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Discussion Starter · #1 ·
I am trying to pinpoint possible reasons as to why my engine performance is not up to par. First off, here list of minor jobs done on it recently:
1) Basic tune-up (plugs, cap & rotor, air/fuel filter, oil change, canister filter)
2) Replaced noisy fuel pump with remanufactured pump, no change in performance.
3) Replaced fried Oxygen Sensor, noticed minor difference.
4) Replaced PCV valve (clogged), noticed no difference.
5) MSD Blaster coil on stock ignition
6) Complete use of Prolong lubricants (oil additive, fuel cleaner, transmission fluid, etc.)

Many of these helped, but there was still a major lacking in engine performance. Here are a few things I have noticed:
1) From idle, it hesitantly reacts to the throttle, it seems the gas isn't quickly being burned right when the gas is pushed ... ignition problem or fuel injection???
2) The low-end performance is quite sluggish, it accelerates like my parents crappy Geo Prizm
3) Will give a minor boost at around 20 - 25 mph if floored (after pressing the gas, car delays for about 2 seconds, then quickly revs up and lunges forward), but the engine power disappears again at about 35 - 40 mph. 4) All driving ranges it appears that the engine just can't get wound up very quickly
5) The car puts out black smoke only occasionally or in small amounts (collection of smoke on exhaust tip)
6) Engine had a tendancy to flood if not allowed to warm up in very cold weather.
7) Fuel seems to always burn too rich, even after replacement of Oxygen Sensor
8) Gas pedal seems loose, will tightening throttle cable make the pedal feel new again?
9) Vacuum pressure seems fine
10) Mechanic mentioned that valve seals seem to be a little worn, and that I am burning oil
11) If valve cover is removed, there are dried oil deposits around the cam and stuff

Lastly, once I had the thing running on only 5 of 6 cylinders for a few days (spark plugs were very fouled), and I am concerned that the unburned fuel in that unactive cylinder could have moved into my catalytic converter and possible damaged it (I don't know if this is possible, but I have heard that it can happen). I sure would hate to remove that cat, but I think I just might have to...

Sorry about the novel here, but I need some advice because i'm new to this car stuff being only 19. Thank you for your time and help.
 

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> I am trying to pinpoint possible reasons as
> to why my engine performance is not up to
> par. First off, here list of minor jobs done
> on it recently:
> 1) Basic tune-up (plugs, cap & rotor,
> air/fuel filter, oil change, canister
> filter)
> 2) Replaced noisy fuel pump with
> remanufactured pump, no change in
> performance.
> 3) Replaced fried Oxygen Sensor, noticed
> minor difference.
> 4) Replaced PCV valve (clogged), noticed no
> difference.
> 5) MSD Blaster coil on stock ignition
> 6) Complete use of Prolong lubricants (oil
> additive, fuel cleaner, transmission fluid,
> etc.)

> Many of these helped, but there was still a
> major lacking in engine performance. Here
> are a few things I have noticed:
> 1) From idle, it hesitantly reacts to the
> throttle, it seems the gas isn't quickly
> being burned right when the gas is pushed
> ... ignition problem or fuel injection???
> 2) The low-end performance is quite
> sluggish, it accelerates like my parents
> crappy Geo Prizm
> 3) Will give a minor boost at around 20 - 25
> mph if floored (after pressing the gas, car
> delays for about 2 seconds, then quickly
> revs up and lunges forward), but the engine
> power disappears again at about 35 - 40 mph.
> 4) All driving ranges it appears that the
> engine just can't get wound up very quickly
> 5) The car puts out black smoke only
> occasionally or in small amounts (collection
> of smoke on exhaust tip)
> 6) Engine had a tendancy to flood if not
> allowed to warm up in very cold weather.
> 7) Fuel seems to always burn too rich, even
> after replacement of Oxygen Sensor
> 8) Gas pedal seems loose, will tightening
> throttle cable make the pedal
> feel new again?
> 9) Vacuum pressure seems fine
> 10) Mechanic mentioned that valve seals seem
> to be a little worn, and that I am burning
> oil
> 11) If valve cover is removed, there are
> dried oil deposits around the cam and stuff

> Lastly, once I had the thing running on only
> 5 of 6 cylinders for a few days (spark plugs
> were very fouled), and I am concerned that
> the unburned fuel in that unactive cylinder
> could have moved into my catalytic converter
> and possible damaged it (I don't know if
> this is possible, but I have heard that it
> can happen). I sure would hate to remove
> that cat, but I think I just might have
> to...

> Sorry about the novel here, but I need some
> advice because i'm new to this car stuff
> being only 19. Thank you for your time and
> help.

