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1995 P38 4.6HSE auto won't start


Puffernutter

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4.6 GEMS engine, automatic

Some history

Bought over 12 months ago (cheap because of a horrid rattle). Driven onto a trailer, driven off at the other end, parked and left (with occasional starting) for around 12 months. Last attempts (before I messed with it!) it would just about start, but wouldn't run.

Just completed a gearbox removal and replacement and replaced the rather shattered flex plate (see other thread). I noticed the crankshaft position sensor was bent, so replaced that as well. All back together, all wires connected (as far as I can tell!) No faults from the Nanocom.

So (ignoring the fact I may have a start motor issue as well) it will occasionally fire, get to around 1000rpm for a few seconds, then die. It will take a lot of cranking to get it to start again.

Again, the Nanocom shows no errors on the the GEMS engine.

I still get "Traction Fault" and "Gearbox Fault" on the dash display, I can't see where they can be cleared by the Nanocam and I'm not sure if they are the old faults (uncleared) or new faults and it's more than the flex plate!

Could it simply be old fuel, I've heard of this problem, but had cars with older fuel without issue.

If not, without any obvious faults.

HELP!!!

Cheers

Peter

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Sounds to me like a dying fuel pump, blocked filter, or dead pressure regulator.

One way to test.... turn ignition on for 2 seconds, off, back on 2 seconds, do that a few times, if it starts afterwards then your pump is not delivering the fuel you need, and turning it on and off a few times has allowed it to lethargically fill the fuel rail to get it going, then can't keep up once injectors are opening.

Is there a schrader valve on the fuel rail? Be worth checking the pressure if there is...

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Tried Eeeze start - no change. Looks like it's an electrical/timing problem

as we seem to get bangs from the airbox when it tries to start.

The crankshaft position sensor was changed and I checked all the pins on the flywheel when we re-assembled. Unless it's a faulty crankshaft position sensor?

Where would you look next?

I have a Nanocom, but it seems that's only really helpful with the engine when it's running! The "check engine light" goes out when cranking.

Cheers

Peter

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I still get "Traction Fault" and "Gearbox Fault" on the dash display, I can't see where they can be cleared by the Nanocam and I'm not sure if they are the old faults (uncleared) or new faults and it's more than the flex plate!

That's usually indicative of a bad ground. This could be affecting the ECM/coil packs/other things as well.

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Latest update. Fresh battery (from my other 4.6) fully charged, no change. In fact, if anything it's getting worse being more reluctant to start.


Disconnected the MAF sensor. No change.


Checked the Schrader valve on the fuel rail (doing this solo) after I'd finished cranking and there was some pressure there, so it seems as if there is fuel (which is also confirmed by the fact that the Eezee start had no effect.


Where to look next?


Cheers


Peter

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You checked the plugs for wetness?

You could put them in the oven for 20 mins and fit them, if there is any weakness in the spark the heat will often help kick it into life.

Can you get a timing light on it? Appreciate you are doing it solo, but you could stick a spade connector onto the start solenoid and touch it to a 12V feed (back of alternator maybe....)

When checking the fuel rail, just turn the ignition on and let the fuel pump run for the 2 seconds, and then check the pressure, no need to crank.

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Yes, in the ECM special functions normally. if they're really out of whack, they can cause problems like this (they did for me, although that was with the Bosch ECU, not a GEMS). Also keep a look on them, if they go wrong again quickly you most likely have bad lambda's and/or other fuelling issues.

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I would advise not reseting the fuel trims until the engine is running and live values can be checked.(Especially with regard to oxygen sensor activity) If the long term trims are a long way from the base setting because of say a dying Maf,you may make matters worse. You should be able to see where the long term trim is as a plus or minus % value. This is especially a problem on Bosch v8's where the Maf's slowly degrade. it is also an issue when LPG systems don't mirror what the petrol ECU would do.

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Frustration levels rising! Having swapped batteries, I've obviously upset the alarm!

I'm getting "Keycode Lockout" and "Engine Disabled" on the dash (and the bloody horn going off!) After a period of time, the Keycode Lockout goes and I'm just left with "Engine Disabled". The "check engine" light is out, so that means a loss of sync between GEMS and BECM

Not a problem, out with my trusty Nanocom, into "Learn Mode" ignition off and on and .....nothing!! Still engine disabled.

