92 PU $800 spent, still runs bad after 2 weeks in shop

92 Nissan PU 2.4 Litre/146 cubic inch OHC , 4 cyl , Elect Multi-PT fuel injection feedback fuel system, catalytic converter

Crikey, My mechanics have changed out the computer module, the throttle sensor and also some kind of air sensor all supposedly related to a fuel injection problem

They also, replaced the timing chain, worn but not totally kaput yet. ( approx 110,000 miles )

My wife say's it lugs down at high speeds when you hit the accelerator

I noticed while it's idling, when I advance the accelerator ( in neutral ) at some point the engine seems to throttle excessively.

In other words, the acceleration of the motor doesn't seem to track the gas pedals position linearly, but maybe this is normal for an unloaded engine,, dunno.

I guess it should be mentioned that the mechanics put in "used" parts salvaged off of another truck which had been rear ended. We don't use this truck nearly as much as a lot of people might, so I am thinking, perhaps the parts they put in might be as worn out or even worse than the originals.

I guess the question is,,, does this seem like a familiar problem?

If so, rather than trouble someone to re-post old news, what then might be good keywords to use in a google search of the archives of this newgroup for previous discussions about this problem?

PS. another question. I have a degree in electronics and am experienced in componentl level debugging of microprocessor based systems. So, I'm not intimidated by the electronics of the fuel injection system, however, as knowledgeable as one might be in this field, troubleshooting such circuits are a major ordeal unless decent service literature can be obtained

So, the last question is,, what kind of service literature can I expect to find in this regard? I'm guessing that the microprocessor module is going to be treated pretty much as a "black box" with little or no information as to what's inside it,, right?

Thanks very much But even more, thanks from my wife who is at wits end needing her truck.

--Dave--

Reply to
Dave Moore
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Reply to
Al's

TPS ?

Reply to
Meat Plow

Did ya bother to have the fuel injectors cleaned?

Reply to
doS

Bingo.

Zero.

Exactly. There are stand alone EFI systems that allow the user to program the fuel curves etc (we install these systems on -hot rod- cars) but for the OE electronics, they don't supply any info on the core programing.

BTW this sounds like a "hot wire" air sensor problem to me. Someone with some sense might be able to clean it and fix the problem. Has anyone checked the fuel pressure when the problem occures? Another question, are you using bosch platium spark plugs? I've seen these cause all kinds of starnge problems like this.

Reply to
Steve T

thanks, I'll check into those things

: >

: > Crikey, : > My mechanics have changed out the computer module, : > the throttle sensor and also some kind of air sensor : > all supposedly related to a fuel injection problem : >

: > They also, replaced the timing chain, worn but not : > totally kaput yet. ( approx 110,000 miles ) : >

: >

: > My wife say's it lugs down at high speeds when : > you hit the accelerator : >

: > I noticed while it's idling, when I advance : > the accelerator ( in neutral ) at some point : > the engine seems to throttle excessively. : >

: > In other words, the acceleration of the motor doesn't seem : > to track the gas pedals position linearly, but maybe this is : > normal for an unloaded engine,, dunno. : >

: > I guess it should be mentioned that the mechanics put : > in "used" parts salvaged off of another truck which had : > been rear ended. We don't use this truck nearly as much as : > a lot of people might, so I am thinking, perhaps the parts : > they put in might be as worn out or even worse than the : > originals. : >

: > I guess the question is,,, does this seem like a familiar problem? : >

: > If so, rather than trouble someone to re-post old news, : > what then might be good keywords to use in a google search : > of the archives of this newgroup for previous discussions : > about this problem? : >

: > PS. another question. I have a degree in electronics and : > am experienced in componentl level debugging of microprocessor : > based systems. So, I'm not intimidated by the electronics of the : > fuel injection system, however, as knowledgeable as one might : > be in this field, troubleshooting such circuits are a major ordeal : > unless decent service literature can be obtained : >

: > So, the last question is,, what kind of service literature can I : expect : > to find in this regard? I'm guessing that the microprocessor : module : > is going to be treated pretty much as a "black box" with little : or no : > information as to what's inside it,, right? : >

: > Thanks very much : > But even more, thanks from my wife : > who is at wits end needing her truck. : >

: > --Dave-- : >

: >

: :

Reply to
Dave Moore

Not sure, I'll ask the mechanics whether they did that. thanks

: >

: > Crikey, : > My mechanics have changed out the computer module, : > the throttle sensor and also some kind of air sensor : > all supposedly related to a fuel injection problem : >

: > They also, replaced the timing chain, worn but not : > totally kaput yet. ( approx 110,000 miles ) : >

: >

: > My wife say's it lugs down at high speeds when : > you hit the accelerator : >

: > I noticed while it's idling, when I advance : > the accelerator ( in neutral ) at some point : > the engine seems to throttle excessively. : >

: > In other words, the acceleration of the motor doesn't seem : > to track the gas pedals position linearly, but maybe this is : > normal for an unloaded engine,, dunno. : >

: > I guess it should be mentioned that the mechanics put : > in "used" parts salvaged off of another truck which had : > been rear ended. We don't use this truck nearly as much as : > a lot of people might, so I am thinking, perhaps the parts : > they put in might be as worn out or even worse than the : > originals. : >

: > I guess the question is,,, does this seem like a familiar problem? : >

: > If so, rather than trouble someone to re-post old news, : > what then might be good keywords to use in a google search : > of the archives of this newgroup for previous discussions : > about this problem? : >

: > PS. another question. I have a degree in electronics and : > am experienced in componentl level debugging of microprocessor : > based systems. So, I'm not intimidated by the electronics of the : > fuel injection system, however, as knowledgeable as one might : > be in this field, troubleshooting such circuits are a major ordeal : > unless decent service literature can be obtained : >

