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jazzmaster
jazzmaster, ASE Certified Tech
Category: Ford
Satisfied Customers: 2951
Experience:  ase certified--32 yrs experience
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93 f150 miss at all conditions- new cap,wires,plugs,rotor,coil

Customer Question

93 f150 miss at all conditions- new cap,wires,plugs,rotor,coil swaped out distrubitor(that helped a bit) cleaned pcv and iac- no codes scanner wont read at connector (fuses good)
Submitted: 1 year ago.
Category: Ford
Customer: replied 1 year ago.
ignition module was tested-came back good and I repaired 3 broken vac lines (bought it at auction)
Expert:  jazzmaster replied 1 year ago.
hi, what size motor is in this ?is this a bad miss or slight miss ?did you do a compression check of the motor ?
Customer: replied 1 year ago.
302 motor the miss is odd it starts out bad cant get it over 1000 rpm then it gets less can get up to 4000 rpm it (does not back fire or smoke any thing out exhaust) the plugs were normal color not oil fouled or damaged
Customer: replied 1 year ago.
is the fact where you plug in scanner not working tied into this and or do I need to replace the engine computer?
Customer: replied 1 year ago.
will it react if I pull the vac line to the fuel pressure regulator? I did it didn't change any thing so is that a problem there seems to be good engine vac. but I don't no shit
Expert:  jazzmaster replied 1 year ago.
did you check all the fuses ,if not that would be a good place to start .
that plug sometimes you have to wiggle the connector from the scanner in it .those were a little pain sometimes to get the scanner to read ..
I would do a compression check any ways
and you may want to check the exhaust back pressure to see if the cat isn't maybe clogged a bit
or a simple way but be careful because hot air will be coming out ,is to remove the o2 sensor before the cat and see if it has more power ..jazzmaster ..
No ,it wont change much when you pull the vacuum to the fuel pressure regulator .
Customer: replied 1 year ago.
all fuses in dash were checked (both sides) they were all fine---one fuse ---15amp under the hood was blown and I replaced that but still scanner no go (cigarette lighter/power point work) im not sure but the pipe was disconnected behind cats when I got it when the miss is bad that truck has no power at all and will shudder when it gets better it misses but I can get it up to 40 mph but wont spin tires (stock 15")
Customer: replied 1 year ago.
24 July 2015 05:26is the fact where you plug in scanner not working tied into this and or do I need to replace the engine computer?will it react if I pull the vac line to the fuel pressure regulator? I did it didn't change any thing so is that a problem there seems to be good engine vac. but I don't no shit
Expert:  jazzmaster replied 1 year ago.
I had accepted for the phone call but it showed that I didn't but I did ...jazzmaster ..
Customer: replied 1 year ago.
it never rang here on my end
Customer: replied 1 year ago.
funds are tight will do it by text
Expert:  jazzmaster replied 1 year ago.
ok,
Customer: replied 1 year ago.
so what about no change when I pull vac. line off fuel pressure reg what about engine computer? why would pluged partialy converters cause this miss?
Expert:  jazzmaster replied 1 year ago.
I mentioned in my one post that unplugging the vac at the regulator won't really change anything ..
if the vehicle is running the ecm is most likely not the cause of a misfire .
if the cats are clogged this causes more back pressure and the motor can't breathe as well ,most times the issue gets worse the warmer the motor gets or the longer it runs .
even though the plugs may look normal .
have you taken a fuel pressure check or checked the fuel filter ?
Customer: replied 1 year ago.
fuel filter was replaced with all the rest of the stuff so I guess hack off converters and see what happens them there aint much else I can do
Expert:  jazzmaster replied 1 year ago.
no, take out the o2 sensor before the cat and see if you have more power I wouldn't take off the cats if they are still good .
Customer: replied 1 year ago.
if I do will the miss go away or not
Expert:  jazzmaster replied 1 year ago.
most likely not but does this truck seem to have a lack of power other than the miss going on ?
have you done a compression test of the cylinders ?
if not that would be a good thing to do as it will tell you if that is the issue .a low cylinder will give you a miss ..jazzmaster .
that is one of the first things I do on a motor with a miss ,after checking the other basic things .
