Just a reminder, fuel pressure is only 1/2 the story the other 1/2 is fuel volume.
It could possibly be a fuel filter or pump issue.

 

yes sir i under stand pressure and volume are two different things,,,i guess it wont hurt anything to just change the filter,,they are relatively cheap,, and it shouldn't take very long to do it

i will pick one up and put it on the to do list for this weekend while i am changing oil

ocharry

 

ok i'm back

pafman;

i did the power break thing for you,,not sure what i was looking for ,,i guess a miss when the pressure was on,,,didn't see anything,, no miss or vibration ,,nothing,,,but if that is what i was looking for,,,there are times when i am driving down the road when this old girl doesn't have a problem too,, and it could be for miles,, the problem isn't always there,,it is intermittent

i did the power break thing right after i started it,,took it up to about 2-2500 rpm for about 30sec,,,,nothing,,i drove it to town and stopped at the post office left it running,,when i came out i did it again ,, nothing,,,i drove to work,,which is 60 miles on the highway and did it again in the parking lot,,,nothing?????

as for the trm numbers,

ST FTRM 1% 0.0
LT FTRM 1% 0.0
ST FTRM 11% 14.1

these were the test results while running down the highway,,, cruse on 65mph,,,i was watching the numbers and they were moving around some,,i think that's what they are supposed to do with varying road and throttle conditions,,weather conditions were windy,,driving quartering into a SW wind

air intake sensor said 63*,,,motor run temp 194-199*

when the engine was cold the trim numbers were moving around from -.8 through -2.3 ,,,,they would cycle through those no. just repeating until the temp started to come up,,, when the motor was warmed up,,the numbers were similar,,but while driving down the road they did have a wider spread,, i think that is where the 11% thing is coming from,,i didn't wright the numbers down ,,kinda hard to drive and play with the scanner and right stuff down ,lol,,,,,also i would think the computer is watching fuel delivery and it should be varying with load conditions if everything is working right,, so the numbers should be moving around,,right??

all system checks were OK,,,,no codes

ok i think i got all the info you wanted

and if you think i should look elsewhere for the problem,,,you got any ideas where to look???? cuz i am out

i am going to change the oil this weekend,, and the fuel filter as suggested by hanky,,i put a new one in my oil box yesterday

i don't know maybe my scanner isn't as good as i thought it was,,it is telling me there isn't a problem,,, i think,,but i know SOMETHIG is amiss ,,lol,,pun there,,,,i feel it every time i drive it

ok,,guys anything else??? any thoughts??? things to look at or check???


thanks
ocharry

 

i wanted to see what the lt ftrm hot was too. if the lt trim is going up fairly high, you have a lean condition where the pcm it attempting to richen up the fuel mix. and the opposite is the case with a negative lt frim.

i once had this 01 gp with a 3.4 in the shop. when cold it ran fine but hot it would act up. it was misfiring but not recording them. after MUCH grief it turned out to be the reluctor on the balancer and the crank sensor. it was off enough to cause some slightly odd firing and a very high lt trim (which also destroyed the cat). i'm not saying to replace your's, but it may be worth a look into.

 

hi pafman;

well i had my scanner record the three fuel trim readings

so i went to the LT TRM and walked through the graph for you,,, it took 408 frames and i will read it for you ,,here we go

at frame 0,,it was reading 0.0,, kinda looks like just before that it was at .8,,and dropped to 0.0 at frame 0

at frame 33 it went back to .8
at frame 69 it went back to 0.0
at frame72 it went to -.8
at frame 233 it went back to 0.0
at frame262 it went to -.8
at frame 265 it went to -1.6
at frame 393 it went to -.8
at frame 400 it went back to 0.0

between the frame changes it was a flat line,,,so if i am reading this right,, the total swing here is 1%

all i have is the numbers this scanner is recording,,i don't really know what they are telling me,, or how big of a swing i can have and still be in what is,, " A GOOD ZONE "

i will say i notice the timing on this motor,, seemed kinda high to me but maybe that's how the newer motors operate,, was up around 40*,,IIRC
quite a change from the old days when i was making big ponies,,lol

so tell me about this reluctor,,is it a sensor on the block that reads crank position from the balancer for timing,,or other things,,, where is it located?? what does it tell the pcm?? is it on the balancer its self and the sensor is mounted to the motor to read the crank?? can it be moved to read differently?? man i got 50 questions about this one

tell me tell me ,,,LOL

also this may or may not help us with the run down,,,,this motor what ever is wrong with it and i'm sure there is a problem somewhere,,,,is still getting 30.5 to 31.5 mpg,, i have seen it at just over 32 a time or two ,, that could have been a good strong tail wind tho,,,,but it is consistently right in the 30.5 -31 range,,, and it seems to like shell gasoline better than other brands,,,,i had a 90 beretta that really liked BP gasoline,,,go figure

also it starts fine,, hot or cold,, when warm it does a very mild serg,, most people may not notice it,,like when i come to a stop,,brake on in gear,, there is a very small fluctuation going on,,if you look close you can see the tach riding it,, needle is moving with it,,i may be just super sensitive now because i'm looking for a tell here,,lol,, i don't know,,,just giving you all the info i have ,, or think i have

ok you have what i have,,difference here is you know what to do with it,, so please look the info over and let me know what you think,,,, and if you need more or other info i will try and make it happen,,, i really would like to put this to bed

thanks very much

ocharry

 

ok, i thought you were giving me hot and cold compairisons and left off the hot LT. lt looks fine to me.

