bad injectors?

95five-oh · Oct 25, 2006

When i rev my car out past around 3500rpm, it makes a pinging, knocking sound. It doesnt do it every time, sometimes i can wind it clear up to 5k and it doesnt make the noise. Other times tho it starts knocking its a** off when i get close to 3.5k, and loses a considerable amount of power. It also seems like it does it worse when im really on the gas; if i slowly creep up the rpms its not as noticeable. I just cleaned my MAF, the injectors are original but were flushed about 15000 miles ago. Any ideas what might cause this? btw its much more noticeable in hot weather.

95Vert · Oct 25, 2006

try replacing your maf. have you checked you iat, act, ect? How about a dirty fuel filter, or the spark plugs?

95five-oh · Oct 25, 2006

maf is barely a year old, and i just changed the plugs....iat? act? ect? no idea what they are.

stangla2 · Oct 26, 2006

timing may be off.

Adam95GT · Oct 26, 2006

im having the same problem... but only like once a week... and other times i hear a little noise but no real ping... everyonce in a while it will ping and blow some blackish grey smoke... i was told a posible failing injector / Maf as well... im gonna change the plugs n wires and i guess clean the maf as well.... How ever... if it is an injector.... would you be able to tell when you change the plugs... because the failing injector would show up as a lean plug correct... (whitish in color)

HISSIN50 · Oct 26, 2006

How long has it been going on? A clogged fuel filter or pump on the outs are also possible. It'd be cool to see fuel pressure when this happens.

Good luck.

Adam95GT · Oct 26, 2006

O YEA MY FUEL PUMP IS LOOOOOOOUD!!!!!!!! It whines like holy hell LOL! i forgot about that... found a wal 190 with 8 k on it used... cheap as hell.. is that even worth it? $20... Oh and what pumps can we use is it 86-95 or 94-95 specific... Dont mean to hijack

95five-oh · Oct 26, 2006

HISSIN50 said:
How long has it been going on? A clogged fuel filter or pump on the outs are also possible. It'd be cool to see fuel pressure when this happens.

Good luck.

This is kind of an ongoing problem the last year and a half i'd say. The reason i've never taken it in to the shop is because it doesnt do it every day, and otherwise runs good. Yesterday however i went to pass a road crew truck on the highway, i nailed it hard in 4th, and it was pinging badly and i could feel a definate loss in power. Would running some stp cleaner in my tank clear a clogged filter or pump?

ProKiller · Oct 26, 2006

it might help. what is your timing at? what grade fuel do you use? are you consistant with that grade? is the timing set to that grade?

i'm of the mind the timing is your culprit.

95five-oh · Oct 26, 2006

ProKiller said:
it might help. what is your timing at? what grade fuel do you use? are you consistant with that grade? is the timing set to that grade?

i'm of the mind the timing is your culprit.

I always run 93 octane in my car. As for the timing, I don't know what its currently set at, how do I check/adjust it? Thanks for the help.

urban96 · Oct 26, 2006

Adam95GT said:
O YEA MY FUEL PUMP IS LOOOOOOOUD!!!!!!!! It whines like holy hell LOL! i forgot about that... found a wal 190 with 8 k on it used... cheap as hell.. is that even worth it? $20... Oh and what pumps can we use is it 86-95 or 94-95 specific... Dont mean to hijack

i belive 85-97 used same fuel pump. 98 they switched to returnless system

HISSIN50 · Oct 26, 2006

We indeed use the same pump as earlier (and later) models.

Adam, if you dont mind the labor, you could go for that pump. I have two cautions: there are some counterfeit Walbro pumps out there. And you will probably want to replace the tank grommet, which will double the cost of the project.

Tim, I would not count on any detergents to fix the issue. I'd swap the fuel filter (10 minutes and 10 bucks). As far as diagnosing it further, it might be tough. Like with your story about the roadcrew and nailing it afterwards, I wonder if there's a MAF issue at hand. Anytime you're at WOT, MAF and Fuel pressure/volume are huge.

