Code 12 Problem - Hard Start

[KINGPIN33]

Well I've been battling this issue along with many others since I've "fixed" the BHG... Its been on-going...almost 2 years now arrr...

Anyhow,

I am getting code 12 with HARD COLD starts, takes 2 cranks to get it going and then it stumbles a bit then all is fine. :1zhelp:

TSRM SAYS:
-------------------------------------------------------------
Diagnosis
-No "NE" or "G" signal to ECU within 2 seconds after engine has been cranked.

Trouble Area
-Distributor, or CPS, circuit
-Distributor or CPS
-Starter signal circuit
-ECU
-------------------------------------------------------------


- I've done the resistance check on the CPS and all checks out
- I even checked the connectors for good contacts on cps etc and have rewired/soldered them.
- I've pretty much ruled out the CSI and its timer switch with restance testing
- I've rechecked the timming and its all good at 10 TDC with the diagnostic box jumped.
- I have new ignition wires and spark plugs.

What else should I be checking? Some people say this code deals with the ignitor, but I see no mention of it in the problem area list unless it falls under the "Start signal circuit category"

-Thanks

 

[Nick M]

The bottom line is the ECU isnt recieving the pickup signal from the CPS due to part failure or wiring.

The other choice is the ECU, which is very rare.

 

[toml]

I have the *exact* same problem since my BHG Rebuild. Code12 after a hard cold start, takes two or three cranks to start it, then it stumbles a little and starts up fine.

I, however, haven't checked my CSI or replaced the ignition wires.

I do have a spare ignitor that I will put in to test.


KINGPIN: Did you do any mods to your engine whilst fixing the BHG?

 

[KINGPIN33]

I have the *exact* same problem since my BHG Rebuild. Code12 after a hard cold start, takes two or three cranks to start it, then it stumbles a little and starts up fine.

I, however, haven't checked my CSI or replaced the ignition wires.

I do have a spare ignitor that I will put in to test.


KINGPIN: Did you do any mods to your engine whilst fixing the BHG?

The only mods I have is the HKS air filter, but that should not affect it at all. I'm going to clear the codes again and make sure I get the same code.

I have a feeling that the stumbling is caused by extra fuel being dumped in the beginning and then when it fires up, it runs very rich. I noticed that if I cranked a lot before it finally starts (the max time limit set by the cold start timer switch to let the CSI spray gas) then I get a very rough start. But as the weather got warmer, it took less cranks and when it finally started it didn't stumble as much as it did before.
BUT IT ALWAYS takes 2 CRANKS to start. I can stick the key into the ingnition then crank it for 2 seconds then shut it off, then try again then after 2-3 seconds it starts with a minor stumble.
I am left to believe that something is not igniting while its cranking possibly the ingiter or coil pack or something.

 

[toml]

I always love your posts jetjock, they're so helpful... but could you just explain the 'air gaps' a little further, or are they in the TSRM somewhere that I could read up on?

I'll grab a scope and muck around measuring the CPS + ECU terminals.

 

[toml]

Thanks again Jetjock.

Can't seem to find anything about the air gaps in the TSRM, but I might be looking in the wrong spot.

Although that probably isn't of great importance since I can just borrow my father's CRO and check the voltage it gives (voltage across NE<->G1 and NE<->G2 I presume?)

 

[KINGPIN33]

Thanks for the replies, I will take a closer look at the CPS this weekend.

I agree I always like his posts too. How else you think I knew about the CSI and cold start timer switch?
- Thanks again

 

[toml]

Yeah, maybe I should just do a search for every post by jetjock and IJ... read all of them and I'd be super knowledgable on the inner-workings of our engines!

 

[toml]

jetjock, if you're still watching, any opinions on the best way to tap the scope into the CPS? Unhooking the CPS connector to chuck the scope probes in didn't seem like a good idea...

 

[Nick M]

With a Fluke.

 

[jetjock]

The best way is to back probe the connector.

 

[toml]

I might have a scope, but that doesn't mean I know how to use it...
I'm assuming "back probe the connector" means sticking the 'scope probes into the back of the connector. I have no idea what a Fluke is...

Am I on the right track?

 

[toml]

After actually playing around with the connector, the only way I can think of getting the 'scope probes on there is to take off the CPS cover and hope that there's exposed contacts in there.

Is this what you meant by 'back probing the connector', jetjock?

 

[toml]

OK, now I can't seem to find any information on _exactly_ what signals the CPS is meant to be giving out, but I can't measure any signal on the G1 and G2 contacts of it, at the ECU connector.

The NE contact seems to be giving a nice steady signal of about 4V peak to peak.

Now my understanding is that without the G1 and G2 signals, the ECU won't be able to run -- correct?

 

[Nick M]

Fluke makes some very nice diagnostic electronic testing tools. They make something called a DSO, which is short for digital storage oscilliscope. That is a hand held version of those big Sun engine analyzer machines, that measures to much more accurate figures. It allows you to graph things like injector pulse duration, a cam position sensor wave form, crank position, ignition voltage, oxygen sensor, or what ever you want to see in a graphed form.

 

[jetjock]

I have a Fluke DSO ScopeMeter, a model 97. Don't use it too much these days as I prefer the automotive laptop based scopes made by PicoTech. All my DMMs and other electronic test gear is Fluke though. They do make nice stuff.

 

[toml]

There are 4 terminals on the CPS connector:

G1, G2, G-, and NE

<snip>

Hope that helps....

Wow, that MORE than helps. I don't know where you managed to find all that information, but it is greatly appreciated.

 

[DiZzy]

alright after reading all this imma gooing to pick ur brains so me and my friend hacve been at this for a while trying to get his 89 turbo running we had it running for 4 hrs aprox then he went a long run and died >.< SO we have narrowed it down to something in the main fuse area and CODE 12 now i think theirs a split wire somewere but god damit it cranks no pro but dosent fire no spark nothing ignitor works we tried it on my 87 lol and the main fuse works we truied it on my 87 lol so i need some help here links anything to trace these wires or somthing were so dam close to fuind it but a wiring diagram of were4 exactly this wire runs pm me with some info please i want to get it working tomorow


Gary.