rubber and varsol do not like each other and yes it may give you a temporary improvement but long term you are rotting everything in the tank from tubing to o-rings.

of course others will disagree with me, but my next car is getting oil changes and thats it. I find the more chemicals I dump in my car, the more problems i create for myself long term.

[OldMazzies]

Makes sense. So it might work to hit it with pulses of +/-12V, but without knowing the spec that would be risky as there are a number of coding schemes that could have been employed - maybe it wants smoother signal than it would get if I just touch battery leads to it.

It was a fellow at Autozone who pointed out that SeaFoam can be used in the manifold. He indicated it was mainly for "steam cleaning" the combustion chamber and that actually water could be used. My Astro has 170K miles and did seem to benefit. Maybe it knocked some crud off in there. I had this done right away because I was already planning to get the catalytic converter replaced and didn't want any junk going through the new one. Is this "steam cleaning" possible on the Millenia? Where my engine was so recently rebuilt, I'm thinking I'm unlikely to benefit, as you indicated. I'll look into the gas line antifreeze treatment and probably give that a try. The P0421 did not return this last time. I'm not sure if it could be something related to the season why it has not returned - it had returned at least twice before. I've only seen P0505 this latest time, and getting that IAC valve from you hopefully it will go away and not return. I know there are some other potential causes though.

[bigb]

Young Padewan... put a little trust in me. put down the seafoam and step away from the ledge hehe

1st... I'll say it again. Don't play with the IAC unless you have the proper tools. It's $700 something new, and they are not the most plentiful used.

I use this to test the valve, which most people probably don't have

This is officially the CRAZIEST thing I have ever bought for my Milly


2nd... Ignore the 421 and 431 for now. Replace the IAC and drive for a few months throwing in a little 150ml bottle of gas line antifreeze every tank. your problems will be solved.

also, even if they are not, ignore the codes anyways. this is not a real problem and there is a TSB about it. downstream o2 sensors are like $200 something dollars each, even aftermarket. hardly worth it.

Linkage:
http://eunos.com.au/data/800/tsb/MIL...P0430-0431.pdf


For the EGR code... we will get to that one, but let's sort out these ones first. hopefully it will just go away

[OldMazzies]

Have you seen anything about OBD II code readers that hook up to laptops? I'm thinking that might be a worthwhile investment for me to make, especially if I could get one that would work for both the Chevy Astro and the Millenia. I haven't done any significant looking yet, and it looks like that device you bought does what I'm hoping such a device would be able to do for Mazda & Ford for a pretty good set of years, at least. Any idea what limitations those have? You mention the device you bought has some "factory goodies".

[bigb]

Maybe you misunderstood, but the device I bought IS the dealer tool. It's what they use at the Mazda dealer.

First, I don't know if you are aware, but bookmark this site

milleniatech.net

go to the documents section and download the FSM and engine manuals. Even though it is for a 96, the information is almost the same.

for a laptop scan tool I really dont recommend them. Originally I did have one... and they are cheap (~$50) to start off as a learning tool, but honestly it's a frigin pain to lug around. I'd recommend just getting a decent handheld unit and then you can use it for anything anywhere without needing to pull out the laptop. you can even throw it in the trunk on long trips in case an emergency pops up.

I really recommend this unit as it is very competitively priced and also has built in graphing of live data.

Autel

I have a videoscope from that company and was very pleased with the quality of the tools. I wasn't expecting much since the price was low compared to other tools with similar features, but it really impressed me.

I also have one of these that I use occasionally with good results however it does not have a graphing option. for this price range I prefer the Autel unit but Innova is also a good company

OBD Scantool | Canadian Tire


If you are just starting off with this car stuff and want something to get your feet wet, I recommend the tools from scantool.net. That is the one I started with and it was a good entry level tool. If you get serious after a year, then maybe you can step up to a handheld unit.

http://www.scantool.net/scan-tools/p...5-compact.html

I think the one I had was originally ELM2 or ELM3. Quite a while ago

[OldMazzies]

I could start a new thread out of this, but I'll just post here anyway as bigb I think you've seen this before and I've been reading threads trying to investigate.

Thanks for the info on the OBD scanners and tech info. I was aware and have downloaded several items. Full P0505 info, however seemed to be missing from milleniatech.net, however, unlike the write-up for P0400, for example.

Now to describe this morning's drive to work. I was trying to catch my ride so hurrying a bit as I was late and missed it at the location I usually get on. I accelerated pretty hard (not floored or anything, just more than usual) from the stop sign to merge with 35 mpg traffic and the car stalled briefly, then I went on. The TCS/TCS Off lights were then on. I was surprised because I didn't think the road had been slick, but I have now read here that when that pair of indicator lights come on together it means the car is operating in "limp mode". I was unable to drive faster than about 60 mph without losing power and drove on in to work (going 60 in a 75 part of the way - not real fun getting passed by semi's!). I noticed the TCS/TCS Off indicators would stay off for a time after restarting the car, but I'm thinking 3 out of 3 times they've come back means it's a consistent problem I've got.

