No torque

#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.

#32

Compression generally equals torque. And of course torque and horsepower are very intertwined. If the motor is low on compression the horsepower peak will be higher because that dynamic compression increases with RPM but you’ll still have a low torque number. I would not waste my money on new injectors, rebuilt one seem to work fine on everything I’ve built over the years. Bottom line is, put in the new motor.

#33

Throttle linkage is good?
Previous owner must not have wanted to go fast and would have never known it was low on power.

The prior, prior owner suffered through a cracked head due to overheat. See if I let someone use my car to do a simple DE event. Guess it was too difficult to turn on the fan. I replaced the head and, based on the performance expected from the prior owner, assumed all was well. Either my DE adventure guy, or who knows what in between, and heat must have got piston ring tension as you say there is an oil puff.

Just some thoughts. Don’t overthink it. It has rebuilt injectors, that is not the problem.

RP

#34

Wow! thanks for all the ideas and help.

Yes, the throttle linkage was way off and we fixed that in March. OK now.

Thanks for the info in the injectors. I think you just saved me some coin.

We have the electric fan wired now to a separate switch so I can turn it on manually. Works great now.

For what it is worth, the acceleration in the standing start is pretty good. I don’t start losing ground until I get to 3rd gear.

Are you sure the Diff and gearbox are OK too? I figured the wheel bearings are OK because they don’t make noise?

#35

“If the motor is low on compression the horsepower peak will be higher because that dynamic compression increases with RPM but you’ll still have a low torque number.”

Let me rephrase that…If the motor has low compression, it will make horsepower at a higher rpm because as the rpm increases, the dynamic compression increases. It will still have low torque. Compare your hp/tq curve with a known good motor and I think you’ll see your motors peak hp is at a higher rpm.

#36

[quote=“pwbacon356” post=81291]Wow! thanks for all the ideas and help.

Yes, the throttle linkage was way off and we fixed that in March. OK now.

Thanks for the info in the injectors. I think you just saved me some coin.

We have the electric fan wired now to a separate switch so I can turn it on manually. Works great now.

For what it is worth, the acceleration in the standing start is pretty good. I don’t start losing ground until I get to 3rd gear.

Are you sure the Diff and gearbox are OK too? I figured the wheel bearings are OK because they don’t make noise?[/quote]

Don’t make noise is a good indication of still good.
I’ve not owned the car since…2011?
The components were good at the time, but the prior owner put it into a tire wall(?) and there could have been some bearing damage. Doubtful if it don’t make noise.

Have you removed windows yet to lose weight?

We are off topic.

RP

#37

Yep, we put the car on a diet.

I have taken out the front windows, winding motors and all the heater core & control stuff. I have also installed a fuel accumulator so I can run the car with a less than half full tank. All in, I think the car is now about 10 pounds under minimum so I put a spare tire back in. I am so slow no one cares but me how much the car weighs.

I was also thinking about the gearbox and diff. Any chance they could be off and causing a loss of power from the engine to the wheels? I assume the gearbox would be complaining if something were off. The gearing seems right as I compare video from other cars. I shift about 20 to 40 yards later because I don’t get to 6K Rpm at the same spot on the track. I shift at 6K and don’t run all the way to the 6,250 because the power starts to drop off at 6K RPM. The Diff seems to engage in turn 1 like it should and I get decent acceleration through a corner. When I drove another car and the diff was out, we lost power in corners. Turned out to be loose diff bolts too. Not my problem now.

#38

Gearbox…you generally can’t hurt it. ATF changed yearly. Diff, same, AmSoil 90W110 (?) and change yearly.

#39

I would expect your engine to perform poorly with such high leakdown numbers. Above 10% means you needed to rebuild long ago to have a front running engine. I’m with chuck, you won’t make any power until your motor can make compression and leakdown is currently your limiting factor (at least on cylinder #4). I suggest you start with the basics. Do a dry compression test, wet compression test, and a leak down test then post the numbers.

#40

Thanks for the advice. I think you are right. At this point I am doing a process of elimination to makes sure the engine is the only possible problem. I planned a few months ago to build a spare motor so I could drop it in when it was ready. All the parts for the rebuild are already in and off to be balanced. The head is refreshed and ready to go. Assembly should start in a couple of weeks.

I can do compression my self and will do so again this weekend. I have to get someone else to do leak down, so I am not going to bother with the expense and time since I know a new motor is going in.

Chuck told me to get everything else sorted first, and work on the power last. I hope I am there. The suspension, ignition, sensors, cooling, cameras and TraqDash are all in place.