Half-Life | '91 DS 318iS Slicktop | Track & Weekend Warrior

[Digitalwave]

Well, thankfully I think I found the issue with the car misfiring and fouling plugs. My MAP sensor had gone bad, and was reading very erratically. Replaced it with a new Delphi unit, along with the brand new 24 lb/hr injectors, and the car is running well again. Now just to finish up the tune!

Had to change the weatherpack connector for the MAP sensor, mine didn't have the right notches in it for the GM style connector.





Where I previously mounted the MAP sensor was too difficult to take it in and out, so I made this little bracket out of 90* aluminum. Came out great!







The MAP sensor is now properly mounted upside down (so no residual oil in the line or anything like that can foul the sensor element):





Picked up a sandblasting cabinet. Nice to have in the shop! I cleaned up my ground post, it was pretty nasty. The one on the left is the one that came off the car, the right is now like-new after glass bead blasting.





Here it is installed, I used dielectric grease after scrubbing each connected with a brillo pad to clean them up.





New Bosch Gen III 24# injectors installed. I had to replace my fuel rail as well. I didn't realize it before, but it was bent! Someone must have pried the hell out of it trying to remove it at some point.





Installed a new VC gasket. Mine was new, but the rubber textured type, and it was leaking. I think these ones with the bead around them are less leak prone. We will see.





Got a brake light switch mounted on the clutch pedal for launch control activation. I am not sure it is going to work well in this spot. The switch disengages too easily. In my testing, while it worked, if you leave your foot on the pedal with ANY pressure at all, it will switch and trigger the lower rev limiter again. I think I am going to have to change it to a switch at the bottom of the travel, instead of at the top. I'll have to do more testing. Not entirely sure how helpful this will be in reality, and may scrap it entirely.





Last but not least, here is the tentative spot for the tablet gauge cluster. It's just big enough to see fully through the steering wheel, and I am going to retain my shift light because it works better than any alerts you can set up in the cluster.

[Digitalwave]

Love this car. Curious about 2.5 things:

1) do you ever get nervous running the Febi rockers with that cam?

2) how does your car feel down low with said cam on a 2.5?

2.5) do you think upping your compression helped significantly in supporting said cam?

Thanks! I'm not expert and I did not build this motor (bought it used), but here are my thoughts about your questions:

1) I am always a little weary of ANY M20 rockers, but I have never broken one in over 10 years of owning E30's. I keep my rev limit fairly conservative and try not to abuse it.

2) It's still quick below the cam comes on (around 4,600 RPM). But my car weights 2,400lbs and I'm running a 4.10 diff. With a 3.73 and a full weight street car, it might seem slightly lacking down low, but I would bet it's still faster than a stock M20 below the curve. It just has a more noticeable transition into the power band.

2.5) I think the compression did, but more displacement would have helped more. This is arguably too much cam for a 2.5L. I'm still making a lot of power right by the redline.

In summary, I wouldn't run this cam on a street car, but for my purposes I quite enjoy it. The sounds it makes are heavenly, too.

[AWDBOB]

Love this car. Curious about 2.5 things:

1) do you ever get nervous running the Febi rockers with that cam?

2) how does your car feel down low with said cam on a 2.5?

2.5) do you think upping your compression helped significantly in supporting said cam?

[Digitalwave]

BMW Style 4 from an E38 16x8 ET23. Tires are 225/45-16. All info on the car is on the spec sheet in the first post/page 1.

[dasmanschaft012]

What wheels/tires are those? Alpina reps? Interested in width and fitment.

[Digitalwave]

Worked on the car a little bit this weekend. I pulled out the injectors to get them tested this week. I just want to know if they had any issues or not. I already ordered new 24lb injectors as I need the head room anyways (especially when I move to ITB's). My fuel rail looked kind of bent, so I ordered a new one, and a new FPR as well. Now my entire fueling system will be new.

Here's an example of my cylinder 2 and 5 fouled plugs:







Fuel stuff out:







I wish I had some better photos, but the next project I've been working on is a Nexus 7 tablet as a digital dashboard. I also bought an external 10Hz GPS for lap timing and for other data (like MPH for the cluster). This is where I'm at for the dash so far.





