Need troubleshooting help...

[coupe]

Drive car everyday and no problems, until now...

After car has warmed up, there's a pinging under acceleration (from 1/4-throttle up) and it seems to have started with the cool weather a few weeks ago. I pulled timing back 14º, then 12, then 10...now it's 9º and not better. I also have played with fuel-pressure, but no help. Then I suspected the C&L meter, so I took the cold-air-kit elbow off and just mounted the filter on the end of meter...no better. Then I changed the electronics in the C&L...no better. I put in new plugs...no better. Car is fine under normal driving, but step on it a little, especially under a load like 3rd or 4th gear, and it sounds like I have 87-octane gas...I have tried some other gas stations too and nothing helps.

Here's the kicker: When car is still fairly cold in morning, I cannot get it to do it...runs strong and pulls smooth..once it gets up to operating temp...it does the knock/ping.

Only other thing I changed around the time it started doing this is the electric fan. Could there be a problem with not enough airflow over the aluminum heads? The fan keeps water temp way cool in traffic but maybe it's not doing enough airflow...
Or could it maybe be the fuel-pump is going south (again) and the preignition is just a lean knock?

My only other guesses would be a bad TFI? or distributor?

I have always fixed troublesome things like this with timing adjustments, better gas, plugs, cap/rotor, etc.. but It's not working. Feedback please.

[86GT]

Just a grasp buyt what about the ECT or ACT sensors?

[QWKSNKE]

out of curosity, how many miles are on the timing chain?

[jwillburn119]

hey guys... that sounds like part of the same problem i had 3 months ago when my hall effect sensor inside my distributor came loose, and contacted the cam vane... you should check that out, i am half positive that is your problem...you have already checked everything else so... you might as well... i tore my whole motor down before i found that out

[coupe]

Unplugged CTS, then ACT, then both together, thinking the CPU might put default on it but it still pings, only with the check engine light on.
Timing Chain is a Crane piece, maybe 10-15k on it.
I will check distributor today; fortunately I have another to try.

[jwillburn119]

well???

[coupe]

I took distributor apart (what I could) and cleaned up. It's spinning freely and really it wasn't that bad, looked almost new. Put cap & rotor in for good measure and it seemed to help a little. But still pings a bit under 1/2-throttle or more. Next thing I'm trying is the TPS. I have a new one anyhow so it can't hurt. I will update.

[Dale McPeters]

Carbon build up?
Bad winter fuel?
:dunno:

[LeeH]

I have seen loose O2 sensors cause the exact same problem.(Exhaust leak before the O2s)

[coupe]

:think: on the O2 sensors...I also think they're in need of replacement. Did find out though with the warmer air temp like yesterday, hardly any pinging. Cool air tonite...back to square 1. ACT will go next.

[coupe]

Okay. It's got to be something simple: When car's cold (let it start & run just enough to warm fluids), I can romp on it under load and it is perfect. No ping. Once it gets to operating temp on the water-temp gauge, it is no longer safe to put the TPS past about 1/4 under any load...in any gear. I'm putting a CTS and ACT on tonite.

[jwillburn119]

well cold air is more dense... which would cause it too detonate if the gas wasnt good... say the station where you got the last tank of gas is cutting corners... adding 87 to 93... something like that? have you refueled the car yet?

[TheJeanyus]

well cold air is more dense... which would cause it too detonate if the gas wasnt good... say the station where you got the last tank of gas is cutting corners... adding 87 to 93... something like that? have you refueled the car yet?
That wouldn't matter since he backed the timing way off and it was still pinging.

[coupe]

True. It is not timing so in goes a fuel pump and new filter.

Too bad I can't hook up my Weldon Pump yet. :evil: It would blow the 24# injectors out the exhaust.

[jwillburn119]

why dont you just replace everything?

[streatleathul]

Ck mass air flow for dust or trash

[Shankin]

1st i would check to see if the balancer has spun causing you to think there is 10 degrees and there is actually around 20 or so.

[93Cobra#2771]

First question:
Have you pulled the codes?

Second question:
Fuel pressure OK under load?

Third question?
What kind of condition is the motor itself? Burning oil? Etc?

[coupe]

aftermarket elastomer balancer.
1)no codes.
2)no gauge...but I need to check it for sure.
3)great. not a drop of oil. I'm thinking it is lean, since it's much worse when weather's cold...fuel pump will be replaced ASAP.

[93Cobra#2771]

If it makes you feel better, a buddy of mine broke the crank on his motor after suffering similar conditions for several months. Made for some cool pix, though. :D

Of course, he was burning oil like crazy, and I suspect he was having a lot of preignition from the heavy carbon deposits. He could hear the detonation, but didn't listen about taking it easy on it...

I suspect a fuel delivery issue. Fuel pump may be reducing fuel delivery once it gets heated up/has a decent load on it. Do you run it low on fuel a lot?

[coupe]

No. But the fuel pump is an issue. I got one "unknown" from a friend when mine crapped out last year. It might be a 190, not sure. :shrug: Car ran fast with it so it must be an upgrade. Screw it, I found a 255 For a decent price and will buy it anyhow...at least until I set up my bigger fuel system.

[gearhead143]

Find some one with a lab scope and ramp the pump. This will give you the condition of the pump in a wave form.

[coupe]

Screw that. I have a pump; should be here today (new one this time).
Thcar is doing a little "surging" now. The pump's going out. Hope it gets me home today.

[Italian LX]

While you've got the gas tank out, you can do this little mod for future pump replacement. ;)

http://www.deepstageperformance.com/tech-fuelaccess.html

:nice:

[TheJeanyus]

While you've got the gas tank out, you can do this little mod for future pump replacement. ;)

http://www.deepstageperformance.com/tech-fuelaccess.html

:nice:
You made a typo..or two. :yup:

Overview
The following information is designed to take you through the complete installation and give you an idea of what is involved in the modification. The pictures shown are of my '88 copue; however, the trunk/hatch are should be identicle in all 87-93 fox bodies.

[coupe]

I like it Brian, great idea... But I'm about to have an external Weldon pump and my own lines.

[gearhead143]

Sorry for the reply, I have been a drivability tech for 20 years and thought I would throw out a helping suggestion.

[Italian LX]

Sorry for the reply, I have been a drivability tech for 20 years and thought I would throw out a helping suggestion.
Don't appologize for replying to a thread; constructive suggestions are always welcome here. I believe coupe's point was that he was already intending to replace it anyway and wasn't going to go through all that trouble.

[coupe]

:werd: my bad. Sorry for the smart remark. :(

Replaced pump/strainer/filter today. Of course the car is running better overall...but guess what.
:nono:
New TPS...no help.
Cleaned out EGR (was clogged with soot)...no help.
Changed computers...no help.
I'm getting frustrated. Car drives & runs sooo smooth & throttle response is fantastic...but under a certain load @ certain throttle, it sounds like a tank of diesel in it. I run 93 allways.
Hooked up the code-scanner tool. Nada. :shake:

[jwillburn119]

maybe carbon buildup on the pistons is pushing your compression above what the fuel can handle... happened to me... you said the maf was sooty(spelling) and i know thats not what you want... but it could very well be i had almost a 32" of buildup on my pistons... and that was a 1995 so...

[coupe]

The EGR was full of soot. I bet I do have some crap in my cylinders, but it wouldn't have just started happening quickly like it did. It was all-of-a sudden doing it. Damn thing. :banghead:

[93Cobra#2771]

Sometimes even cleaning the EGR out won't fix it - a new one may be the only option...