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1970-1995 Range Rover Classic
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Discussion Starter #1
This is a NAS spec 1996 4.6. Canisters and some other 'stuff' had already been removed. Hence they swapped the engine ECU for a normal one.
The owner had already changed the sparkplugs and cables, replaced with Champion and Lucas as it should be.


We received a P38 with horrible misfires, terrible emission and no power, we are a bit further but still I am scratching my head. While in the beginning it would not pass 2000 rpm it will rev up nicely now...

Found a bad coil, a pretty bad camshaft sensor and a missing knock sensor. Camshaft sensor was replaced by a new one, coil and knock sensor by confirmed (in a Disco 4.0 currently present) second hand.

Cleaned injectors, aligned some bad looking pins on the driveplate. Some are still not perfect.

All this improved the car by 80%. But P0340 still comes back and when accelerating hard I get terrible misfires, it misses on various cylinders.

I have tried the Disco's ECU which improved it a little bit. I also noticed the ECU is getting very how where it is near the exhaust manifold.

Also we found out there were no catalyzers present. Put some in, made it worse


As always, I value your feedback!!
 

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1995-2002 Range Rover Classic
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1,413 Posts
since you mentioned the cats are removed, are the o2 sensors present?, have you considered a worn out camshaft, what are your compression readings, have you considered timing being off, maybe bad timing chain. possible internal failure, burnt valves?.
 

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Premium Member
1970-1995 Range Rover Classic
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455 Posts
Discussion Starter #3
since you mentioned the cats are removed, are the o2 sensors present?, have you considered a worn out camshaft, what are your compression readings, have you considered timing being off, maybe bad timing chain. possible internal failure, burnt valves?.
Thank you.
Rafa checked the chain and timing last week. There was a bit of filing stuck to the sensor so I said please take the cover off there's bound to be more.

I was wrong. But your idea of the worn camshaft makes sense. Would that influence the signal?

The crankshaft signal did not make me happy.
Didn't get a nice cam signal at the ECU but it looked better close to the plug. Sorry I was holding two probes and had no hands for the pictures.

Later the apprentice took a photo of the Discovery sensors, they looked much better to me. (2nd picture)

Tomorrow I have to return the scope. Gotta do my best in the morning.


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You didn;t answer about O2 sensors. There was never an NAS P38 produced WITHOUT cats and 4 O2, thus is no NAS ECU that is a "normal one". ALL NAS EUs require accurate reading from both upstream o2 sensors and both downstream O2 sensors.

Not only are they federally mandated on every petrol car for 1975 and newer but it is federally illegal to remove a functioning cat. A non function cat must have failed emmision testing must have a legitimate NEED to be replaced that can be established and documented according to EPA guidelines and procedures. Folks that don't do regional emission testing must obtain a test from a federally licensed station PRIOR to REPLACEMENT with a cat of identical specifications.
 

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But he's in Costa Rica so all the federal mandated emissions stuff is irrelevant. If the ECU has been replaced with a non-NAS version, it should run fine whether it has cats and O2 sensors or not. Only NAS cars had post cat sensors, the rest of world cat equipped cars only had pre-cat sensors anyway.

From those traces it certainly looks like a cam sensor problem to me. Check that it has the 5V supply going to it if it has been replaced with a new one.
 

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It's an NAS rig. A change of venue it is not going to change how it is going to behave when it doesn't receive expected information.
 

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1970-1995 Range Rover Classic
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455 Posts
Discussion Starter #7
Ok friends the car had one O2 sensor missing of the 2. Yes, I have put a new one in AND Rafa passed RTV yesterday.
But I did mention they changed the ECU for a normal.one, so that it doesn't look for NAS stuff.

I buy them in Europe or Australia if I can't find them at a decent price.

But I can't understand why that makes the car run lumpy when more power is wanted.

I will check the supply, good point.

What do you think.of the crank signal?

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1995-2002 Range Rover Classic
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1,413 Posts
have you checked the sweep of the tps for a missing signal? a worn cam would set misfire codes as well as knocking codes and the engine will run rough because of the valves not functioning properly.
 

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1970-1995 Range Rover Classic
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455 Posts
Discussion Starter #9
TPS is looking good.

There are no codes but the dreaded p0340.
It keeps coming back Only when the car is hot (98°c +)
And
You accelerate to the bottom or near on.
It doesn't happen all the time.

Today I realised the battery is pretty useless so I borrowed one from an l322.
That definitely improved the camshaft signal but I still get the error.
Sigh.
I also checked every injector signal. All the same
Somebody please look at the signals.. What do you think? 1 is CKP and CMP accelerated

2 and 3 are injectors , the only ones that produced errors previously (not today)

This is with the cam sensor as a reference.


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1995-2002 Range Rover P38A
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116 Posts
Hi Annette,
The graph is showing unevenness. Heat probably makes it more uneven. Recommend following the code P0340 (camshaft position circuit error) looking for a wiring issue (with the O2 sensors as well). Like Richard G said about the voltage. Had a BMW, about the same year as your rig, that gave a camshaft position switch error and it was a frayed wire on the downdraft (exhaust) O2 sensor. CPS was fine. A lot of BMW thinking in a Rangie.
Good luck.
 

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Premium Member
1970-1995 Range Rover Classic
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455 Posts
Discussion Starter #11
Update..
I have taken the whole harness out and it isn't pretty.
Going to San José tomorrow to buy one at the wreckers

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1970-1995 Range Rover Classic
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455 Posts
Discussion Starter #13
Sorry to revive this one.
I bought another 2 second hand harnesses.

Made 1 good one out of the 3.

Still haven't got rid of the error.

The sensor is new

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