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Ed Higginbotham
Ed Higginbotham UberDork
3/27/19 8:33 a.m.

In reply to jimgood :

Good suggestion! Thanks, Jim.

mazdeuce - Seth
mazdeuce - Seth Mod Squad
3/27/19 8:50 a.m.

Thanks for documenting all of this Ed. Building a race car is a lot of work. 

Ed Higginbotham
Ed Higginbotham UberDork
7/11/19 9:30 a.m.

It's been too long! Since the last update, stuff started getting crossed off the list and we had it ready to race at HyperFest at VIR. Showed up and added stickers because race car.

Made it through tech and got a log book for the car! That was such a fulfilling moment.

Then on Saturday during practice I only got about halfway around the track and the car started bogging down. But it was bogging in a weird way. at exactly 3500 RPM it would just drop off a cliff and want to die. It got worse and worse until the end of the warmup lap it was very hard to keep it running. After getting back to the paddock we started investigating. No codes and all the usual suspects checked out fine. We started just throwing parts at it blindly. That always works well. Two new coils, new plugs, a new fuel filter. Crossed my fingers and went out to qualifying. It did the exact same thing. 

Rather than guessing some more, I started walking through the paddock stopping by anyone who had an E36 and asked if they had that issue. Found an extremely knowledgeable BMW guy who was there crewing for a fleet of E30s. He was positive my issue was the throttle position sensor.

I then wandered over to where the Spec3 guys were paddocked hoping they'd have a throttle position sensor. They didn't but they were very intrigued by my issue since they hadn't heard of such a thing before. They were kind and helpful enough to chat for a while and mentally work through some ideas of what it could be. Their opinion: It's not the TPS. They threw out their guesses as a bad MAF or cam position sensor. Then one Spec3 guy who wasn't actually racing that weekend (just there to hang out and help) said "Have you checked your differential speed sensor?" My what??? I had just put in my limited slip and was not aware something needed to be plugged in.

Went back to the car, dove under the rear and low and behold there was an open female plug on the diff cover and the matching male connector dangling right beside it. Are you kidding me? Plugged it in and the car ran great the rest of the weekend. PS: You can watch me not notice this issue in real time on page 3 of this thread.

Now I just want to emphasize how amazing this was. Just from me describing this bogging issue, this guy guessed correctly the issue was a diff speed sensor. He and the rest of the Spec3 guys are my new heroes. I saw the genius again at the tech shed the next day and yelled to him that he was correct and that he was my hero. He seemed slightly put off by this, but whatever.

During the race my bogging issue was solved. But I found a new problem. This car has a very severe case of the E36 fuel starvation issue on right hand turns. Every time I went around turn 1 the car would bog and die for about 5 seconds. That torpedoed any chance I had at a decent finish and I felt like I was causing an unsafe situation exiting turn 1 at about 30mph every lap so i brought the car in. Solved that issue by running with a full tank (HEAVY) for all our sessions on Sunday. But I had a fantastic time and was able to give the 944 guys some competition.

Finished fourth in class in the one race I actually competed in and it was actually a very good sorting weekend. The car handled great. 

The next to-do items:

  • Install a dual fuel pump system to get rid of the fuel starvation issue and allow me to run at a lighter weight.
  • I'm about 20 hp shy of my maximum power/weight ratio for my class (1:14) so I'm going to order an ECU chip. They claim to boost you about 20hp so that should put me in a good competitive position. 

Loaded up and ready to go home.

Ed Higginbotham
Ed Higginbotham UberDork
7/11/19 10:07 a.m.

Oh and shout out to GRM forum member CrookedRacer for cutting out the inside of my doors with surgical precision (shown in the first photo in the last post). 

Ed Higginbotham
Ed Higginbotham UberDork
7/16/19 9:52 a.m.

Progress! Just finished the dual fuel pump system. I routed them in parallel as done in this DIY article: http://www.pumpkininc.com/content/doc/guide/ag-8.pdf I think BimmerWorld's kit routes them in series, but I've heard it works both ways. 

The various materials and fittings were slightly challenging to find so I'll include the parts list and links to where I got mine if anyone is interested in doing the same.


Here's how mine looked when finished. I dropped the tank about half an inch to make fishing the lines through the middle easier. It's crowded in there now! I'm calling it Hose Clamp City.

Driver's side (new pump)

Passenger side (existing pump)

Ed Higginbotham
Ed Higginbotham UberDork
7/19/19 6:10 p.m.

Got a chip from BimmerWorld. Should be a little closer to my target power/weight ratio. We'll see when it hits the dyno over the next few weeks.



