Ricardo Vega

Hey guys, was wondering if anyone can help me to see how I test my CPS on 1987 928 S4?
Been having idling issues, black smoke and I already replaced MAF. Read up on a few postings that some have had the same issues on having and the replacement of CPS helped.
I've searched on how to test bu only seen a few that have tested on a tool with an LCD screen that shows oscillations.
So my question is can I or can't not test it with a multi-meter? And if yes, how do I test it out?

Thanks

Ricardo Vega
1987 Black/Plum 928 S4
125,xxx miles.

SeanR

If it's not new, replace it so you don't have to worry about it for 15 years. A multimeter will not be able to tell you anything.

Ricardo Vega

Cool, thanks for quick reply.

RV

Wisconsin Joe

Actually, a meter will tell you something.

There are three connections in the plug. One is for the shielding on the cable. The other two are for the sensor.

If you put the meter on "ohms" it will show resistance across two of the posts. If you pass a piece of steel over the end of the sensor, the resistance will change (I forget the exact values). There are "sensor testers" out there that do essentially the same thing.

BUT...

I had an intermittently bad sensor. The car would randomly stall or not start. It worked with both the meter and sensor tester. Replacing it fixed all the starting issues.

G8RB8

^^^That will give you unreliable information. Personally I would rather have no information than unreliable information.

worf928

This ---^

because of this ---\/

To answer the original question: the best way to test CPS operation is with an O'scope at the back of the EZK connector.

Ricardo Vega

OK, thank you guys for insight. I just logged into forum and have already order new CPS. Will be here on Friday.
Is there anything unique I need to do when I install it? Like have a certain position engine should be se at or anything else I should be aware of?
Thanks.
RV

davek9

No alignment required, just swap it out.
May want to start soaking hex head bolt and the body in the block seat as some are hard to get out.

Dave k

siscogts

The only thing i can tell it's that cps is a pita to remove,after many years... As suggested before, acetone-atf fluid mix is the only stuff that penetrated between bell recess and cps in my car, so i removed the sensor with no big problems...

Ricardo Vega

Awesome, I've already sprayed it with a bolt remover can, will spray again tonight again. I get part in tomorrow. I'm hoping that is my problem. Car has been acting up. Changed out MAF already. Thank you all!

RVII

ROG100

New crank position sensors $78

Kevin in Atlanta

MrMerlin recommends using mechanics wire under CPS connector and a wood dowel to pull the CPS straight up. I've had good results using that method.

fraggle

I used the wire method, but tied it around a hammer with some mass so I could apply some impulses, like hammering it in reverse.

Ricardo Vega

Hey guys, thanks for all feedback and just to give some updating and feedback on my newly installed CPS. That didn't fix my issue at all, if anything now its worse than before! Kinda odd.
So to give you all my initial issue, car would rev high and low(I guess hunting) after I would drive I drove it for a while. I did end up ordering a new MAF from Louie Ott. Installed and that wasn't the issue.
So I cleaned up all grounds, or most of them and nothing new.
I just installed CPS on Sunday and now car dies on right away, I need to press gas to keep it going. Sometimes I press gas all the way down and car hesitates just limping along till it kicks in with power. If I coast it and pull off gas it dies. If I start it without pressing on gas it dies. I have to press gas even at a stop while I have my foot on brake pedal. Any suggestions? I have checked the flex plate already. I check it every 6 months.

RVII

G8RB8

Check for vacuum leaks to start. Make sure the quadrant is properly adjusted.