This sugesstion is illegal, and I am only suggesting it, it is nothing I personally have ever done to a car (wink, wink, nudge nudge). Take the catylitic sp (should be held on by 4 bolts in front, for in back)off and proceed to hollow it out by jamming a pipe thru it. I realize that this is quite crude, but it works, or so I heard. It did wonders for my '79zx errr, I mean my buddies car, yeah thats it.
 

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Discussion Starter · #3 ·
You may want to get a new Cylinder Head Sensor (located between and below #5 & #6 sparkplugs). It made a difference on my '83. Your cat could be clogged as well. This can be checked by removing it and running the car aroung the block. It'll be loud.

> I am trying to pinpoint possible reasons as
> to why my engine performance is not up to
> par. First off, here list of minor jobs done
> on it recently:
> 1) Basic tune-up (plugs, cap & rotor,
> air/fuel filter, oil change, canister
> filter)
> 2) Replaced noisy fuel pump with
> remanufactured pump, no change in
> performance.
> 3) Replaced fried Oxygen Sensor, noticed
> minor difference.
> 4) Replaced PCV valve (clogged), noticed no
> difference.
> 5) MSD Blaster coil on stock ignition
> 6) Complete use of Prolong lubricants (oil
> additive, fuel cleaner, transmission fluid,
> etc.)

> Many of these helped, but there was still a
> major lacking in engine performance. Here
> are a few things I have noticed:
> 1) From idle, it hesitantly reacts to the
> throttle, it seems the gas isn't quickly
> being burned right when the gas is pushed
> ... ignition problem or fuel injection???
> 2) The low-end performance is quite
> sluggish, it accelerates like my parents
> crappy Geo Prizm
> 3) Will give a minor boost at around 20 - 25
> mph if floored (after pressing the gas, car
> delays for about 2 seconds, then quickly
> revs up and lunges forward), but the engine
> power disappears again at about 35 - 40 mph.
> 4) All driving ranges it appears that the
> engine just can't get wound up very quickly
> 5) The car puts out black smoke only
> occasionally or in small amounts (collection
> of smoke on exhaust tip)
> 6) Engine had a tendancy to flood if not
> allowed to warm up in very cold weather.
> 7) Fuel seems to always burn too rich, even
> after replacement of Oxygen Sensor
> 8) Gas pedal seems loose, will tightening
> throttle cable make the pedal
> feel new again?
> 9) Vacuum pressure seems fine
> 10) Mechanic mentioned that valve seals seem
> to be a little worn, and that I am burning
> oil
> 11) If valve cover is removed, there are
> dried oil deposits around the cam and stuff

> Lastly, once I had the thing running on only
> 5 of 6 cylinders for a few days (spark plugs
> were very fouled), and I am concerned that
> the unburned fuel in that unactive cylinder
> could have moved into my catalytic converter
> and possible damaged it (I don't know if
> this is possible, but I have heard that it
> can happen). I sure would hate to remove
> that cat, but I think I just might have
> to...

> Sorry about the novel here, but I need some
> advice because i'm new to this car stuff
> being only 19. Thank you for your time and
> help.
 

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You didn't mention how long it's been doing this, if it came on suddenly or gradually, or if timing was included in your minor jobs. I'd definitely double-check the timing before you start ripping the catalitic converter apart.
 

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Discussion Starter · #5 ·
Well, the engine has performed sluggish ever since I got it a year ago. I doubt it's the catalytic converter, so i'll check in more obvious places first. I had timing done on it once, and that didn't change things much (then again, I had a friend in autoshop check it for me), maybe I will get the timing looked at again.

Another thing I forgot to mention in my first post, engine seems to take FOREVER to warm up, could it be the thermostat?

Thanks.
 

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Re: Check the exhaust flow

> Well, the engine has performed sluggish ever
> since I got it a year ago. I doubt it's the
> catalytic converter, so i'll check in more
> obvious places first. I had timing done on
> it once, and that didn't change things much
> (then again, I had a friend in autoshop
> check it for me), maybe I will get the
> timing looked at again.

> Another thing I forgot to mention in my
> first post, engine seems to take FOREVER to
> warm up, could it be the thermostat?

> Thanks.

This is a crude cat test, but if it's really clogged, you should be able to notice. Have someone rev the engine while you have your hand in back of the exhaust pipe. I've actually seen a zx that was so clogged in the cat that you could hardly feel the exhaust when reved up.

It sounds like you wouldn't have missed this if so obvious, but... just thought I'd mention it.

After 15 or twenty years, these cats can become pretty limiting. I decided to check mine when I changed the tranny. I poured about a half a cup of crap out of it. Then it mysteriously got a hole in it. HUGE difference in performance. And mine didn't appear to be clogged.

Anyway, it's not difficult to remove, you really should at least pull it and check it.

My two cents,

Matt
 
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