Maybe it's the computer??!!

[jonysho]

I thought my timing belt was bad but when I tore into it I think it may not be. I went ahead and replaced it just in case it might have slipped or got off time, and so I can say it has a new belt.

But the only thing i can think of now is maybe the computer. has anyone ever had their SHO just die and not restart becuase of a bad comp. Let me know if this might be it. ANd also if anyone has or knows where a good computer might be for a 91' MTX. Thanks alot!!!

The SHO from HEEEELLLLLL!!!!! shoot shoot

 

[jonysho]

My SHO is my daily driver so I need to get it going quick. Any info would be appreciated.

I sure hope I get it fixed soon. The funny thing about the SHO is no matter how much trouble you have with it you can't wait to get it fixed and feel that" pull you through your seat acceleration after 4K. thumbs_u thumbs_u Gotta love the SHO. Of course I haven't felt that in about three months.

 

[SHO Boom]

have u tried the obvious things, like checking grounds and loose connections, have u replaced the cps and cid? dont just assume its a computer, check the little things first

 

[SHOfear]

Yes, my XJ2 went one day after an electrical storm, must have been struck by lightning. The car, however, still runs with a faulty computer. It will start up, but as soon as it shuts down, the engine will flood and not start up again. I would check your CPS, and could very well be a loose connection. From the brief description you just gave, it sounds like a CPS. SDPatt would no better than all of us. Give a full description of the problem, an hopefully he can chime in.

Steve

 

[jonysho]

What is the CPS? WHere is it located?

Here is a descrition of what has happened to my car. This may be long because the problem has been going for a while.

About 3 months ago I started to notice a drop in power, not too much but still noticable. Then the problem got worse. It became hard to start, would run very doggy if I just jumped in and took off. It would just sputter and almost die when I tried to accelerate. I would have to feather the throttle until the RPM's built up. If i let it run for about 2 or 3 minutes it would not cut out when i would take off, but it would still run very badly. It acted like there was a major restriction somewhere. So I checked the fuel filter, pump, lines...all good. Then I thought maybe the cats were clogged, so I had them removed. Still no effect.

I then ran the codes and it said I had faulty fuel injectors. I replaced the the whole rail and all with new injectors. Came back code 9 (all good). STill no go.

Checked out the MAF, TPS, and the coil. No problems.

I replaced the plugs and wires. Plugs are properly gapped and the wires are on correct. We checked timing. It came back 20 degrees ATDC. Then on the way home my car died completely. Won't restart, THe timing belt looked fine but As I said earlier I replaced it anyways. I haven't got it back together yet but I don't think that was the problem. I have checked everything I know to check and am at a complete loss.

Are there any other ideas as to what could be wrong?? Please, this is driving me crazy.

We also checked compression, came back 150 across all cylinders. WHat the heck is it?

 

[RStalveyARFF]

150 for compression? damn that's low. should be around 190 across the board.

 

[SHOfun 93]

Check your TPS voltage, and your EGR area. Mine bucked and acted crazy when my EGR nostrils got clogged. I am not sure what kind of exaust gas recirculation that the gen 1s have but it might be that..

 

[jonysho]

What is the EGR? Where is it at. How do I clean it. Or fix it?

 

[SHOfun 93]

Right behind the throttle body on the intake, when you pull the throttle off, you will see 2 snake-like nostrils. Often those get carbon buildup on them and will cause the car to run badly, bucking and stuff like you said. Best thing is to remove the intake off the motor, then remove the throttle body, take some berrymans B-12 cleaner and spray out the intake, and make sure that you take a hanger and poke it through those "nostrils" and make sure they are clean. I did that on mine and it still didn't help, because the small DPFE sensor on the rear of the intake was faulty on my 93. Heck I am not sure that you gen 1 guys even have a DPFE, but start by cleaning those little nostrils. I think some guys have pics of what I am talking about and can help you with pics to match my description. thumbs_u

 

[Todds93SHO]

CPS is Crank Position Sensor. If this is gone it definitely won't run because the computer won't know where the crank is, or for that matter when #1 cylinder is at top dead center.
To check this, when you're cranking the engine over to start it the tachometer should move, the needle should go to about 5-700 or so. that shows the CPS is working.
Give it a try if you haven't already.

 

[sdpatt]

The CID (cam) sensor is the one that tells the EEC when the #1 cylinder is at top dead center and is used only during cranking. The CPS creates three spark events per crank revolution to provide the base 10 degrees BTDC timing to fire the plugs (The EEC uses the other input sensors to adjust this for the engine conditions). Either of these sesnors failing would not cause the gradual loss of power you described. They would cause hard starting (but normal running) or no running at all, respectively.

This sounds like restriction of the fuel supply system or the exhaust system. Jonysho, you said you checked the fuel system. Did you verify there was about 40 psig at the fuel rails? Did you check the pump or replace it?

When you removed the cats, were they intact with no loose internal parts? If the ceramic was damaged, it may have traveled down the exhaust piping to restrict the resonator or even the mufflers. Can you separate the cat-back and blow through it with a leaf blower to verify good flow?

There is something really wrong if you are measuring 20 degrees ATDC for the ignition timing. This should be impossible. When you replaced the timing belt, was the Woodruff key on the crankshaft in one piece? Only if the crankshaft timing belt pulley has been re-aligned by a failed Woodruff key could the timing be far from 10 degrees BTDC. Could you please describe how you are measuring the timing? If it truly is 20 degrees ATDC and the Woodruff key is okay, the EEC itself may be failing.

The cylinder compression is a bit low, but the engine should still run. It just may not put out the original 220 hp.

I am sorry you are having so much trouble with you SHO.

 

[luigisho]

jonysho, GenI cars don't have the EGR system as far as I know. The only exception might be a California emissions vehicle.

 

[Toolman]

The compression tester would not hold pressure, but what it did show was that they were all equal enough across the board. And the cats were in good shape when removed, so I don't think the exhaust is our problem.

 

[jonysho]

I am not to familiar with the whole timing bit but I am quite sure I put the new belt on right. Tommorow I will check to see if the CPS is working. I will also check to see if the fuel pump is working. Might have Toolman send me that 190 LPF, need it with my mods anyways. It has to be either fuel or fire. What are the odds that the computer might be whacked and be the cause of all my troubles. There were times when my LPM was loose and didn't get a good connection. Could this have screwed up the computer?