DjGreggieP Reader
7/22/19 8:56 p.m.

Been meaning to ask. What are your thoughts on the depowered steering rack? It's an option I am thinking about on my e36 but no one locally has done it.

Car is lookign good! I am wanting to do the reinforcement plates as soon as the deer damage is completely repaired and paid off

Ed Higginbotham
Ed Higginbotham UberDork
7/23/19 8:30 a.m.

In reply to DjGreggieP :

Thanks! Yeah the reinforcements are a must for cars that see track time or have stiffer springs. 

As for the depowered rack, it's definitely more resistance than stock. Driving around the paddock, it's okay, but on track it is more difficult to turn than any car I've had on track before. My shoulders were sore after the first session. But it's really only hard to turn when you're going really fast. I'm running a lot of caster so the steering wheel REALLY wants to return to center the faster you go. Just need to hit the gym more!

Ed Higginbotham
Ed Higginbotham UberDork
7/31/19 9:27 a.m.

Guys. I did a bad, bad thing.

This past Saturday I thought I'd pop the oil pan off and replace the stock oil pump nut with one that could be safety-wired on. (These nuts tend to back off on these engines. Then boom.)

I held the engine in place, dropped the front subframe and started removing oil pan bolts. I was about an hour or two into the job when I went for the last bolt at the back of the oil pan. It's one of two 4-inch super long bolts. The head snapped off as soon as I applied any pressure. 

What ensued was FOUR DAYS of pulling, prying, drilling, crying, and hammering, trying to get the pan off without major damage. I ended up having to remove the transmission, driveshaft and exhaust, but I finally got it out last night!

And it only cost me four days and one pinky fingernail! laugh Sheesh... I was so happy to get the bolt out last night I just took a photo of the oil pump and left. Felt like going out on top. I'll be replacing the nut and putting it all back together this evening.

Lof8 Dork
7/31/19 10:04 a.m.

I hate when a "quick" job turns into a huge ordeal.  Congrats on conquering the bolt and also getting the car out on track.  Lookin good!

MTechnically Reader
7/31/19 10:18 a.m.

Sounds like you're oil pan project turned out a bit like my E39 M5 suspension rebuild. Take solace in the fact that you managed get the eventual win in stead of having to tow it to a shop...

Ed Higginbotham
Ed Higginbotham UberDork
7/31/19 10:35 a.m.
Lof8 said:

I hate when a "quick" job turns into a huge ordeal.  Congrats on conquering the bolt and also getting the car out on track.  Lookin good!

Thanks! Yeah I've never had one bolt give me that much trouble. It was truly remarkable.

Ed Higginbotham
Ed Higginbotham UberDork
7/31/19 10:36 a.m.
MTechnically said:

Sounds like you're oil pan project turned out a bit like my E39 M5 suspension rebuild. Take solace in the fact that you managed get the eventual win in stead of having to tow it to a shop...

E39 woes? I've got those too! I bought a 2002 540i and I'm just about to start a coolant system and vanos rebuild. Then figure out why the trans is stuck in limp mode...

MTechnically Reader
7/31/19 10:57 a.m.

Sorry to hear about the 540.

Have you done any diagnostics on the transmission yet. I'd definitely check the level and condition of the fluid.

Hopefully you have some kind of scan tool, as it will help you narrow down whether you are dealing with an electrical or mechanical issue.

Beyond that I don't know enough about the automatic E39's to give you any specific ideas, but hopefully that helps.

Ed Higginbotham
Ed Higginbotham UberDork
7/31/19 11:04 a.m.

In reply to MTechnically :

I have PASoft running on a dedicated WinXP machine. It's telling me that the EDS2 and EDS4 solenoids are bad. But when I check their resistance at the transmission control module they seem to be within spec.

Here's a thread on BimmerForums where I go into all the details and everything I've tried. I haven't done anything with the fluid, but I'll have to if I dig to the solenoids. I appreciate the input!

MINIzguy HalfDork
7/31/19 11:17 a.m.

I have a fuel starve issue on my 328i too. Anything less than 3/8 tank and it doesn't like it. I still need to do the oil pump nut, and also reinforce the subframe/RTAB pockets in mine still! Been to a few autox events and a few track nights and still doing alright.

Ed Higginbotham
Ed Higginbotham UberDork
7/31/19 11:39 a.m.

In reply to MINIzguy :

I’ll be sure to report back with how this dual fuel pump system does on track. And I hope your oil pump nut job goes quicker! Haha

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