Porsche 803 3.5" HFM is NOT entirely plug and play.

[MIKe30]

Just getting this posted on the internetz for everyone else that will run into the same issue I did for the last 2 weeks. The porche bosche 803 3.5" HFM is not entirely plug and play.

OBD2 applications have 4 prong connectors at the MAF. There are 2 grounds, black and brown/orange. On the stock MAF the ground pins 1 and 4 have continuity and are essentially the same point. On the Porsche HFM, the ground pins 1 and 4 do not have continuity - they are open. You MUST get continuity between these points just like the stock MAF. Doesn't matter where you do it, so it doesn't necessarily have to be on the pins where they plug in. I did it in the wire harness leading up to the plug.

Spliced mine together this morning and voila, no more jerky car when started, no more bucking bronco feeling when trying to take off, no more stumbling idle that shuts the car off, no more table 11 code 08's. Nice and smooth now from the get. Was very very very happy to finally figured this out after getting some help over on bf.c. Unfortunately everywhere I searched I could not find the solution to the issue, luckily a nice guy chimed in on one of my local threads over there.

Writing this up to help future obd2 guys. Hope this helped, good luck!

[flyboyx]

good job on getting it running correctly. i am really glad to here you are on your way.

not exactly related to your thread, but i just picked up a 3.5 inch bmw 540i hfm from local craigslist. from a performance standpoint, what is the difference between these two? will they provide the same results? i see a lot of people running the porche 803 and i was wondering why would one choose this over the stock 540i hfm?

[matt]

It was me... I am nowhere near local to NJ. :rofl:

It's the signal ground vs the power ground. For some reason, the OBD2 ECU requires them to be tied together. I honestly don't even know how it checks for that, but it does.

[mbonder]

Glad to hear it Mike, can't wait to see the car in person!

Matt

[e30polak]

Damn I could've answered this for you had I known you were OBD2. Sorry for being lazy, I learned this a while ago from Osh at RMS.

How's she running???? :D

[MIKe30]

It was me... I am nowhere near local to NJ. :rofl:

It's the signal ground vs the power ground. For some reason, the OBD2 ECU requires them to be tied together. I honestly don't even know how it checks for that, but it does.

hahaha! I kept thinking of you over here but was like, nah - why would he be in the jersey subforum? lmao. Thanks again dude.

Glad to hear it Mike, can't wait to see the car in person!

Matt

You already did ya dork. It was at GP when you pulled up haha

Damn I could've answered this for you had I known you were OBD2. Sorry for being lazy, I learned this a while ago from Osh at RMS.

How's she running???? :D

you suck! I spent $400 in parts I don't need because of this (tps, cps and cps with harness). Figured something was causing the jerkyness but wasn't giving a code. Bah, live and learn.

she's running so much better. Either have a small vac leak or my iac is on its way out. Dips below idle and sometimes doesn't want to come back up to idle immediately, takes a few seconds. Other than that she's running nice.

Even when it was running like shit I got two e46 m's under my belt by a car. Next is a caddie cts-v :mrgreen: (i hope **crosses fingers**). Fell asleep last night and didnt go out though...maybe tonight.

I'm a little worried though - I hope I am running as pig rich as I think I am. According to you, you pulled 1-2 cars on e46 m's. Thats without cams or pistons. Can't imagine picking up another 40 whp off of a fine tune. Hoping this maf makes a big difference at WOT and that somethings not broken or just off :/

[e30polak]

you suck! I spent $400 in parts I don't need because of this (tps, cps and cps with harness). Figured something was causing the jerkyness but wasn't giving a code. Bah, live and learn.

she's running so much better. Either have a small vac leak or my iac is on its way out. Dips below idle and sometimes doesn't want to come back up to idle immediately, takes a few seconds. Other than that she's running nice.

Even when it was running like shit I got two e46 m's under my belt by a car. Next is a caddie cts-v :mrgreen: (i hope **crosses fingers**). Fell asleep last night and didnt go out though...maybe tonight.

I'm a little worried though - I hope I am running as pig rich as I think I am. According to you, you pulled 1-2 cars on e46 m's. Thats without cams or pistons. Can't imagine picking up another 40 whp off of a fine tune. Hoping this maf makes a big difference at WOT and that somethings not broken or just off :/

Maybe an older CTS-V, cause we have mo chance against the new ones. :p

I'm guessing the MAF issue was probably robbing you of power. The main reason I pulled like that on the e46s is that I got to choose the gear and speed. Therefore, I'd start around 4k each time, and my weight advantage allowed me to pull early. I have a much shorter final drive then you, since I'm running the ZF with a 3.46. When I had the 3.25 gears I barely pulled a car, the 3.46 really turned the car into a torque monster! You'd do much better against an e46 from a 3rd gear roll IMO. :nice:

Get that tune cleaned up and send us some dyno results, and some vids!!! :D

[bender]

glad to see you got this thing sorted out mike! i know its been a long road :)

[mbonder]

You already did ya dork. It was at GP when you pulled up haha

Now I'm going to have to agree with Fred, you are a guido ;) I meant SEE it, engine, suspension, exhaust, take a ride, blah blah...

Hopefully next time.

Matt

[MIKe30]

Maybe an older CTS-V, cause we have mo chance against the new ones. :p

I'm guessing the MAF issue was probably robbing you of power. The main reason I pulled like that on the e46s is that I got to choose the gear and speed. Therefore, I'd start around 4k each time, and my weight advantage allowed me to pull early. I have a much shorter final drive then you, since I'm running the ZF with a 3.46. When I had the 3.25 gears I barely pulled a car, the 3.46 really turned the car into a torque monster! You'd do much better against an e46 from a 3rd gear roll IMO. :nice:

Get that tune cleaned up and send us some dyno results, and some vids!!! :D

hmm, you're making me want to keep my 3.73 (actually, replace with 3.73, my current one stopped locking up). I was thinking 3.46 since most of my power is made up top... but I got the jump and pulled everytime. First e46 was a vert with a slightly slipping clutch. I pulled little more than a car according to him. 2nd gear @ 40 mph. Puts me at about 4k IIRC.

Second e46 was a coupe. 2nd gear @ 35 mph. just under 4k which is nice. If I slam the throttle down above 4k in second I spin - even with bfg g-force sports on a nice day. Pulled on him no problem. From a dig, it wasn't even close but he had his traction contorl on. At 60mph in 3rd, he was close until 100ish +... from there to 150+ it had to be 2-4 cars. Want to run him again with the HFM working to see if it changes. And it's a newer cts, maybe it's not the v? 4 door caddie, like an 06 or so, beats the m's by about a car. not supercharged, IIRC. I also estimate about 80 lbs of shit in my trunk.

annd of course, DISCLAIMER!! ***OF COURSE THIS IS ALL ON A CLOSED COURSE, NOT PUBLIC ROADS***

glad to see you got this thing sorted out mike! i know its been a long road :)

Now I'm going to have to agree with Fred, you are a guido ;) I meant SEE it, engine, suspension, exhaust, take a ride, blah blah...

Hopefully next time.

Matt

Fred said I'm a guido eh?? Well you tell Fred I'm a porkchop and not a guido. Portuguese and proud m/f! ;)

you meant EXPERIENCE it. haha. but yea I get it.