99 safari misfire

[since_1971]

1999 safari 2 wd 178K

cant get better than 15 mpg combined

was getting the dtc 300 code,

I have a consiant missfire, I think it is on #3 cylinder at lower speeds.( seems to even out at hiway speeds )

I installed the wires and sprayed the senonddary ign system for cracks.

I changed the coil/plugs/wires/cap/rotor. the cap/rotor twice, cuz I noticed a small crack, in which I think is #3 side. ( would an worn dist. cause that? )

the van had a bad cat when I got it so the problem could have been there for a while.





changed the fuel filter last year and tried to keep at least 25% of fuel in it.
have not changed the crank pos. sensor.

I sometimes smell alittle fuel after I shut it off but could not find the leak.

the mechanic wants to change the distubotor and the upper intake manifold gasket.

kind of stumped here

Carl

[Phantom]

That code means that misfire is random (coming from various), often caused by a faulty or cheap quality Distributor cap and rotor , Check this TSB bulletin it may help.

[rev_les]

X2, and check the distributor gear for any grooves. Be sure to mark it WELL before you pull it out, it's easy to drop back in a tooth off.

[since_1971]

I first put a summit brand in, then replaced it with another generic.
still has the miss, both times
should I try an ac delco?

[Phantom]

I first put a summit brand in, then replaced it with another generic.
still has the miss, both times
should I try an ac delco?

Yes, or preferred one that has brass terminals ( Accel brand , or MSD) , they resist corrosion better and give better electrical contact than the aluminum terminals , Ac Delco will work fine though .

[since_1971]

got it, good cap/rotor
but would a intermittent misfire only on #3 indicate a bad fuel injector/spider?

[Phantom]

The code for misfire on cylinder #3 would be P0303, why do you say #3
You might have a clogged injector , but P0300 is a random misfire code whens means it is random cylinders that are misfiring , not necessarily the same cylinder each time , have you had it scanned recently to see if more codes show up? a weak camshaft sensor can cause it too , but it has a code of P0340 that may not show up it it is only intermittently .

[since_1971]

because I can hear #3 click in the cap.
before it was 030x...when it was random, now just cylinder #3.
It still be a bad cap/rotor. will also check dis. gear

[Phantom]

because I can hear #3 click in the cap.
before it was 030x...when it was random, now just cylinder #3.
It still be a bad cap/rotor. will also check dis. gear

You can hear #3 click in the cap? How can you tell ? 1 , 3 , 5 within ans inch of each other ,
P0300 - random misfire ,, means various cylinders are misfiring ,
P0301 -cylinder #1
P0302 - cylinder #2
P0303 -cylinder #3 etc. .....030x would indicate any of the P030x codes , have you had it scanned recently?
if you hear a click in the cap you should look to see if any debris in the cap

[since_1971]

it was a new clean cap

[rev_les]

Run some fuel injector cleaner through it as well, you may have a poppet sticking...it might not be ignition related at this point.

[since_1971]

right, the fuel system has not been check, other than visually., When I got the van I bought the factory manuals, and it says to check that some how...
thanks

[since_1971]

I got a some berrymans
I threw the can in, well not all of it...I saved some for later.
Man that stuff is not cheap, but works every-time. It costs more than beer, so I figured I can kill to birds with one can...as well as a few brain cells
Not really,I hope it works

[since_1971]

ok hello there board...

put in two cans of fuel treatment...berrymans and the big bottle of lucas.. drove 250 miles----no change

there is a fork in the road..
my mechanic wants to change the distributor ( the whole thing not just the gear )
and
change the seal in the intake manifold, not the one to the engine, the plastic to plastic one.
for a total of $650.

It feels like a scam.. It was running fine in till he tuned it up..

I'm still thinking it's a vacuum leak..

I just don't know

Carl

[since_1971]

ok hello there board...

put in two cans of fuel treatment...berrymans and the big bottle of lucas.. drove 250 miles----no change

there is a fork in the road..
my mechanic wants to change the distributor ( the whole thing not just the gear )
and
change the seal in the intake manifold, not the one to the engine, the plastic to plastic one.
for a total of $650.

It feels like a scam.. It was running fine in till he tuned it up..

I'm still thinking it's a vacuum leak..

I just don't know

Carl

[Phantom]

Have you cleared the codes and no more codes returning? if you have a P0303 code that would be cylinder #3 , and may be a weak plug wire, here is a vacuum line diagram to check with .

[since_1971]

is the #3 plug hard to get to?
I suspect it could of been skipped on the tune up

[Leeann_93]

You'll need a swivel socket, but it's not that hard. Go through the wheel well; it's the easiest way.

[rev_les]

number 3's easy to get to....put the front up on jack stands, even easier of you pull the front tire.

[since_1971]

We out a new distro in and no change.
and checked the fuel pressure--- 40 to 48 psi i think.
checked for vac leaks...none..

but with the dog house off and at night I clearly see the problem.


This mis-fire was caused may defective sparkplug wires...
has anyone seen this kind of discoloring?

thank you to all those who helped...

now for a mpg test