AO

Bosch does not actively promote the older sparkplugs. If you search the web, you should be able to find someone who carries them still.

I know on the GT's the Bosch copper is called a "Super PLUS" Part# WR7DTC. Not sure about the GTS's, but I know you can get them in a colder temp range like WR6DTC which may be what Ken was referring to.

928ntslow

Andrew...I get the idea, but my car is a 5 spd.

I didn't have time today other than to by-pass the temp II sensor and try to start it up.

I am sure I will get it figured out...just later than sooner.

GTS=Got To Start!

John Speake

Short across the injectors ?

AO

D'Oh! Sorry... thought it was an auto. Do you have spark?

dr bob

Keith--

I'm not sure that shorting the two temp sensor II leads together will do anything for you. Two thermistors in the housing reference independently to ground, one to each terminal. Verify that they are in range with an ohm meter to ground.

I'm on a project away from home and the manuals. I posted a note describing a quick-and-easy test for diagnosing shorted injector wiring via the ignition protection relay socket on the brain bracket. Search is your friend. I think the target was a car that PorKen was working on at the time, but a few others chimed in as they were chasing similar problems. A stray ground in the engine harness can kill the motor; isolating the fault to one ignition side can allow the car to run on four cylinders, but that can't happen with the ignition protection relay in place.

Back to work...

928ntslow

I just got a chance today to do some more diagnosing.

I checked the injector plugs...this is what I did:

With the battery disconnected, the EZK and LH disconnected, I had unplugged all 8 injector plugs. FWIW, I removed the fuel pump, LH and ignition relays from the panel as well.

I checked continuity across the plugs and from each plug pin to ground.

Cylinders 1-4
-all plugs show continuity across the plug from pin to pin
-both pins per plug show continuity to ground

Cylinders 5-8
-all plugs show NO continuity across the plug from pin to pin
-only one pin (consistent with all...left pin I believe) per plug shows continuity
to ground

I then disconnected the double relay with the red and green led light under the ECU's and checked all 8 plugs again. NONE of them have continuity across the plug and neither pin of each plug has continuity to ground.

First thought might be the relay, but I think the relay just breaks the connection to the LH.

Remember, I checked the EZK and the LH separately in another 1993 GTS and that car started and ran fine.

Not sure if it is important, but I have an X in place of a cat. I know some guys jumper this double relay, but I don't think this is the problem.

In light of the above, it seems to me that a short at one of the injector plugs is NOT the issue.

What is the next thing I should check at this point? It seems I might be on track to where the issue is emanating from.

Thanks for the help!

ADDED: You know, it's kinda weird, because after looking at the flow chart, all of the grounds on the injectors are connected. So it would seem that injectors 1-4 would be consistent with whats happening with 5-8.

John Speake

Hi Keith
The measurements with the protection relay in circuit don't seem right.

In the Tech Info for MY89 it is clear the relay connects 1,4,6,7 with one set of contacts and 2,3,5,8 with another set of relay contacts to +12v. when exhaust sensor temps are equal.

There is no indication that when not energised that a short circuit to ground is caused.

You could try linking terminal 87 to A1 and also 87 to A2 on the relay base and repeat your measurements to make sure there is no ground connection introduced. (be careful not to mistake the terminal "AL " with A1...)

If you are clear of shorts to ground with those links in place, reconnect LH and EZK and try to start the car.

928ntslow

Thanks John

You are correct in that 87 to A1 connects 1,4,6,7 and A2 connects 2,3,5,8

I checked all 8 plugs starting with 87 to A1. No shorts across the plugs, but one side of plug showed continuity to ground...being each of the 1,4,6,7.

I then checked 87 to A2. No shorts across the plugs, but one side of plug showed continuity to ground...being each of the 2,3,5,8.

So out of all 8 plugs, no continuity across, but all showed continuity to ground on one side of plug....of course all pins showing continuity were consistent to the same side of the plugs

I think this tells me there is a short before the double relay...correct? If so, where to next?


ADDED: I just looked at the CF chart. It seems the "+" side of the injector plugs are grounding out. So in following that to what feeds pin 87 is the relay XXV (which has been removed, so we can rule that out), the Mass Airflow Sensor and the Tank Vent which leads back to the MFI control unit. I think it was mentioned that this could be a MAF issue. How would I check these?

ADDED#2: Just pulled the plugs on the "tank Vent" and the "Shift Valve Resonance Flap (Flappy)" with no changes in continuity from the above procedure. However and not sure if it means anything, I pullled the plug on the Mass Air Flow Sensor and the "ground" went away. Have I a fried MAF???

Bill Ball

Keith:

You might try to open up the MAF plug boot and see if the brown wire shorted to the black one. If not, then do a MAF swap.

John Speake

Hi
I just did an ohms test on a MAF here pin 2 to 3&4) , it measures over 1Meg ohm to ground..... looks like you may be nearing the source of the problem.

As Bill suggested, peel back the boot on the the 6 wy MAF connector to check for shorts.

If OK, check the pins on the MAF, the numbers are molded into the MAF connector.

928ntslow

F i n a l l y got the chance to do a bit more investigation. I swapped out the MAF and that didn't make a difference. Checked for spark and it is strong. Checked the cam timing, belt tension and that is AOK. I did not check the MAF plug yet though.

So rather than repeat all the other things I had traced, just look through the previous pages. I've been around the car and STILL no luck.

It was mentioned before about the alarm system. I had previously checked for voltage at the ignition relay terminal with the key in the #2 position and it had 12v's. I did have a brief thought but forgot about doing this until it was mentioned on the PacNW board. I should try the key in both door locks and see if that does anything. Unfortunately, it made no difference.

HOWEVER, (again) I think I may be onto something. The GTS's have LED lights in the posts. I didn't notice at first that the LED's were flashing quicker than normal. I found this out when I was turning the key back and forth. When I turned the key to unlock the passenger door and then turned it back to lock it, there was a noticeable difference in the LED flash...it was much slower. This is how it should be under normal circumstances.

I would think that if possible, the thing to do is by-pass or disconnect the alarm system to see if this "might" be the issue. (God, please!)

Thoughts?

IcemanG17

Keith
After all the checking you have done and things you fixed (fuel)...it has to be the alarm...thats the last thing I can think of??? Since my 88 doesn't have one, I don't know how to disconnect-bypass it...but I'm sure Alan or someone on here has BTDT

RyanPerrella

Interesting, is the current thought that there is an immobilizer at work here?

Do these cars have that function? Or am i misunderstanding what your after here?

AO

Keith, the LED flash rapidly for the first 30 or 60 seconds then go to the slow steady state. Sorry, but it sounds normal.

SO you have spark.... that's good. It eliminates a lot of possibilities. You need to focus on fuel delivery.

You have fuel pressure, so that leaves injectors. I would bet dollars to donuts that if you put a noid light on one of your injectors, it would show they are not firing.

I believe you said you swapped the LH, so go back and jumper all the realvant relays - remember that you need a 3-way for one of the relays - LH I think.

ACG

Keith, sorry to hear about your troubles. I am a 928 newbie and can't help you... hope you can figure it out in time and see you soon on the Portland streets.