loss of power with more throttle

[Torinalth]

well, this happened twice before, but it was very minor, and quickly went away... now its stying here. I can go around 1/4-1/3 throttle and everythihg acts fine... 1/2+ throttle and i get a little surging or it just boggs masssivly...

first i thought it was my clutch letting go, but the RPMs dont go up... I thought my rera end was dead.. but still would have the RPMs spike. I can go 70 on the highway, but i cant accellerate to pass someone. my fuel filter was changed 15-20k ago, been running 89 in the tank. only engine mods are in my sig. MAF is stock origional, i dont seem to see any leaks in the track... will look more into that later.

oh, this only happens under load... i can jam the gas and spike to redline in neutral... its only when its trying to push the car. possibly the MAF going bad? vacume leak? pump going out? clogged injectors? will seafoam the car tonight to see if that can help.

anything else?

Torinalth

 

[DBMSTNG]

my guess is a vacuum leak.

 

[tha great one]

i hd that problem one time before but it was just the rubber lining on my K & N filter came off and was getting sucked up in my MAF and clogging it up. I doubt if thats it but just check anyway.

 

[steve kelekian]

Check the obvious: plugs are tight, coil wires are good and not shorting out, vacuum leaks. Then check the fuel pressure, make sure it is within spec. could have a restriction in the tank at the fuel pump. That's why you only see it once an awhile and now it is here to stay. Pressure test could show signs.
Good luck!

 

[merc123]

Make sure your air intake is tight. I messed around with my CAI and the tube came off right behind the MAF. The car would actually stall and not restart.

 

[kid rock]

+1 to the vacuum leak/check your cai!

Si

 

[streethorse]

if not a vacume leak, sounds like a fuel problem, you may have pumped
some ethanol gas that dispersed water or trash in your fuel system, may as
well change that fuel filter to eliminate that posibility.

 

[Yellow2002GT]

Check plugs and intake track first for loose fittings or tightening up. Then check all your vacum lines and fittings. If you run your tank close to empty alot your filer could be bad also......if all the above are good its more than likey the fuel pump! Steeda has a stock replacement that flows 40% more fuel......My car was starving for fuel on top end also....changed the filter and pump and made a huge difference!

"ED"

 

[Torinalth]

well i poked around for a while and think i have it figured out... the intake is fine. went over everything with a fine tooth comb and carb cleaner (to rev the engine if there IS a leak) and found nothing... however i dont have a definate answer, but i know its now some sort of fuel issue.

this happened when i was at about 1/4 tank and the temp was over 93 (one of the hottest days so far). i let it sit for a while in the parking lot while i did some office work (bout 30 min) and it wasn't nearly as bad, but was still an issue. i ran it down a lot farther that i usually let my fuel lever go, but wanted to see if it was bad gas/vapor locking/water/etc.

anyhow, i dropped 4 gallons off new 89 and it seemed to go away. had a few slight hesitations on my first WOT hits and since then its smoothed out and havnt seen the issue again. I am kinda wondering if my pump is going out and the heat was killing it. without enough fuel to cool it (the new fuel is always cold, and kinda thinking it got the pump back to normal temps?)

aside from the pump getting hot, the only other thing i can think of was either garbage in the tank that was "swooshed" away with the new fuel being dumped in, or something....

I'll be working at making it happen again this week (supposed to be pretty hot) and see if i can narrow it down.

Torinalth

 

[Torinalth]

pulled the codes on the car from the SES light at advance auto and said cylinder 1 and 5 are getting misfire... replacing plugs tonight and seeing what happens. wish me luck

Torinalth

 

[Torinalth]

how cold does the engine have to be? its lightly warm to the touch now, heads are maybe 20 degrees above ambient... i really want to get theis done tonight instead of having to wake up early.... its been sitting for bout 5-6 hours now, hood open. thoughts?

Torinalth

 

[merc123]

Tried seafoam yet?

 

[Torinalth]

current plugs are copper top and bottom, and are now at the 40k mark... going to replace them tomorrow morning and the seafoam the hell out of it (intake and tank) and pray its fixed I'll let yall know tomorrow. going to let it sit overnight and get completely cold, then get a jump early tomorrow.

Will post results when i am done and have tested it a bit.

Torinalth

 

[merc123]

Change plugs AFTER seafoaming, not before.

 

[stangGT97]

Change plugs AFTER seafoaming, not before.

agreed, you don't want to risk fouling brand new plugs. Also, 40K on coppers is kind of a lot of miles, I wouldn't doubt that is the source of your problem.

 

[Torinalth]

weeeeeelllllll the car wouldnt stay running any more once i got it home... so i couldnt seafoam it... just had to let it cool so i could change the plugs and pray that was the problem... well, changed them out to NGK TR55IX (yes the iridium, wanted to give em a try for myself since there were lots of posts for and against them) and it fired up and stayed running, good sign.

inspecting the plugs, well the problem was evident... since i dont know the cylinder numbers, i'll use my naming process P and D for passenger and driver, and 1-4, 1 being towards the front, 4 towards the cabin.

these were Autolite 764s, ran nice, but they had at least 40k on them, and some hard abuse too.... D1&d3 had fair deposits on them, slightly ashy in color as well, especially around the base of the electrode. D2 was pretty well charred, and ironically D4 was the best looking of the lot. P1 and P3 were horrid, charred pretty well, with a semi brownish tint. the center electrode was very worn at nearly a 45* angle and the top electrode was a lot thinner then the others. P2 was normal wear, if night slightly ashy... P4 was the worst... nearly gone center electrode, very worn top electrode, and blackened, heavily.

now that the new plugs are in it seems to be running correctly.. seems a little rough... a little... but it might be my imagination after it was running so damn poory over the last 2 days. will be beating on it today and the rest of the week to see how it turns out. it did get noticably worse in the heat... and its fairly cool today as its raining... so when it gets to mid 90s again i'll know for sure if its fixed.

oh, the COPs were great. no signs of rust, wear, anything. all seated well, and gripped the plug nicely. also took the time to disassemble the entire intake track from filter to plenum (since the motor was too warm to change the plugs at the time) and made sure everything was put back together sealed and tight. didnt think this was the problem... but always nice to make sure.

Thoughts?

Torinalth

 

[stangGT97]

well if your car drives better w/ new plugs then that may have been the only problem. Its too bad you didnt seafoam before putting in the irridiums, you might also have a lot of buildup which is causing your car to run rough

 

[Torinalth]

thing i dont get, why would there be a problem with seafoaming it now with new plugs... just doesnt make sense... granted i dont know everything... but to me it doesnt seeem to make a difference.

Torinalth

 

[stangGT97]

well think of all the carbon that will be burning off when you run seafoam through it... i just wouldn't want to expose all that junk to my new plugs in order to avoid the risk of fouling them

 

[SigmaPride]

This is a debatable issue, but I know people that have done it on new plugs with no problems. You could argue that its going to clean the plugs anyway. I'd bet you'd be fine either way. Run half in the intake and the other half in your gas. If you are worried just wait until next time.