Hey guys, I searched the forum and the FastLane catalog but can't find the answer to my query, hopefully someone here can help.

My 300D has been struggling.
I recently replaced:

All Glowplugs
All Injectors
All Shocks
Idle Sensor
Relays

I've done soo much and I've gotten the car into tiptop shape, bu my tachomoter refuses to wake up, and sits at 0 weather the car is on or off. Also, my idle speed is too low.

I think the engine CPU is bugged/shot.

Any ideas?

Anyone know how much a new CPU will cost me?

Thanks for your help guys.

__________________
-Sam
93 300D
210k - Sold, but not forgotten.

I'm not 100% sure on your car but the tach usually has a sensor on the front of the engine by the crank pulley (some cars use the cam but I don't think yours does). If that sensor is bad the tach won't work... might try replacing that before replacing something really expensive.

__________________
1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k

I already replaced the Idle Sensor.

No one knows how much a CPU is?

__________________
-Sam
93 300D
210k - Sold, but not forgotten.

If your car is 1985 or older. You don't have a CPU.
Call Phil.
We arn't dealer's and don't have part's cat.'s.
Charlie

Are you sure the tach is read from the Idle sensor on that engine? I have a 91 2.5 Turbo and I have a working tach. What about the crank sensor?

How was the car while it was still warm out? Or do you live in a warm climate?

Recently it's gotten colder here, and this morning it was down to about 25F/-4C overnight. Started up like a charm after 15-20 seconds of glow action. No troubles. Was your car okay at some point recently, or has it always been this way?

BTW, I know your car is a '93 because it's in your signature! I believe the CPU/TCM for these cars is, at the dealer, about $1100 Canadian. I got a quote from them in the summer... fortunately that was NOT the problem!!

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1991 MB 300D 2.5 Turbo (207000km) (now gone)
1993 Audi 100 CS Quattro (300000km)
1999 VW Jetta TDI (290000km)
2002 Audi A6 3.0 Quattro (150000km)
2005 MB E320 CDI (34000km)

You make referenc to your ENGINE "struggling" (not enough data for US)
what OTHER symptoms of malaise is the engine exhibiting???

Tachometer non-functional is either sensor / guage / connection problem.
sillly me , It might be Voltage Fluctuation.

'90 300D Black over beige MB text.

Don't be too fast to replace your CPU. They are very reliable and the problem is normally traced to a sender/sensor.

I'm also don't think you ECU is bad. There is a forum member here named "grdenko" that thought the ECU in his 2.5 turbo was bad, he bought a used one somewhere and installed it and nothing changed. You might want to drop him an e-mail and see if he still has the used ECU.

Was the overvoltage protection relay (or its fuse) one of those that was replaced (checked)?
Fault there causes same symptoms, plus things like no a/c compressor, ABS.

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'91 350SD 270kmi
'83 300CD 290kmi
'82 Volvo GL/Diesel 140kmi
'76 Deutz D3006 975hrs

My 2 year old Electronic Parts Catalog shows a list of price of $1740.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
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