New to the Millenia S, purchased for daughter.

Car is missing and has random fire to the coils, dealer says it needs a ECM. Has anyone ever replaced one and if so did you go with a used one? or reman one?

Thanks

 

ecm? holy cow. dealer has you by the wallet. 0300 is random miss, is that what the code is? any other codes? i would first go with plugs. 60k is recommended change interval. the most common problem with plugs is the idiot that buys some bs plug, like iridium, or some other that the parts guy at autozone convinces them to buy. afaik, only the ngk 3741 comes properly gapped(.7-.8mm, .028-.032in). all the rest have way too wide(1.1mm, .044in). and no matter WHAT anyone tells you, a precious metals tip plug SHOULD NEVER be regapped. if it dont come from the factory with the proper gap, dont use it. the second most common problem is that if the car is taken to a shop to have work done, and one of these was to change the plugs, the right bank never gets done. you get charged for it, but because of the labor involved, the shop doesnt change them. so, if your car has more than 60k on it, i would suspect plugs. wrong plug/gap is classic random miss.
next would be coils. these suckers are pricey. you got 6. with discount, about 175/each. you can find them on ebay, i have gotten brand new for as little as 5 bucks. but you gotta jump fast(we have 2 99s', i have learned). early coils(95-96) are 4 pin, later are 3 pin, either will work on your car. when the gap is too big, it puts a trememdous strain on the coils, and if the coil is weak, you get a miss. also, over time, the valve cover gasket leaks oil into the wells, and the oil can short out the coil, so random miss.
then there is the possibility of bad gas. google top tier fuel, and stay with those brands. your car should run 91 octane or better. it has a knock sensor, so you can use lower grade, but performance will be down. if you go to mom and pop places for gas, there is a good possibility you will get water in the fuel. gas will float on water, so the pickup in the tank will draw water with the fuel.
your biggest problem with this car is maintenance. there is not a lot of people who have experience with this car, and the dealer is not a good place to start. the fact that they want to sell you an ecu tells me that they are fishing. you will end up spending a lot of money and time, and you will be paying them to learn about your car. you will pay the highest prices for parts and labor, and in the end, will not have any better result that a good independent, just much higher cost. just because they are the dealer, does NOT mean they have any experience with this car. it is a very low production model, and probably no one there has worked on them, and if they have, it is very limited.
bottom line is, if you cannot do the required work/maintenance on this car yourself, you should get rid of it. feel free to pm me and i will send you my phone nr, if you need more assistance

 

To add to what keninn said,

I reviewed the P0300 error in the Millenia service manual. There are basically 7 steps that should be followed to check out a P0300 error code.

1) Is ignition system OK?

2) Is ignition timing within spec?

3) Is crankshaft position sensor air gap OK?

4) Is fuel system (LH and RH) OK?

5) Is Exhaust Gas Recirculation system OK?

6) Is compression at all cylinders normal?

If all 6 were OK, then they move onto #7.

7) Erase diagnostic trouble code from memory. Is same code number present after rechecking? If "Yes", then replace the ECM. If "NO", then it's just a temporary system malfunction.

If I were you, I'd like to see proof that the dealer checked items 1 - 6. I very much doubt that they did.

 

i would not pay attention to what he^ posted. this is useless information, and exactly what the dealer is doing, reading from a manual that has very little practical use. also, both^ and the dealer have no experience with the 2.3 engine. again, you will be paying for someone to learn about your car. in the real world, start with the spark plugs. most likely the right bank has never been changed, and if they have, the wrong ones are in there. the biggest mistake with new plugs is the gap. too wide a gap will make the coil work a lot harder, and with the heat back there, plus oil in the well, can lead to the coil(s) failing early. also, with the larger gap, the engine is way more susceptible to missfire. one problem with just changing plugs, the right bank will take a couple hours, much more if this is your first time. a LOT of stuff has to come off just to get at them. add in the time needed to clean the wells, chase the threads, and other small jobs, and it becomes a real chore. so, when i do them i also swap out the coils with known good ones. otherwise you may be doing it all over again. if you dont have another set of coils, swap the left bank coils, but mark them. the left bank will take about 30 min to change out

 

keninn,

Thanks again for your vote of confidence.

