Help! What is keeping my car from starting???

[bimerguycw]

I came back from out of town for a week and now my car won't fire. It turns over strongly and has 13 v on a freshly charged batt but just won't fire or even act like it will. I reset the electronics while charging also. I had it started once during the week and no problem.

Followed many of the Bentley diags for "car will not start" starting from top of chart and have not gotten to all of them with limited time today. So far I have checked the main relay, MAF sensor voltage, coil resistance(0.7 ohms), Intake temp(2.2 kohms) and engine coolant temp(5.1 kohms). The Eng Cool Sensor was out of spec but I can't believe this would not let the car fire whe turning over during start.

I remove one plug and noticed fuel wettnes on it and assume I'm getting fuel and have not checked the fuel relay yet.

What have you guys seen to be the most likely items I should check?

Thanks,

[Springfield1952]

What e34 do you have and where are you located?

Curt.

[bimerguycw]

Thanks for the read.

I'm in NC and have a 95 530iA.

[Javier]

Unplug CPS connector and check there is about 1200 ohm between two of the contacts (when measuring towards the sensor) and the third contact is open circuit to the rest of them (Shield).

Javie

[bimerguycw]

I had more time to check the system and the CPS measured 522 ohms like a M20/M30 vs. the Bentley number of 1280 ohms.

So I bought a new one from dealer(best price in town) and before installation I measured 522 ohms also not 1280 ohms.
Is the ohm value accurate in the Bentley or what. The car has been starting with the CPS I had but now that I've measured it I wonder what is right. Does a bad CPS usually have an open or short or can they have a nominal value and be bad?

Thanks again

[Javier]

though every thing is possible.

The car has been starting with the CPS I had ...

What does it means, already started? Problem solved?

Javier

[bimerguycw]

I thought we had the problem determined with your suggestion since it read 522 and the Bentley says 1280. But now that I have the BMW part from dealer and it reads 522 from the box, it makes me wonder if this is the problem and wonder if these usually fail as a 0 reading or open rather than some value other than Bentleys 1280 for a M60 engine.

FYI - I did measure the Camshaft sensor since you had mention the Crank sensor and is identical in appearance and it measures in the 1280 range.

Any further Ideas...I'm open to suggestions to verify the CPS as the problem. In the meantime I'll try some of the other things like the fuel relay before I replace the CPS in case I return it.

[bimerguycw]

Well, after checking fuel relay and determining I have fuel to cylinders, I decide to check the ignition by removing the plugs and found that all 8 plugs were wet with fuel and appeared to have no spark as they were almost completely wet with none dry. So while I noticed this I decide to replace these recently installed NGK's with my saved Bosch 4's and then tried to start it again and no problem.

So, I still wonder what happened with the car since the last start-up several days ago. Why didn't start and why were all 8 plugs(NGK's) wet with not onbe of them firing enough to at least dry the plug on some yet when replacing them it starts???

Can the plugs get so fouled with fuel that it can't start until dried & cleaned? That's one of the differences between plug changes, nothing else was replaced.

[Javier]

and found an "up to 93 models Chilton" (not good reference, but) that states that Camshaft sensor for M42 and M50 is to be about 1280 +/-130 and Crankshaft should be 540 +/- 50. Unfortunately, I have a 535i so can not go down and take a reading on sensors to verify, but I'm starting to guess Bentley is wrong. May be Bill can confirm/comment.

Besides that, sensor normally get opened (you get open circuit instead of a finite resistance reading) or both main leads shorted, or one of them shorted to shield. Yours is not, so with 522 ohms I wouldn't dare to sentence faulty, specially considering above paragraph.

I do not believe that what was keeping your car from starting was the spark plugs. All of them went by together??? They were wet! yes, it happens when you have no spark, but what caused that? I would still suspect on the CPS, and unfortunately, if it is starting now, it is hard to diagnose.

Got once an M42 CPS that was intermittently failing until it was faulty long enough to catch it. Have always though that temperature may have something to do with this behavior. If you have a broken lead to the sensor, fooling with it may reveal a good/no good condition wile it is being measured, as you may figure out, these are merely speculations, and only time will tell. Disgusting thing here, is that you may find yourself stuck in an inconvenient place with the car refusing to start after a sudden stop of the engine.

Wish you the best luck.
Javier