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P38A Project Car - 1998 Autobiography Engine Rebuild
- Thread starter pwood999
- Start date
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- 3,878
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That's the one. Thanks for the offer, but for now I have done the bypass & connected the header tank pipe directly to the outlet on the N/S head. Inlet is all fitted & sealed now, so will see if I need it later. Now I know the part number, there's some on flea-bay for less than the petrol to Bucks !!
Pete
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Latest update: Filled up the oil & water, and reconnected starter motor. Turned the engine over using jumper wire across starter relay, with spark plugs out to get new oil around as much as possible. Then decided to check compression. Cylinders 1,2,7 & 8 all around 200psi, but 2,4,3 & 5 only 175psi. Squirted some oil into the bores and all seem to be ok now. I suspect the new piston rings will need some running in.
Installed spark plugs and tried to fire it up. No spark
. Then realised I had forgotten to reconnect the crank sensor . . Doh. Engine starts, but is extremely lumpy & backfiring. Hmm . .. maybe plug leads are in wrong order ? Only faults on Nanocom are missing O2 sensors - must reconnect these as well, but doubt they are causing the major misfire.
Next job is to re-check all wiring & have a look at the spark plugs.
Installed spark plugs and tried to fire it up. No spark
. Then realised I had forgotten to reconnect the crank sensor . . Doh. Engine starts, but is extremely lumpy & backfiring. Hmm . .. maybe plug leads are in wrong order ? Only faults on Nanocom are missing O2 sensors - must reconnect these as well, but doubt they are causing the major misfire.Next job is to re-check all wiring & have a look at the spark plugs.
Henry_b
Think outside, no box required.
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You'll have to seat the rings both the barrel face and the taper face will initially only make line contact with the cylinder wall the contact area will increase as ring wear/break in occurs
If the bores were honed correctly the rings will line contact in a very short period of engine operation, dropping oil down the bores will extend the time it takes to break the rings in.
The rough surface of a honed cylinder is in part to promote a wear pattern between it and the ring face. In order to do this, the rings will remove the microscopic peaks created by the honing process creating the proper height of these peaks and the depth of the valleys will improve the potential for the piston ring seal. Lubrication is another critical element in this process but oil can only achieve its intended goals of lubrication and improving ring seal when the other conditions are met.
When throwing the engine together, a light machine oil for the cylinder wall and rings is ideal..
O2 sensors would help it's running
Oh and a break in oil would be beneficial, or an additive atleast
If the bores were honed correctly the rings will line contact in a very short period of engine operation, dropping oil down the bores will extend the time it takes to break the rings in.
The rough surface of a honed cylinder is in part to promote a wear pattern between it and the ring face. In order to do this, the rings will remove the microscopic peaks created by the honing process creating the proper height of these peaks and the depth of the valleys will improve the potential for the piston ring seal. Lubrication is another critical element in this process but oil can only achieve its intended goals of lubrication and improving ring seal when the other conditions are met.
When throwing the engine together, a light machine oil for the cylinder wall and rings is ideal..
O2 sensors would help it's running
Oh and a break in oil would be beneficial, or an additive atleast
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Exhaust connected & O2 sensors installed. One sensor is broken, but the GEMS ECU should at least resort to the other.
New problem with battery ground clamp. No longer tightens, so need to replace it. Bit of a PITA while local parts centres are closed.
New problem with battery ground clamp. No longer tightens, so need to replace it. Bit of a PITA while local parts centres are closed.
Henry_b
Think outside, no box required.
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Battery terminal bodged with foil, but will replace it.
Still having issues getting engine to run. Before the rebuild all the coils, plug leads & injectors were working ok, as were all the sensors. Had to sort some dodgy connections on the Cam Sensor, but I'm sure I wired it correctly. No sensor faults on Nanocom, so I guess I need to scope test the sensors.
Now wondering if I misread the timing marks on the crank & cam when installing the new timing chain. Otherwise perhaps the injectors are not firing correctly due to something in the LPG or Injector wiring. Will be making a Noid LED tomorrow.
Still having issues getting engine to run. Before the rebuild all the coils, plug leads & injectors were working ok, as were all the sensors. Had to sort some dodgy connections on the Cam Sensor, but I'm sure I wired it correctly. No sensor faults on Nanocom, so I guess I need to scope test the sensors.
Now wondering if I misread the timing marks on the crank & cam when installing the new timing chain. Otherwise perhaps the injectors are not firing correctly due to something in the LPG or Injector wiring. Will be making a Noid LED tomorrow.
Henry_b
Think outside, no box required.
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Are the coil packs secured properly?
They Earth through the bolts securing them, just a thought.
Maybe worth getting a timing light on it?
They Earth through the bolts securing them, just a thought.
Maybe worth getting a timing light on it?
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Coil packs have all 4 bolts in place, but didn't realise they formed the ground. Will definitely check that, and add an earth wire if necessary.
Got some Spark Testers & Noid Lights arriving soon which should help.
Got some Spark Testers & Noid Lights arriving soon which should help.
Henry_b
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Those lights should help..
narrow down an Ignition or fuel issue.
narrow down an Ignition or fuel issue.
martyuk
Well-Known Member
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Just had a look in the ETM to remind me, and the coil packs don't ground through the engine block - so having all the bolts in won't make a difference.
The coils all get a 12V feed from the fusebox, and then the engine ECU grounds the coils it's firing to complete the circuit - there's no other grounding for the coils.
