I've just about had it

ace_944 · 02-22-2011, 10:57 AM

Ok i've been having no tach bounce for awhile and am having one hell of a time trying to figure it out. The sensors are adjusted correctly the wires are fine my new DME isn't fried what the hell could it be? I'm going through and double checking my grounds right now and haven't seen anything so far. My main question is what can effect the wires resistance readings? Im getting 156 kilohms from both test spots on one and 33 kilohms/ 1 mega ohm on the other. If i cant figure this out within the next week im giving up on this car its to much BS to put up with.

kfray · kfray's Garage

It is not clear what test you are running, I do not want you to give up on you car.
What year and model is your car. What test are you running. What parts have you changed.
Have you checked the DME relay.

ace_944 · 02-22-2011, 01:22 PM

My cars a 87 944 n/a im talking about the test you use check the resistance at the connectors that you plug the ref/spd sensors into. And ive changed lots of parts on this car the ones im thinking it has to involve is either the dme wire harness or something more wired in towards the fuse box. Is there anything other than the wires or the dme itself that would effect these readings? Right now im looking through the DME wire harness to see if theres any wires that are fried kinda leaning towards the possabilty that the ground connections on the harness where all the smaller grounds come into one big ground could be bad.

AKCJ · 02-22-2011, 01:46 PM

It sounds as if you're testing the resistance wires that the speed & reference sensors plug in to. I haven't heard of this test but I don't know much about the electronics end of things. I have heard that you can ohm the sensors themselves as a partial test of the sensor but that it's not a for sure thing.

Seems like you may have to get a new sensor?

Could it be a bad ignition switch?

John_AZ · 02-22-2011, 02:01 PM

ace,
Are you sure the new to you DME computer is OK? I saw your thread on WTB and is it possible that the used DME may have issues?

If you are certain, here is a DME connector terminal diagram that may help from S ECU Repair on post 5.

No Injector Pulse

GL
John

ace_944 · 02-22-2011, 03:30 PM

They have the procedure on clarks and the sensors are new though i should pop them out and take a look at them but the readings are whats throwing me off.

kfray · kfray's Garage

Can you point to the test you are running.

bell · bell's Garage

where are you at? i have a slick tester at our shop which reads realtime what is going into/coming from the dme.......

ace_944 · 02-23-2011, 05:13 AM

Im doing the sensor resistance check. IGN-02, Speed and Reference Sensors - Checking, Replacement, and Adjustment

minho78 · minho78's Garage

Go with the basics.
Do you have fuel pressure at the rail?
Do you have spark?
If you don't have one of those your car won't start.

As for the tach bounce I looked at mine a couple of times and it never bounces. Sensors are new.

kfray · kfray's Garage

Quote:

Originally Posted by ace_944

I'm doing the sensor resistance check. IGN-02, Speed and Reference Sensors - Checking, Replacement, and Adjustment

Just to be clear you have disconnected the speed and reference sensors at the back of the engine and you are taking measurements at the sensor connectors not the engine harness connectors. Is that correct?
Do not give up reload!

ace_944 · 02-23-2011, 07:27 AM

I'm taking them from the female side of the connector not the sensors themselves. Don't tell me its the other way around, even then i got no readings from the sensors and they're new.

kfray · kfray's Garage

Quote:

Originally Posted by ace_944

I'm taking them from the female side of the connector not the sensors themselves. Don't tell me its the other way around, even then i got no readings from the sensors and they're new.

The readings are for the male sensor connectors not the female engine harness connectors. Granted the diagram shows the female connectors at the back of the
block. Take the sensor connector readings again keeping in mind the pin diagram is for the female connector, you need to reverse the pin #s to read the male sensor connector pins.
This should help.

ace_944 · 02-23-2011, 08:25 AM

Tested the sensor one reading comes to within spec but the other reads O.L. not 1 megaohm that seem right? And if it is what test should i run for the other end, harness side? Or what else could be causing no tach bounce? could the igniton switch be the problem?

kfray · kfray's Garage

Quote:

Originally Posted by ace_944

Tested the sensor one reading comes to within spec but the other reads O.L. not 1 megohm that seem right? And if it is what test should i run for the other end, harness side? Or what else could be causing no tach bounce? could the ignition switch be the problem?

These readings are good. The O.L. indicates higher resistance then the meter scale you had selected, switch the meter to the highest resistance scale.

The connectors at the block are prone to failure with age.
Check for continuity from the connectors to the ECU/DME Computer connector.
With reference to the connector drawing in ING=02
pin 25 to ECU connector pin 25
pin 26 to ECU connector pin 26
pin 78 to ECU connector pin 5
pin 27 to ECU connector pin 27
pin 8 to ECU connector pin 8
pin 23 to ECU connector pin 23

Have you perform the DME checks?
http://www.clarks-garage.com/pdf-manual/fuel-05.pdf

Pin 86 of the DME Relay is connected to the Ignition switch Switch. If you have a alarm system jumper it out.
http://www.clarks-garage.com/pdf-manual/elect-23.pdf
Do not give up reload!

ace_944 · 10:48 AM

Alarm system has been jumped out for awhile, wires all check out on dme harness. I'm guessing i messed something up when i pulled the fuse box out. Gonna pull it again and see what went wrong. Was hoping it wouldnt have anything to do with that but im guessing a old brittle wire probably snapped when i was pulling it out or putting it back in. But again im wondering what would cause >>>no tach bounce<<< thats the only reason why i havent moved on looking for no spark or something like that. This problem was going on before i pulled the fuse box, but it wasnt the reason i pulled it.

kfray · kfray's Garage

Have you perform the DME Relay checks?
http://www.clarks-garage.com/pdf-manual/fuel-05.pdf

Pin 86 of the DME Relay is connected to the Ignition switch Switch.
http://www.clarks-garage.com/pdf-manual/elect-23.pdf
Do not give up reload!

bug · 02-24-2011, 02:08 PM

Your DME could be faulty, some fail unexpectedly and intermittently often causing expierienced mechanics to replace parts willy nilly.

ace_944 · 02-25-2011, 08:43 AM

OK in the process of taking my car apart i saw that there is a small connector that goes right next to the ignition switch assembly it has 2 wires one green and one red i also saw that unlike most connectors on these cars you can install it the wrong way theres no kind of key so which wire should go where? And if installed incorrectly could it be the cause of all my problems?

kfray · kfray's Garage

Do you know what this connector connects to?
Are the wires solid or two colors?