I have a BMW 525I, 1995 with 135000 miles, last week it didn’t start, Starter was good (Cranking good) called AAA and towed to my friends work shop he worked on it for almost 4 days according to him checked ignition system, fuels system, and wiring every thing works good, I am out of town and today he called me that the problem is with the computer and he is looking to find a used one, my question is would this be a good idea to go with a used one or buy it from a dealer, I don’t know how long will be the warranty on the used one and how much will it cost me, need your opinion should I go with used one if he finds one or ask him to get one from the dealer and could any one tell me how much will be a new one, Thanks.

Best Regards,
John

New ECMs for a Honda Civic are around $1,100. I'd hate to hear what they cost for a BMW.

When my 1993 Civic's ECM failed three years ago, I installed a Cardone remanufactured ECM, with a lifetime warranty, for $250. I bought the ECM from O'Reilly Auto Parts. Shop for price and warranty, particularly on ECMs.

I am expecting $1200-$1500, but I don't know how much will be the used one, do you recommend to get used one if the price is reasonable?

Thanks.
John

Yup. Make sure your friend knows what he's doing and has exhausted all other possibilities first. Has he tested all under hood and under dash fuses with a test light or multimeter? Has he checked for codes? What tests did he perform on your current ECM to conclude it's bad? Has he cleaned the main ECM ground? There are many people who take advantage of others when it comes to electronics diagnosis--be careful.

Thanks

If the Check Engine Light comes on and goes off normally, all fuses are good, there are no codes, you have spark, the fuel pump runs, but the engine does not start, the Crankshaft Position Sensor (CKP) may be bad and should be replaced. CKPs, because of their proximity to the crankshaft and exposure to the elements (water, salt, grease, dirt, and stones), commonly fail. After ruling out the CKP, I would focus on the ECM.

I am out of town and the mechanic told me that he replaced some sensors it didn't help, he thinks it is the computer, how would you check if the computor is bad, Thanks.

Regards,
John

If the Check Engine Light comes on and goes off after two seconds, when the ignition switch is turned to ON, the ECM is likely fine. During start-up, the ECM checks everything out and the CEL will stay on if anything is really wrong.

The ECM (computer) is nothing more than a “power transistor,” whose job is to supply the proper voltage to a host of sensors, under constantly varying conditions. Therefore, have your friend check for 5 reference volts, at key sensor connectors, when the ignition switch is turned to ON. I'm not familiar with your car, but the Throttle Position Sensor or MAF Sensor may work for this test. If instead of 5 reference volts, he records .3 volts, for instance, the ECM is likely bad.

Here's the K-Test that I use on many Hondas:

The K-Test: Remove the MAP Sensor connector and turn the ignition switch to ON (Position II). Using a multimeter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it's probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate.

I would certainly ask him if he replaced the Crankshaft Position Sensor (CKP). CKPs cause a lot of problems and are prime suspects in crank but won't start situations.

Hello TXGreasMonkey,

Thanks for your advices I will forward these to my friend and will let you know, Thanks.

Best Regards,
John

Hello TxGreaseMonkey,

FYI I am still out of town and my car is still not fixed , the CKP is replaced two times, and a rebuild computer has been installed but still it would not start, do you have any other suggestion before I ask my friend to take it to a dealer, one other thing have heard any thing about the key chip, some one told me if the memory on the key chip is lost the car wouldn't Start, Thanks.

Regards,
John

It could certainly by an immobilizer problem. I've worked with several people in Great Britain on Hondas, where they had to have their original ECM remanufactured because of the immobilizer system. My experience has been that when you have a major problem with the vehicle, it's often better to go to the dealer for servicing. I think you are at that point, particularly with a BMW.

All right I will try, Thanks.

Regards,
John

Hello TxGreaseMonkey,

After almost a month and cost me a lot that my car was in the work shop and per yours suggestion took it to the BMW dealer it finally got fixed yesterday, I want to share the following with you that what they did and what got the car fixed thanks for you help and it is greatly appreciated.

13655 DME faulty 5.00 checked fuel pressure, no fuel pressure.
Checked fuel pump for power fuel pump was not getting any voltage, applied voltage to the pump found pump working, replaced fuel pump relay pump still not getting voltage.

Checked faults found DME fault for no power supply, checked power to the DME and getting 12 volts, checked all 4 power supply to DME and all were good.

Checked for spark at coils and no spark.

Performed Oscilloscope measurement from the crank sensor which gives the RPM signal, the crank was sensor was giving out signal, for trouble shooting replaced the sensor still engine didn't start.

Jumped the starter immobilizer relay engine still didn't start.

Suspect bad DME or bad EPROM, Replaced the EPROM engine still didn't start with the new EPROM.

Removed the DME and installed into a donor car with the same engine the donor car did not start with the suspected faulty DME and started with its original DME.

Replaced DME and programmed it to the vehicle and the engine started, end of my story, Thanks.

Best Regards,
John

Thanks for the update. The story ended pretty much as I expected.

Yep

Hello TxGreaseMonkey,

After I drove my car for a day and parked inside the Garage found a puddle of oil under the car, cleaned the bottom and drove it and parked still a puddle of oil, had no time to investigate or take it to a work shop due I was leaving on a trip will be home on Friday what would you suggest to be checked, I hope it will not be costly the previous problem cost me close $3000.00.

It looks like engine oil, I checked the drip stick can't tell if have lost much, checked the brake fluid reservoir it is OK, I hope it wouldn't be the seal between the engine and the transmitter, please advise, Thanks.

Regards,
John

Thoughts:

Check the drain plug on the oil pan. Also, try tightening the oil filter a little more. If the problem persists, the mechanic may not have ensured that the old oil filter gasket came off with the filter. It may have stuck to the engine block. Then, he may have installed the new filter and gasket on top of it, which will not seal properly.

Examine the color of the fluid. If it's pink, it's likely automatic transmission fluid.

First thing I checked the drain plug it was OK and no leak from there, there was no oil change done this time, and the oil filter is on top of the engine not at the bottom, any thing else, Thanks.

John

Leaks can be on the top of the engine and drip down. This is what makes tracing leaks from the bottom up sometimes difficult. Check all fluid levels and go from there. Good luck.