Item #1 to check (ignition system) is essentially what keninn is referring to. Have all the plugs been checked? Changed? Etc. I may not have had any experience with the 2.3L engine, but I've owned the 2.5L for 8 years, now. I've also had previous vehicles that have suffered QC issues with their ECM, so failure does and can occur. On one of my vehicles, I had to have the ECM replaced twice due to QC problems with the solder. The first time, was under warranty. The 2nd time was when a shop spent hours of diagnosis time - then concluded, that the ECM installed a few years earlier by the dealer had failed again. They installed an ECM manufactured by an aftermarket company, not GM, and I never had any more issues for the next 4 years or so that I owned it.

 

Thanks for all the information, really helpful. I purchased a used ECM from the local salvage yard LKQ A&R. So I plan to put new plugs and install the ECM and see what happens. Hopefully that will correct it, if not I will be checking codes.

I will let you guys no, the out come. Dealer mentioned a misfire on #6 but the coil was OK, I belive and a mass air flow code.

So I should use NGK 3741 plugs?

 

I won't comment on the specific part # for the plugs, since I don't own the 2.3L - as noted. However, regarding the MAF code, it may just be the MAF needs cleaning. It's located within the rubber intake tube. It can be located by looking for the screen area along with the small wires. Don't touch the wires when cleaning it. They sell spray for Mass Air Flow cleaning at Autozone - or, any parts store. I've found it under the CRC brand. It only runs about $4.00 a can. Use only the spray to clean the MAF - no scrubbing, no wiping, etc.

I'm looking forward to your update on the ECM - and, if that resolves the issue. New ECMs are over $1,000 from the dealer. Plenty of them on eBay for $100 + shipping, though. Good to hear you found one locally. If you don't need or use it, you can always sell it.

 

Thanks

Just info I did find a company Eu Spec that sells and remaufactures ECM's, if you send them yours they will check it repair and check all other circuits for around $356 with shipping both ways included, which is not bad.

I will replace ECM and plugs Saturday.

 

you wasted your money on the ecm(pcm). if you go to the other forums, you will not see any posts about a bad pcm, but you will see a whole bunch of posts about plugs, and coils. also, NEVER accept what someone says the codes were, you should get WHAT code it was, not what they say the code was for. case in point, when our black car got it's first codes, it was 0170/73, scanned at autozone. they interpreted it as the mas. second was o2 sensors. what it actually was, a broke tee, so it was running lean. again, if you check the other forums, you will see a LOT of posts about broke tees/vacuum lines associated with the 0170/73, but no one fixing those codes with mas or o2 sensors.
also, and you will find this out, the pcm is a bitch to change. it is behind the radio, but in such a posiltion that the harness is really difficult to unplug. be prepared to remove the side panels of the console to gain access to the harness connectors, and even then it will test your mettle. i would first change plugs/swap coils, and clean the wells. here is a trick i have done that works very well. when you have the plug out, clean the well. i like brake cleaner for this, it dries with no residue. the inside of the well has to be squeaky clean. with your finger, you can feel the groove where the valve cover gasket is. take some good silicon sealant, and rub it all around where the gasket is. i like hylomar for this, but any sealant that is oil and hi heat will work. i have done this to both cars, and no more oil in the wells.
a miss on #6 would throw a p0306 code, not 0300. again, you should find out what codes were thrown, not the interpretation. and, afaik, the ngk 3741 is the only plug that comes with the proper gap. beware of any plug with a -11 after the part number of the plug. for example, the old number for the 3741 is PZFR5F. however, there is also PZFR5F-11, which is used on some acuras and bmw. the -11 means 1.1mm gap
a general rule of thumb, is to attack the lower number codes first, sometimes fixing the lower number codes will also fix other codes. this is very true on the 2.3. i would bet that the right bank plugs are original, and long overdue

 

Thanks for the info and tip.

You are right about the codes, this is the first time I have taken a car to the dealer to be checked and we will see if they were right or not. They said the ECM had a ground and the coil was good it just was not getting the signal from the ECM.

The previous owner said he had a mechanic change all the plugs in the back and put a new coil, we will see if that is true or not.

It was tight getting the ECM out and I am sure it will be tougher getting the connectors plug back in.

I will let you know the out come.

Thanks for the info, good stuff.