E320 no start

[BrokenSockets]

Hi All,

After I did the head gasket replacement, fired up the 94 E320 (M104.99) and it ran nicely. Took it for a drive -had two several second bouts of high reving, but they seemed to correct themselves.

It worked well for a few miles - couple of short trips around town.

The next morning after rain and cool temps, it started hard and missed badly. Not drivable. After the weather dried up and warmed up, I tried again and had the same result when I could get it to run at all.

I checked the engine harness (which I already suspected) and it was full of dust and bits of cracked insulation as I expected. I completely rewired the harness.

No I get no start. It cranks but not in a good sounding way - almost like it's restricted somehow, then after a couple seconds it stops cranking. I can pull the injector wires off and it sounds fine when cranking continuously, so I don't think it's mechanical.

I have re-checked my harness wiring with a meter and everything tests good. Coils and injectors ohm out within spec. Fuel pump fuse is good, all other fuses look good. Can't detect any shorts in my wiring job. I did delete the air pump coil connector, as the pump was removed it from the system, but can't see how that could be in play.

I have not yet looked at the ETA wiring. Could a bad ETA harness cause a no start like this? I know that it could be the cause of the surging I had on the first test drive.

Any other ideas?

[BrokenSockets]

Other info- ABS light goes off after Key on.

Tested for fuel, almost no fuel - getting occasional bursts at valve. Fuel pump not running at key on 3 out of 4 turns.

Now cranking with occasional catch when (I asume) it get a bit of fuel.

Fuel pump wiring connector is in well under rear seat on pass side? because we had a bad plugthat I patched yesterday. It was the source of water infiltration fulling the p/s footwells for a couple of weeks before we tracked it down. Maybe corrosion in the FP wiring?

planning to test when I get my meter over there.

[timmyr]

hello .

checking the wiring for corrosion couldnt hurt.

you can also try a search for both OVP relay and fuel pump relay .

to get to the relays, remove the battery, then the black plastic cover behind the battery. OVP- is tall, metallic colored, and has a fuse under the clear plastic cap. the fuel pump relay, if i remember correctly is green


good luck

[BrokenSockets]

Still cranking with no start, occasional hiccup like it might catch.

I disassembled the FP and OVP relays. The relays all test good and click nicely with a 12 volt source. I resoldered all connections and sprayed relay contacts with contact cleaner and reassembled.

I have 12 volts at the fuel pump connector in the back seat for 2 seconds at key on, 10 volts continuous while cranking. FP's running while cranking with good fuel spray out of test valve. (planning on picking up a tester to get a number)

What else to check?

I saw a no-start post from someone talking about vacuum problems or air tube to idle control causing cranking with no start, but I think it was a 103.

[timmyr]

another thing that comes to mind... if you dont know when the fuel filter was last replaced, now might be a good time to replace it.

check out the following link:

M104 Code 11 on pin 14 re-start problem

specifically post#3 (tapitty tap test) the last time i had a no start issue this resolved my problem. the #3 post also has the part number for the newer/updated OVP relay


i have also read that a leaking Fuel Pressure Regulator can cause similar no start issues, so you could also check that out as well(pull the vacuum line, if there's fuel in it, you have a bad fuel pressure regulator).

try and get a fuel pressure gauge, it will be of much use to you in diagnosing your problem.

good luck

[BrokenSockets]

Fuel filter - don't know when it was replaced.

Don't know about OVP - when it goes does it not cut fuel pump power?
I can hear the FP running and can measure voltage at the connector under the rear pass. side seat. I am also not getting the ABS light.

Is the FP supposed to prime every time you turn the key to ON? Mine will do it once, then not again for several seconds regardless of how often you turn the key or remove the key and they re-insert and turn.

Is there a delay or pressure monitoring at work??

Also, No fuel at regulator vacuum line.

[BrokenSockets]

more testing today - new OVP had no effect

plugs are all getting wet with cranking

all three coils tested again have good spark

I still think it must be timing related somehow - any idea on the cam sensor question? I measure the harness lead and it reads .25 volts with key on. The sensor has varying resistance while cranking.

[timmyr]

hello again,

did you check your fuel pressure with a gauge, or are you just basing the notion that your fuel pump is ok on the fact that the plugs are wet?

i was convinced that the ovp would fix yer problem, oh well at least you wont have to worry about that sucker for some time now.

"Took it for a drive -had two several second bouts of high reving, but they seemed to correct themselves. "

you mentioned that you rewired the engine harness, i would just like to remind you that the same biodegradable wire insulation is also used on the ETA or electronic throttle actuator. you may want to check and make sure that this is not causing your problems.


I'm not really sure about the camshaft sensor. i believe that all that exists on the camshaft(intake cam) is a solenoid, which is used for the variable valve timing (explanation of how it works: Please explain how variable valve timing on my M104 works... )


from experience, i have experienced a no start issue which was caused by the CPS (crankshaft position sensor) . i would suggest that you search the forum for CPS tests.


good luck

[BrokenSockets]

Would not a bad CPS give me no fuel and no spark? I have lots of both.

I read up on that cam sensor - my mistake on looking for voltage. I was reading posts on later model years with hall effect sensors. I realize now that This sensor generates an AC signal and does not require supplied voltage. I also read thgat it should still start with a bad Cam sensor.

Still not running......

[pmckechnie]

Pluged exhaust (usually the cat) will give you the same results. Fire, Fuel, and Compression but no start.

Paul

[BrokenSockets]

I though of that, but it seems strange it would happen suddenly. It was running fine before the head gasket failed, it ran well for a whole day after the head gasket repair, then the next morning it just wouldn't fire up. That's what has me thinking electrical/timing.

I suppose I could disconnect the pipes to eliminate that possibility.

It did have what sounded like a backfire in the intake once or twice in this "trying to start" saga.

[timmyr]

"plugged exhaust" seems possible i guess. in your first post, you mentioned that you had to rewire the engine harness yourself. i guess that its possible that if the car was being driven around with a bad head gasket and wiring harness, that the cat has now failed/clogged, you might as well rule that out by dropping the exhaust.

if its not a clogged cat....

you mentioned that you have both fuel and spark, do you have air? also check to ensure that there are no obstructions in the air filter box, crossover pipe, ETA. if there are no physical obstructions, check the forum for pictures and adjustment procedure of the throttle linkage(make sure all the springs and levers are present) which is hooked up to the ETA. is the throttle plate in the ETA moving freely when you manually operate the throttle linkage?

turn the key to: key on , engine off position. do you hear the ETA's high pitched hum/buzz? it should be continuous, as long as the key is in this position. in an earlier post , i mentioned that some people on the forum have had to either replace/rewire their ETA's due to crumbling wire insulation. have you inspected the ETA wire harness?
here's a good recent thread on : proper spark plugs(BOSCh F8DC4 COPPER PLUGS), ETA harness repair/syptoms, CPS testing. check it out:
W124 E420 several codes on several pins

if your problem is not related to an air restriction on either the exhaust/intake side, i would have to agree with your post #16, however i would be looking for an electrical problem.

good luck

[BrokenSockets]

Well, I found the problem.

First problem was definitely the wire harness, which I rebuilt, but got a no-start condition afterwards.

The answer is - when doing wiring and encountering a problem, don't just test once or twice, test at least 3 times. I had swapped pins 9 and 10 at the 44 pin engine harness connector block. This reversed my wires for the #1 and #2 coils.

Found the error with more continuity testing - started right up after i fixed it.

I feel like a boob - an entire wasted week.