Timing marks on crank/cam are just a couple of indents from memory - one on each sprocket and they should be pointing towards each other when the chain is installed. I've dug out a picture of my engine when I built it:
The Ignition coils get their power from F26 in the engine bay fuse box, which also powers the O2 sensor heaters, and an ignition sense feed to the engine ECU. Could be worth checking that (though I would have thought it would have thrown a fault in the ECU if it was missing...) as if there was a broken wire on one of the O2 sensors, it could have shorted and popped the fuse. Then you'd get no spark for sure.
Hope this helps,
Marty
The coils all get a 12V feed from the fusebox, and then the engine ECU grounds the coils it's firing to complete the circuit - there's no other grounding for the coils.
Timing marks on crank/cam are just a couple of indents from memory - one on each sprocket and they should be pointing towards each other when the chain is installed. I've dug out a picture of my engine when I built it:
The Ignition coils get their power from F26 in the engine bay fuse box, which also powers the O2 sensor heaters, and an ignition sense feed to the engine ECU. Could be worth checking that (though I would have thought it would have thrown a fault in the ECU if it was missing...) as if there was a broken wire on one of the O2 sensors, it could have shorted and popped the fuse. Then you'd get no spark for sure.
Hope this helps,
Marty
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Marty, that picture is the Thor cam sprocket, but yes the marks are similar on GEMS, and I definitely aligned then as shown. Did some quick checks today with multimeter & scope.
- Coil primaries all show < 1ohm, and all plug lead pairs measure 26Kohm through each coil secondary. No coil shorts to earth, so they look ok.
- Removed all spark plugs so the engine spins freely. Cranking fuel pressure = 30-40 psi. (still need to check regulator pipe)
- Spark tests using plugs 2 & 3 earthed with jump leads, show simultaneous sparks on both. Will repeat for all 8 later.
- Scope test on Crank & Cam sensors not good. My other P38 looks like the attached pic, but something badly wrong with this engine.
- Crank sensor shows some pulses, but not what it should look like. Probably just enough to trigger the sparks, but not right. Need to get underneath & check the sensor isn't bent or broken.
- Camshaft sensor has no output. GEMS should be using default timing, but need to re-check the wiring.
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Afternoon update:
- Cam sensor wiring all checks out. Must be a failed sensor . . .ouch expensive.
- Crank sensor bent. It was straight when I fitted the flywheel before installing the engine into the car. Measures 1300ohms but not sure if this is good or bad ? After straightening the pin out and checking it doesn't get hit by any of the flywheel tangs. Tried the scope test again, but no signal except one or two spikes per revolution.
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I think I have discovered how the crank sensor got bent. Found two of the reluctor teeth missing. One of them turned up in the bell housing by the inspection cover, but the remainder is still missing.
Gotta change the flywheel now. Luckily I removed the radiator for easier access to the camshaft sensor, so hopefully should be able to move the engine forward about 6 inches and do the flywheel without removing too much.
Gotta change the flywheel now. Luckily I removed the radiator for easier access to the camshaft sensor, so hopefully should be able to move the engine forward about 6 inches and do the flywheel without removing too much.
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Yesterday, got everything disconnected between engine & car to change flywheel. Eventually decided to pull the engine rather the try to change flywheel by moving engine forwards. There would have been enough room, but working on engine stand is much better.
New (2nd hand) flywheel arrived, inspected & flex-plate swapped over because mine is in much better condition. Changed flywheel with engine on floor, and used locking tool to torque up the bolts.
Now the fun part. Mounted engine on stand & first cranked the engine by hand to make sure the crank sensor was not being hit by the reluctor tangs. Then connected battery to starter motor so I can spin the engine. Connect oscilloscope to crank sensor. Old sensor is producing 4V waveform, and new sensor gives 6V waveform.
Just for good measure, now I can access the plug holes easier, squirted some oil into the bores & re-measured all the compressions. All are now between 200-220 PSI, so maybe I didn't quite get the oil in properly before.
New (2nd hand) flywheel arrived, inspected & flex-plate swapped over because mine is in much better condition. Changed flywheel with engine on floor, and used locking tool to torque up the bolts.
Now the fun part. Mounted engine on stand & first cranked the engine by hand to make sure the crank sensor was not being hit by the reluctor tangs. Then connected battery to starter motor so I can spin the engine. Connect oscilloscope to crank sensor. Old sensor is producing 4V waveform, and new sensor gives 6V waveform.
Just for good measure, now I can access the plug holes easier, squirted some oil into the bores & re-measured all the compressions. All are now between 200-220 PSI, so maybe I didn't quite get the oil in properly before.
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Looks like the patient will make a full recovery.
RangeRoller dt
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No wonder you couldn’t find the bolts. What happened to the tree?
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Tree ? Aah yes partly cut down.
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so while I was removing the engine, the torque converter spigot got stuck in the crank boss, and it got pulled out of the gearbox. Checked the transmission oil pump lug position, and marked the converter with tipped, but still spent over an hour today trying the get it back in. Lots of turning, jiggling, etc. and it finally pushed all the way in.
Wifey thought it was funny, but short-ass like me has to sit in the engine bay to reach the torque converter !!
Wifey thought it was funny, but short-ass like me has to sit in the engine bay to reach the torque converter !!
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It's a long way down!! Don't get any oil on the driveway..
