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Grrr '00 Milly S, why u mad? so what happens when a 1540 isn't the solenoid?

5K views 10 replies 4 participants last post by  Kutcht1 
#1 ·
2000 Mazda Millenia S with 99000 miles on it. I purchased it on the cheap from a mechanic who tried to work on it and didn't replace the timing belt tensioner when he did The timing belt and it wouldn't run for him. I redid his work as well as replaced valve cover gaskets and fixed the vacuum line errors that he made. The car basically ran fine after that aside from an odd low boost thing that it did sometimes coming off of throttle running down the road. The car would immediately boost to 10 pounds and then go down to 2 pounds according to the boost gauge. Soon after code 1540 started popping intermittently and the TCS light and all those fun things at all these cars do. So I did my homework and found the part numbers, broke down and spent $100 for the 2 associated solenoids. I put them in and now the car is actually worse. Instead of being an intermittent 1540 now it is multiple times during my 15 mile commute back and forth to work. I have to shut the car off rolling down the road and then start the car in neutral to reset it.
CODES?
173 front bank fuel trim
1455 only when the gas tank is half full or lower.
1540 of course, but sometimes the TCS light doesn't come on, even though the car is stupid and it doesn't rev past 2500.
Solenoids are new, vacuum are correct.
So what other engine management is involved with how this car decides when to activate the 1540 code and cut the fuel at 2500? I don't have a problem spending money on the car, I know that, I own another 2000 Milly S identical to this one. But this car is genuinely frustrating me.
My thoughts/ suspicions are perhaps the The Throttle Body sensor or maybe the map sensor, .... And I guess it's worth noting that the TCS Off button does not work, or something is wrong with with the wiring as pushing the button does nothing.

any other thoughts from you guys?

What is the elephant in the room I'm missing?
 
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#2 · (Edited)
Three things:

(1) For the P1540, did you change both the ABV Solenoid (Vent) and ABV Solenoid (Vacuum) valves, part numbers KJ0218741A and KJ0318741A? And check all those little vacuum hoses back there?

See this post:
http://forums.mazdaworld.org/100-millenia/111977-p1526-p1540-tcs-lights-abv-solenoid-valves.html

(2) Another thing I was thinking since you are getting fuel trim codes and 1455 when the tank is low is maybe the Fuel Pressure Regulator has a bad diaphragm inside. Have you checked out the Pressure Regulator and Fuel Pump?

Here is a thread to check that:
http://forums.mazdaworld.org/100-mi...mp-fuel-pressure-regulator-testing-guide.html

(3) Another thing to check is intake gaskets. Get a small can of propane (like a plumber uses from Home Depot) and gas it (don't light it of course) all around the intake gaskets. Or use spray carb cleaner and spray around the intake gaskets. If there is a change in idle, then may you have intake leaks. Intake leaks on the intake gaskets from all that intercooler plumbing on the S will cause that 2,500 bucking, jerking, and stalling. For intake gasket leaks you can either order new intake gaskets (which there are many gaskets and they are expensive), or get a can of Permatex copper spray and reseal them. To do that - Gently wipe the oil off the metal gaskets, lay out a large sheet of cardboard, give a thin coat to one side, let it dry about 10 minutes, flip them over, spray the other side and let it dry, then give them a second coat. Two thin coats will make those gaskets good as new.

 
#3 · (Edited)
Hey thanks for the reply! I was getting concerned after 75+ views and no input.

So yes, both the KJ02 ($60) & KJ03($62) brand new from my dealership, so I'm not suspect of that part any more.


I don't suspect a boost leak. The gauge reads full boost while it is cutting out, so it is a fuel cut or spark/ignition cut by the ECU that is affecting drive-ability.

I've sprayed/soaked the entire upper plenum area looking for a vacuum leak. I found an ill-fitting tee (worn out/stretched out hose) but replaced all the lines associated as well as the tee. I don't believe it is a vacuum issue at this point. Everything else operates as such. Even verified the proper actuation of the ABV Valve itself at idle, applying vac to the back of the diaphragm and noting the engine intake note change. it is functioning properly in regards to actuation.

The fuel pressure comment intrigues me. I don't see anywhere a sensor that actually references the fuel pressure. How does the ECU know if there is a fuel pressure issue and therefore step in and trip the 1540 code to cut fuel? I can toss on a fuel pressure gauge and drive around a bit to check readings relatively easily.

Any thoughts on the non-functional TCS override not working? Could the transmission control be tied into this issue? I'll be tearing it apart today to check the button continuity & wiring.

If the fuel checks out I guess I'll pop off the plenum again and dig around for an obvious inconsistency.
 
