Help please, DME/KLR problem

[951Boost]

Howdy all. I could really use some help trying to solve this problem as I’ve run out of ideas and reached the end of my troubleshooting skills.

A bit of background;

Car is an ’89 all stock except for gutted cat, LBE and ZT-2 wideband and until this issue started was running great. Had just logged over 300 miles the previous w/e, including a few laps at the track.

Maybe just a coincidence but the problem started after I installed a blink code test LED and one set of my backup DME/KLR boxes with just purchased aftermarket chips.

Let’s assume that I have sufficient common knowledge not to make the usual mistakes of making lousy solder joints, connecting +/- wires without a load in between, took proper measures to avoid static discharges and can correctly install a chip in it’s socket.

So this is what I did;

1) Disconnected battery, Installed LED, reconnected batt, started car, all ok.

2) Disconnected TPS, checked for codes (got 4-1, so that was good), shut car off.

3) Reconnected TPS, restarted car, all ok.

4) Disconnected batt. again and installed DME/KLR boxes with aftermarket chips, reconnected batt. Car started and idled fine until it reached normal operating temp (1st mark on gauge) at which point the idle abruptly dropped and then went back to normal (not a gradual or “hunting” drop/raise like an ISV issue, it dropped about 400 rpms at once and almost stalled, then went back to normal). This was repeated about 3/4 times within a 30 sec. time frame until the car finally stalled.

I took about 30 mins. to answer a phone call (engine cooled off), I then restarted it and ran fine until it again reached normal operating temp. at which point the above symptoms were repeated and it died again.

Troubleshooting;

1) Waited about 20 mins. Visually inspected the connection at the NTCII temp sensor and it looked ok. Restarted it and ran fine until again reached normal operating temp. at which point the above symptoms were repeated and it died.

2) Switched KLR to original unit that I had just removed from the car, IT WOULD NOW CRANK BUT NOT START. So now things are going from bad to worse. I started to suspect a bad connection between the KLR and DME.

3) Switched DME to original unit (at this point I was using the original DME/KLR units that I had just removed from the car about an hour before, and had no issues). Would crank but not start.

4) Installed my second backup DME/KLR. Would crank but not start.

5) I then tried all DME/KLR’s with each other, i.e. DME 1 with KLR 1, 2, 3. Then DME 2 with KLR 1, 2, 3 etc. etc. Would crank but not start.

6) I then tried ALL the DME’s with the bypassed KLR by jumping pins 9/16 at the KLR connector. Car started, idled and ran fine with all of them. It reached normal operating temperature and continued to run fine. AFR at idle and during short drives was correct.

I stopped troubleshooting since I didn’t have a multimeter or test lights with me. So at this point it looked like I had 3 good DME’s and 3 bad KLR’s??? That seems too weird.

As an embarrassing note, the only really known good DME/KLR’s were the ones originally installed in the car. My two sets of backups (including the ones I installed the aftermarket chips in) were untested by me. I bought these from trustworthy individuals that assured me they had no issues. Pretty dumb on my part I know, it would have been nice to know that these units were ok ahead of time, but being that I don’t have a lot of free time and considering the sources, doing this got filed in the “to do someday” category.


Fast forward to the following weekend and my next attempt at troubleshooting;

1) NTCII temp sensor, tested from DME pin 13 and also at sensor. Marginal, readings are off when cold but close when warm. Also tested wire for shorts/breaks/resistance, it tested fine. Using bypassed KLR; car ran super rich at startup and would not idle. It was about 35*, much colder than during my first test session the previous weekend, after the day warmed up to around 60* it started, idled and ran fine. I then installed one of the KLR’s and it would not start at all, I then tried the two other KLR’s and it still would not start. I bypassed the KLR again and it ran fine.

I can’t see how a bad NTCII temp sensor would cause the car to not start with the KLR installed yet run fine with it bypassed (got a replacement sensor on the way).

2) Still suspecting a bad connection between the KLR and DME I checked the following KLR pins, which I thought were relevant to this issue;
#6, (to general ground) Battery voltage with ignition on (power to KLR).
#9, to DME #21, .6 ohms
#14, 0 to 1 ohms (ground)
#16, to DME #32, .6 ohms
#20, 0 to 1 ohms (ground)
#24, to DME #31, .6 ohms

Well I guess those test out ok?

