No torque

#12

From the dyno plot, it appears that something is causing your motronic system to pull timing or your cam timing is screwed up. I’d start troubleshooting the Motronic first as it’s most likely.

As already suggested by others, I’m also suspect of your coolant temperature sensor or wiring. If the Motronic doesn’t receive a signal from the CTS, sees extremely low resistance indicating that your coolant temperature is very high, or you simply have an open circuit, it will pull timing and kill your torque. To check, measure the resistance of pin 45 on the DME connector across ground with your engine at ambient temperature. This is the only way to verify wiring and the sensor. With coolant temperature of 68 to 86 degrees F, you should see resistance values of 2500 to 1707 ohms. Higher resistance is better and resistance decreases as coolant temperature rises.

If the CTS and wiring check out, my only other suggestion is cam timing. If retarded, you will lose torque down low and alter peak power. Significant retardation will have a large negative impact on torque while only slightly reducing peak power. This begs the question on your cylinder head thickness which should be 4.909" or greater; this is easy to measure with a caliper or 5" micrometer, but likely tricky in car. Otherwise, you could be off a tooth on the cam gear.

#13

One other thing. What is the history of the motor. Junk yard, with car, rebuilt, timing belt changed, etc?

#14

And bring the data home so you can set up better charts that exactly show what’s going on.[/quote]

Is anyone maintaining a database of these Dynojet run files? I think that would be a good thing to start doing. I have 3 files for my original motor, and 3 files from my Fish motor I would me more than willing to make public.

#15

And bring the data home so you can set up better charts that exactly show what’s going on.[/quote]

Is anyone maintaining a database of these Dynojet run files? I think that would be a good thing to start doing. I have 3 files for my original motor, and 3 files from my Fish motor I would me more than willing to make public.[/quote]
I have lots of old runs of mine on a couple different motors, but I agree that it would be good to have data from a whole bunch of us. I coordinated with the dyno we had at RA in Jun? for the data. They didn’t use a F/A sniffer tho, so that made the data less useful to us. They told me I could get the data after the event. I must have tried to contact them 12x by email and phone in the months that followed. When they finally picked up the damned phone it was to say, “oh, sorry, we deleted that data last week.”

If a group of SE types have another Balanced Performance dyno day, I’ll put the issue on the skyline and maybe we can end up with data.

#16

It came with the car. I refreshed the top end at the end of last season.

I appreciate all the helpful hints–I’ll do spark / wires, and have my shop check the timing.

#17

Definitely inspect cam timing. Did you mill the head?

I would not throw any more money at it until the Cam timing was checked.

#18

interesting read. I’m tracking down issues with my setup and coolant temp might just be it. Dash works, but oem coolant gauge does not. If I read pin 45 and it does show that it is going into limp mode for coolant temp, is there an easy way to bypass that? or do I get new sensor, wiring, etc?

#19

I guess I should have followed up with this.

Compression was down a bunch. After staying steady for a few seasons, it just dropped off a cliff.

#20

Consider getting an aftermarket temp sensor and gauge. If you can, get one of the good ones with 2 wires to the sensor, a stepper motor, and ~270deg of sweep. I went thru a lot of happy-ass gauge solutions in order to find the most expensive and complicated way to do anything. I’d have saved myself a lot of time and money if I’d have bought high end gauges like STACK or it’s Autometer equiv with:
–2 wires to sensor so accuracy not impacted by ground quality
–Stepper motor and 270deg sweep for precise reading of temp with eyeball
–Data out to your data logger
–Programmable gauge color so the whole gauge face can go Yellow or Red at a temp of your choosing
–Programmable threshold out so you can run an external warning light.

Sometimes a person can go cheap and get away with it just fine. But other times going cheap means you slowly increment up buying and installing increasingly capable solutions until finally you end up with the solution you keep because it does everything you want really well. But then you have a pile of your discarded solutions that turned out to be a waste of time and $$.

#21

I have nice oil pressure and water temp gauges with warning lights and buzzers. Just wondering if the stock sensor has anything to do with my power loss. I’m away from the car for awhile, so I’m trying to build a cache of internet fixes to try when I can work on the car.

#22

Ah so, I misunderstood. There is a brown sensor and a blue sensor. The cable harness should be color coded the same. One goes to the DME and is important. The one that goes to the cluster gauge is not important. I don’t remember which is which. My car is in my trailer in storage so I can’t go look either.

