Bad TPS signal.

[Noggy]

I put a post on Patriq's thread, who had a similar problem which cured itself, so thought I'd start my own plea for help.

Car is a short circuit spaceframed saloon racecar using a 2 litre Zetec silver top with DCOE carbs. Car has no alternator. The car was test run on the edis alone, which was fine.

Installation: Car is negative earth, edis and MJLJ are mounted next to each other 2 or 3 inches apart. One of the bolts holding the edis to the car is also acting as the earth point for the edis, TPS and the MJLJ. The edis and the MJLJ are mounted about 24 inches away from the coil-pack, but they are seperated by a steel bulkhead.

Current operation: Without engine running, TPS signal sweeps reliably and linearly from 0 to 100%. With engine running TPS will only go to about 10-12% and mapping only gets to the 2nd load cell. Engine speed sites work fine, so it is getting speed based advance.

Like I said on the other thread, I ran out of time at the weekend and couldn't put any time into starting to diagnose what the problem is. I now can't even recall if I calibrated the TPS, but if the dial is sweeping to 100% I guess I did?

Cheers.

[Noggy]

Well, bit odd this, and follows the lines of Patriq's previous post.
Went up the workshop with an open mind, hooked up laptop (it has a serial port, so no usb issues here) and same problem was witnessed.
First thing I tried was removing the tps from the car to see if there was an installation problem, all was ok.
Put pot back on car, recalibrated and now all is ok!
Seems strange, I thought I had calibrated it, I was getting full travel on the screen load gauge.
Motto is check and check again. Good thing is we're now race ready for Sunday.

[brentp]

Sorry for no reply- In retrospect I can see why a non-calibration would make the readings weird. Are you seeing a smooth 0-100% now on throttle position?

Good luck at the race! will you share your results?

[Noggy]

Hi Brent
Well, that's the weird thing, with the engine off the 0 - 100% sweep was fine. But with the engine running it would only go to 10 - 12%.
Now, if observed on the runtime screen, the TPS signal is good.
Quick question, on the TPS calibration (load calibration) window, what is the purpose of the 'Write Calibration' box at the bottom of the scaled value column? I'm sure I read in one of your other replies that part of the auto-calibrate process flashes the correct TPS output to the MJLJ?

[brentp]

It's for when you hand-edit / customize the data in the calibration table. Not needed when you use the 'wizard'

[Noggy]

Thanks, that's kind-of what I guess-umed it did.
I'll let you all know how we get on tomorrow and try and post some pics.

[Noggy]

Well, bit of a mixed day really.
Got a first in the first race.
Got a second in the second race.
http://www.youtube.com/watch?v=WRzec5eE75g
And in the third race the oil filter came loose, dumped all the oil and seized the engine.
MJLJ worked a treat though, but could do with a RR session to get it spot on.

[brentp]

Ugh- Lost oil pressure - the bane of racers everywhere! Do you have a blog or a team web page?

[Noggy]

Ugh- Lost oil pressure - the bane of racers everywhere!

Yeah, bit worrying, it was the oil filter which came unscrewed, second time it's happened. Need to make a clamp to hold filter in place.

Do you have a blog or a team web page?

Sorry, nothing like that. Racing and fixing takes far too much family time as it is!


Quick question Brent, I can only view the run time in the current power up, correct? It would be nice to see what revs it was pulling.
We'd be interested in helping out with the beta testing of the race capture unit when its ready if you need noisy bumpy applications.

Cheers for your help and support.