Kanishka Prasad

hi guys

i have a mercede c200 2.0 litter 1994 japan assembled model

my first question is


does my vehicle have psm or hfm engine managment system ?


and let me come to the problem im having

the engine back fires from inlet and misfires and wont accelerate above max 4000 rpm

gives black smoke

wont idle

the RPM fluctuates

engine stalls

and here is what i changed

mass aif flow sensor
fuel pressure regulator
iginition coil packs
spark plugs
iginiton wires
fuel filter
fuel pump

my wiring loom is in good condition

and i checked if the variable cam solenoid works and i get 0 volts to the solenoid at any RPM with in 0 - 4000 in my case

and i feel its a BAD ECU with poor ignition timing .

and unfortunately i couldn't find a replacement ECU online

can some one help me with this









Mercedes c200 1994 2.0 litter <br/>japan assemble version

Plutoe

Post the VIN!!

Kanishka Prasad

WGB2020202F183869

Plutoe

The mfg code on your VIN is not WGB----it should be WDB and therefore you have a 111.941 which is a HFM\SFI!!

Russell Ormerod

You have an air mass therefore u have HFM! Did u use a genuine airmass or pirate carp?

Check for degraded wiring loom too. The ecu could be damaged if the wiring is bad.

Kanishka Prasad

yes i had bad wiring loom in throttle body ! and i rewired but still the problem is not fixed !!

and this ECU replacement parts are not available online !! so any idea of how to repair the
ECU

in such cases like bad TB loom !! what sort of areas does the ECU affect with ?


thanks alot

Russell Ormerod

Bad throttle loom does not damage ecu. But bad engine loom will. Shorted maf wiring is usually the culprit. What are your fault codes? Usually u need to completely rebuild those throttle bodies.

Kanishka Prasad

ye did a full rebuild withe the throttle body !! but stiill the same symptoms !! how can i check the ECU ? please can you give me some tips !!
i feel the engine retards !! its misses but wont back fires at 2000 RPM when the throttle is pressed its stall the engine for sometime and with a backfire it start to increase RPm this is very irresponsive !! and the vvt solenoid has not signal from the ECU !!

i know it is the ECU but i cant swap it cause its a japan spec !! and this particular ECU is not available !!

Russell Ormerod

Firstly if your car has an immobilizer with a red green lamp on interior mirror you cannot stop ecus as they are married to immo. U would need to make it virgin. If u have no immo. Then u can use any ecu from same year. Don't worry about Japan version. Secondly have you checked if you have power on vvt solenoid there should be 12v with ign on. I asked you about fault codes? Explain how u rebuilt the throttle body. Did you renew the brushes in the potentiometers? Did you service the motor? How can u be sure it's the ecu? The VVT not working will not cause your problem. To test vvt you must actuate with diagnostics tool. Your issue sounds
Like a bad maf, what are the maf output values? 12kg/h is the spec at idle engine at 80 deg AC=off
Rebuild engine loom too. If throttle loom was bad the rest will be bad too

Kanishka Prasad

no i dont have the red green lamp on interior mirror ! and yes checked the voltage to the VVT at ign it is 0 volts and no difference at idle or incresed RPM .

so here are the fault codes DTC
diagnosing on pin 4 at 38 pin connector

number of blinks of LED (analog diagnosing method since its 1994 ) the scanner didnt show nay readings

2
3
4
5
6
7
8
9
12
13
14
16
17
21
22
24
25
28
30
37
38

well i rewired the TB and i crossed checked the resistance values in the TB potentiometer cross referencing to you tube video ( )

but as you can see the actuator shaft is welded so we cant remove it but i managed to rewire it successfully

and i checked the motor alsoo it works with a dc 5 v

well i have replaced the MAf from the company itself !! can that alsoo be causing problems and i didnt check the maf outputs how can i test it ? your advice might help a bit more for me to dig up the problem

and i checked the engine wiring loom also nothing seems to be the degraded !! i check the connection with a multi meter

and also i crossed cheeked each and every line with diagrams that i took from the WIS.
the wiring loom is okay as feel !!


as i have mentioned in the first post

i have replaced

MAF sensor
crank sensor
cam sensor
fuel pressure regulator
fuel pump
fuel filter
coil pack
coil HT leads

all genuine parts
cost me like half the car value !! im so frustrated !!

