EA81 supercharger revamp by Tweety

steptoe · Post by **steptoe** » Sun Sep 15, 2013 10:08 pm

Just as well I wasn't there to screw things up

Subydoug · Post by **Subydoug** » Sun Sep 15, 2013 10:25 pm

For future reference jonno, If its a signal, and you want to drive it, best to be on the safe side and pull it high thru a high ish value resistor

.

Doug

Tweety · Post by **Tweety** » Mon Sep 16, 2013 6:32 am

As I said to Greg, all this is quite confusing to me. I'm not electronic savvy. But I'll take it one step at a time. I'll get the multi meter today

steptoe · Post by **steptoe** » Mon Sep 16, 2013 7:46 am

ah, this is electronics, not just plain electrics

So, the ECU just uses the change in Volts as a signal -of course ! It does not need it as power to power anything as such. So, if I put a resistor in, 5V might still get through, but would not power a 5V light bulb brightly then Doug?

I have had to something simiar with 12V to feed back to a cruise control for a clutch switch , thought 12V pos may have zapped something but was advised it would be fine and was for years !
Stick with it Tony, you will learn something as a start!

Subydoug · Post by **Subydoug** » Mon Sep 16, 2013 9:20 am

The resistor is only to limit current. Its sole reason of being is to stop electronics from letting out the magic smoke. Il explain how it works for you steptoe. Remember our friend Ohms law? V = IR, or voltage = current x resistance.

So, say the ECU can only tollerate 40ma at 5v into its input. We go to out law,
V=IR
in this case, V=5v, I=0.040A and R=X ohms

rearrange it to,
R=V/I
R = 5/0.040
R =125 ohm.

So that input to the ECU would need at least a 125 ohm resistor in series with the signal.

Back to Tweety, I dare say that Subaru put protection front end inside the ECU's, but for a few cents its best to be on the safe side

.

Sorry Tony, little bit off topic, keenly waiting to hear how the new MAF sensor goes

Regards

Doug

Tweety · Post by **Tweety** » Mon Sep 16, 2013 6:19 pm

Yeh Doug, bought the Multi meter $34 at Jaycar not bad price. Cold and raining here. Tomorrow. Been up since 4am. Will inform.

Now what do I do again? oh yeh, have printed it out. lol

I was telling Tambox that I commenced a radio tech course in the RAAF in 1973 (I know I sound and look younger lol) and got to month 2 out of 11 then failed the course. As soon as we got to capacitors and what they do and dont do- that was the end of my tech course.

So I am proficient at using a test lamp...and making bird crap with an arc welder.

tambox · Post by **tambox** » Mon Sep 16, 2013 6:52 pm

You forgot to mention you are the world wide expert on SPFI EA81 Trikes, according to most internet links:D

Subydoug · Post by **Subydoug** » Mon Sep 16, 2013 8:02 pm

Awesome Tweety, Perfect multimeter to have for someone like you. I was lucky because my boss got me a fluke meter for work

.

This thread has some interesting things about testing the TPS.

http://www.ultimatesubaru.org/forum/top ... last-page/

Regards

Doug

Tweety · Post by **Tweety** » Mon Sep 16, 2013 9:08 pm

That was a great read. Similar symptoms to mine. really good Doug.

Will test tomorrow and read up on the procedure.

Tweety · Post by **Tweety** » Mon Sep 16, 2013 10:09 pm

pictures help.

http://www.autozone.com/autozone/repair ... 5280066fb8

Subydoug · Post by **Subydoug** » Tue Sep 17, 2013 9:18 am

Nice find Tweety, So the SPFI TPS is partly a variable resistor. Very cool.

Doug

Tweety · Post by **Tweety** » Tue Sep 17, 2013 11:58 am

Ok, got a few issues including the engine not starting now but more on that later.

The SPFI TPS test has been completed. I'll try to simplify this as bes tI can. There is a problem.

According to the detailed test this was done as per proceedure.

Step1/ Checking continuity between terminals A and B

action- checked and ok.

Step2/ Check for continuity after inserting a thickness gauge between the stopper screw and stopper. Using an ohmmeter, check that continuity exists between terminals A and B, when the throttle is fully closed, and that no continuity exists when the throttle is fully opened.

action- checked and ok

Step3/ Insert a feeler gauge (thickness gauge) of 0.0122 in. (0.31mm) between the stopper screw on the throttle chamber and the stopper (this corresponds to the throttle opening of 1.0 degree). Ensure that continuity exists between terminals A and B.

Insert a feeler gauge (thickness gauge) of 0.0311 in. (0.79mm) between the stopper screw on the throttle chamber and the stopper (this corresponds to a throttle opening of 2.5 degrees). Ensure that continuity exists between terminals A and B.

result- .31mm feeler ok, .79 feeler not. Adjustment requiredas per instructions which are

" If above specifications are not as specified, loosen the throttle sensor attaching screws, then turn the throttle sensor body until the correct adjustment is obtained."

Step4/ "Throttle Opening Signal"

Check continuity between terminals B and D, then terminals B and C

Using an ohmmeter, measure resistance between terminals B and D, then between B and C (changes with the opening of the throttle valve).

