PO305- cylinder 5 misfire

s70glt novice[Will] · Post by **s70glt novice[Will]** » 17 Jan 2012, 21:26

I got a CEL after doing a highway pull to about 130mph. Some said it was either fuel trim, as that is the limit for the GLTs and others said it was a misfire. It was... After that stunt, the car will some times skip or lurch forward when i really put the pedal down. (around 4k rpm) it sound as if the revs are dropping 500 and instantly going back up. The Tach has no change during this. Neither does boost pressure. The CEL will flash also.
I have disconnected the SAS bung to the exhaust (no port on the obx).
Any clues to what this could be? I really want to get it fixed by the weekend and get my 16t and Green tune in

thanks in advance!

Post by **rspi** » 17 Jan 2012, 21:35

Replacing the tune may clear up that issue. It's likely an injector/fuel delivery problem. I have spoken to people that have GLT's and they claim they have done 145+. I'd have to ask my daughter what's normal, I've never driven that fast.

Chances are it was a misfire. If that hesitation/bucking is consistent, I'd keep digging. Don't hear of to many problem over 70 MPH.

s70glt novice[Will] · Post by **s70glt novice[Will]** » 17 Jan 2012, 21:46

Its not consistent....it happenes sometimes and doesnt others. BUT when it does, it keeps bucking until i let off. And it wasnt at high speeds, just at about 70. the first time, and about 45 the next. the first time it caught me off guard, i was off the gas after about 3 "bucks" the next time, i kept on to read the tach, boost, and CEL. so about 5 seconds. lol, my eyes moved QUICK. and your daughter drives that fast?? normal? lol. at speeds up to 120 its fine. after that, it slows way down and i just need more space. But replacing the tune sounds risky. if it is the tune great, problem solved. but if it isnt, wayyyyyyyyyyyyyyy more stress, and i dont want to damage my engine. ive dumped lots of money and love and dont want it to die so close to the final product...

s70glt novice[Will] · Post by **s70glt novice[Will]** » 18 Jan 2012, 00:04

is that it? i would think theres a lot more to a misfire like this... any more suggestions? im installing the turbo and tune tomorrow with help from a friend. thanks for any more suggestions!

s70glt novice[Will] · Post by **s70glt novice[Will]** » 18 Jan 2012, 20:32

Uhoh... A new warning light flashed on for a second.... i keep getting problems. i also have delayed throttle response. could cleaning the throttle body help? anyway...this scared me...

The one next to the arrow and blabk space (is that supposed to be there? no? what is it then?)

I think this is a clue to my current problem...
Judging by the rough symbol, it might be the radiator fan not working.
for reference, i adjusted my wastegate two turns and i got a CEL from it. dont worry about boost, its still well within safe levels.

HELP?! Im planning to install the turbo and tune tomorrow, as today we loosened everything and soaked it in pb blaster.
I would like to know how to fix this. thanks in advance.

Post by **rspi** » 18 Jan 2012, 20:39

There is alway the chance that you have a tube that is collapsing causing your bucking??? Well, maybe not, I see you have silicone vacuum lines. How old are your wires, plugs, cap, rotor? Do you have a HD ingition coil?

Yes, my daughter does drive fast. I popped the GPS one day and seen 130 mph in there. I gasped for air.

I had a little talk with her and let her know that I would drop her off my insurance if she got a speeding ticket. If anyone will have that much fun it should be the person paying the insurance.

What octane gas are you running?

s70glt novice[Will] · Post by **s70glt novice[Will]** » 18 Jan 2012, 20:43

I replaced the cap and rotors when i got the car, about 2k ago. i used the good bosch ones. no HD ignition coil. wires are original. if by wires you mean spark plug wires? doesnt matter, i havent replaced any wires.

Thanks rspi, and everyone helping me.

s70glt novice[Will] · Post by **s70glt novice[Will]** » 18 Jan 2012, 20:49

Also, i believe the bucking is caused by the cylinder 5 misfire. Or would the misfire be caused by restriced boost? aka, all 4 cyl have enough air, but cyl 5 doesnt and therefore too much fuel is in the mix, causeing a misfire? there are no popping noises that would suggest excess fuel coming through the exhaust. My mileage has dropped to 18 (from about 20-22) although i have been deep in the pedal to try and locate whats going on.

89 octane. my dad doesnt believe the numbers and thinks its mumbo-jumbo, but i wouldnt let him put anything less then 89. i got a few tankfulls of 91, and it ran great! it may not be that though, as the symptoms come off and on

Also, what does the light mean?

Post by **rspi** » 18 Jan 2012, 20:58

Man, I hate to tell you this but the wires do matter. When they start breaking down it will show, especially under stress. They have a date on them, 02/98 (week/year). So, if they are older than 5 years old, i'd replace them.

I really don't think a misfire will cause bucking. I was thinking more like a collapsed turbo tube, or intake tube. Causing the car to starve for air or boost pressure. I really don't know that much other than what I try to remember from what I've read around these forums. You can try to ask the guys over on www.TurboBricks.com or www.SwedeSpeed.com.

s70glt novice[Will] · Post by **s70glt novice[Will]** » 18 Jan 2012, 21:05

thank you! ill check all my lines. and intake. i got a new k&n filter, that might help. and ill check the date, but i believe they might be from when my grandma got the car (2000) that would explain some of it...
thanks anyway, ill give the install a green light and if the problem persists, i wolnt drive the car under boost. (it will be so hard not to.....boooossssst

)