Lastly, while messing around with TunerStudio, I noticed that my MAP sensor was reading all over the place with the engine off. It should read steady at atmospheric pressure with the engine off, basically 100 kPa at sea level. I noticed my sensor was wandering all over, but at the most, reading around 82 kPa (and jumping as low as 50 kPa). Soooo, I think my MAP sensor was faulty, and possibly a big part of the problem we ran into with tuning recently. I had a spare sensor here, plugged it in, and it was a rock solid signal at 102 kPa. We will see in a week or so once I get the new injectors, spark plugs, and valve cover gasket installed and can drive the car again.

All done after a long night of work:

[

[Sh3rpak!ng]

I'm sure you'll figure it out. Goodluck getting it sorted quickly. Launch control is so damn cool. I'm a little jelly :p

[Digitalwave]

Getting really frustrated with the car at this juncture. We started tuning on Monday, and it went really well. Car was running great. Yesterday, we picked up where we left off, but from the get go something was wrong. On startup, the car had a lean misfire, and wouldn't even driven until we enriched the VE tables considerably. The car was not happy, with AFRs jumping all over, and overall much more rough. The car hadn't been touched since we parked it on Monday. The temps were a good 20* colder, but it shouldn't have had that much effect.

We came back and started looking for vacuum and exhaust leaks (didn't find anything). We pulled the plugs, and they didn't look too good. Uncategorized Groups and especially Forum looked fouled. I don't have a bore scope, but from peeking into the cylinder you could tell it was wet in there. There was some oil on the threads, but I think my valve cover gasket is seeping some.

We had also noticed that my valves sounded louder than normal (which could be injector tick), and if you remove the valve cover cap and sniff in there, the oil definitely smells like gas.

After putting in brand new spark plugs, the car ran awesome again. AFR's were stable, and the car was MUCH smoother (no more misfiring). Drove down the road and less than a mile later, the new plugs fouled again.

That being said, I think I have a bad injector or two (probably cyl. Forum is the worst). Maybe leaking, maybe stuck open, I don't know. Since my IDC's were hitting 90, I am going to take the opportunity to move up to 24# injectors instead of rebuilding these. I will probably replace the FPR as well, since it's of unknown age/origin. I am going to have the injectors tested locally, which will hopefully confirm an issue with at least one of the injectors.

Haven't ruled out the possibility that there is oil in the combustion chamber, rather than fuel, as the "wet" substance you can see through the spark plug holes. However, my car has never consumed oil or blown smoke from the exhaust, so it seems less than likely that all of the sudden I have a piston ring issue.

I will definitely need to do an oil change as well before running the car again.

Gotta say, after we dialed in some WOT pulls on Monday, the car was feeling phenomenal. Pulling really hard to redline. Noticeable power difference with the AFM delete and better fueling than my Motronic tune had.

[rzerob]

Style 21's, nice.

[Digitalwave]

Thanks for the kind words all! Glad to see this thread help others or even just inspire.

Just a short update today. After the initial hardware installation (MAP, wideband, VTPS, etc.), the Megasquirt conversion slowed down a bit. The initial configuration was pretty easy, but I started getting confused after finding conflicting information about rising edge versus falling edge input capture. I figured that out, and posted the solution in this thread. Shortly after, I had a tuner start working on my car. We made some progress with the idle, and cruising at low load/low rpm as well. Shortly thereafter, we realized there was a crank signal issue (VR signal) at 4,800 RPM. We did some things to diagnose it, but didn't have any luck fixing it. Long story short, a brand new OEM CPS fixed that issue, as documented in this thread. Cliffs: make sure your MS has a proper resistor in the VR+ input, check your CPS air gap (1.0mm +/- 0.3), and when in doubt... new CPS?

It was odd that this CPS worked fine with Motronic, but it seems that Motronic is much more lenient on a poor VR signal that Megasquirt is. Glad that got sorted out.