and the ECU has a

ST27c1024 eeprom
bux 127 as ignition driver transistor
micronas dema106B for hall sensors
infinion SAB80c166w

Russell Ormerod

U need to clear those faults first and then recheck what comes back!
Star diagnoses or any scan tool will be able to read live data from that ecu.
So if u don't have 12v on cam solenoid check in wis where Power comes from and what fuse. I can assure you power does not come from ecu.
Usually I machine the welding off and strip the TB completely to rebuild it!
I am afraidnu need a scan tool. It's going to make your diagnoses much easier. That way u can see maf values and Throttle body angles. U also need to learn the throttle end stop values with the tool. DO NOT MESS INSIDE THE ECU! not until you have properly diagnosed all inputs correctly. Measuring wire resistance does not always help. You must measure what the ecu sees that is voltage levels.
So step 1, clear faults run the engine recheck what comes back.
If that does not help. Get hold of a scan tool
Good luck

Kanishka Prasad

thanks friend and what scan tool would you prefer !! and where can i find the
replacement potentiometer for the TB and leads ? i have a obd2 snanner but not a xentry
im not sure whether my model will show live data !! will it ?

i cleared the faults grounding the pin 4 clears all the codes but again it comes back !!


and in the TB if u strip off the welds how are u re welding it !! doesnt it miss align !!

Russell Ormerod

Any decent scanner will read live data. And yes your ecu supports live data, actuation, and coding. HHT is the genuine MB tool if u could get your hand on that you will be sorted. I watched that you tube video. That guy does a half job. Also there is no need to grind that washer off to lift the gear. That pin can be knocked out complete from the underside. There is an access hole from the rear. I do machine off both levers for potentiometers. Brushes u find only from another used TB. I reweld it with a Tig welder. Not an easy job. You need to power the potentiometer and adjust output voltage before u weld. It needs to be spot on.. to the mv. or TB will not program.

Kanishka Prasad

damn seems like its a hard job to do !! okay ill see if it sorts out the problem !!

Russell Ormerod

How is the loom between TB and ecu? Cut it open to see. Maybe source a second hand TB to test with. I have repaired hundreds of these looms and TBs and really you need the scan tools to make a proper fix

Kanishka Prasad

that loom is also i good shape !! unfortunately my friend in my country parts are very expensive !! i tested every thing i made a cut but ill further see if have some damaged wires ! but as i feel this is a improper ignition timing !! i feel the engine is retarted !! back fires a hell lot !! wel im using OBD 2 scanner ! unfortunately it didnt show nay codes so thats why i tested it with the manual method !!

Russell Ormerod

Very strange u get no codes but u get codes with impulse method.. Your backfire or popping sound in intake is typical of a lean mixture. Check fuel pressure also! The only way ignition timing can be out is if u have damaged segments on the flywheel. Only way to test that is with a scope on the crank sensor input. Make sure u have a clean signal

Kanishka Prasad

yes !! very strange !! well i tested the crank sensor too !! it give 0.6 volts of AC signal !! i replaced it too !! but for a physical damage to happen i didnt run the vehicle that rough i did my maintenance well !! and i replaced the fuel pressure regulator , fuel pump , fuel filter too !! and i check the voltage at the fuel pump it pumps continuously while it runs the engine and its 14 to 12 volts


and im afraid that its a kinda of a huge back fire ! and it blew off the intake plastic cover also and replaced it too !!

Russell Ormerod

Voltage check on cps means nothing. Scope test only. As a start. If u happy with maf and its genuine MB or Bosch. Then cut the maf plug open and rewire it to the ecu. Is there power at the maf?

Kanishka Prasad

i ordered the MAF from the company itself !! the MAF gets 12 v and there are two return wires to ECU i checked them all !! and there is continuity !!

Kanishka Prasad

so friend what do u suggest me to do first !! cause i have checked all what u said expect for the scope test on the CPS but its a new one !!

and the TB i didnt check it completely as u said !!

Russell Ormerod

Ok then maf is good! Let's start with fuel pressure? I know u replaced it all. Even better disconnect return line back to tank start the car and measure quantity back to tank. You should have around 1L in 30-40sec

Kanishka Prasad

okay ill check that and let u know !!

Kanishka Prasad

yes i was able to collect around one liter for the time you said !!

Russell Ormerod

Well the next step is a diagnostic tool that can read data. Send me the values so we can check further. Also check wis why u don't have power at vvt.