#23

The blue sensor is the important one that provides coolant temperature to the DME. It’s very important that this sensor operates correctly and bypassing would not be rule compliant. It’s pretty easy to test with a multimeter and the specs are in the Bentley. You need to know the temperature of the sensor when performing the test so it’s best to leave the car in the garage over night and assume ambient when you start the test. Validate the sensor is working by measuring resistance at the sensor. Then validate that your wiring is good by measuring resistance across ground at pin 45 on the DME connector. If you have a noticeable difference, you have a wiring issue…

#24

Bobe30, good info from Richard.
If it falls off after temp this could be a simple fix.I’m watching and learning every day.

Who knows where the sensors and wiring junk came from…But I can guarantee it was/is clean.

RP

#25

Good info. Thanks doooods.

#26

I had a similar problem. Torque was about 140 at best and max HP about mid 150’s . Problem is the EVERYONE in the field pulls away from me in the straights. I have done everything suggested here except throttle body. Replaced coolant sensor, new O2 sensor, plugs, plug wires, crank position sensor, ECU that ends in 173. After today, I am done. either I am a really bad driver, and if you think so please keep into yourself, or the motor is shot. The only thing left is to rebuild the motor. I am burning a quart of oil per race and I get a puff of blue smoke when I let off the gas. Compression and leak down are reasonable but not great. I have the feeling I am arranging chairs on the Titanic, so rebuild is next.

#27

I don’t want to patronize you by saying stuff that is obvious, but it’s common to see people in your position…down on power and not sure why. Usually they rebuild the engine. But what they should have done, imo, is spend some more time trying to better understand why they are down in power.

What were the compression and leakdown #'s? Tests need to be on a warm engine and need to do the tests both wet and dry. Tests have to be repeated several times to make sure you’re getting repeatable results.

Get dyno data that includes AFR. Get the data, not just the paper. This allows you view your graphs using WinPEP such that you can zoom in on the AFR. This can alert you to engine management problems.

Paul, I note that you didn’t mention injectors. Good Bosche injectors are more likely to provide a good spray pattern then the cheap injectors or “old but cleaned/flowed” that a lot of people use.

#28

Thanks for the tip. I have been at this for about 6 months and out of ideas. Compression and leak down were decent, but not great. One cylinder, it may have been 4, was down 10% more than the others. The car sat for a while so I was hoping it would clear up with running.

I am kind of out of patience. I show up and spend the better part of $1K for a weekend and run like crap. I have done all the sensors, timing, ignition, etc. I have also done the brakes, suspension, alignment etc. I may have been ahead if I had just started with a shell, but then I would not have 10 races to my credit.

When the car was built, nothing was doe to the lower end, so my conclusion is there are many miles on this lower end.

I have not tried injectors but will make sure I have them when I install the new engine. I also like your idea of putting in numerical temp gauges so I can see exactly what is going on.

Anything else?

Paul

#29

Spending more time and energy trying to attack the problem with a scalpel (getting more detailed info) is at odds with running out of patience and saying “fuck it” and getting a new engine.

So if you’re out of patience, put in the new engine. But use new OEM injectors and be sure to get the data file from dyno and that they sniff the tailpipe once the new engine goes on the dyno.

#30

I just checked the price of new injectors. Pelican parts has generic rebuilt ones for $44 each, BMW rebuilt ones for $77 each and new ones for about double that. So here are another several hundred dollars to the total bill.

Which ones do you suggest?

BTW, sorry for your door ding… I looked at the video last night and I might have done better by going left, certainly for you anyway. I remember at the moment thinking about the flash of the green car I saw on the left and the opening on the right, so that is why I went right. it was grass either way.

#31

Injectors. Contact Chris or Ziggy at Bimmerparts. Tell them that you’re a SpecE30 racer. Ask for Bosche injectors. Not rebuilt, new.

My door wasn’t the worst of it. Fixing the rocker under the door, and fixing the fender area in front of the rear wheel is going to be the hard part. Wasn’t your fault tho. My perception is that you were cautious and slowed way down. Ok, it didn’t go perfectly, but the fact you slowed down so much, in my mind, exonerates you from any criticism. You tried hard to avoid trouble. That’s all anyone can ask of a person.