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HELP!!!!!!forester stumble

Featured Replies

ok so the car is not mine

99 forester came in with blown motor(rod knock BAD)

had check engine light, abs light on

swaped in a nice 40k unit, clean motor

put motor in, new fuel filter, plugs, wires,pcv,air filter

do the usual warmup, no check engine light

good exhuast flow(no pluged cat)

heat kicked in nice and engine warmed up nice

shut it off and then fired it up to drive it

stumbles like a rabid dog, backfires, argues

then will run great, then it will crap out

what i know

swaped coil-nada

new wires plugs-nada

swaped/adjusted TPS-nada

idle control clean-nada

checked intake and exhuast-nada

fuel preasure is 40psi during stumble-nada

no check engine light

im really confused

it WILL run, and great, when its running right

its full of power and responsive, smooth idle

but nothing i do seems to make it right

HELP PLEASE!!!!

Howdy J, it's the devise located in the middle

of the firewall that sends the trigger pulses to the

coil pack.

 

Evo, I thought this at first also, but I believe he would

get a CEL for misfire if this or the coil pack was

the issue.

 

J, do you know how old the front 02 sensor is?

 

Did you use the original intake manifold and the

original sensors?

(i.e. crank, cam, CTS)

  • Author

no ignitor in usual place.

i now what you speak of, but there isnt one in that place

also

intake and sensors are from new motor

i have some sensors from old motor, no idea on o2

Possible the ignitor is mounted with the coil pack

as seen on page 5 of OB99W's link.

 

The knock sensor also comes to mind.

This year still has a MAF as I believe

they went to the MAP system in 2000.

 

Since you have most of these, it may be

a case of thowing the other parts you have

at it.

 

McBrat just had a similar problem with an EJ22T

(recent post)

turned out to be the 02 sensor.

 

Why no CEL is a mystery.

Here's a pdf that outlines the testing procedure for the updated coil/igniter assembly with 4 spades at the primary side.

Hopefully, the attachment shows up this time.

might be good to give exactly what the old (which we already know) and new motors are from.

year, vehicle, auto/manual.

  • Author

car is 99 forester auto

donor is the same

1 year engine car thing

fuel trims were peaking

im swaping front o2 now

  • Author

update

i think the front o2 did the trick

did a fresh restart from cold with a battery disconect

did its relearn fine, everything normal

test drive was good too

no problem at all

i put it in the yard to cool off and im oging to take a cold test drive in an hour to see if its fixed for good

  • Author

update,

front o2, both cats, still have issue

now it has to warm up before it will let the motor RUN

can go out and drive it, and for about 10 minutes it runs bad

and slowly gets better, then it runs fine

great power, full rev range

no CEL light ever

 

?????????????????????????????????????

  • Author

not being right, i think the rear o2 heater has failed and is sending the wrong signal till warm, any body owant to confer????

The rear O2 sensor is primarily if not totally for catalyst monitoring, and will not affect drivability like you are experiencing.

 

Should throw a code for O2 heater. Can you look at Amp draw on the heater with your scan tool?

 

What are the fuel trim #'s?

  • Author

well my monitor is a bit on the fritz, so icant give exacts, but lean, not rich, fuel presure is good, im guessing fuel is about 9.1 maybe less, so real lean

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