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Hank

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Since: Dec 11, 2005
Posts: 29



(Msg. 1) Posted: Mon Jul 16, 2007 9:55 pm
Post subject: 85 2m4 engine problem
Archived from groups: alt>autos>fiero (more info?)
85 2m4 180K miles runs good cold after it warms up it looses power on
low rpms. The car when i say it looses power it like stumbles or bucks
mainly noticable uhen the rpm's are low like running on the highway
climbing a hill at 60 65 mph it will buck if I down shift to 4th
getting rpms up it will climb the hill easier Also when I am first
getting onto the highway it will start to buck if I try to accelerate
to quickly.

I replaced the O2 sensor as it had a code and I replaced the plugs,
cap & rotor and one plug wire as it was 18K ohms the rest are around
2K. swaped the MAP sensor and replaced the TPS as well.
I replaced some of the more older looking airline tubes as well.
There are no codes at this point.
Any help would be great as its driving me crazy.
Hank

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Les Benn

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Since: Dec 24, 2006
Posts: 95



(Msg. 2) Posted: Tue Jul 17, 2007 9:03 am
Post subject: Re: 85 2m4 engine problem [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
"Hank" <hank.RemoveThis@guess.net> wrote in message
news:m73o93p8jb7nc7nnq2ujifclflhqb59idd@4ax.com...
> 85 2m4 180K miles runs good cold after it warms up it looses power on
> low rpms. The car when i say it looses power it like stumbles or bucks
> mainly noticable uhen the rpm's are low like running on the highway
> climbing a hill at 60 65 mph it will buck if I down shift to 4th
> getting rpms up it will climb the hill easier Also when I am first
> getting onto the highway it will start to buck if I try to accelerate
> to quickly.
>
> I replaced the O2 sensor as it had a code and I replaced the plugs,
> cap & rotor and one plug wire as it was 18K ohms the rest are around
> 2K. swaped the MAP sensor and replaced the TPS as well.
> I replaced some of the more older looking airline tubes as well.
> There are no codes at this point.
> Any help would be great as its driving me crazy.
> Hank
Hank have you changed the fuel filter?

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Brian

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Since: Jul 08, 2005
Posts: 30



(Msg. 3) Posted: Sun Jul 29, 2007 5:58 pm
Post subject: Re: 85 2m4 engine problem [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
Have you checked the exhaust backpressure yet? You could have a clogged
catalytic converter, muffler or collapsed pipe. You can check it at the O2
sensor location. The book mentions that it should be no more than 1-1/4 psi.
That may cause the idle problem as well as loss of power after building up
pressure..unrelated to the temp. It would also cause the temp to increase
faster than usual as the pressure builds. Might be worth investigating. My
first guess would be clogged cat since that is common on older vehicles.
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Hank

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Since: Dec 11, 2005
Posts: 29



(Msg. 4) Posted: Tue Jul 31, 2007 9:55 pm
Post subject: Re: 85 2m4 engine problem [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
On Sun, 29 Jul 2007 17:58:53 -0500, "Brian"
<bds1computer.TakeThisOut@sio.midco.net> wrote:

>Have you checked the exhaust backpressure yet? You could have a clogged
>catalytic converter, muffler or collapsed pipe. You can check it at the O2
>sensor location. The book mentions that it should be no more than 1-1/4 psi.
>That may cause the idle problem as well as loss of power after building up
>pressure..unrelated to the temp. It would also cause the temp to increase
>faster than usual as the pressure builds. Might be worth investigating. My
>first guess would be clogged cat since that is common on older vehicles.
>
Not sure how I can check that out ?
Hank
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Brian

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Since: Jul 08, 2005
Posts: 30



(Msg. 5) Posted: Fri Aug 03, 2007 5:04 am
Post subject: Re: 85 2m4 engine problem [Login to view extended thread Info.]
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remove O2 sensor and attach a guage there?
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ron41

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Since: Apr 12, 2004
Posts: 11



(Msg. 6) Posted: Wed Aug 29, 2007 9:42 pm
Post subject: Re: 85 2m4 engine problem [Login to view extended thread Info.]
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get you an oem vac, that is the problem had it for years before I
figured it out. replaced with junk copy it ran for a while then
problem came back, thought that couldnt be it just replaced it. got
oem and sure enough. oh and it was heat related and will never ever
give you a message! cost like $40 but i would bet my $40 on it!

On Fri, 3 Aug 2007 05:04:44 -0500, "Brian"
<bds1computer DeleteThis @sio.midco.net> wrote:

>remove O2 sensor and attach a guage there?
>
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