Car Hesitates...

97GTSTANG · Feb 26, 2008

Under WOT, my car hesitates, it acts like there is not enough fuel or some plugs are bad, i am not sure what it is. If i just shift under 3000rpm or let it climb slowly above 3K, then its ok, other than that, it will hestitate and the engine will make a noice like its straining.

Any suggestions?

Thanks

[BlackDiamond] · Feb 26, 2008

I'd try the simple things first like fuel filter and such, but it maybe the fuel pump problem?

TrueBlue03 · Feb 26, 2008

My car had the exact same problem. downshifting and then stepping on it, or just trying to step on the gas hard while passing someone...the rpms would start to climb normally, then cut out and cough and feel like it wasnt firing correctly at random spots intermittently above 2500 rpms....The car felt like it was missfiring, bogging down and cutting out like it didnt have fuel pressure.

I did quite a few searches on here and found a lot. As blackdiamond mentioned, There are many things that could be causing this. Start with the cheapest first.

Make sure Mass airflow sensor is clean/ properly functioning
Change fuel Filter
Change spark plugs
If this doesnt solve it, make sure your fuel pump is working correctly.
Also try disconnecting the battery to reset computer

i changed my fuel filter first, then cleaned out the mass air sensor then changed the plugs and disconnected the battery for 1 hour.... this cleared up about 95% of the hesitation... every now and then i get 1 little tiny hiccup. Could changing the spark plug boots help this possibly?

BLOWN00GT · Feb 26, 2008

i had a similar problem that might help... when i installed my blower i never regapped the plugs. it would drive fine under 4000 but anything over it just wouldnt go... it bucked and shook really bad. regapped my plugs and it was good to go... i would check plugs like they said and maybe you have a bad coil pack...

97GTSTANG · Feb 26, 2008

The plugs and wires were changed 4 years ago, maybe its time for a new set? I will get those replaced first them. for a PI Swapped car, the gap is at .54?

97GTSTANG · Feb 28, 2008

Is it time to change plugs if they were changed 4 years ago? THey are the Autolites copper.

TrueBlue03 · Feb 28, 2008

yea i would if tweaking with the other things didnt do anything. How many miles since you changed them?

StangYellow · Feb 29, 2008

97GTSTANG said:
Is it time to change plugs if they were changed 4 years ago? THey are the Autolites copper.

In my past experiences, copper plugs last less than 8K miles... at best. Get some normal Autolite plugs and I guarantee your problem will be gone

97GTSTANG · Feb 29, 2008

Thanks, I will do that. Since i had them installed its been about 45K miles

TrueBlue03 · Mar 2, 2008

Well my hesitation came back. Gettin pretty annoying. During WOT my car starts bucking and surging and coughing pretty bad... feels like missfire

What else could it be? the car has 42,000 miles on it...im doubting its the fuel pump.
-Would changing the spark plug boots help also?
-Maybe the TPS?
-Could it be that its out of tune? My car has never been tuned with the basic bolt ons it has and i'm running no cats w/ MIL eliminators.

Feels like a misfire but its not showing any missfire when i tried to get it diagnosed in the shop. When i changed the plugs the problem disappeared 95% but was back in full force 2 days later. Im tired of spending money and getting no results. The true meaning of fix or repair daily

RedDaemon · Mar 2, 2008

my car does this on occassion as well. ill get on the gas and it will hesitate and buck where if i try flooring it, theres no power at all.

subscribing.

Ryan441 · Mar 2, 2008

my car is also doing it. i think it might have something to do w/ bad gas maybe.

RedDaemon · Mar 2, 2008

ive changed both my plugs and COPs + boots. I believe one plug has moisture in it. When I am home for spring break I am going to check to make sure that the intake is not cracked and causing problems with the plug.

I have heard this suggested before, but only realized its possible relevance to me just recently.

TrueBlue03 · Mar 2, 2008

my car never exhibited any hesitation until I parked it and let it sit for 8 days. When I returned from the trip and started it, the hesitation/bogging/missfire became very evident on the first loop around the block, and has been doing it for a month.

I've been doing research on this problem here and on multiple other forums and everyone has their own suggested fixes, but none of them have worked on my car so far... I'm gonna run over to autozone today and pick up a couple spark plug boots to interchange and see if that does anything.

TrueBlue03 · Mar 4, 2008

well i changed the spark plug boots and the problem went away completely for 1 day. Parked the car, got up this morning to drive to school, and the problem showed up again. It's back at about 50% of what it originally was when it was really bad.

No one has any more suggestions?
The only thing i see left to change in the ignition are the COPs, but they look to be in fairly decent condition. I also tried cleaning the metal conductor in a couple of the COPs that had a little gunk on them, just to see if it would have any affect.... no luck

depressing. I finally have my GT at full bolt ons and it just craps out when i floor it anywhere from 2500 - 4000 rpms.

97GTSTANG · Mar 5, 2008

I have an appointment this week to get the plugs and wires changed, hopefully that will solve the problems for me. I hope its not a cracked intake, but if it was, then i should be loosing coolant?

TrueBlue03 · Mar 5, 2008

sometimes... but you never know where the stupid plastic intake manifold is going to crack. Also, it may be slowly leaking somewhere and you havent noticed it yet. I think i may almost be due for another as my second one is starting to ooze a little coolant in the same place before it blew out last time...directly under the aluminum crossover where it connects with either side of the manifold. stupid fords

but still no one else has anything to add about the hesitation?
the check engine light hasnt gone off even once during this past month of the car hesitating.

TrueBlue03 · Mar 7, 2008

bump for Update.
I got my car looked at again by another shop.

I dont want to spend an arm and a leg replacing everything...so what could be going wrong?
My fuel pump going bad? Fuel pump monitor/regulator? Or could my cars ECU be causing the fuel pump to do weird things?

Irish50 · Mar 7, 2008

I have the same issue, i hit a bump hard a couple months ago and my car started running poorly. I replaced my spark plugs with iridiums and cleaned my injectors and the car ran smooth as silk then I started noticing it returning in 5th while trying to accelerate to pass on the freeway. I replaced the plugs because one fouled out according to my check engine light, but since the replacement the light hasn't come back. The end of the month Im going out to my parents place, Im hoping to replace the fuel filter and clean out the intake sensor and flush my coolent, hopefully i find something. After hitting the bump i woundered if it could be a bad cat but i would imagine the car would hesitate more smoothly than acting like it's miss firing.

Irish50 · Mar 25, 2008

I have an update for my ride.

I changed the fuel filter and oil the other day and found that the problem hasn't changed. I did realize that my car appears to run perfect untill the engine gets warmed up, (I dont think driving the piss out of a car is good right after you start it) but i was able to get results by shifting to third at low rpm's and the engine didnt bog at all. as soon as it warmed up the bogging started right up, and then i drove the piss out of it and it feels like it's missing a little across the power band.

O2 sensors?
Bad Coil?

I dont think it's the fuel pump considering it acts fine before the engine warms up.

Any luck on your car?
Update???

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