My car started getting the dreaded ABS/PSM light combo. I checked MAF reading with Duramtric and it was 0 so I repalced the MAF and there areading now. However every first start of the day the car will throw ABS/PSM light combo and code P0103 and also 5525 code in PSM module. There are no other codes, no overboost, underboost codes, no misfires. Just one code in the ECU. I thought the MAF I got might have been defective so I took it back and got another one. Cleared fault memory and installed the new MAF, on cold start same thing happens. The code comes on before I even drive the car. MAF is OK.

I am having the car pressure tested tomorrow, we'll see what turns up.

The diagnostic manuals lists:
P0103 - Possible fault cause
-Intake air system on pressure side (between turbocharger and engine) leaks - still need to check
- Short circuit to B+ (B+ is + 12 volts) - assuming this si OK since i get a reading on MAF
- Mass air flow sensor faulty - replaced, good
- Throttle jacking unit faulty - TB ? not sure what this is

I've also read that this could be the ECU - hoping thats not the case here.

 

Went through the car found a few leaks. One was a check valve on top of the TB to the left. Boost leak test is fine. Maf is replaced, also got a brand new optima red top battery since mine was going and i thought it may be a voltage issue.

ABS/PSM lights come on on the first startup before I even start driving. If I restart the car they no longer come on until the next day.

Very weird ....

 

pressure test at the TB.. see what shows up...

 

ill give it a shot. cant hurt. we pressure tested from turbos and it holds alot of pressure...

did 60-100 in 2.6 seconds, 50-70 in 1.0sec went to shift to 4th and felt like the TB closed and car shut the power down. let off the gas , got back on and it was fine. no codes after this. veryy strange

 

Ok what about if you run less boost.. turn down the Wgs.. just to see if it still does it...
what TB and plenum do you have...

 

Dont want to mess with WG since they were preset by Tial and that's how I was tuned. Car is down for exhaust fab now. What is the proper way to test wiring?

I have an IPD 75mm Plenum and 997 OEM 75mm TB.

 

Well that's a bad idea lol don't ask me how I know.

Get a $35 mytivac 8500 hand pump. See where the wgs start to crack. Write it down. Then lower the boost lets say 3 turns.
Run it and see if it's boost related. You can always turn It up to where it was anyways. It's easy.
997tb Is not 75mm. Do u have a iPd for the 74 mm tb ?
What did u change exactly before it started to happen. THats the cause.

 

Alter resolve some leaks and the over boost issue the car still with the error P0103 like yours. Every first start of the day the car will throw ABS/PSM light combo. Soon I will do a pressure test. I have too a big plenum.

 

sometimes going back to basics is the only way.. and even returning to OEM is required... I suggest putting back the oem TB and plenum... then you know for sure...
and start from there...
sometimes things do not go as smooth as they should...

 

i had that plenum and tb for almost a year...

 

Ok so thats not it...

lower the boost manually see if it does it... thats what I would do...

 

I had the TB take a **** on me. It is part of the abs system. One of the functions of the abs is to kill the throttle. There is no stepper motor for idle control like in a non fly by wire TB setup. The fly by wire motor does double duty. I would look at that first, I would send you mine but I have a V band welded to it. If you have a 75mm TB any 02 and up N/A TB will work. Hope this helps.

 

I'll give that a shot because that last line of the P0103 description does say as one of the possibly faults...

- Throttle jacking unit faulty

Gotta find a TB now...

Thanks Tim !!

 

So I replaced my TB with a brand new one and I still have the weird P0103 code come up. It does not come on every day. It only comes on the first time I start the car on every other day or so. ABS and PSM lights up no CEL. I have pressure tested and smoke tested the car a few times now and cant find any additional stuff beside what I already replaced (check valve, some hose clamps)

 

Have not dealt with this on a porsche yet,but on others p0103 is maf sensor circuit high.Meaning the engine controller was looking for a voltage reading from the maf other than the reference it sends out.With it being an intermitt. issue and occurs at key on/no start-possible wiring issue like a spread pin connector.The female conn. has a small contact tongue inside that actually is the connection,if spread or weak you end up with improper or no voltage flow thru the connection.Could also be the engine controller,or the maf signal wire shorted to volt or voltage induction into the signal wire fron failing/damaged wire insulation.Mercs are real bad about having spread pin conn.'s,maybe same part sourcing ? I would closely examine the conn. at the tb first.But sounds electrical to me