My 2000 millenia just had a new timing belt, water pump, serpentine belt, and valve cover gaskets installed. she came back from the shop with pending codes. i figured they were vacuum related so I changed out all the vacuum lines. the abv vent/vacuum and an egr solenoid were alos replaced a few months ago with similiar symptoms (TCS indicator lights/car going into limp mode) but different codes.

any help with diagnosing the P1540 and P0170 on my 2.3 would be much appreciated. I wont be taking her back to that shop because they left some bolts/nuts off the car and took 14 days to do the initial work. I dont trust they can diagnose this issue correctly anyway.

 

any performance accessories on vehicle

 

yes, i have an intake and exhaust system but they are not the problem. the car only started throwing codes after the vcg's timing belt and water pump and serpentine belt were replaced. when i picked the car up from the shop there were pending codes and it has been throwing P1540 and P1450 lately, havent gotten the P0170 in a couple weeks.

since i dropped the car off with no codes or problems (just routine maintenance) and picked the car up with pending codes i think it is safe to say that whatever is wrong with the vehicle is related to the work that was done.

 

You said you changed your abv vent solenoid a few months back for a tcs light
and the car going into limp mode a few months back.sounds like the problem existed for a while. Possibly the aftermarket components. When you replaced the t belt timing became more accurate.(no play of beltdeflection)the problem is more evident. I work on alot of these 2.3s every one I seen withan intake or exhaust set p1540. Before you spend any more money first try to put a 1.5mm office in the vent side of the abv vent hose, Mazda has a tsb,it worked for me several times. If not put the stock components back on the car. Also if
your car has high milage check compression if any if thecylinders are low, 1540 or a fuel trim code will set.

 

when the abv vent and abv vacuum soleniods go bad they throw a 1540 and 1525/26. cant remember which. i also ohmed the solenoids which read over 40 and were bad. The solenoids were replaced, codes went away, and i havent had that same problem since. Solenoid issues are well documented on this forum, if they were the problem, I would have had plenty of responses by now.

currently i am getting intermittent codes and power loss/hesitation before going into limp mode. I will repeat: the car had no problems before going in for timing belt, water pump, vcg service.

I have 2 of these cars and my brother has had 2 as well. I am very familiar with the vehicle. the intake and exhaust is not the problem, the exhaust is brand new (codes were there when i put it on) and the intake has been problem free for 2 years. It has been smoke tested and is sealed, the vacuum lines are brand new all over the engine. I also know of two other millenias with that exact same intake and exhaust setup, they have never had this problem. Checking the compression could help narrow down the problem though, thanx.

 

Both of you guys are correct.I own three of these cars and
have experienced p1540. First your intake, I had a
intake on my 2.3 for over a year, then after about 20k
I experienced a lack of power followed by the 1540 and p0170
fuel trim code it did indeed turn out yo be the intake. may be during
the vcg replacement the vac lines got crossed when removing the
intake to replace the vcgs. P0170 is a duel trim code for th right bank. Is
it rich or lean failure?? Compression should be checked??
If it's lean your intake you have on the car could have made the maf fail,
leading to the lean faults. The iat sensor is part
of the maf and if bad can cause a p1540 too. It happened
to me.if you are true and the problem did start after the tbelt and vcg
make sure the tbelt is on correctly.timed,and all the vac lines are correct.
Next check the compression you couldhave A bad cyl causing all your concerns

 

what is the number of this tsb? i would like to see it

 

two vacuum lines going to the rear bank were mixed up as well as two of the electrical connectors to the rear bank of solenoids as well. car is running better than ever.

can you believe that the mazda dealer had this car for two weeks and couldnt figure this out? they told me i had low compression on cylinder 3 and that the "engine isnt serviceable" and i would need a new one....ridiculous.