Bad idle, rough run, stall, won’t start

[Rado]

Hi guys, it seems I fked up a bit and can’t chase the issue.

I decided to drive the car to get more issues out of it and fix them. After driving it for a week daily I notice rough start, not consistent. Yesterday check engine came on, I press the button and got 5 lights.

I then purced to go deeper and accidentally spark something with my home made blinker. I found quickly the blown fuse for diagnostic port.



Now the idle is rough, it’s so bad that it stalls. After a few tries it won’t stay running.

When cold started it, the air pump was working intermittently, later it won’t engage at all.

No check engine or any other lights present.
I took the ignition caps off and clean the terminals, the caps were old and cracked but dry and no too bad looking.
I also put about 1/4 of gas since it was close to empty.


What have I done and where do I look for the issue?
1994 E500 145k miles very untouched and unserviced since new. Probably just bare minimum.
I did the tune up about 3 months ago, sparks, all fluids and all filters.

Thank you!

 

[gsxr]

Start by checking all the blade-type fuses on the BM/GM module inside the CAN box.

Have you removed the caps, rotors, and rotor bracket to inspect the back side of the insulator also? Need to figure out what's going on with the "rough start" prior to the current problem. Also need to figure out if, possibly, the car is only running on 4 cylinders.

The air pump normally runs intermittently after a cold start, and runs very, very infrequently with the engine at operating temp.

The engine wiring harness has been replaced, already, correct? Nevermind - I see in your OWNER thread the harness was replaced in 2004.

Any current fault codes stored on any module?

 

[Rado]

Have you removed the caps, rotors, and rotor bracket to inspect the back side of the insulator also?

I only removed the caps to check for moisture or bad connection. I didn’t go deeper as it was running very smooth before the short.

Need to figure out what's going on with the "rough start" prior to the current problem

That’s me being picky, rough meaning not like new but not rough like running on 4 cylinders. Rough like my 2013 GL450 with with 120k miles. just sometimes starts in half a turn and sometimes it turns 2 times, I just thought I’ll give u all the info for better assistance.

Also need to figure out if, possibly, the car is only running on 4 cylinders.

When cold started it, it run very smooth for 10 sec, I was celebrating early, then it dropped and went rough. The more I try the rougher it gets, then won’t start, I’ll probably go and do another cold start and will confirm this theory.

The air pump normally runs intermittently after a cold start, and runs very, very infrequently with the engine at operating temp.

since I have this car, air pump will work on cold start constantly until it cut off and won’t come back until next cold start or maybe will come on intermittent while driving but I can’t feel it.

The engine wiring harness has been replaced, already, correct?

only the upper engine harness, the lower harness is crusty, I left it for a later project but after washing the car and the engine - the oil pressure gauge is dancing constantly. Not sure this will have anything to do with my current situation.

I replaced all fuses in the fuse box under the hole with new ones just to be sure, but this are the only fuses I did, have to google where it has more fuses.


I suspect the fuel sistem but also weird cause it was working well prior to short, I did check for pressure when the car refuses to start and it’ll spray a lot of fuel from the rail. I do have all new fuel sistem in the trunk just in case.

Any current fault codes stored on any module?

i was getting some but after the short I threw away the home made device, will need to figure out a way to read them.
I used to have BMW dealer app and Mercedes wis and xentry for my other cars, just wondering if I can put the old app for this cars on the laptop or emulate it somehow.
Any info will help as I’m planning on digging this deeper.

 

[Rado]

Here’s a video of it cold starting and quitting

 

[gsxr]

since I have this car, air pump will work on cold start constantly until it cut off and won’t come back until next cold start or maybe will come on intermittent while driving but I can’t feel it.

To clarify: At a cold start, the pump should turn on and run continuously for several minutes. After the initial few minutes, as the engine warms up it may turn on/off intermittently. At full operating temp it may run briefly, very infrequently.

I replaced all fuses in the fuse box under the hole with new ones just to be sure, but this are the only fuses I did, have to google where it has more fuses.

The only other fuses are in the BM/GM in the CAN module box.

I suspect the fuel sistem but also weird cause it was working well prior to short, I did check for pressure when the car refuses to start and it’ll spray a lot of fuel from the rail. I do have all new fuel sistem in the trunk just in case.

Next step is connecting a fuel pressure gauge to the rail and watching the fuel pressure as the engine stumbles and dies. If the pumps are running normally, pressure should remain at ~50psi.

i was getting some but after the short I threw away the home made device, will need to figure out a way to read them.

You'll either need to fabricate another home-made reader, or buy one. I recommend picking up the breakout box that allows plugging in 4mm pins into the numbered holes, which is FAR easier than trying to figure out which tiny 1mm hole is the correct number. Details here, also read the top few "Sticky" threads in the De-Coding subforum.

I used to have BMW dealer app and Mercedes wis and xentry for my other cars, just wondering if I can put the old app for this cars on the laptop or emulate it somehow.

You need the SDS / DAS / Xentry software, with support for HHT-Win (this is required!), along with the MUX (multiplexer) and 38-pin cable. HHT-Win will get you full diagnostics including live data stream from each powertrain module, if everything is working correctly. Video below shows what HHT-Win displays.

 

[gsxr]

Here’s a video of it cold starting and quitting

Uh - yeah - that ain't right. The smog pump shouldn't be randomly turning on & off as seen in your video. For grins, I'd check voltage and verify it's steady at ~14v or so with the engine running... with no major spikes (15v+).

The LH module controls the smog pump and also the fuel pump, btw...

 

[Rado]

Fixed,

The only other fuses are in the BM/GM in the CAN module box.

you were right, I skipped this module since last time I had a fried fuse for abs, it was here and I though this complet unit is for abs
Found another fried fuse, changed it and it’s back operating smooth with pump working properly

I feel stupid for not trying everything before I post the issue.

You need the SDS / DAS / Xentry software, with support for HHT-Win (this is required!), along with the MUX (multiplexer) and 38-pin cable. HHT-Win will get you full diagnostics including live data stream from each powertrain module, if everything is working correctly. Video below shows what HHT-Win displays.

marked and will work on it when have more time.

ps Brake hoses coming today