1991 SHO sputtering an hesatating when accelerating.

[Bryan]

As the title says my 91 SHO feels like its hesatating, sputtering and even sometimes bucking when I go to accelerate. Idling for the most part is smooth. But when you go you can really feel it.

 

[sperold]

Could be a lot of things, but the first thing to eleminate is the Throttle Position Senser (TPS).
Get some codes read with a scanner or the paper clip method.
Your symptoms can be caused by a great number of things, but start with the simple ones.

 

[rubydist]

yup, first thing to do is pull the codes.

codes on the obd1 will not always point you to the problem, but if they do, you know you are not wasting money guessing.

but, a sick tps will generally not throw a code, so if you get no codes - replace the tps.

 

[Bryan]

Ok will do that and get back as soon as possible.

 

[Bryan]

Okay ran the test (as best as I can figure) About three times just to be sure. And it seems I only got two codes.

41 and 11. Hope this helps.

 

[rubydist]

11 is the code for 'all clear'
41 says right (rear) bank is lean

41 could be caused by a bad o2 sensor, since they typically fail by reading lean. However, it could also be caused by a bad vacuum leak. If the car really is running lean, that will typically result in a big drop in both power and fuel economy. To further complicate this, a bad tps will typically cause the pcm to think the throttle is less open than it really is (and for some reason the pcm prioritizes the tps above the mafs) and that will cause the engine to lean out badly at certain throttle settings.

If you have not changed the o2 sensors of late, I would replace at least the rear one. I would be very temped to also put on a new tps, as they are not real expensive. Then, reset codes and see how it runs and what codes appear.

 

[Bryan]

Ordered a tps from my local parts store today. It should arrive by tomorrow so we'll see how it goes after I get it swapped out. And thanks for the heads up.

 

[Bryan]

Installed the new tps and sadly the car is still bucking, sputtering, and a general loss of power. I am assuming my next spot to check th plugs, wires or injectors. I am gonna take her to my local shop first and find the root of this problem.

 

[AREA 91]

Installed the new tps and sadly the car is still bucking, sputtering, and a general loss of power. I am assuming my next spot to check th plugs, wires or injectors. I am gonna take her to my local shop first and find the root of this problem.

You can always drop it off to me for some love.

 

[SHOdded]

Check out the plug wires, plugs, and DIS. Any/all of these could be causing misfires. Check for oil in the plug wells, that could be shorting out the plug(s). Also check if the plugs smell of unburnt fuel. The coil is generally foolproof, so highly unlikely to be the culprit. Then move on to the injectors if all of the above check out.

 

[Bryan]

Check out the plug wires, plugs, and DIS. Any/all of these could be causing misfires. Check for oil in the plug wells, that could be shorting out the plug(s). Also check if the plugs smell of unburnt fuel. The coil is generally foolproof, so highly unlikely to be the culprit. Then move on to the injectors if all of the above check out.

The plug wells are probably full of oil since my plug well seals as well as the valve cover gaskets are bad (burns off about a quart every two weeks because of this) so I'll pull the wires tomorrow. And what is the DIS? Also is it hard to reach the back plugs? The front 3 seem easy enough to get to, but becauseof the air intake the back ones look like it would be a challenge to get to.

 

[SHOdded]

The DIS is part of the ignition system, a gray flat module that sits on the passenger side of the intake; can't miss it. Some things known to go wrong: the connectors break, taken off and not reattached with enough heatsink grease, loose/incorrect mounting bolts , or the module may actually be faulty.

The "rear" plugs are more effort to reach, but with some patience + a long extension socket, doable without removing the intake. A mirror will help with inspection once you pull the wires off. Take your time to do it.

Since you believe you have oil in the plug wells, I would first make sure the wells were cleaned out and dry before removing the plugs. Don't want anything falling into the combustion chamber. If the plugs are stubborn, a very small amount of penetrating oil let sit for some time (overnight) should help.

 

[Bryan]

The DIS is part of the ignition system, a gray flat module that sits on the passenger side of the intake; can't miss it. Some things known to go wrong: the connectors break, taken off and not reattached with enough heatsink grease, loose/incorrect mounting bolts , or the module may actually be faulty.

The "rear" plugs are more effort to reach, but with some patience + a long extension socket, doable without removing the intake. A mirror will help with inspection once you pull the wires off. Take your time to do it.

Since you believe you have oil in the plug wells, I would first make sure the wells were cleaned out and dry before removing the plugs. Don't want anything falling into the combustion chamber. If the plugs are stubborn, a very small amount of penetrating oil let sit for some time (overnight) should help.

Okay I'll check it out and thanks for the heads up!

 

[rubydist]

if you do take it to the shop, take it to AREA91, not just some regular mechanic who has no idea how the SHO works - it was hard to get a mechanic who knew what to do with a SHO back in the day, much less now...

 

[SHOdded]

if you do take it to the shop, take it to AREA91, not just some regular mechanic who has no idea how the SHO works - it was hard to get a mechanic who knew what to do with a SHO back in the day, much less now...

x2 on this.

 

[Bryan]

You can always drop it off to me for some love.

Hey that would be great! So how do I get in contact with you so you can take a look at the car?

 

[Bryan]

Update! I checked the DIS Module... The plug on the back side (closer to the firewall) is cracked and half of it is broken off. The plug is still attached to it, but I gather its time to replace it. Cleaned out the front 3 plug wells (full of oil) and put them back in. I didn't attempt the rear 3. Simply way too much in the way. Guess it would be best to remove the air intake. Is it hard to take it off?

 

[Bryan]

Just pulled the codes and this time I got 24. What does this one mean?

 

[SHOdded]

http://www.shophoenixproject.com/eec/code2.htm

24 Intake Air Temperature (IAT) or Vane Air Temperature (VAT) sensor out of range - IAT VAT

Not sure what that really has to do with the issues on your car. Have rarely seen an actual IAT fault mentioned, more likely wiring.

Several threads will come up when you search for "IAT Range". An example:
http://www.shoforum.com/showthread.php?t=124438

But replacing the DIS plug is looking like a good move. The break possibly happened due to an accident or bad engine mounts.

 

[Bryan]

But replacing the DIS plug is looking like a good move. The break possibly happened due to an accident or bad engine mounts.

You are correct. The car was in an accident at some point. I had to replace the Sub frame,motor mounts, transmission mount, front suspension, sway bar end links, tie rods, strut rods, brakes and the passengers side drive axle. I have only now gotten into the engine problems. Also I think I may have bumped something to get that one code. Will try and see if anything popped off when I was checking out the rear plugs.