The ohmmeter should read 3.5-6.5 kilo-ohms between terminals B and D.

Result- B and D is 4.7 ohms- ok.

Result- B and C is 0.5 ohms throttle closed- ok (less than 1.0). Throttle fully opened - 4.9-5.1 ohms....far in excess of 2.4 ohms.

Now interesting enough the reading of 2.4 ohms (its suppose to vary with increase and decrease of throttle) occurs at half throttle right where the dead spot begins.

I assume this sensor is RS!

The battery has been on trickle charge. Took it for a test run. The engine certainly started well and idle was nice and not as high when first started as it was previously- good. Got it home and revved it and it misses beyond half throttle!!! bogs down, loses revs.

Then the starter motor strained to turn the engine over. Connect the charger to the battery and it indicates fully charged. Turn ignition on and eCU connectors and find ECU code is 3 long flashes in addition to the 5 quick flashes it normally has for model designation. Check the trouble shooting manual and cant find 30 in the codes but 31 is throttle sensor.

So has adjusting it to achieve the second feeler guage setting upset the sensor for higher revving? Gee....I'm at a loss. opinions? Also posting this on USMB.

Subydoug · Post by **Subydoug** » Tue Sep 17, 2013 2:21 pm

Progress tony!

I suspect your flat spot is a rich spot. I dare say your variable resistor is a bit crusty and warn, so when it finally gets out of part throttle and idle, it thinks its flat out. The ecu then goes, "hmm, maf sensor isn't saying lots of air, tps must be crap!".

This doesn't nessecarily mean the maf sensor is ok, could be bad which might not be helping the situation.

If you set the idle tps positions according to the instructions it's probably not the issue. It would have bad accell enrichment on takeoff if that was the case.

Might be worth giving the associated connectors a spray with some contact cleaner.

Regards

Doug

Tweety · Post by **Tweety** » Tue Sep 17, 2013 6:27 pm

I think the spray on the contacts is worth my time actually.

I've started another thread on USMB http://www.ultimatesubaru.org/forum/top ... nsor-test/

A guy- NARU suggested a number of things. Interesting that with full open throttle the B and D should be MORE THAN 2400 ohms. Mine was 5000. But he said that it should be 80% of B and D = about 3700 in my case.

I noticed that the TPS has a good amount of adjustment. So with WOT I noticed I could adjust the ohms to 3700. Oddly enough when I checked the ohms of B and C it was 300 ohms (previously 500). In effect I got the TPS exactly where it should be.

He also told me to check terminal D it should have 5 volts- it does. ok there

I test rode Tweety and there is an improvement- gets to 110kph now where it struggled to get over 100 before, is smoother and the dead spot is not near as bad- about a 50% improvement in fact if I get that amount is improvement again I'm certain the problem will be solved.

Now I have codes 31 and 35. 31 Naru said was only for an open or shorted TPS and 35 is a canister purge- I dont have anti pollution on my 81 at all (trikes are exempt).

Progress!!!

A concern is that terminal B is suppose to have a good ground. I put the MM across it and there is no resistance. (reads O.L on my MM)

Subydoug · Post by **Subydoug** » Tue Sep 17, 2013 7:50 pm

O.L? put it in Volts mode and measure again, you probably find some voltage there.

Thats awesome man, Tweety's gonna be rolling around pulling all the babes in no time

.

Regards

Doug

steptoe · Post by **steptoe** » Tue Sep 17, 2013 9:40 pm

Especially now he has the elctronic lingo sorted ! Only took him a few days to go from no idea to checkin stuff on his own and reporting back to us !!

Tweety · Post by **Tweety** » Tue Sep 17, 2013 10:12 pm

arhhh yes Jonno, the unknown brings me to my knees until I get into it and realise it isnt that hard. Like anything I've done in life though- I liek to end up with some level of expertise for peace of mind.

I noticed GD on USMB is making SPFI kits for ea series. Maybe old Subie owners will flock to me for info. Could call myself General Bogieman or something lol

I'm now wondering, if I got that ,much improvement whether I should try to adjust the WOT to a lesser ohmage. so I went from 5000 to 3700. 3700 being 80% of that other figure. but say I went down to 3000 (2400 being the minimum). Wonder if it would give a better top end?

Think I'll wait till the MAF's get here. I'll measure the current readings of the MAF then replace it and see what happens.

tambox · Post by **tambox** » Wed Sep 18, 2013 7:56 am

What duty cycle is it running now in top gear?

Tweety · Post by **Tweety** » Wed Sep 18, 2013 9:42 am

mmm. is that where you put the mm onto the wires to the injector? havent done that yet,. havent got those small alligator clips to enable me to clamp the test rods.

gotta wait till I get to a civilized society...

steptoe · Post by **steptoe** » Wed Sep 18, 2013 3:41 pm

i can share one thing with ya Tony, mm is short for millimetre. if ya wanna shorten multimeter, the industry calls 'em dmm for digital multi......

pedant signing off.....