• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

99 backfires

1

1980dg

NAXJA Forum User
Location
st marys wv
i have seen this listed a lot of times but no one has a real fix my 99 backfires when i am driving around 2500 rpms it also idles real bad but only sometimes has anyone fixed this and sometimes when you stop at a stop sign it will die

things i have done
new parts
tps
crank sensor
air temp sensor
flushed radiator new temp sensor thermistate
sparkplugs thay were white running lean
new cat side o2 sensor
cleaned header side o2 sensor
cleaned idle sensor and the intake
seafoamed
cleaned all conections on everything
i checked for arking plugs in the dark

the codes i am getting are open injector curcuit 1 and 3 i have put a screwdriver up to my ear and the injecter and thay all hit the same even when it acts up

i am going to check fuel pressure monday does anyone know what that is supposed to be at i read it in here but cant find it again 50 lbs and then kill the motor and should only leek down to 30 lbs in 5 min is that right

this is my first post and my first offroad project i was raceing rc cars for years and went full size so forgive my if anything i have said sounds dumb
 
For 2000, it's 49.2 +/- 5 PSI. Try plugging and unplugging all of the connections you can see like the injector plugs, PCM plugs, etc. to cut through any old age tarnishing of the contacts.
 
1980dg said:
sparkplugs thay were white running lean
Click to expand...

The fact that your plugs show that you are running lean may be a big clue. Backfiring can definitely be indicative of a "lean" condition.

I would suggest some comprehensive VACUUM testing. Use a vacuum gauge; vacuum testing can tell a lot about how an engine is performing.

Common culprits would include intake manifold, throttle body, be sure to check all CCV plumbing while you're at it.
 
ok i will pull the injecters and swich them around also a vacuum test and a fuel pressure test thank you for input also i dont know how old the fuel filter is i got the jeep cheep becouse it backfired it was doing this when i got it
 
Don't forget to check the EGR. If a 99 has EGR.
 
Thanks for info on the EGR.
 
Do you mean with the switch in the RUN position you can remove the key?
 
your running to rich, which is why it is back firing. the unburnt fuel leaves through the exhaust and when it hits the cat ignites. The leaky injector could cause this
 
Jeepcherokeeboy97 said:
your running to rich, which is why it is back firing. the unburnt fuel leaves through the exhaust and when it hits the cat ignites. The leaky injector could cause this
Click to expand...

First post says plugs were white. Sign of lean, right?

And no, key coming out won't cause your problem. If you continue with this lean backfiring you could burn an intake valve. You can do a compression check on that, but if it already had happened, you should have seen a difference in your spark plugs. You say they were white and didn't say that any plug looked different than the others.

Hopefully you'll find an intake leak.
 
You must log in or register to reply here.

Similar threads

O
2000 XJ Failed Colorado Emissions high CO
2
Replies
27
Views
2K
Ken M
K
V
High temp woes
2
Replies
21
Views
399
Vitzaa
V
A
Renix TPS nightmare
Replies
19
Views
3K
Saudade
Saudade
C
91 XJ missing at 2000 +rpm only when at operating temp
Replies
0
Views
1K
cptmiker
C
S
another No Bus and faulty instrument cluster thread...
Replies
0
Views
28
stuckinthemidwest
S
Back
Top