Cuts off at Times

[SpecM]

OK, so... Replaced the CPS, still happens. Getting Code 1261 Fuel Pump Relay still

Greg: tested TPS, checked out good

[SpecM]

a fancy scan tool says:

code 3 : EKP relay (fuel pump relay I think)
code 15: check engine light malf (what?)

[jlevie]

You may have a problem similar to one I had on my first Spec E30. For over a year I chased an intermittent problem. In the course of hunting for a fix every part of the fuel and engine management system (and even the engine) was replaced at least once with new or known good parts. In the end the third used engine engine harness was the fix. Then a couple of years later that harness developed a fault in the wiring for the gauge and ETC sensors. The first two harnesses had damage to the coax that carries the CPS signal to the DME, age mostly. There is a new OE harness in the car now.

But check the fuel pump relay socket connectors and do a resistance check from the DME connector to the relay and a check of the relay coil power circuit. While watching the meter, wiggle the wires to the socket. If you see more than a few tenths of an ohm, the connector is bad or or there is a harness fault.

If you don't find problems with the wiring to the relay socket, try a known good DME. If that doesn't help replace the engine harness.

[SpecM]

grabbed a used 173 DME local

and...

its not cutting out anymore!

I had put on my used AFM (which the PO had tinkered with) and it was running a bit rich, so I put my other AFM back in. Now it does something new: when slowing down in gear from a higher rpm WOT pull, the CEL will blink and the engine power will dip oh-so-slightly, but not nearly the same way. Its not cutting out, just a tiny blip.

And my rear brakes started sqeeking :(

[jlevie]

What fault code is stored in the DME now?

[SpecM]

ok: new set of symptoms! It does not cut off randomly anymore, but it will still loose power and have a CEL when cold. it is now very hard to start, when it does it spits and sputters, and I have to hold the throttle for 10 seconds or so until it passes. it then idles fine (or as well as a cold m20 will). it will then lack power and the CEL will come on between shifts (when I let off the throttle) for just a couple minutes, only for one acceleration. once I get to speed its OK and once the engine warms up its OK.

The way it runs when first started sounds like a misfire, but feels like a fuel issue. The way it runs when cold seems to be an enrichment issue also. The code is 1261 'Fuel Pump Relay' still.

Two questons: where does the fuel pump relay control circuit get power from? and under what conditions will the DME open the ground?

[SpecM]

now that my car has cooled down, I tried again. I jumps pins 30 and 87 on the fuel pump relay socket. fuel pump came on, car still had trouble starting and spit and sputtered. once running, it leaves a big puff of smoke and runs rich as hell.

I will test the CTS and circuit next, but why the 1261 code?

[SpecM]

issues are back LOL

same symptoms as this guy: http://www.r3vlimited.com/board/showthread.php?t=274348

[SpecM]

what is the third wire in the CPS harness for? I only see two in the wiring diagrams

[jlevie]

The CPS cable is two shielded signal wires with the shields connected.

[SpecM]

Good so I can back-probe a lapscope to the two CPS wires at the DME and have a tech ride shotgun to check timing input.

The issue is most pronounced when I release the accelerator from high rpm / high load, ie when engine braking or upshifting.

Sent from my Vortex using Tapatalk 2

[SpecM]

The first two harnesses had damage to the coax that carries the CPS signal to the DME, age mostly. There is a new OE harness in the car now... ...If that doesn't help replace the engine harness

is it possable that the signal to the DME would only be corrupted when the rpms are dropping? the issue only occurs when I let off the throttle

and how did you get a harness? my dealer told be they are NLA. are they made-to-order?

are there any other issues that will cause the fuel pump relay control circuit to open?

[jlevie]

The harness has to come from Germany, but they are definitely not NLA. It took a bit over a week for it to come in at my dealer.

[SpecM]

both the dealer and Blunt tell me that I cannot get one

I am now convenced that the issue is in the CPS signal to the DME. It is having the exact issues you describe in your "man vs car" rant. But I fear that another used harness will have the same or other issues, as you experianced in your Spec racecar

Is it possible to repair just the CPS wires? Is it a true coax, like for audio equipment? Or can I build my own and run an overlay harness? I'm pretty handy with electrical stuff

[jlevie]

If the harness has gone NLA, that has happened in the last 9 months. I'd have to check with my dealer to find out.

It is possible to repair a harness. You take it out of the car split it open and critically examine every wire, repairing as necessary.