: > So, the last question is,, what kind of service literature can I : expect : > to find in this regard? I'm guessing that the microprocessor : module : > is going to be treated pretty much as a "black box" with little : or no : > information as to what's inside it,, right? : >

: > Thanks very much : > But even more, thanks from my wife : > who is at wits end needing her truck. : >

: > --Dave-- : >

: >

: :

Reply to
Dave Moore

: > I guess it should be mentioned that the mechanics put : > in "used" parts salvaged off of another truck which had : > been rear ended. We don't use this truck nearly as much as : > a lot of people might, so I am thinking, perhaps the parts : > they put in might be as worn out or even worse than the : > originals. : : Bingo. : : : >

: > PS. another question. I have a degree in electronics and : > am experienced in componentl level debugging of microprocessor : > based systems. So, I'm not intimidated by the electronics of the : > fuel injection system, however, as knowledgeable as one might : > be in this field, troubleshooting such circuits are a major ordeal : > unless decent service literature can be obtained : >

: > So, the last question is,, what kind of service literature can I : > expect : > to find in this regard? : : Zero. : : > I'm guessing that the microprocessor : > module is going to be treated pretty much as a "black box" with : > little or no : > information as to what's inside it,, right? : : Exactly. There are stand alone EFI systems that allow the user to program : the fuel curves etc (we install these systems on -hot rod- cars) but for : the OE electronics, they don't supply any info on the core programing.

)`:

: BTW this sounds like a "hot wire" air sensor problem to me. Someone with : some sense might be able to clean it and fix the problem.

There's a gizmo ma-bob that they gave me that he said was some kind of air sensor, and he said, "see how that dirt dauber ate through the side of it" because the edge of it was chewed off and there was a dirt dauber mud nest on it also. However, I think it got chewed by a small rat or mouse that was living in the truck until it got gutted by the fan belt or something one day.

Sometimes when we'd back the truck out, the little guy would bail and head back for the garage. I tried to catch the little bugger, but he out maneuvered me :-) So the next plan was have one of our better mouser cats ready to do the honors, but twice when I had the cat on standby, the little guy was nowhere to be found. Then after that, his luck turned sour anyway.

So, I have the gizmo ma-bob that is supposed to be an air sensor and looking inside you can see some kind of gold plated structures in it. I''ll drag it in tomorrow and have a better look.

Something should probably should be mentioned. When the motor is started cold, it starts ok, but after it has run awhile and is at a stable operating temperature, it has trouble starting.

So this would seem to jive possibly with what you said about the hot air sensor maybe?

However, when it has trouble starting, it acts like the starter motor is too weak to crank the motor, like the battery is weak or there's too much voltage drop to starter motor. But I still am scratching my head as to why any of those things would be worse when warm.

I mean, even if you were to remove all gas and fire from a motor, the starter motor should still crank the engine at least 10 or more revolutions I would think, but when it's warm, you better hope the fire and gas kick in after a few revolutions or you're out of luck.

So I believe that the starting problem is probably a separate problem from the other high speed lugging problem IOW, a problem with the battery, solenoid or starter motor. Unless the friction of the motor is simply becoming atrocious when it's hot.

I'm not too worried about the sarting system problem, I can certainly diagnose that myself, but the high speed lugging problem is a bit beyond my scope of knowledge, which ends at standard old time carburetion

: Has anyone : checked the fuel pressure when the problem occures?

The mechanics supposedly originally fixed a problem with the fuel pressure being too high. Unfortunately, I haven't gotten them to relate specifically what was causing that problem and just exactly what they replaced or did to recitify it.

:Another question, are : you using bosch platium spark plugs? I've seen these cause all kinds of : starnge problems like this.

It's quite possible I am. I recall buying some at one time. But though I do remember putting them in my 82 Corolla wagon, I can't recall if I put any in the truck.

Anyway, the trucks back with the mechanics and one guy said that perhaps it needs a bit of tweaking after the new micro-module self adjusts itself, or after the other parts seat or break in some.

I should have some word soon, and if they nail it, I'll certainly report the results. If not, I'll just jump off the nearest bridge :-)

Thanks a lot for the advice

--dave--

: : -- : : Steve : :

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Reply to
Dave Moore

: >

: > Crikey, : > My mechanics have changed out the computer module, the throttle sensor and : > also some kind of air sensor all supposedly related to a fuel injection : > problem : >

: > They also, replaced the timing chain, worn but not : > totally kaput yet. ( approx 110,000 miles ) : : TPS ?

I give up, what does 'TPS" mean ?

Reply to
Dave Moore

Throttle Position Sensor

Reply to
willshak

: >: >

: >: > Crikey, : >: > My mechanics have changed out the computer module, the throttle sensor and : >: > also some kind of air sensor all supposedly related to a fuel injection : >: > problem : >: >

: >: > They also, replaced the timing chain, worn but not : >: > totally kaput yet. ( approx 110,000 miles ) : >: : >: TPS ? : >

: >

: > I give up, what does 'TPS" mean ? : >

: Throttle Position Sensor

Oh, that's all ? Thanks. There's some guy in another newsgroup whose handle is "TPS", so I thought maybe it had some kind of esoteric meaning or something :-)

They did change out the TPS, only they got it from another truck in a wrecking yard which might even have more wear on it, who knows.

I did some measurements on the original one and the resistance is very solid without any bad spots, except near the beginning of it's travel there are some inconsistancies. ( assuming that "the beginning of it's travel" is at the position where the internal spring returns it to)

Considering that the problems seemed to occur around the midpoint of the accelerator, I guess any inconsistancies at either end of the TPS probably wouldn't account for the problem.

Reply to
Dave Moore

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