So my questions: Could this be related to my IAC valve I'll be replacing soon? Reading a thread here it seemed to indicate the problem could be spark plugs or abv SOLENOID(vacuum-KJ01-18-741A, and/or vent KJ03-18-741A). Already the EGR valve and/or solenoid(s) are suspect - could those be releated? The one-way valves also I saw as possible causes - there hasn't been any recent work on the vacuum hoses, however, so if it's that then I think it just broke.

This afternoon before driving home I plan to get the code read to see what if anything additional has been logged. I do wonder if I risk further damage driving it in limp mode for awhile? If absolutely necessary I could make other arrangements and drive it less.

Update: the DTC was P1540 Lysholm air bypass valve (ABV) control system malfunction (from milleniatech.net). Since the generic description at the auto parts store was something about a radiator and/or AC sensor failure, I looked for and jiggles connectors in that vicinity. I also noticed the coolant was about 1/4 inch below the Low line - my coolant leak is not stopped! I added a bit of antifreeze. Limp mode didn't start this time until almost an hour later. I was driving quite gently.

[bigb]

ok so you seem to have 3 unrelated issues here and I will address each of them.

P505 is the IAC valve. This code is fairly isolated and this system is "upstream" from other diag codes. What I mean by that is that there is nothing failing upstream that could cause this failure. An example of a “downstream” failure would be an O2 sensor code, but that could be caused by the o2 sensor itself, or more likely something upstream such as poor spark or a bad injector.

Given that we can be fairly certain the IAC is bad unless you have a fluke electrical problem with the connector or harness. You can safely install the new one I sent you and this code will probably never come back. Also, this part does not need to be removed to work on the other codes, so go ahead and do the repair since it is isolated from the other failures




P400 is the EGR valve. Probably unrelated to the other two and could be either a bad valve or a plugged up port. Since this causes the least amount of problems (other than rough idle and perhaps a decrease in fuel economy) save this one for last.





P1540 is one that I have had personally and so have many others on the form. First, let me explain. The ABV valve is used to bypass the supercharger when the engine is idle, or when you quickly engage or let off the throttle. The key here is rapid change. It basically acts like a blow off valve in a turbo if you want to think of it that way, except it is controlled by a solenoid and manifold vacuum.

When this code is thrown you get the "limp mode" as you describe since the car cannot trust that the ABV is working. The ECU therefore limits the response of the car so that you don’t damage anything even if the charger is engaged all the time.

There is a small chance this could be caused by the IAC (5-10%). The reason being is that this ABV vacuum circuit is highly dependent on manifold vacuum. If you jam the throttle quickly and the IAC is stuck open or does not respond, it basically mimics a vacuum leak. In this case fixing the IAC will resolve this code.

My advice for this one is to first change the IAC and continue to drive for a few days. Only then if the 1540 code keeps popping up look further into this one. It may go away on its own and save you time looking for the problem

Now, if you still see P1540 after you replace the IAC then it is a vacuum related issue. At this point it can be one of two things. Either the solenoid is bad, or there is a broken or misrouted vacuum line.

To test the solenoid, what you want to do is get an ohm meter and check the resistance of the coil. It should be 10-40ohm or anywhere in that range. If the coil is open circuit, short, or very high resistance then the solenoid is marginal and probably dying. The solution here would be to replace the solenoid. If the solenoid passes the resistance test, take a 9V battery and use some wire leads to jumper the solenoid. If you hear it click, you know that it is working. The reason we use 9V is that it is a lower voltage than needed and if it works with a 9V standard battery, 12-14V from the car will definitely open it. When new this solenoid should open with only 6-7V. If you have a benchtop adjustable power supply that would probably be best, but if not the 9V battery is my "poor mans EE test"

If the solenoid checks out, then you my friend have a vacuum leak somewhere. What you want to do is download the vacuum diagram from the tech section and trace all the lines looking for problems.

Specifically where I have found issues is the following places:

1) The blue line that goes from the intake manifold to the MAP sensor. If the hose clips are missing, I’ve seen the vac lines get blown off from the manifold side. Just make sure the lines on the front and rear bank are still attached. The front you can see easily, but the rear bank one is under the intake manifold and you kind of have to look from the side to see it.

2) The second line to check is the greenish yellow line that goes from the ABV to the ABV Solenoid (Vacuum). Go through every branch in this line and make sure there are no cracks in the hose, or that any T’s are broken. If I were betting, I would bet that there is a broken or disconnected T somewhere along this line. Also, there are 2 check valves near the supercharger. Make sure they are installed in the correct orientation since I’ve gotten this code once when I installed a check valve in the wrong direction. The diagram shows the green / white check valves and you can tell by the color if they are in the right direction.

That should more than solve your problem.

Let us know how it goes