2002 C70 No start after head gasket job

goldmandan · Post by **goldmandan** » 24 Aug 2015, 16:35

I just got done with a new head gasket put in on my 2.3T. I made sure ALL screws and bolts went in properly without any one missing. All parts are tight etc....... I put the battery on and the engine will crank over but not start. I do have fuel coming to the cylinders (put a screwdriver at the fuel purge valve and fuel came out strong). I pulled a sparkplug and grounded it on the valve cover and cranked, no spark. I checked codes..... one was 2400 (fuel pump relay signal low- permanent code) and the second was 3100 (engine RPM sensor signal missing- permanent). Is the RPM sensor the one that is attached to the back of the exhaust cam? This was the ONLY part related to the ignition that I took off to get the head out. Other than the coils themselves...... Please let me know what to go after

Dan

Post by **FLXC90** » 24 Aug 2015, 17:15

Isn't RPM signal a function of the crank sensor? But I think the system reads for agreement between cam and crank sensors. Since you had CPS out for head removal, it is more likely the suspect. What condition was your cam sensor plug in? I have three with crumbled plastic plugs on my shelf. Also, the obvious, ensure crank was positioned properly when reinstalling TB? I don't know if an out-of-phase condition would throw your code. Common wisdom is car will start but cutout with bad crk sensor, but will run but not start with bad cam sensor.

Post by **abscate** » 24 Aug 2015, 19:29

You should expect to crank for at least a minute or more to get an engine to fire up after major work

10 seconds of cranking, 30 seconds rest.

The crank sensor code for EC 3100 refers to the one sensing the flywheel I believe.

goldmandan · Post by **goldmandan** » 24 Aug 2015, 20:51

If you mean that I positioned the crank and cams exactly as I took them off then yes. But I did remember once I took the exhaust cam off about the phaser..... damn I thought............ I set the mark according to the timing mark on the timing cover. But when I went to put the cam back in I noticed that the mark I made corresponded with the phaser's "rest" position so at 0 advance which should be correct.....

The only cam sensor I took off was the one on the back of the exhaust cam. I know i just threw it into the box of parts and probably dropped it once and also threw other bags of bolts on top of it. I'm sure it's toast.......... as for cranking the engine for 1 minute or more.............. if I have fuel but no spark..... how can 1 minute of intermittent cranking get the car to finally start? Does the ECU have to be reset or something by letting the engine spin for the cam sensor to pick up cranking RPMs? I don't believe it...... it either gets spark or not......... The cam sensors wires all go to the ECU and i'm sure gives signal for the ECU to transfer power to the fuses giving power to the coils......

Any help is much appreciated!! I Will report back on my findings

Post by **abscate** » 25 Aug 2015, 03:48

If I recall correctly the ECU will use the cam sensor as a backup if it does not detect the crank sensor. I don't how the dynamics of this how it switches over , I think it's pretty much instantaneous.

It's easy to disturb other stuff working on the head.

Did you preset The cam load on your VVT engine when you replaced the cams? That would mess up your timing.

goldmandan · Post by **goldmandan** » 25 Aug 2015, 05:51

When I put the cams back I made sure the exhaust cam (which has the VVT) was at "rest" and the timing mark was right on the dot with the timing cover. All marks ligned up........... I get no spark. The timing is fine. even if it was within the 15 degree "advance" range it would still start. Just you would get a more torquey or more hp setting if I remember. but nonetheless it would still start......... Where is the crank sensor on the 2.3 T? I found the engine RPM/Cam sensor on the back of the exhaust cam.......

Post by **abscate** » 25 Aug 2015, 19:33

I think you have to turn the crank another quarter turn and return to get the timing right.

The rpm sensor sits down near the flywheel.

goldmandan · Post by **goldmandan** » 26 Aug 2015, 17:40

I followed the wiring to the cam and crank sensors. They were covered with electrical tape. I had moved the crank sensor wiring when taking the head of and straigtened it since it was all tangled and twisted. Come to find out the wire broke out from the connector...... got a connector from the junkyard and spliced it in....... car started right away. AGAIN, if you have NO spark. it cannot be timing related..... your car will still run even if it's 4 teeth off. As long as you clear the valves of course

but it will run sluggish. The way to set the timing when you take the belt off is to make sure the cam that has the phaser/advance on it's marking lines up with the timing cover mark when it is at REST. This will allow for full advance travel once the engine is started again.

Now onto my next problem............. will make new posts