3) Using the Porsche workshop manual I conducted the following tests;

a) Test point 2; checked voltage between DME pins 35/5. Result, batt.voltage with ignition on. KLR pin 6 to pin 14, result, batt. voltage with ignition on.

b) Test point 9; TPS, performed all tests except “cut-off”. All were within specs.

c) Test point 10; as mentioned above (#1) some issues with sensor so I have a new one on the way.


4) Disassembled DME shell/plug and visually inspected pins/wires in the back; no obvious issues. Still can’t figure out how or even if it’s possible to disassemble the KLR shell/plug to inspect the wires. Please see my other thread >>LINK<< about this.

5) Checked pins from back of KLR (all three units) to PCB, and from ribbon cables to PCB. They tested ok. Also looked over PCB’s with a magnifying glass for anything obvious and they seem OK.

I don’t own an O scope so I can’t perform some of the more esoteric tests, I guess if it’s really necessary I could try and buy a used one (and learn how to use it).

I would like to start a list of other tests to do or things to try next w/e since I don’t have access to my car during the week.

Any suggestions would be greatly appreciated.

Thanks in advance.

[soxnail]

Lets break this down into smaller parts..
First lets fix the no start with a klr in problem. Then we can look at the temp related weirdness.
First I am surprised that the car starts with KLR 9 jumped to 16 ?? (but the klr is a mystery to me right now, I am working on it) It should be pin 24 to pin 16 klr...
Any way I think the resistance tests you have done are probably not real relevant at this point. (sorry). What you need to test is
a) Disconnect both dme and klr
1) test that the pins 9,16,24 on the klr connector (harness side) are high resistance relative to car gnd.
2) test that the above pins are not shorted to each other.

b) Connect the dme and test the resistance of as in step 1 and 2 above.

c) disconnect the dme and connect the klr and repeat 1 and 2 above.

d) not esential but you can repeat the above step c with all your klrs.
Post results.
we will go from there
Sox

[951Boost]

Hi Sox, thanks for the help.

Just want to double check about pin 9 and 16 at the KLR, according to the PWM;




So this is OK?

I will do the tests this weekend as per your instructions.

I realize troubleshooting needs to be done in order but if you can add a few more steps to check it would be great. I only have access to my car during the weekend and no access to the internet during that time.

Thanks again for taking the time to help me with this.

[soxnail]

Yup I stand corrected it is indeed 9 to 16...
I will add some more steps. Let me think about it
Sox

[soxnail]

sorry everything I can think of needs to start with known good on the klr connector wires...
If you have a phone on the week end that you are trouble shooting pm me the number and we can do some of it over the phone.
Sox

[951Boost]

ThanX Sox, I'll PM you my phone #. I'll get started with what you suggested first thing on Saturday.

[soxnail]

Will call you Saturday (at a civilized time).
Sox

[951Boost]

Thank you Sir, PM sent.

[951Boost]

OK here we go

1) test that the pins 9,16,24 on the klr connector (harness side) are high resistance relative to car gnd.
Tested from KLR harness plug pins to good car ground; All pins meassured infinite ∞

2) test that the above pins are not shorted to each other.

No shorts/continuity.

b) Connect the dme and test the resistance of as in step 1 and 2 above.

DME #1- Pin 9, infinite ∞. Pin 16, 14.25k. Pin 24, infinite ∞.

DME #2- Pin 9, infinite ∞. Pin 16, 14.10k. Pin 24, infinite ∞.

DME #3- Pin 9, infinite ∞. Pin 16, 13.99k. Pin 24, infinite ∞.

c) disconnect the dme and connect the klr and repeat 1 and 2 above.

Well here I got a little confused. Being that the KLR needed to be connected to the harness plug for this test I stripped a bit of insulation from the wires (that had continuity to pin 9) to get a clean reading. My area of confusion here is pin 9. According to the '89 wiring diagram there are two wires that connect to that pin. They should be a 1mm GN wire and a 1mm GN/YE wire. Found the 1mm GN/YE wire but the only other wire that had continuity to this pin was a thick (maybe 4mm) GN wire, upon stripping the isulation it appeared to be a braided wire. So when meassuring for this pin I meassured those two wires.

KLR #1- Pin 9 thin wire 1.5ohm, thick wire .1ohm. Pin 16, 6.21K. Pin 24, 103K.

