harry yarnell Posted July 7, 2003 Share Posted July 7, 2003 I've just purchased a '90 that will barely run. I suspect cam sensor issues. Or maybe timing chain. What's the relationship between the cam sprocket magnet, and firing order? In other words, I hope to eyeball the magnet up in the sensor hole; where should the crank pulley be? #1 firing? Other? Link to comment Share on other sites More sharing options...
Guest Posted July 7, 2003 Share Posted July 7, 2003 Just went through a similar problem, wouldn't hardly run when cold. After the engine ran for two minutes, the computer, which was bad, would get out of the loop and let the engine run on the defaults. This condition was further exacusabated by the fan motor that would put out a big spike and bring the computer down and the whole cycle would begin again. The message on the computer suggested that the cam timing sensor was bad. Good luck Link to comment Share on other sites More sharing options...
Guest kennyw Posted July 7, 2003 Share Posted July 7, 2003 harry, another Reatta? how many does that make now? ken, arbutus Md. Link to comment Share on other sites More sharing options...
harry yarnell Posted July 7, 2003 Author Share Posted July 7, 2003 Harmonic balancer? What was I thinking; they're no marks on the 3800 balancer. Too many cars with different ignition systems, I guess. Have a headless 3800 up on the enginge stand, and indeed, when the cam magnet peeks thru the sensor hole, #1 is at TDCDr. Watson, are you counting? Link to comment Share on other sites More sharing options...
padgett Posted July 7, 2003 Share Posted July 7, 2003 If you lose the cam sensor or magnet, an E041 code will set. Crank sensor will not set a code (but probably won't start at all. Odds are on the ESC. Link to comment Share on other sites More sharing options...
harry yarnell Posted July 8, 2003 Author Share Posted July 8, 2003 The reason I bring up the cam magnet, is to check timing chain alignment. If I see the magnet in the 'window', and I'm at tdc for #1, the chain probably hasn't jumped.BTW, whats an ESC? Link to comment Share on other sites More sharing options...
2seater Posted July 8, 2003 Share Posted July 8, 2003 You are probably correct in your conjecture. The cam sensor is used for injector timing only, and it is used to sense when #1 is on the compression stroke so the injectors start in the correct sequence. The crank sensor has two different sets of windows to give the ignition the same signal to get the ignition timing correct. The two sensors do different jobs but their purpose is somewhat the same. I believe the later model Series II did away with the cam sensor and the more powerful computer does both jobs from the crank sensor only. Link to comment Share on other sites More sharing options...
padgett Posted July 8, 2003 Share Posted July 8, 2003 That would be a neat trick since you cannot tell from the crank sensor alone which stroke you are on. Then again when mine failed the engine still ran well so maybe it just flips a coin and sees if the engine speed increases during crank. If not, try the other one. Or maybe it just remenbers where it stopped. Or maybe since it fires two cyl each time it does not really matter... Link to comment Share on other sites More sharing options...
harry yarnell Posted July 8, 2003 Author Share Posted July 8, 2003 Read my lips; CAM sensor. Link to comment Share on other sites More sharing options...
2seater Posted July 8, 2003 Share Posted July 8, 2003 You would be correct about the ignition not caring which is the correct cylinder to fire since they are paired and it fires every revolution, and I could be incorrect about the elimination of the cam sensor. The cam sensor signal is foolproof for determining the correct cylinder on compression but it is not critical to normal operation. Batch fire and continuous injection work well also, but probably not as smoothly or efficiently at lower speeds. I went back and looked at my cam timing spec's and the lobe center for my '90 is 114 degrees ATDC so if the injector fires during the valve open period (or just ahead of it), it would have to be well ahead of the actual TDC for the cylinder ready to fire. I will investigate further. <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" /> Link to comment Share on other sites More sharing options...
harry yarnell Posted July 8, 2003 Author Share Posted July 8, 2003 Well, the cam magnet isn't dead center of the hole for TDC of #1; more like centered at 6 o'clock in the hole for TDC. Verified on two engines. Engine will still barely run and backfire up thru the intake. I still suspect crank sensor. it was destroyed in removal (a common problem on mid Atlantic cars). Tomorrow is another day to purchase a crank sensor. Stay tuned. Link to comment Share on other sites More sharing options...
harry yarnell Posted July 28, 2003 Author Share Posted July 28, 2003 Well, I've been away from this problem car to take care of 'chores', and to get a fresh perspective. The problem, now, has been found! This rascal would barely run; backfire up thru the intake. I don't have an assistant to help, so it's difficult to see whats going on under the hood while your trying to keep it running from the cab, but I bet you could have heard the vacuum leak from the missing PCV hose/grommet. Not from the cabin, though.The entire rubber hose/grommet was MISSING. Gone. No where to be found. Engine runs fine now that the grommet has been replaced. I tried removing this item from three parts motors, and all three broke apart in an attempt to remove. Apparently getting brittle with age. This is another part that should be eyeballed from time to time as our cars get older.Don't forget the coolant bypass hose/fitting on '91 (and later on other GM makes) code L motors; they're plastic and have a history of breaking. Link to comment Share on other sites More sharing options...
Shelby Posted July 28, 2003 Share Posted July 28, 2003 As discover last Saturday the plastic vacuum supply tube to the HVAC controller is old and cracked. Small crack BIG problem. Big Pain In the butt. I am going to Check and/or replace all the vaccuum line. It look like Reattas get hardening of the the arteries at about 14 or 15. Link to comment Share on other sites More sharing options...
padgett Posted July 29, 2003 Share Posted July 29, 2003 Is part of the reason I run engines cooler than the factory did - plastic and rubber thingies last a lot longer. Link to comment Share on other sites More sharing options...
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