MAF sensor rewired by previous owner, tuned?

[WhyNot?]

Hi all!
Fantastic forum and threads!
I have fallen for a 420T 1997, it goes like hell.... but with symptoms.
1. Loss of power randomly, engine almost dies 5ms when accelerating creating a thump, when 80C or when recently warm and starts driving again. Never when cold.
2. Erratic idle, sometimes not.
3. The exhaust smoke smells rich.

Troubleshooting:
Disconnecting MAF @ MAF sensor, takes away symptom #1 but worsens number symptom #2. Car still goes like hell but pedal needs more push initially.

Investigations:
MAF sensor cables looks fine, made a cut close to the sensor and checked the isolation. Followed and pinged/beeped each cable to the ECM bay and found that the previous owner soldered the yellow/white, yellow/green together with a white cable, do not know where it comes from but it has 12V.

Questions:
Is this an attempt to trick the MAF sensor to allow a rich mixture, I think the yellow should have 5V but now always have 12V?
According to diagram the yellow/white and yellow/green should connect to ECM pins 67 and 68. Any risks doing this? Any pictures how to open the connector at the ECM?


Thank you for reading!
All the best and stay safe!

 

[WhyNot?]

Sorry, I also had error code P0100.

 

[Petrol-Head]

P0100 is the MAF meter. Were there any numbers after that?
P0100-004 is voltage too high/low

I have access to a lot of vehicle data / recalls / service bulletins etc but I need a reg number to search.

 

[WhyNot?]

Thank you for reading and helping Petrol-Head!
VIN: WDB2102721A265997
Engine: 11998512012681

 

[mattkh]

Wow a v8 4.2
How many MAFs in the engine, 1 or 2..?

 

[WhyNot?]

Thank you for reading my thread mattkh!
Yes it´s a V8 and it goes like hell, the exhaust is "leaking" so you can hear the lovely V8 sound. One MAF in the middle.

 

[mattkh]

......1. Loss of power randomly, engine almost dies 5ms when accelerating

Is that supposed to be 5 milliseconds ?
Also, roughly at what revs..?

 

[WhyNot?]

Yes 5 milliseconds and it can come between approx 1500-4000. Thinking it may be only in closed loop and when in open loop all works fine, but I don´t know. Maybe it is flooding with to much fuel as the MAP is telling ECU it ha maximum air flows all the time when it makes these 5ms hick-ups. Theses are my amateur speculations/guesses.

 

[WhyNot?]

All,
Issue solved by replacing the MAF sensor. I was wrong about the wrongly connected wires for it, my mistake was not checking the exact colors, sorry.
Anyway, now I have a smooth, calm idle and no hick-ups/misfires, so relieved, the part is a Ridex MAF (55$). I was on a path of vapor lock and everything else for a while. Thank you for your support!

 

[mattkh]

Glad it is sorted. Enjoy.
By the way, if you have the box, can you tell me where the Ridex MAF is made. Thanks.