I get "unable to communicate with BECM" when I interrogate using the Nanocom, so is that the problem.

I have an EKA code, but that doesn't seem to work either.

I don't want it to defeat me, it was cranking earlier this week, but there are obviously problems in the ECUs somewhere - any suggestions?

Once I get it cranking again, then I can think about why it isn't firing!

Cheers

Peter

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If its gone to Keycode lockout you can't communicate normally with the BECM. You have to get the EKA code in.Which if you cant do via the door you have 3 options.First is to fix why the code won't go in via the latch.(Which needs doing anyway) Second is to send the BECM to Rick at Callrova to have it unlocked.And the third option is only possible from memory with BECM's with a Pam micro number 36 or higher. Testbook T4 can ram the EKA code into BECM direct,now what I dont know is if you can do this with Nanocom, I guess you could ask on the Nanocom forum ?

Low battery voltage and spurious RF activity will both be enemies to a P38.So a decent battery and disconnecting the RF receiver if it isn't a ywy500170 type are only going to help.

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Been surfing the Nanocon Evolution forum. I have found where I can enter the EKA through the Nanocom and I also have the EKA, which I assume is correct (although I suppose there is no guarantee!)

However, I still have the problem that with the key in position II, the Nanocom wont communicate with the BECM.

Not sure what the next step is. Where is the BECM located?

Cheers

Peter

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It won't communicate in the normal way cos its in lockout - thats why I said about trying to use your nanocom to enter the EKA. Testbook overrides the lockout and shoves the EKA in,thats what you need to get your nanocom to do.BECM is under drivers seat.(RHD)

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An update. Trying to be logical! I still had "Keycode Lockout", I couldn't get the BECM to talk to the Nanocom, so I was fearing the worst (as it turns out, my BECM is s/w version 20, so the "DISARM" function wouldn't have worked anyway.)

Opened the door, got the alarm sounding etc.

Checked the BECM power fuses, all OK.

Checked the power at the BECM studs - all showing 12v.

Tried the EKA code, no joy. The noticed a brief "Bonnet Open" message on the dash.

Weight the bonnet corner down with a box of wall tiles! Key in to position 2, then out again. Wait for all the error message to subside - no "Bonnet Open"

Enter the EKA through the door lock - I can see the tell tale illuminate after each turn. Do the sequence, turn the key again and it all unlocked!

I can now crank again. It's still not starting, but at least I can crank it over.

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This is what I've found out tonight (after it started cranking again).

1. It will crank for 5-10 seconds, then fire once or twice and die. That is reasonably repeatable, sometimes it takes longer to fire.

2. When I push the Schraeder valve after cranking I get a small pulse of fuel (2" or 3" coming out of the valve) - does that indicate enough or too little pressure?

3. There is a smell of fuel when cranking.

4. I've measured the resistance on the original CKP sensor, it was 1.8kohm and it does change when something metallic is wafted near it!

I haven't checked for a spark yet, that's next. I've also ordered another CKP sensor, just in case I've been unlucky and have been sold a duff one!

Anything else to suggest?

Cheers

Peter

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Good that you fixed the EKA lockout without having to send away the BeCM. Some debugging before taking drastic measures is useful.

Can you see the values of your current fuel trims with Nanocom? What do the long term fuel trims say?

Honestly, it sounds like it's flooding.

You can always go "back to basics": unplug everything the GEMS ECU doesn't need to run: lambda's, MAF, cam sensor, ...

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Fuel rail pressure (at the Schraeder valve) is 41.1 psi. So it looks like its good from the tank to the fuel rail!

Tonight's job is to work logically through the engine to see what is there and what isn't, including:

Checking for a spark

Wetness on the plugs

State of the teeth on the flywheel

Characteristics of the CKP sensor

Then I may have a better idea of what I have and haven't got!

Cheers

Peter

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Once modern plugs have been wet in a Rover V8 they often simply won't start an engine.Best leave them out overnight to allow the cylinders to dry out. Then put at least 4 new plugs in and 4 old ones,(Cheaper than 8) The 4 new plugs should get it running and the others will often then recover.

I would strongly recommend that you remove the lower flywheel cover plate and carefully inspect the tangs on the flywheel before trying to start it again.I've seen them bent and missing,all of which will confuse your Gems ecu.

Access to a good scope could tell you all these answers without taking anything apart, especially scoping the crank sensor.

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