I'd expect a fuel pump to go south pretty quick. When they get hot, the diaphram inside the pump gets weak/floppy and stops pumping decently. Let the pump cool down, and it might come back to life till it heats back up. Also, if the tank was run low of gas, the pump can get damaged, and the fuel filter can get clogged (the bottom of the tank has impurities and sediment).

Good luck.

95five-oh · Oct 26, 2006

HISSIN50 said:
We indeed use the same pump as earlier (and later) models.

Tim, I would not count on any detergents to fix the issue. I'd swap the fuel filter (10 minutes and 10 bucks). As far as diagnosing it further, it might be tough. Like with your story about the roadcrew and nailing it afterwards, I wonder if there's a MAF issue at hand. Anytime you're at WOT, MAF and Fuel pressure/volume are huge.

I'd expect a fuel pump to go south pretty quick. When they get hot, the diaphram inside the pump gets weak/floppy and stops pumping decently. Let the pump cool down, and it might come back to life till it heats back up. Also, if the tank was run low of gas, the pump can get damaged, and the fuel filter can get clogged (the bottom of the tank has impurities and sediment).

Good luck.

I'll try and swap the fuel filter sometime this week. I initially thought it was something with the intake/maf and the motor not getting enough air, but its got a clean K&N filter and the Maf is fairly new. Thats what lead me to believe it could be fuel related as the timing has never been fooled with on the car as far as i know, and i've always run 93 octane. Thanks again for the help guys.

HISSIN50 · Oct 26, 2006

95five-oh said:
I initially thought it was something with the intake/maf and the motor not getting enough air, but its got a clean K&N filter and the Maf is fairly new.

Clean K&N: does that mean recently cleaned and reoiled? If so, the two elements in the MAS might have gotten some oil on them. That can really hose performance. I'd consider cleaning the MAS again. When I clean one of the cotton/gauze air filter elements, no matter how little oil I use, I clean the MAS a couple times not long thereafter to try and head issues off.

Good luck.

95five-oh · Oct 26, 2006

HISSIN50 said:
Clean K&N: does that mean recently cleaned and reoiled? If so, the two elements in the MAS might have gotten some oil on them. That can really hose performance. I'd consider cleaning the MAS again. When I clean one of the cotton/gauze air filter elements, no matter how little oil I use, I clean the MAS a couple times not long thereafter to try and head issues off.

Good luck.

I never oiled it (which I probably should have), so i don't think there would be any oil in the MAF. I actually just put this K&N on my car, it previously had just the stock style filter along with the big plastic box it sits in. Before I put the K&N on, i wiped down the inside of the MAF with a clean rag and then put it in place (keep in mind the MAF itself is barely a year old). According to my dad, who owned the car before me, the fuel pump and filter were both replaced about 15,000 miles ago. The injectors are original and have over 150k on them.

mo_dingo · Oct 26, 2006

Not to be a party pooper. But I tried everything on my car to get the pinging to stop. I did a h/c/i on my car, and there was enough carbon on my pistons and cc's to decrease the combustion chamber size. That creates a pseudo glow plug and causes preignition.

In the end, taking a wire brush to my pistons was the only resolution. Another would be to richen the a/f mixture by 5% or so with a tuner.
Scott

HISSIN50 · Oct 26, 2006

You'll want to oil the filter up. It will actually filter to a finer degree when oiled and with a light coating of dirt.
Check K&N's site for further detail.

I think AEM is about the only company out there with a free flowing element which requires no oil (which makes it quite enticing).

Good luck.

95five-oh · Oct 27, 2006

Well the carbon buildup scenario does seem pretty likely, unfortunately as of now it's my daily driver so i dont have the time to take it apart and clean the internals. Hopefully i'll be getting a truck DD soon and the mustang can sit and await mods and rebuilding.

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