420a No-start until cam sensor is removed

[djjohns55]

Ok I'm currently troubleshooting a Completely stock 98 GS

I first changed the HG because water and oil were mixing. and I found out the head was warped. The car cranked up and ran quite well except for the leak.

I installed another head and the exhaust cam was binding because the engine was burning up the starter and it was insanely difficult to turn the engine over and it. It also broke off the dowel on the Exhaust cam. I trashed the exhaust cam and the head.

I got another head machined ground valves, cleaned and new valve stem seals pressure tested.

Now Ive worked out all of those problems and now I've installed the new head and timed it up and the engine turns over. It acts like it wants to crank but it will start up.

I'm getting fuel and good compression. Spark is iffy thing because I get good spark most of the time but sometimes I get a very faint spark on all cylinders. Ive changed the coil with a working coil and the engine acts like it wants to crank even more but it still doesnt. Ive changed the spark plugs and the wires are fairly new and they work well on my car.

The weird thing is that when I unplug the cam sensor I can get the car to crank and it runs quite rough it will not idle either. If I open the throttle body up, the car will run smoother but not perfect. While we had the car running I tried to plug the cam sensor up and it died.

I changed out the cam sensor and it still does the same thing. I havent changed the crank sensor yet but I was assuming that since the car will run w/o the cam sensor the crank sensor is good. My next step is to check the timing again,and check the crank sensor and if all fails find another ecu.

I've even swapped out the magnet on the back of the current exhaust cam that im using because one of the plastic dowels were broken.

NO engine codes! I scanned for some hoping it would help but nothing came up.

Could I have possibly messed up the ECU when the Cam was binding??
Can someone explain how the cam sensor and crank sensor communicate with the ECU?
What could it be??

Thanks for any input!!

 

[1996dsm]

sounds like the timing is off to me.

 

[dr1665]

I concur on timing. Still sounds like it's off to me.

Grab your Chilton's and trace down the lines between the ECU and both the CMP and CPS. Make sure they are not broken or shorting out. Disconnect the fuel pump relay and backprobe the sensors at the ECU to be sure you're getting the alternating 5VDC at the ECU. If you are, then the sensors and the wires are good to go and it's more than likely your timing being off.

But what is this about removing a magnet or running with a broken cam dowel? That dowel is what keeps the cam gear lined up right. Marks don't mean shit if the dowels are gone. If you've got a cam with a missing index dowel, then you can't time the engine right and you're headed towards head #4.

 

[zephyr2oo5]

Wait how is it possible for it to run with out the cam sensor plugged in? It needs that sensor to tell the computer when to pulse the injectors right?

 

[VelocitàPaola]

The ECU uses that sensor and the crankshaft angle sensor to determine RPM and engine orientation. The car cannot function without either of them.

 

[djjohns55]

Ill check the timing again but I could slide the pin in and out of the tensioner. I did have trouble timing the engine because the intake cam would roll a half of a tooth or so after the 21lbs with the torque wrench. What do you do to keep the inake came from rolling when you line the cam notches up?? or what am I doing wrong??

But what is this about removing a magnet or running with a broken cam dowel? That dowel is what keeps the cam gear lined up right. Marks don't mean shit if the dowels are gone. If you've got a cam with a missing index dowel, then you can't time the engine right and you're headed towards head #4.

1st- the exhaust cam in head number two was binding and it broke the cam gear dowel. I trashed that exhaust cam for sure.
2nd- in head number three on another exhaust cam the magnet/cam trigger on the back of the cam can be removed so I removed to check the plastic dowels on the cam trigger and one of the dowels were broken, so I replaced that too. that still didn't fix the problem

as for the engine running w/o a cam sensor. I tried to unplug the cam sensor on my eclipse and it would not crank. I had to check because I also thought that the car needed the cam sensor and the crank sensor to crank up and run. the car will run rough and rich with out it and it wont idle. I will try to get a video of it tomorrow to possibly post.

I will look at the timing again but before I do it again I would like to know what to do about the intake cam rolling while timing the engine.

Thanks

 

[zephyr2oo5]

A half a tooth wont matter for your timing I ran mine like that for 12000 miles. To fix it so the Cams are on roll the crank COUNTER clockwise a half a tooth, then the cams will line up and itll be spot on for time. But like I said I ran mine with it a half off for 12k and it ran great. Until one day it stopped.

 

[VelocitàPaola]

It's impossible for the timing belt to be off by half a tooth. The teeth ensure the belt is either spot on, or off in whole number increments.

 

[zephyr2oo5]

It's impossible for the timing belt to be off by half a tooth. The teeth ensure the belt is either spot on, or off in whole number increments.

Read your Haynes. It says when setting cam timing aligh the cam teeth exact and roll the crank 1 half tooth Counter Clockwise to ensure proper timing.
So if you set the crank to TDC and the cams will be about a half a tooth off. Car will run just fine but will idle a little funky. Like I said I drove mine for 12,000 miles like that and never had any problems.

 

[VelocitàPaola]

Read my Haynes? Would you settle for not only reading, but actually understanding the Factory Service Manual?

Under tension, the belt keeps all timing components perfectly spaced in exactly whole tooth increments. Some manuals suggest mis-aligning the crank and cam sprockets by half a tooth or so so they fall into perfect alignment once the belt is put under tension. The only times you'll see misalignment by a fraction of a tooth is when significant material has been removed from the mating surfaces on the block or head.

 

[djjohns55]

The timing was off because the cam was binding in this head again also and it broke off the dowel off of my second exhaust cam. I also have a video of the car running without the cam sensor.