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 Post subject: No power getting worse
PostPosted: Wed Jul 08, 2015 4:59 pm 
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Joined: Wed Jul 08, 2015 3:50 pm
Posts: 2
Year and Trim: 1991 Pontiac Bonneville se
I have a 1991 Pontiac Bonneville se I have replaced the fuel filter the spark plugs new battery new alternator the heat sensor for the fans. The problem I have and is getting seriously worse is when I start up and put in gear I have to put in first gear because when it is in over drive or drive it won't go anywhere no power but when in first it has enough power to get going and when the rims get around 4000 I can shift into 2nd and so on and so forth where do I start.

PostPosted: Wed Jul 08, 2015 6:47 pm 
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Joined: Tue May 27, 2008 8:53 am
Posts: 5387
Location: Las Cruces, NM
Year and Trim: 1993 Buick Park Avenue
1994 Buick Regal Custom
I don't recall the exact issue, but you likely have an issue in the transmission.

There have been multiple threads you may wish to search for that have come up over the years.

Some had the issue where the car wouldn't move until the transmission warmed up, other indicate no engagement unless using the 1/2 option on the gear selector. It usually boils down to a pan drop and filter change in the tranny with new fluid, possibly a faulty pressure modulator, or an internal issue.

THis is assuming the issue is that the transmission is slipping, which sounds like what it is doing.

Did the issue arise after swapping the mentioned parts? Were the above parts addressed simply because they failed, or was it in an attempt to resolve this issue?


1993 Buick Park Avenue - 197k - Some odds and ends done - Simply won't die
1994 Buick Regal - 78k - Bone stock - Always ready for a good kicking
1990 Oldsmobile 88 - Gone to a better place

PostPosted: Thu Jul 09, 2015 4:53 am 
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Joined: Wed Jul 08, 2015 3:50 pm
Posts: 2
Year and Trim: 1991 Pontiac Bonneville se
The parts were changed to resolve the issue. Before the parts were changed the car would have no power when there was 1 8th of gas in the tank but if it had more than that it would get up and go.

The last thing I changed was the plugs and wires and it got worse but the fans also stopped working and I haven't got that fixed yet. I did though run a toggle switch to turn the fans on all the time. I just need a little help to fix my Bonne and all info is appreciated.

PostPosted: Thu Jul 09, 2015 1:08 pm 
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Joined: Thu May 01, 2014 9:37 pm
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Year and Trim: 1993 SLE
1998 SE
2001 SSEI
2002 SSEI
Although it sounds like it may be a slipping transmission, it's difficult to determine from your descriptions whether the problem is instead with the engine or a restricted exhaust system.
I am including as many details as possible because I have absolutely no idea whether you have extensive experience with car repairs or are just starting to learn how to fix your own car.
The intention is to be very informative, rather than insulting.
Do the engine RPMs increase but the car does not go forward or do the RPMs not increase much?
When the car is idling, is it running smoothly or is it running rough?
Was it much worse immediately after you replaced the spark plugs?
Were any of the spark plugs fouled or abnormal looking when you removed them?
Here is a very good illustrated page of what spark plugs should and should not look like
Here's another chart

If it got worse immediately after replacing the spark plugs, a spark plug wire may have been connected onto the wrong plug.
Original coils are stamped to show which wire goes to which cylinder.
All the odd numbered cylinders are closest to the radiator, even cylinders are (obviously) closest to the firewall.
Cylinder #1 is the cylinder closest to the radiator and the tire on the passenger's side of the car.
You can check here if your coils are not marked
It is also possible that one or more spark plug wires has gone bad.
You can either replace the wires if they are very old or just check them.
Visually, there should not be any cuts or gaps in the boots or insulation.
You can check them with a multimeter set to 20,000 ohms scale and make sure that each wire is able to conduct the electricity to your spark plugs.
The shorter wires should all read around the same resistance and the longer wires will have somewhat greater resistance but still be close to one another in resistance.
Things I would do after checking the plugs and wires:

1)Check the computer and see if any diagnostic trouble codes have been set
You do that by following the instructions here:

2) If any codes are present, you can find what they indicate here .
Post your findings whether codes are present or aren't, to help others be able to help you.

3) Check fuel pressure with a fuel pressure gauge.
These can often be borrowed from AutoZone or Advance Auto, etc. if you don't want to spend 35-50 dollars to buy one.
Expect the reading at idle to be around 38 PSI.
It is also a good idea to check and see that the fuel pressure increases by about 10psi when you disconnect the vacuum line to the fuel pressure regulator.

4)Vacuum readings can tell you a good deal about the engine and vacuum gauges are inexpensive.
Again, they may be available for loan from some parts stores.
With the engine warmed up at idle, there should be a steady reading of 17-21 inches of vacuum. Next, hold the engine RPM at 2000 and watch the gauge. The pressure should momentarily drop but then go back to being close to what it was at idle.
If the pressure slowly drops, then you have a restriction in the exhaust system.
This would either be damage to the exhaust system or a clogged catalytic converter.

5) The transmission, if slipping, will cause the RPMs to increase when you give the car gas but the car won't go forward powerfully.
The very first thing to check is that there is enough transmission fluid in the tranny.
Fluid should be checked with the car warmed up and idling, while on a flat surface.
It is best to slowly shift the lever through all the gears before checking the level, for greatest accuracy.
Too much fluid is as detrimental as too little.
You can find more details here
If the fluid level is right where it should be, then I would do a transmission filter and fluid change.

Hope this helps and that you will let us know what you find.

Your fans will not work if the coolant level drops too low.
With the engine cold, check to see that the radiator and coolant overflow tanks are full.

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