Today, varg from the forums took over tuning duties, and it went really well. We've got the idle down, cruise is good, and we did a lot of WOT pulls. Things are looking and feeling really good. We are going to work on the tune some more later this week. My injector duty cycle is in the 85-90% range, so these 20# injectors are pretty much tapped (leaving a margin of safety). Don't have many pictures to post since my last update.

My old CPS. The new one didn't have that dent you can see on the top. I have no idea if that was related to the issue or not. Resistance was exactly the same between the old unit and the brand new one.






While changing a jumper on my daughter board, went ahead and soldered in CANBUS outputs for later AiM race dash usage... :devil:




While trying to figure out the VR signal issue, we used the proto area to add jumpers to multiple resistors for easy testing. Since the CPS itself ended up being the issue, I don't need this any longer, but I will leave it until if/when I need the proto area for something else.






The new rimzz:




Shoutout to Derek @ DedericMS and varg for the help figuring out the VR signal issue. Derek has been very helpful in supporting his PNP Megasquirt product.

[mitchlikesbikes]

God damn, the attention to detail in here is insane. Thank you for some inspiration.

[paynemw]

M20B25 wiring harnesses usually sell for less than $100. Sometimes it's easier to just buy another one, rather than trying to fix one with issues.

Thanks for the info. I have yet been able to find a decent Motronic 1.1 harness for anything less than $200. I'm actually picking up one tomorrow, but I will most likely have to re-create it, which is my intent.

Regardless, clean clean build, and thanks for the tip about changing boots to allow for the T style ICV, I didn't even think of that. I was interested in removing the unnecessary vacuum lines and converting to the M1.3 style intake boot.

[Digitalwave]

So, did you do any engine harness repair? I'm guessing you're running a mixture of M1.3 harness with your MS2 and other goodies. I'm having issues with my harness and my buddy is as well, and we were looking at building new harnesses, I was curious to get your input given the cleanliness of your M20b25 and the fact that you have also changed out a handful of sensors, and alot of stuff looks mixmatched, like earlier style ICV, newer style boot with minimal vacuum lines from the booster, L-Jetronic vacuum plate, etc.

My engine harness is actually a 100% stock Motronic 1.3 harness. Not a single spliced wire. The sensors that I added are all independently wired.

The T and L style ICV's are interchangable and use the same connector. You just have to match the intake boot to the ICV. I prefer the looks of the L shape. The silicone intake boot doesn't have the nipple for the brake booster, but it isn't necessary. The two lines coming off the side of the throttle body still have the stock check valve, and they go directly into the brake booster now (without the extra L off to the intake boot).

The L-Jet vacuum plate was added simply to get a clean looking additional vacuum source for the MAP sensor.

It's nice to have a clean, untouched wiring harness. My last E30 had some shoddy work done to the engine harness for a Miller MAF conversion. It also had some issues within the harness for the CPS wiring, that were causing a break-up at high RPM. That was really hard to diagnose and fix. That is all part of the reason why I went with a fully plug and play MS2 setup, where I wouldn't have to modify the wiring harness at all.

M20B25 wiring harnesses usually sell for less than $100. Sometimes it's easier to just buy another one, rather than trying to fix one with issues.

[paynemw]

I had an AFM delete pipe welded up and powder coated. I also sourced an early model intake manifold vacuum cap that has the extra vacuum port on it (I think for L-Jetronic?). I routed the silicone vacuum line below the manifold, and mounted it along the stock wiring harness bracket under the manifold. It's accessible, but pretty well hidden.

So, did you do any engine harness repair? I'm guessing you're running a mixture of M1.3 harness with your MS2 and other goodies. I'm having issues with my harness and my buddy is as well, and we were looking at building new harnesses, I was curious to get your input given the cleanliness of your M20b25 and the fact that you have also changed out a handful of sensors, and alot of stuff looks mixmatched, like earlier style ICV, newer style boot with minimal vacuum lines from the booster, L-Jetronic vacuum plate, etc.

[Digitalwave]

Interesting. Do you think heat soak of the IAT was the issue on your car? Or it just needed more idle & startup tuning in general. I won't be tuning the car, I'm having a local Megasquirt guru do it (Linfert Performance).