Fuel air mixture problems??? possibly timing??

Demon_Crest · 12-08-2007, 05:19 AM

89 xt6 w/ 2.7L

I dont really know whats going on for sure but i think i've narrowed it down to being a problem with the fuel air mixture. It sputters when idling and as soon as i give it gas it starts backfiring out the intake. Its completley robbing me of all my power.

I've had to deal with this problem once before. At that time it was the fuel. This time i factored it out. It has brand new fuel injectors, fuel filter, spark plugs, distributor cap and rotor. All my vacuum lines are hooked up. Im kinda running out of options on what to do. (other than taking a hammer to it... lol) I dont know if it could also be the timing too. The accelerator seems sluggish instead of quick and responsive.

Any ideas??

somick · 12-08-2007, 12:14 PM

As far as know timing should be 20 degrees BTDC. What is your reading?

Do you have any codes stored? Did you try D-check?

Next step would be probably compression check.

Sam

Demon_Crest · 01-11-2008, 08:23 PM

Ive been busy working a lot. but since i lost my job i have decided to take a couple minutes to look into the car again. I found out the problem. Had to look at reference pictures i made to realize it.

I hooked up my throttle cable to the cruise control and the cruise cable to the throttle. I reversed them and put them back in their correct spots and the problems seem to have worked themselves out.

Thanks for the info on the timing. It turns out that i had it timed right to 0 degrees. i made the neccessary corrections and it is runnin pretty good now. Thanks for the help.

Demon_Crest · 01-21-2008, 08:30 PM

ok now im bak near step one. it was runnin fine and just now started actin up again. it wasnt till i was driving uphill and it started to stall out and lose power. its backfiring thru the intake again. i checked the timing and its still good. (note- when i first checked it it was at 10* btdc and not 20*) im startin to run low on options. there arent any mechs here that have a clue what theyre doin when it comes to workin on it. patience is runnin low.

somick · 01-22-2008, 12:22 PM

You sound exactly like me. The only difference is that I drive 92 Loyale 1.8. That might be the Subaru thing!

Check out your PCV valve.

My vacuum lines are also all hooked up but they are old and hard as a rock. I am planning just to replace them and see wether this will help.

Try www.ultimatesubaru.org. This site is really greate and the members there are more knoledgeable than some mechanics.

Good luck,

Sam

Demon_Crest · 01-22-2008, 08:59 PM

thnx alot. i always hear ppl complainin about pcv valves goin out that it just never crossed my mind. i appreciate it. luckily enough i think its the first part i can buy that wont cost me an arm and a leg. only $6

somick · 01-24-2008, 05:10 PM

Quote:

Originally Posted by Demon_Crest

thnx alot. i always hear ppl complainin about pcv valves goin out that it just never crossed my mind. i appreciate it. luckily enough i think its the first part i can buy that wont cost me an arm and a leg. only $6

A week ago I bought one from Kragen made by Fram, installed it... and put back the old one. I suggest you to go to dealer. It should not be that expensive.

Sam

Demon_Crest · 01-26-2008, 04:48 AM

hmm. no such luck. im guessing the only thing left is the throttle itself. i think i need to check into the throttle positioning sensor. ill try to get a video so you guys can see and hear exactly whats going on. it might make more sense that way.

maybe i just missed hooking up a wire somewhere. or maybe i damaged the throttle positioning sensor. im gona check into that tomorrow.

by the way my pcv valve was clogged and not working properly.

somick · 01-28-2008, 01:55 PM

There is a testing procedure for TPS both in Haynes and FSM. Since you drive 2.7 I do not know wether it is the same as mine 1.8. Try the site I mentioned above. They have tons of information there.

Sam

somick · 01-28-2008, 02:16 PM

How about your MAF?

Did you test it?

Demon_Crest · 02-01-2008, 07:46 PM

Update:

Ive spent a good deal of time at USMB. They have all been a lot of help. I did a code check and found out it was my IAC and o2 sensor. Turns out it was just a bad o2 sensor. MAF turns out to be good. While replacing the o2 im gona do a backflow test to see how the cat is doing.

I also found out that i did my timing wrong. It turns out that your supposed to have the 2 green plugs(the ones in the trunk next to the ecu) plugged together while u do your timing.

So close.... Yet so far.

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