Customer: replied 1 year ago.
No tester I will get one tomorrow I'm not understand why its missing I no motor needs to breath but plugs looked good..if cylinder was bad wouldint foul plug or back fire or pull oil out exhaust
Expert:  jazzmaster replied 1 year ago.
not all the time do the plugs get fouled ,right away that is .a back fire may not happen either .
I really think a compression test needs to be done ,
this is often over looked and then people start putting in parts .
so ,please at least check the compression .
if that turns out ok ,then we can look at other causes .
thank you ..jazzmaster .
I just want to help you with this problem and I don
t want you to buy any more parts ,at least not yet .
It is important to check the compression !
Customer: replied 1 year ago.
I will get a comp tester tomorrow it has miles on it but the guy before me never put time into it or its its a differnt motor dash say 202121 miles. Calipers were shot rotor on pass side paper thin but still .what is acceptable comp range dry
Expert:  jazzmaster replied 1 year ago.
cool, the compression or should I say ,what you want to see is above 120 on each ,it could go higher up to 180 .if there is a difference of say you have 175-180 on all of the cylinders except one or two and that may read 100 that would give you a miss .
as long as there isn't a difference of more that 50=60 with the readings then we can proceed to look further .thank you for doing the compression .that hopefully will tell us more about the condition of the motor ....
WITH that many miles it could have a burnt valve or excess carbon in the valves .
I thank you ..jazzmaster ..
Customer: replied 1 year ago.
So no fix unless heads come off wow can't win thanks for your time but tomorrow i will toss compression test for my mind I'm gunna sell it for parts I guess
Expert:  jazzmaster replied 1 year ago.
ah, don't give up just yet..
I know how you feel ,after working so long on this and putting parts in .
so, let me know what the compression reads on all the cylinders and we can proceed more ....thanks
Customer: replied 1 year ago.
I will let u no tomorrow as far as plugs I pulled out 5 were normal 3 were nit like others they were damp not golden color but they were not carboned or oil fouled they still sparked ok the 3 were first 3 on driver side
Expert:  jazzmaster replied 1 year ago.
yep , let me know what the readings are then ,,thank you .
Customer: replied 1 year ago.
I can hold my hand over the exhaust and it feels very hot
Expert:  jazzmaster replied 1 year ago.
it is going to be hot .
were you trying to feel if there was a lot of exhaust pressure coming out ?
Customer: replied 1 year ago.
Yes that was the idea there is noticable pressure there can hear\feel miss at tail pipe but hot as hell
Expert:  jazzmaster replied 1 year ago.
yep, you will feel that miss at the tail pipe and yes, it should be hot ..
Customer: replied 1 year ago.
Well I'm off to bed I will be on at 8pm cst tomorrow
Expert:  jazzmaster replied 1 year ago.
ok, I will talk to you tomorrow ..jazzmaster ...
Customer: replied 1 year ago.
well the comp is 100-105 idn it seems to pick up acceleration (less sluggish) and I tried to power break it no go but I let off brake a bit then it did im wondering why the miss is less and what it takes to knock it out I got new gas in so im wondering if injectors are dirty and do they make some thing that cleans valves (additive-gas) so I don't have to rip that apart?
Expert:  jazzmaster replied 1 year ago.
the compression is a bit low ,so the vehicle may not have the power it had when the compression was better ..
The best way to clean injectors is power flushing them ,but they have a 3 stage kit .
one goes into the gas tank
one goes into the oil and the other is put in through the motor via a vacuum source .
to clean out the intake .
.it sometimes helps to ,while the vehicle is running to spray into the throttle body ,that will also clean out the intake ,throttle sensor ,and throttle body ..
the additive in the tank will clean out some carbon off the valves .
Expert:  jazzmaster replied 1 year ago.
If I helped you -Please rate me positive and we still can continue with this issue if needed .
this is the only way I get credit for helping .
please don/t rate if you are not satisfied yet ..thank you ..jazzmaster ..