the reluctor is nothing more than a metal ring that blocks the cps (crank postition sensor) from seeing itself in an on and off manner. picture the top of a rook in a chess set. if for some reason it moves or become damaged, all sorts of goofy things can occur. but i will add this would be VERY unlikely.

with your decription of it getting worse the hotter the engine gets, it sounds very cps related. could also be an ignition module.

the cps is located behind the crank balancer, and will require a balancer puller to change. the ignition module is located under the coils and will require much $$$ to change and a 5.5 mm socket.

you may want to have your MAF sensor (mass air flow) sensor cleaned. i would recommend letting a pro do this as they are VERY fragile and VERY $$$. it shouldn't cost much to do this and may solve the issue as well.

with out feeling it myself and being able to view data when malfunctioning it is very hard to make a judgement.

 

thanks for the input,,

i did buy a coil set and module used from a 98 with 43000 miles on it,, i thought i would change it out as a unit,,surely if the symptoms don't change that should rule out the coil and module,,,if that were to make a difference at least i will know what direction to look

well the crank sensor isn't a problem,,i have a balancer puller,, i still have those kind of tools from the old days when i was building motors,, maybe my old school stuff won't work on this newer stuff ,, we shall see

is there any way to check the crank sensor???

as for the mass air,,hmmm well i guess i will save that for last,,,since i am guessing,,,i will go for the cheaper stuff and see how it goes

yes i know about you not being able to feel what is happening,,,and the big problem is it is so sporadic

so,, oil change tomorrow,,and a fuel filter change and coil and module swap out

i can't thank you enough for the input,,and guidance,,,we will see where this leads

i will keep you up to date

thanks again

ocharry

 

Among the things it could be are;
Crank sensor,Ignition module,possible cracked spark plug, plug wire with a questionable connection. What brand plugs and wires did you install?
I know replacing a crank sensor can be a pain, but without some special diagnostic equip we're flying blind. Does the vehicle have a tach? If it does, when the misfire occurs , does the tach lose its signal and drop to almost 0 ?

 

hanky is right on with the crank sensor diagnosis, it's pretty indepth for a forum. but remember, the pcm is not registering any misfires, so that should rule out plugs or wires. i have seen ign modules & crank sensors cause wierd running symptoms without registering misfires.

also, a standard balancer puller will not have the attachment for pulling a 3.8 balancer. the threaded hole at the front of a 3.8 crank is VERY deep, and unless your puller has a VERY long arbor you will need this. i made my own attachment. you take a grade 8 7/16th (it may be a 1/2 inch but i will check mine) bolt, about 4 in long. put it in a vice and cut off the head (making it 3 in long). take a center punch and strike it in the center of the cut area. than drill into the center (7/16 bit) just untill you have a nice inverted cone for the puller cone tip to mate into. then after you remove the balancer bolt, you insert this new "tool" into the crankshaft and pull away. just remember to pull it out when finished!

instaling a new cps can be difficult to line up correctly so the reluctor does not contact the new cps! be very careful compairing the mounting of the old cps and new cps.

 

hanky;

i did replace the wires and plugs,,the problem didn't change from old plugs and wires to new plugs and wires,,,but they were ac iridium plugs and what ever the best wire set they carry at oreilly's i don't remember the brand name,,i used to use bosh wires but they don't have a lifetime warranty anymore,,,only 1 year,,,these plug wires had a lifetime warranty so that's what i went with,,seems like they were about 50 bucks,,,and the price of those plugs,,wow what a change in price,, and i did use the dielectric grease on both ends of the wires when i put them on,, and under the new coil when i changed it

i am going to change out the coil pack and module today,,hopefully that should eliminate the module and possibly another could be bad coil or weak coil

yes this car does have a tach,,and no when the problem is happening it doesn't go to 0,,,,BUT the RPM does vary some,, the tach will show a 100-200 swing,,,i have watched it and it is moving around when the whatever we are calling this thing,, when it is happening,,i thought that could be just the tach,,,and like i said in one of the other posts,,,when i get off the highway going to work there is a light i have to stop at and i,,just the other day noticed sitting there at the light that the engine was changing idle speed if you will,,kind of a really mild surge,,and the tach was riding that little wave,,up and down,,,may have only been 100-150 RPM,, but it was there

also when this motor is hot from running down the highway it does have a very noticeable stumble from drive to reverse when i change gears in the parking lot,,,sometimes its worse than others

and too there are times when it does this that it is no doubt a miss,,,it will be running fine,, then BAM,,1 miss,,,and back to running fine,,,i know this is a lot of stuff i'm throwing out here on the table for you guys to digest,,just want you to have all the info i can give you ,,,and i understand we are shooting in the dark


pafman;

i see what you are saying ,, all i need to do is fill up the crank hole so i don't mess up the threads,,,i can put a bolt in the lathe and make what you are talking about in a jiffy ,, no problem

ok guys i got to get at it here,,,THANK YOU BOTH VERY MUCH,,for hanging in there with me,,,and i hope i am not to much of a pain in the butt with this,,, but i am determined to figure this out,,one way or another

thanks again

ocharry