94 Bonneville won't go over 40 MPH

94SilverSSEi · Post by **94SilverSSEi** » Thu Jun 04, 2009 8:31 pm

Looking at buying this one car and the guy says it has an "acceleration problem" and that the car won't go over 40 MPH anyone know what this could be
Is it going to be an easy fix

Post by **Jrs3800** » Thu Jun 04, 2009 8:50 pm

Sounds like a clogged cat or fuel pump... But I would really need to look at the car to know for sure

93RedSled-SSE · Post by **93RedSled-SSE** » Fri Jun 05, 2009 9:00 am

Yes, and it could also be running in the "limp home" mode, if it is having an ignition control problem. Often, the engine feels like it is going to "fall out." 94-95 has that goofy OBD vintage (OBD-I with OBD-II connector) that makes it tough to check diagnostic codes without a plug/wiring adapter. My 2 cents, now I have NO sense.

2000Silverbullet · Post by **2000Silverbullet** » Fri Jun 05, 2009 9:56 am

The 94 went into that same limp home mode when the Throttle position sensor went bad ( actually it had melted ).

94SilverSSEi · Post by **94SilverSSEi** » Fri Jun 05, 2009 10:03 am

So how much just to get an idea would any of these problems cost?

2000Silverbullet · Post by **2000Silverbullet** » Fri Jun 05, 2009 10:07 am

The TPS is about $100 and it will take you 10 min to do it yourself.

94SilverSSEi · Post by **94SilverSSEi** » Fri Jun 05, 2009 10:11 am

What if it is the ignition control problem?
OR limp home mode
how woyld you fix this?

94SilverSSEi · Post by **94SilverSSEi** » Fri Jun 05, 2009 10:54 am

Just talked to the guy he said the car just isn't getting any gas and then it won't shift
Sounds like fuel pump and tranny too me
Any other suggestions

2000Silverbullet · Post by **2000Silverbullet** » Fri Jun 05, 2009 8:31 pm

Pull the PCM codes and it will tell you the problem. If you don't have a scanner go to one of the auto shops that does diagnosis for cheap.

Bonneville92V688 · Post by **Bonneville92V688** » Fri Jun 05, 2009 8:48 pm

2000Silverbullet wrote:The TPS is about $100 and it will take you 10 min to do it yourself.

$100 CDN I assume? Rockauto has the ACDelco for $60.79.

94SilverSSEi · Post by **94SilverSSEi** » Sun Jun 07, 2009 4:25 pm

Now he says the car won't run for very long or shift and it has that acceleration problem so anyone's 2 cents would be greatly appreciated
I'm gonna go look at it this Thursday and see what's going on and if I can get it home without towing it

1fatcat · Post by **1fatcat** » Sun Jun 07, 2009 6:11 pm

There is no way to tell without driving it or some diagnostic information. It sounds like it COULD be a badly plugged catalytic converter?

2000Silverbullet · Post by **2000Silverbullet** » Mon Jun 08, 2009 5:33 am

That happened to our 94. The honeycomb inside the cat broke and turned sideways blocking the flow. It overheated the exhaust manifolds and melted the TPS.

94SilverSSEi · Post by **94SilverSSEi** » Mon Jun 08, 2009 7:43 am

This sounds like my solution but is there anything that I could do to make it easier to get it home
Because the way he's putting it, it sounds like it would need to be trailered in its current condition

2000Silverbullet · Post by **2000Silverbullet** » Mon Jun 08, 2009 11:47 am

How far do you have to go to get home?

94SilverSSEi · Post by **94SilverSSEi** » Mon Jun 08, 2009 12:30 pm

Not sure about 40ish miles
Mapquest said 42 mins
The guy said it wasn't driveable very far so I was wondering if there was something I could do to make it run better at least to limp it home

2000Silverbullet · Post by **2000Silverbullet** » Mon Jun 08, 2009 1:24 pm

I drove the 94 like that for about 20 painful miles with hazards flashing letting others pass.
You could loosen off the exhaust flange where the pipe mates with the exhaust manifold to relieve the pressure.........assuming that is what the problem is.

If it's flat and level with minimal stops, you should be OK.

94SilverSSEi · Post by **94SilverSSEi** » Mon Jun 08, 2009 2:19 pm

Thanks
I guess we'll just take it for a test drive and see whats what and see if we think it can make it home if not it will have to be towed

94SilverSSEi · Post by **94SilverSSEi** » Mon Jun 08, 2009 11:37 pm

How would I go about checking the cat to see if it is any good and where is the tps located and how do you check that

Oh btw I don't have a scanner so I need some help before I get there

1fatcat · Post by **1fatcat** » Tue Jun 09, 2009 9:34 am

You check the cat by measuring the back pressure in the exhaust between the engine and the converter. Anything over 1.5 psi at 1500 rpm is considered restricted. In your case, if the cat is causing the problem, you should be seeing 3 or more psi at 1500 and 20+ psi at WOT. You check it through the front O2 sensor hole or by drilling a 1/8 inch hole in the exhaust pipe just before the converter and measure the pressure comming out with a vacuum/pressure gauge.

The gauge you need is probably $20 for a cheap one. Maybe you would be better off to have an exhaust shop do a back pressure test for you? I would think you could find a shop that would do it for around $30?

PontiacBonnevilleClub.com

PontiacBonnevilleClub.com

94 Bonneville won't go over 40 MPH

94 Bonneville won't go over 40 MPH

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