Hi all I am have some problems starting my 4.0 2002 bosch block rebuild into my 1999 gems truck. top end is gems and the block is bosch.
This is what I did so far...
installed rebuilt block and checked the timing gears 4-5 times the engine is timed. Installed a new bosch flywheel used the bosch crank sensor I just discarded the shield wire to connect to the gems two wire. the check engine light goes out while cranking so I think its working. I have spark but the spark seems to fire when valves open and close. I changed the gems cam timing gear to the bosch didn't work so I tried the gems gear same deal.I have checked the plug wires and they are not mixed up. I am thinking now that I need to install all gems parts ,flywheel, gems crank sensor and gems front cam timing gear.I will need to tig weld the gems cps mount plate in the bosch block to do this.I just don't get why all I tried don't work the motor just backfires and burps. Its almost like my ecm programing is off.I didn't try a bosch cam sensor because I think they are the same hall effect as the gems.
Psi tested all cyliders the are 120 to 180 so no sticky valves.
I also cleared one code that said my cam sensor was not working correctly but I cleared it and it never came back.I tested the cam sensor it check out good.also I don't have oil psi yet just want it to fire then I will prim it more.
I am getting fuel.

Any help or any help from the UK if they like helping yanks that is.

 

You need to use all gems stuff if going in a gems vehicle. I'll bet the crank sensor is your main issue. You might get a code for the cam sensor if you aren't using the gems gear with the gems sensor, but it should still run.

 

Page 42 of 591 in the 97 electrical manual shows a shield for the CKP line.

Page 272 of 873 in the shop manual for same years shows this:

Camshaft position sensor (CMP Sensor)
The camshaft position sensor is located in the engine
front cover. It produces one pulse every two
revolutions. The signal is used in two areas, injector
timing corrections for fully sequential fuelling and
active knock control.

In the D2 shop manual, page 316 of 1529 shows this:

The CMP sensor is located on the front of the engine, above and behind the crankshaft pulley. The CMP sensor is a Hall effect sensor producing four pulses for every two crankshaft revolutions.

So I would suspect that your diagnosis points at the CMP sensor fooling the ECU.

As for the CKP sensor, shield line would be an issue at some point.

 

A good test would be to leave the cam sensor unhooked.

A guy on discoweb put a gems engine is his d2 and left the gems cam gear in it. He gets a check engine light but it still runs.

He didn't swap the crank sensor mount, he just re-drilled it. I think it would be easier to swap the mount.

To make things simple for you and any other troubleshooting I still recommend if going in a Bosch, use all the Bosch stuff and if going gems, use all gems.

 

The running without CMP connected is valid, but I think ECU uses the last stored values. So those values might be off now that the new setup has been run. Worth a shot.

 

Is there a way to clear the values? and what new set up was run? the engine don't run.
Thanks

 

Yes I tried that but it was the same
Thanks

 

I think the ecm just don't like the bosch flywheel and sensor.I think its like "wtf is this" so looking on ebay for gems tab flywheel, my old one has missing tabs.

 

That's the first thing I said. Bosh flywheel is 60 teeth, gems is 35.

All Bosch or all gems. No mixing.

 

And there should be one missing tab for sync.