#5 ·
keninn has had two Milly "S" for quite awhile. He has done or dealt with almost everything. He is on here a lot, give him a PM in case. BigB parted his out but also knows the "S" very well.
TomK
 
#7 ·
Well, Ive got the rear IC off replacing the rear motor mount as well as installing the fuel pressure gauge sensor and an EGT sensor for S&G. It's just a matter of another 12 nuts/bolts to pop the upper plenum off again. I'm off this weekend and hopefully wil be able to get back into the garage to tweak & whatnot.

FWIW I did purchase an extra KJ ECU as a spare. I've done what research I could online to try to pin down which ECU went to which year model. I bought one listed for a 2000 KJ, but what came in the mail does not match what I can see currently residing in the car.

But that's the tricky thing buying a used car. You never know what someone else did to it nor why they did it.

I'll update the thread as I garner information. Thanks for the input!
 
#8 · (Edited)
So here's an update:

I've installed the Boost gauge, fuel pressure gauge and the EGT Gauge and have been driving the car for about a week monitoring its behavior. As for the readings from the gauges, it is not exactly what I thought it would be.

As for the boost, it is pretty standard. normal cruise nets around 0 atm. completely off throttle deceleration drags 30 in/hg. Max boost at WOT is 15 psi, but it is modulated heavily during shifting, dipping 5-7 psi. I placed a simple LED piggyback on the harness going to the ABV Valve and have it mounted with the boost gauge so when the ABV Solenoid is active, the LED Lights up. The ABV valve is actually active most of the time during normal driving conditions as well. ((though at this point this is still part of my diagnosis; being too active.....but more on that later, see below))

The fuel pressure is just all over the place, which I didn't expect. Normal driving it holds at 30psi. During deceleration it actually drops down to 20-25psi, in a step. As in it's at 30psi, then it drops to 20psi. Normal driving conditions with positive manifold pressure (boost) will net 35psi. Under WOT conditions I've seen it read 40PSI and have noted spikes to 45psi on two occasions, though I have not been able to replicate the conditions. Standing stop wide open throttle will net 40psi on the fuel rail. And again, during driving conditions, as the boost creeps in with throttle modulation the fuel pressure reacts accordingly. It doesn't seem instantaneous, however, returning a full 1-3 sec delay between throttle input/manifold pressure and fuel pressure increase. It is all being controlled by the FPR, the OE unit using rising rate characteristics: +1 psi manifold pressure = +1 psi fuel.

As for the Pyrometer, I'm seeing 8-900 deg F cruise and 1100-1300 deg F under WOT conditions. so pretty normal there.

But more to the end of why all this went into the car. Lo and behold after swapping out the ECU and installing all of this I have managed to finally throw a code that is rather illuminating: CODE 725

This is not a code that the prior ECU ever triggered, so perhaps the sensor has degraded to a point that is finally tripping a safety or the replacement ecu is more discerning when it comes to the monitored sensors.

Regardless, the naughty list for symptoms is rather juicy: While vehicle speed is 25mph or higher, the engine speed signal from the crankshaft position sensor (CKP) indicates 470 rpm or below for 2 seconds or more. This in conjunction with a [url=http://milleniatech.net/codes/p1540/]CODE 1540[/URL]http://milleniatech.net/codes/p1540/ where Actual charged-air pressure is higher than target charged-air pressure by 19.7 kPa or more..... then it makes sense.

The ECU for a brief moment thinks the engine is turning at 470 or below while the charged air pressure is higher than the target air pressure by 3 PSI (19.7kpa)+. Of course the boost is more than 3 psi, silly ecu.

tl:dr - perhaps a lazy ckps = cranky Milly S

So I'll be picking up a CKPS and installing that Christmas day, and then we'll see where that takes the car.
 
#9 ·
Sounds like you have made some good progress, hope it ends up being the crank sensor as it would be a nice easy fix.
TomK
 
#10 ·
finally after tapping the harnesses with LEDs and driving the car monitoring their control di I realize the ABV was not receiving the inputs it was supposed to be receiving when it should have been. so I pulled the harness and noticed a bit of an interchange opportunity.

Turned out to have two of the harness plugs swapped. The ABV solenoid plug will plug right into the EGR Vent solenoid, and vice versa. And they are the same length, so no differenciation other than the ABV plug harness is wrapped in a bit of green tape, which I never paid attention to when I was putting it back together from when the other mechanic worked on the car. I'm genuinely disappointed in myself for that oversight, because I've been fighting with this for 5 months now :( . FWIW the ABV Vacuum harness is marked with a bit of yellow tape.

Just took the car out and thrashed it and she's a happy S........ for now of course.
 
#11 ·
Nice Work! See, persistence does pay off.
TomK
 
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