No shorts/continuity between those wires (other than the two wires on pin 9 to each other).

d) not esential but you can repeat the above step c with all your klrs.

KLR #2- Pin 9 thin wire .7ohm, thick wire .1ohm. Pin 16, 6.20K. Pin 24, 102.6K.

KLR #3- Pin 9 thin wire .7ohm, thick wire .1ohm. Pin 16, 6.20K. Pin 24, 102.9K.

No shorts/continuity between those wires (other than the two wires on pin 9 to each other).

Also since I was "down there" I tested full AFM function and NTC I (AFM Temp. sender), (PWM Test point 6) All readings were within acceptable range.

Also since I was STILL "down there" I jumpered the NTCII plug and measured for resistance (DME pin 13 & ground). Also checked for shorts/continuity. No issues found.

Post results.

[soxnail]

Ok so did the surgery on the the ign cable work ?
Sox

[951Boost]

Originally Posted by soxnail

Ok so did the surgery on the the ign cable work ?
Sox

Hey my friend it worked like a charm! SHE'S ALIVE!!!

Car started right up with the KLR installed, hit normal operating temp and kept purring like a kitten. I'm sooooo Happy!

Anyway pretty tired right now, I'll update the thread tomorrow with some pics and details.

Sox, thanks so much for helping me with this. You are a Wizard!!!

If you are ever around this neck of the woods let me know, love to buy you a few of these;

[soxnail]

Cool
Sox

[951Boost]

Well thanks to Mr. Sox I was able to solve my no start problem.

The issue turned out to be the wire from Pin 9 at KLR to Pin 21 at DME. It had a break/short between the shielding and the main conductor.

When I first got the car it had a NB gauge that had been installed by the PO. Seems like since he needed to find the O2 sensor wire to the DME the idiot cut into the insulation of every shielded wire in the DME and KLR harnesses until he found the right one.

I guess when I started playing around with the DME & KLR wiring it made the break/short worse.

When I rechecked Pin 21 at the DME connector for proper resistance per Sox’s instructions I could see the multimeter values fluctuating wildly. I couldn’t pinpoint exactly where the issue was in the wire (the PO had hacked this wire in three different places) but I narrowed it down to a 8” area.

THE FIX;

I cut off the entire 8” piece and replaced it with a new wire for the center conductor (GN in the pics) and a separate wire (BK in the pics) to connect the shielding together. I purposely left three butt splices bare in the shield wire so that I could add an aluminum foil shield (good HD aluminum foil from the grocery store folded over itself about 4 times to created a sturdy shield) over the main conductor (Sox’s idea).








All connections were crimped AND soldered, shrink tubed or taped with self-vulcanizing tape. I specially made sure that I had good contact between the foil and the butt connectors.

Finally I checked the foil to KLR pin 10 resistance (shield ground) and it was .1 ohm.

So this fix along with the replaced NTCII sensor seems to have taken care of the problems.

Can’t thank Sox enough for his help with this.

Now to put some miles on her and test that new Maxtronic/Maxbooster setup before she gets tucked in for the winter.

[soxnail]

Don't you just love a happy ending
Sox

[951Boost]

Originally Posted by soxnail

Don't you just love a happy ending
Sox

A happy ending thanks to you Sir.

[soxnail]

You are most welcome my amigo. Now quit embarrassing me LoL
Sox

[nize]

this is great. i love the thorough follow-up.

[951Boost]

Thanks nize. I figured it might help others in the future.

What's been going on with your car? I followed your turbo update thread very closely (loved the thoroughness of it) as that is the direction I want to go with my turbo replacement (same specs).

Did you and your friend ever dyno the cars?

[nize]

the tuning is still ongoing. initial dyno on incomplete tune resulted in 320whp/wtq.

my friend's car went through a complete motor rebuild, and we just got it all back together. he's waiting on a MAF setup before putting it on the dyno with the new turbo.

i actually have an update for the turbo thread regarding the lindsey j-boot adapter, as i've had to mod it to insure smooth air flow. the inside pipe is a bit too long and creates an obstruction. i'll post up some pics and update the thread later this week, or maybe this weekend.

[wpetrozelli]

Can someone tell me where the KLR gets it's 12 volt power? I thought it was pin 6 but since I don't have 12 volts from pin 6 to ground with the key on I am having trouble. This black and yellow wire is broken in engine bay but I cannot find the other end.